# TerraBrain: Oklahoma foundation, drainage and leak library (full text) Source: https://terrabrain.vercel.app. 245 articles. Each article lists its sources; cite the article URL. --- # Are cracks in a garage or house slab a foundation problem? URL: https://terrabrain.vercel.app/signs/visible-slab-cracks Answer: Most are concrete shrinkage and not structural; a crack matters when one side is higher, it keeps widening, or it lines up with signs like sloping floors. In short: Most cracks in a garage floor or house slab come from concrete shrinking as it dries and do not affect structural integrity. A crack becomes a foundation question when one side is higher than the other, when it keeps widening, or when it lines up with other signs such as sloping floors or brick cracks. ## What does this sign look like? Cracks show in the exposed concrete of a garage, porch or patio, or telegraph through floor coverings as cracked tile or a ridge under carpet. They may be hairline, open, or offset with one edge higher than the other. This sign applies to slab-on-grade (https://terrabrain.vercel.app/foundations/slab-on-grade), post-tensioned slabs (https://terrabrain.vercel.app/foundations/post-tensioned-slabs), basement floors and exterior flatwork. ## Why do concrete slabs crack? ### Drying shrinkage Concrete shrinks as it cures and dries, by about 0.0002 to 0.0008 inch per inch [2]. Over a 20-foot slab, that works out to roughly 0.05 to 0.19 inch of shortening, which is why slabs crack even when nothing is wrong with the soil. Inspection guidance cites lab tests finding that synthetic fibers reduce shrinkage cracking by more than 80 percent [3]. This look-alike is covered in material shrinkage and thermal cracking (https://terrabrain.vercel.app/causes/material-shrinkage-and-thermal-cracking-mimic). ### Soil movement under the slab Swelling soils frequently cause distress in floor slabs [5]. Building officials in expansive-soil areas list cracks in garage slabs, walkways and driveways among the effects of foundation movement [6]. Soil can also be lost from under a slab: underground water from leaking mains can scour soil and displace footings [3], and in Oklahoma's karst areas, sinkholes and caverns in soluble rock can cause land settlement [7]. Related mechanisms include center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab), erosion and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) and karst subsidence (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes). ### Post-tensioned slab issues A **post-tensioned slab** has steel cables (tendons) stretched after the concrete hardens to squeeze the slab together. Design guidance calls for a minimum residual average prestress of 100 psi, continuous post-tensioned beams, and confirming that each tendon reaches its specified elongation and load during stressing [4]. A slab whose tendons lose tension behaves differently; see post-tension tendon failure (https://terrabrain.vercel.app/causes/post-tension-tendon-failure). ## How is a slab crack read? | Feature | More consistent with | |---|---| | Hairline, no offset, not growing | Drying shrinkage | | Clean edges, recently appeared | Recent movement [3] | | Dirty or previously filled | Possibly inactive [3] | | One side higher than the other | Soil movement under the slab | | Crack that lines up with sloping floors or brick cracks | Possible foundation movement [1] | Engineering guidance notes that most concrete cracks do not compromise structural integrity, so their physical characteristics are evaluated rather than their presence alone [1]. An **offset** (one side higher) shows that the two pieces of slab have moved relative to each other, which a shrinkage crack does not do on its own. ## How is it documented? - **Width and offset** at several points along the crack. - **Change over time** with a crack monitor; cyclical movement may take six months or more to measure [3]. - **Floor elevation survey**, the engineering step beyond a visual first impression [1]. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). Repair guidance describes epoxy injection for cracks of about 1/32 inch and larger [1]. ## Related - Material Shrinkage & Thermal Cracking (Mimic) (https://terrabrain.vercel.app/causes/material-shrinkage-and-thermal-cracking-mimic) - Post-Tension Tendon Failure (https://terrabrain.vercel.app/causes/post-tension-tendon-failure) - Floor Tile Cracks in a Line (https://terrabrain.vercel.app/signs/floor-tile-cracks-in-a-line) - Heaved or Settled Flatwork (https://terrabrain.vercel.app/signs/heaved-or-settled-flatwork) - Slab on Grade (https://terrabrain.vercel.app/foundations/slab-on-grade) Sources: [1] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [2] Volume Changes – Analysis and Effects of Movement (Technical Note 18), Brick Industry Association https://gobrick.com:443/media/file/18-tn18.pdf [3] Inspecting Foundation Walls and Piers, International Association of Certified Home Inspectors (InterNACHI) https://www.nachi.org/documents2012/Inspecting_Foundation_Walls_and_Piers-revised-January-2013.pdf [4] Recommended Practice for the Design of Residential Foundations, Version 2, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Recommended-Practice-for-the-Design-of-Residential-Foundations-V2-2007.pdf [5] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [6] County Expansive Soils Policy & Procedures, Roanoke County Development Services https://roanokecountyva.gov/DocumentCenter/View/1020 [7] Mapping of Karst Terranes in Oklahoma to Identify Potential Environmental and Hydrologic Problems, AAPG Search and Discovery (Oklahoma Geological Survey author) https://www.searchanddiscovery.com/abstracts/html/1995/midcon/abstracts/1403b.htm --- # Are drywall nail pops and tape joint cracks a foundation problem? URL: https://terrabrain.vercel.app/signs/nail-pops-and-tape-joint-cracks Answer: Usually not. They are most often caused by wood framing drying and shrinking, and point to the foundation only when other signs line up. In short: Nail pops (round bumps where drywall screws or nails push through the paint) and cracks along taped seams are most often caused by wood framing drying and shrinking, not by the foundation. They become a foundation question only when they line up with other signs, such as diagonal cracks at doors, sticking doors or sloping floors. ## What do nail pops and tape cracks look like? - **Nail pops:** small circles or bumps over fasteners, often in rows along a stud or ceiling joist. - **Tape-joint cracks:** straight, thin cracks that follow the seams between drywall sheets, often at ceiling lines or inside corners. These can show up in any house type, from slabs to crawl spaces (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) and basements. ## Why do they happen? ### Wood shrinks as it dries Lumber loses moisture after a house is built and as heating and cooling dry the air. Brick industry data put wood shrinkage at about 0.0025 inch per inch for each 1 percent change in moisture content, which works out to roughly 1 percent shrinkage for every 4 percent drop [2]. As studs and joists shrink, fasteners that were driven tight can stand proud of the wood and push the drywall surface. A federal housing guide shows framing shrinkage deforming a window and rupturing caulk [3]. Nail pops and visible seams or nail heads are listed among the reported wallboard problems in that same guide series [1]. Because this is a materials effect, it is covered under material shrinkage and thermal cracking (https://terrabrain.vercel.app/causes/material-shrinkage-and-thermal-cracking-mimic). A related look-alike, where roof trusses lift ceilings away from interior walls in winter, is covered under truss uplift (https://terrabrain.vercel.app/causes/truss-uplift-mimic). ### When foundation movement is involved Expansive soil movement can crack wallboard, along with brick veneer and door and window frames [6]. Engineering guidance lists these interior indicators of foundation distress [4]: - cracking of gypsum board walls and ceilings - separation of walls from ceilings - racking of door and window frames The significance of these signs may depend on the age of the house and any previous repairs [5]. ## How can the two causes be told apart? | Pattern | More consistent with | |---|---| | Scattered pops in rows along framing, no taper or offset | Wood shrinkage | | Straight seam cracks with pops nearby, no other signs | Wood shrinkage | | Diagonal cracks from door or window corners, doors that rub | Foundation movement [4] | | Gap where wall meets ceiling at interior walls | Foundation movement or truss uplift [4] | ## How are they documented? Map where the pops and cracks are on a floor plan and compare that pattern with a floor elevation survey. Engineering guidance treats a relative elevation survey as the step beyond a visual first impression [4]. If the cracks cluster around a low or high area on the survey, soil movement is more likely; if they are spread evenly through the house, shrinkage is more likely. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) and diagonal drywall cracks at openings (https://terrabrain.vercel.app/signs/diagonal-drywall-cracks-at-openings). ## Related - Material Shrinkage & Thermal Cracking (Mimic) (https://terrabrain.vercel.app/causes/material-shrinkage-and-thermal-cracking-mimic) - Truss Uplift (Mimic) (https://terrabrain.vercel.app/causes/truss-uplift-mimic) - Diagonal Drywall Cracks at Openings (https://terrabrain.vercel.app/signs/diagonal-drywall-cracks-at-openings) - Ceiling–Wall Separation at Interior Walls (https://terrabrain.vercel.app/signs/ceiling-wall-separation-at-interior-walls) - Cosmetic Repair Only (https://terrabrain.vercel.app/repairs/cosmetic-repair-only) Sources: [1] Durability by Design: A Guide for Residential Builders and Designers, U.S. Department of Housing and Urban Development https://www.huduser.gov/publications/pdf/durability_by_design.pdf [2] Volume Changes – Analysis and Effects of Movement (Technical Note 18), Brick Industry Association https://gobrick.com:443/media/file/18-tn18.pdf [3] A Professional's Guide to Durable Home Design: Durability by Design, 2nd Edition, U.S. Department of Housing and Urban Development https://www.HUDUser.gov/portal/sites/default/files/pdf/Guide-Durability-by-Design.pdf [4] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [5] Guidelines for the Evaluation and Repair of Residential Foundations, Version 2, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2022/05/Guidelines-for-the-Evaluation-and-Repair-of-Residential-Foundations-V2-2008.pdf [6] The Mystery of Expansive Soils, STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf --- # Are sticking windows or cracked glass a foundation sign? URL: https://terrabrain.vercel.app/signs/windows-sticking-or-cracked-glass Answer: They are possible signs of foundation movement but do not identify a cause alone. The whole-house pattern and an elevation survey separate it from other causes. In short: Windows that stick, bind or stop latching, and glass that cracks out from a corner, are recorded as possible signs of foundation movement, alongside cracked drywall, cracked brick and floors that are not level. On their own they do not identify a cause. The pattern across the whole house and an elevation survey are what separate foundation movement from other explanations. ## What does this sign look like? - A sash that rubs, binds or needs force to open or close. - A lock or latch that no longer lines up with its keeper. - An uneven gap between the sash and the frame, wider at one corner than the other. - Glass with a crack running out from a corner of the pane. Each of these is noted by window, wall and floor level, because the location is what links the symptom to a possible cause. ## Why does foundation movement show up at windows? The InterNACHI Standards of Practice require home inspectors to report signs of possible foundation movement, and name cracked drywall, cracked brick, out-of-square door frames and floors that are not level as examples [1]. InterNACHI's guidance on the residential code's soil-support section also lists sticking doors or windows among the settlement signs inspectors look for [2]. A window is a rectangle set into wall framing. When a foundation moves unevenly, the framing above it is pushed out of square. Researchers studying expansive soils note that uneven uplift under a building distresses the framing, not only the foundation itself [3]. An opening that was square when built can then pinch the sash on one side and leave a gap on the other. ## What moves foundations in Oklahoma clay? The trade word for soil that grows when wet and shrinks when dry is **expansive clay** (also called shrink-swell clay). - Expansive soil that gains moisture can lift a building; soil that loses moisture can shrink and let it settle [4]. - Swelling clay can press on foundations and slabs at 20,000 lb per square foot or more [5]. - On a uniformly loaded rectangular slab, the corners press on the soil with about one-fourth the pressure of the center, so corners tend to lift relative to the middle when clay swells [3]. - Seasonal moisture change in clay can reach anywhere from 3 to 40 ft deep, depending on climate and soil [3]. Engineers call this depth the **active zone**. - Oklahoma State University measurements on western Oklahoma benchmark soils found the clay fraction dominated by montmorillonite (a smectite clay), with Kirkland rated high and Bethany and Norge rated moderate for shrink-swell limits on low buildings [6]. ## How do you read the pattern? | What you see | What it can point to | Check next | |---|---|---| | Sticking windows near exterior corners | Edge or corner movement, which slab mechanics make more likely at corners [3] | Brick cracks on the same walls; stair-step cracks (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top) | | Sticking interior openings near the middle of the house | Center heave or interior settlement [3] | Interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump), elevation survey | | Openings that work in one season and bind in another | Seasonal shrink and swell of clay [3] | Cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally) | | One window, no other signs | Not enough to identify foundation movement; inspectors report "possible" movement only [1] | Survey the floor before drawing conclusions | ## How is it documented? - Each affected window: wall, floor level, which side binds, and the date. - Whether the same window changes between wet and dry months, since clay moisture follows the seasons [3]. - Nearby signs: diagonal drywall cracks at openings (https://terrabrain.vercel.app/signs/diagonal-drywall-cracks-at-openings), brick separating from the window frame (https://terrabrain.vercel.app/signs/brick-separating-from-window-or-door-frame), floor slope. - Floor elevations plotted on an elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys), which shows whether the low or high points line up with the openings that stick. Inspection standards state that home inspectors are not required to report on the adequacy of structural components or to provide engineering services [1]. Deciding whether movement is structural rests on measurements over time rather than on a single window. ## Related - Distress Pattern Library (https://terrabrain.vercel.app/guides/distress-pattern-library) - Symptom Matrix (https://terrabrain.vercel.app/guides/symptom-matrix) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Elevation Surveys (https://terrabrain.vercel.app/guides/elevation-surveys) - Doors Binding or Tapered Gaps (https://terrabrain.vercel.app/signs/doors-binding-or-tapered-gaps) Sources: [1] InterNACHI Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [2] Foundation Fundamentals: Inspecting Load Paths and Water Paths (IRC R401.2 & R401.3), InterNACHI https://nachi.org/foundation-load-water.htm [3] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [4] Foundations on Expansive Soils – Residential (IHB TB 10-01), Texas Department of Licensing and Regulation https://tdlr.texas.gov/ihb/pdf/TB1001.pdf [5] Expansive Soil, Colorado Geological Survey https://coloradogeologicalsurvey.org/hazards/expansive-soil/ [6] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf --- # Are there gypsum sinkholes in western Oklahoma? URL: https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes Answer: Yes, in places. Gypsum near the surface can dissolve in groundwater, leaving voids that let the ground above sag or collapse. In short: Gypsum, salt, limestone and dolomite can dissolve in groundwater, leaving voids that may cause the ground above to sag or collapse. In western Oklahoma, gypsum of the Permian Blaine Formation lies close to the surface in places. Settlement that keeps going, or that doesn't follow the usual wet-dry seasonal pattern, is one reason soluble rock is considered during an investigation. ## What is karst? **Karst** is a landscape formed where rock dissolves in water. The U.S. Geological Survey groups two families of soluble rock [1]: - **Carbonates**: limestone and dolomite. - **Evaporites**: gypsum and salt, minerals left behind when ancient seas evaporated. Roughly 18% of the nation's total area sits on soluble rocks with karst features or the potential for them [1]. The USGS lists sinkholes among the principal causes of land subsidence, meaning sinking of the ground surface, and notes subsidence in areas underlain by soluble rocks such as limestone, gypsum or salt [2]. A **sinkhole** is a depression or collapse at the surface over a dissolved void. ## Where is gypsum found in western Oklahoma? The Cottonwood soil series formed in material weathered from massive gypsum, mostly alabaster, of the Permian-age Blaine Formation [3]. It occurs in southwestern Oklahoma and northwest Texas [3]. In these soils: - hard gypsum bedrock lies 3 to 20 inches below the surface [3]; - the gypsum layer itself is about 5 to 15 feet thick [3]; and - water moves through the gypsum bedrock very slowly to moderately [3]. The Blaine and related gypsum units are described on Permian gypsum units (https://terrabrain.vercel.app/geology/permian-gypsum-units-e-g-blaine), and the region on Northwest (Gypsum Hills) (https://terrabrain.vercel.app/regions/northwest-gypsum-hills). ## What about limestone and dolomite? The Oklahoma Geological Survey notes that marine carbonate rocks of Late Cambrian and Ordovician age underlie most of the state, and that carbonates reach more than 8,000 feet thick near the Southern Oklahoma Aulacogen, described as part of a failed triple junction, an ancient rift that stopped developing [5]. Carbonate rock is one of the two soluble-rock families with karst potential [1]; see Arbuckle carbonates (https://terrabrain.vercel.app/geology/arbuckle-carbonates) and Mississippian cherty limestone (https://terrabrain.vercel.app/geology/mississippian-cherty-limestone). ## What are the field signs of karst? These are the kinds of observations that prompt a closer look for voids: - a sudden depression or sinkhole (https://terrabrain.vercel.app/signs/sudden-depression-or-sinkhole) in a yard or field, or ponding in a new spot; - settlement that continues after repair or doesn't match seasonal moisture patterns; - a pier that suddenly drops or loses resistance during installation; and - similar sudden problems on neighboring lots. ## What are the limits of the maps? The USGS karst map shows where soluble rock occurs, but it does not rate hazards such as sinkhole collapse [1]. It is a first approximation intended to guide more detailed study of specific areas [1]. Site-level answers come from borings and, in some cases, geophysical surveys that image the ground below. The Oklahoma Geological Survey collects reports of sinkholes through an online form linked from its FAQ page [4]. ## What should repairs consider on soluble rock? Because water drives dissolution, controlling surface drainage near a suspected void is a common first concern; see surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). Repair approaches are described on void and compaction grouting (https://terrabrain.vercel.app/repairs/void-and-compaction-grouting) and working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). ## Related - Karst Subsidence and Sinkholes (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes) - Oklahoma Geologic Provinces (https://terrabrain.vercel.app/guides/oklahoma-geologic-provinces) - Erosion Creeks and Slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Northwest (Gypsum Hills) (https://terrabrain.vercel.app/regions/northwest-gypsum-hills) - Southwest (Lawton and Red Plains) (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains) Sources: [1] Karst in the United States: A Digital Map Compilation and Database (Open-File Report 2014-1156), U.S. Geological Survey https://pubs.usgs.gov/of/2014/1156/ [2] Land Subsidence in the United States (Circular 1182), U.S. Geological Survey https://pubs.usgs.gov/circ/circ1182/ [3] Official Series Description - COTTONWOOD Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COTTONWOOD.html [4] FAQ, Oklahoma Geological Survey https://www.ou.edu/ogs/faq.html [5] Structural / Tectonic Map of Oklahoma (GM-46), Oklahoma Geological Survey https://www.ou.edu/content/dam/ogs/documents/GMs/GM-46_Structural_Tectonic_Map_of_Oklahoma.pdf --- # Can a foundation crack because it was built wrong? URL: https://terrabrain.vercel.app/causes/original-construction-deficiency Answer: Yes. Thin beams, missing or misplaced steel, weak concrete or a poor pad can leave a foundation unable to bridge ordinary soil movement. In short: Some foundations crack and bend more than they should because of how they were designed or built, for example thin or shallow beams, missing or misplaced reinforcing steel, weak concrete or a poorly prepared building pad. A deficient foundation cannot bridge ordinary soil movement that a properly built one would handle. It is identified by comparing the distress with the foundation's actual construction. ## What counts as a construction deficiency? Texas engineering guidelines list inadequate design or construction as one of the causes of residential foundation distress, alongside soil shrink and swell, unanticipated loads, material deterioration, compressible soils, landscaping, leaking plumbing and slope instability [1]. Common examples include: - **Undersized or shallow perimeter beams.** In Oklahoma the active zone, the depth of soil whose moisture changes with the climate, has been estimated at roughly 0.5 to 4 meters (about 1.5 to 13 feet) [5], so a shallow beam bears within soil that shrinks and swells. - **Missing or misplaced reinforcing steel.** Reinforcement needs adequate concrete cover; industry guidance calls for at least 2 inches of cover to protect steel from corrosion [2]. - **Poor concrete placement.** High-slump concrete or extra water, improper finishing and inadequate curing all increase cracking [2]. - **Poor pad and subgrade preparation.** Concrete guidance calls for a stable, compacted, level subgrade and lists poor subgrade preparation among the main causes of cracking [2]. Compacted Oklahoma soils can also settle after construction when their moisture content rises [6]. - **Missing joints.** Omitting isolation and contraction joints, or improper jointing, is among the listed causes of cracking [2]. ## What are the signs of a construction deficiency? - visible slab cracks (https://terrabrain.vercel.app/signs/visible-slab-cracks) - diagonal drywall cracks at openings (https://terrabrain.vercel.app/signs/diagonal-drywall-cracks-at-openings) - sloping floors (https://terrabrain.vercel.app/signs/sloping-floors) These signs are not unique to construction problems. Texas guidelines note that signs such as cracked drywall or racked door frames do not necessarily mean inadequate structural performance [1], and most random cracks that appear at an early age, though unsightly, rarely affect structural integrity [2]; see material shrinkage and thermal cracking (https://terrabrain.vercel.app/causes/material-shrinkage-and-thermal-cracking-mimic). ## How is a construction deficiency evaluated? ### Performance against tolerances Engineers judge a foundation's performance by deflection (how much it bows over a length) and tilt (how much it slopes overall). | Measure | Benchmark | |---|---| | Deflection | L/360, used as an analogous deflection limit [1][3] | | Tilt | More than about 1% is usually noticeable [1]; FPA uses 1% as a limit [3] | | As-built levelness | ACI 117 allows 1.5 inches overall; most residential slabs are within about 1 inch [3] | Because new slabs are not perfectly level, the Foundation Performance Association notes that movement cannot be determined accurately without a baseline elevation survey [3]. See tolerances and standards (https://terrabrain.vercel.app/guides/tolerances-and-standards) and elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). ### Checking what was built Texas guidelines separate structural integrity (load capacity, stability and material condition) from foundation performance (safety, function, durability and habitability) [1]. Confirming a construction deficiency means checking the actual beam size and depth, steel placement and concrete condition, for example by excavating at the beam edge or coring the slab. ## How is a deficient foundation typically addressed? Texas guidelines list underpinning, grouting, mudjacking, crack injection, tendon stressing, and partial demolition and reconstruction among slab repair methods [4]. They note that underpinning locations, sizes and depths must be specified and that underpinning does not improve the areas that are not underpinned [4]. Where a foundation is unsafe, the guidelines call for the client and civil authorities to be informed immediately [1]. See slab or foundation replacement (https://terrabrain.vercel.app/repairs/slab-or-foundation-replacement) and steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers). ## Related - Tolerances and Standards (https://terrabrain.vercel.app/guides/tolerances-and-standards) - Slab on Grade (https://terrabrain.vercel.app/foundations/slab-on-grade) - Concentrated Load Settlement (https://terrabrain.vercel.app/causes/concentrated-load-settlement) - Working with Engineers (https://terrabrain.vercel.app/guides/working-with-engineers) - Slab or Foundation Replacement (https://terrabrain.vercel.app/repairs/slab-or-foundation-replacement) Sources: [1] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [2] CIP 4 - Cracking Concrete Surfaces, National Ready Mixed Concrete Association https://www.prairie.com/wp-content/uploads/sites/4/2024/12/04p_CrackingConcreteSurfaces.pdf [3] Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings (FPA-SC-13-1), Foundation Performance Association https://inspectapedia.com/structure/Foundation-Movement-Evaluation-Guidelines-FPA-TX.pdf [4] Guidelines for the Evaluation and Repair of Residential Foundations, Version 2, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2022/05/Guidelines-for-the-Evaluation-and-Repair-of-Residential-Foundations-V2-2008.pdf [5] Soil Matric Suction and Active Zone Depth in Oklahoma, Oklahoma State University (Er Yue, Ph.D. dissertation, 2017) https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf [6] Settlement Behavior of Compacted Oklahoma Soils (FHWA-OK-02-03), Oklahoma Department of Transportation https://rosap.ntl.bts.gov/view/dot/88914 --- # Can a high water bill mean a leak affecting my foundation? URL: https://terrabrain.vercel.app/signs/unexplained-high-water-bill Answer: A rising bill with no change in use usually means a leak. A leak under a slab can wet expansive clay and push part of the floor up. In short: A water bill that climbs with no change in household use usually means a leak somewhere, and a simple two-hour meter test shows whether water is moving when nothing is turned on. Most leaks are at fixtures, but a leak in a line under a slab can wet expansive clay and push part of the floor up, which is why it matters for foundations. ## What does this sign look like? Monthly use rises and stays high, or spikes, without new people, a pool, or a change in watering. EPA suggests comparing month-to-month use on the bill to spot spikes [2]. This is relevant to slab-on-grade (https://terrabrain.vercel.app/foundations/slab-on-grade), post-tensioned and crawl space houses. ## How common are household leaks? EPA estimates that household leaks waste nearly 1 trillion gallons of water a year nationwide, and that an average household's leaks can waste more than 9,300 gallons a year [1]. About 9 percent of homes have leaks that waste 50 gallons or more per day [1]. Leaks can add about 10 percent to a water bill [2]. Common sources EPA lists [1][2]: - worn toilet flappers - faucets dripping about once per second, which can waste more than 3,000 gallons a year - showerheads and tub spout diverters - irrigation systems damaged by frost or freeze; a leak about 1/32 inch wide can waste roughly 6,300 gallons per month - hidden leaks under sinks, at water heaters, and at washing machine, dishwasher and ice maker supply lines ## How do you check for a leak? | Check | How EPA describes it | |---|---| | Winter usage | A family of four using more than 12,000 gallons per month in January or February probably has a serious leak [2] | | Meter test | Read the meter, use no water for two hours, read it again; any change likely means a leak [1] | | Toilet dye test | Add food coloring to the tank; color in the bowl after 10 minutes means a leak [2] | | Visual check | Look for moisture or mold on walls, ceilings and floors [2] | If the meter moves and no fixture or irrigation leak is found, the leak may be in a buried line or under the slab. See plumbing leak detection and repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair). ## Why does an under-slab leak matter for the foundation? Expansive clay swells when it gains water. Broken water or sewer pipes add moisture that can worsen swelling damage to nearby structures [3]. Foundation design guidance names leaking utility lines as a source of water that can wet the soil and cause foundation heave [4]. Building officials in expansive-soil areas point out that a plumbing leak is one way water reaches the soil under a house and causes interior movement [6]. On the floor, this can show as a hump (https://terrabrain.vercel.app/signs/interior-floor-hump) near the leak. The mechanism is covered in leak-induced localized heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave). Engineering repair guidance calls for testing water supply and sanitary drain lines for leaks when lifting is part of a foundation repair, and for fixing any leaks found [5]. Oklahoma insurance treatment of leaks is covered in plumbing leaks and insurance (https://terrabrain.vercel.app/rules/plumbing-leaks-and-insurance-oklahoma). ## Related - Leak-Induced Localized Heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave) - Plumbing Leaks Under Slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) - Slow Drains or Sewer Backups (https://terrabrain.vercel.app/signs/slow-drains-or-sewer-backups) - Plumbing Leak Detection and Repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair) - Plumbing Leaks and Insurance - Oklahoma (https://terrabrain.vercel.app/rules/plumbing-leaks-and-insurance-oklahoma) Sources: [1] Fix a Leak Week, U.S. Environmental Protection Agency, WaterSense https://www.epa.gov/watersense/fix-leak-week [2] Take the 10 Minute WaterSense Challenge, U.S. Environmental Protection Agency, WaterSense https://www.epa.gov/sites/production/files/2017-02/documents/ws-ourwater-detect-and-chase-down-leaks-checklist.pdf [3] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [4] Recommended Practice for the Design of Residential Foundations, Version 2, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Recommended-Practice-for-the-Design-of-Residential-Foundations-V2-2007.pdf [5] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [6] County Expansive Soils Policy & Procedures, Roanoke County Development Services https://roanokecountyva.gov/DocumentCenter/View/1020 --- # Can a plumbing leak under a slab cause a floor hump? URL: https://terrabrain.vercel.app/causes/leak-induced-localized-heave Answer: Yes. A supply or drain leak under a slab on expansive clay wets the soil, which swells and pushes up a local floor hump with cracks radiating from it. In short: When a water supply line or drain line leaks under a slab-on-grade house built on expansive clay, the soil around the leak takes on water and swells. That pushes up a local hump in the floor, with cracks radiating from it. Finding and fixing the leak comes first, and the area is then watched to see how it settles out. ## How does a leak lift a floor? Expansive clay swells when it gains moisture and shrinks when it loses it, and it is changes in moisture, not the clay itself, that cause movement [1]. Leaking water or sewage pipes add water to the soil around them and can worsen swelling damage [2]. Damage is often caused where moist soil sits next to drier soil [2], which is exactly the situation a single leak creates: a wet pocket of clay surrounded by soil at its normal moisture. A slab-on-grade floor is flexible enough to follow the shape of the soil beneath it [1], so as the wet pocket swells, the slab above it rises into a hump. The movement is differential, meaning it is concentrated in one place, and that is what cracks finishes and racks door frames [1]. ### Supply leaks vs. drain leaks A pressurized supply line can be checked with a whole-house water meter test [3]. Drain and sewer lines are tested separately, and Texas engineering guidelines call for both water supply and sanitary drain lines to be tested for leaks whenever lifting is part of a foundation repair [5]. ## What Oklahoma conditions make leak heave likely? An Oklahoma State University study using USDA soil survey data found that nearly all of Oklahoma has medium or high swelling potential [6], so a leak under a slab in most of the state is sitting on soil that can swell. See plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) and plumbing leaks and insurance in Oklahoma (https://terrabrain.vercel.app/rules/plumbing-leaks-and-insurance-oklahoma). ## What are the signs of leak heave? - an interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump) over the leak area - floor tile cracks in a line (https://terrabrain.vercel.app/signs/floor-tile-cracks-in-a-line) or flooring that tents up - an unexplained high water bill (https://terrabrain.vercel.app/signs/unexplained-high-water-bill) - slow drains or sewer backups - doors that bind and ceiling-wall gaps near the hump ## Is it heave or collapse? The same water can do the opposite on a different soil. On expansive clay, a leak causes swelling and a hump. On loose, collapsible silt, water weakens the bonds between grains and the soil compacts, so the floor drops instead [7]. For the case where leak water removes soil instead, see erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). A broad, slow rise of the whole middle of the house without a single leak is a different pattern; see center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab). ## How is the leak found? - **Meter test.** Read the water meter, use no water for two hours, and read it again; a change suggests a leak [3]. - **Water bills.** A family of four using more than 12,000 gallons a month in winter probably has a leak [3]. - **How common leaks are.** About 10% of homes have leaks that waste 90 gallons or more per day [4]. ## How is leak heave typically addressed? - **Repair the leak.** Leaks found in testing are repaired [5]. See plumbing leak detection and repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair). - **Monitor.** The Texas ASCE guidelines note that non-structural measures followed by monitoring may be prudent before or instead of structural repair, and that repeated elevation surveys show change over time [5]. - **Cosmetic repairs.** An owner may choose cosmetic repairs and door adjustments rather than full underpinning [5]. The Texas guidelines caution against grouting or mudjacking beneath underpinned foundations where soil swelling is expected [5]. ## Related - Center Heave (Moisture Build-up Under Slab) (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) - Plumbing Leaks Under Slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) - Interior Floor Hump (https://terrabrain.vercel.app/signs/interior-floor-hump) - Monitoring Program (https://terrabrain.vercel.app/repairs/monitoring-program) - Hydrocollapse (Collapsible Soil) (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil) Sources: [1] The Mystery of Expansive Soils, STRUCTURE magazine (NCSEA / CASE / SEI) https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [2] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers et al.) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [3] WaterSense Challenges Homeowners: Take 10 Minutes to Find and Fix a Leak this Week, U.S. Environmental Protection Agency https://www.epa.gov/node/265001 [4] Fix A Leak Week: Household Leak Facts, U.S. Environmental Protection Agency (WaterSense, archived page) https://19january2017snapshot.epa.gov/www3/watersense/pubs/fixleak.html [5] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [6] Soil Matric Suction and Active Zone Depth in Oklahoma, Oklahoma State University (Er Yue, Ph.D. dissertation, 2017) https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf [7] Collapsible Soils, Colorado Geological Survey https://coloradogeologicalsurvey.org/hazards/collapsible-soils/ --- # Can an under-slab plumbing leak move an Oklahoma foundation? URL: https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab Answer: Yes. A leak under a slab can make expansive clay swell and lift the floor or soften and wash out looser soil, so the leak must be fixed for a lasting repair. In short: A leaking water or sewer line under a slab keeps feeding water into the soil beneath the house. On Oklahoma's expansive clay that can make the soil swell and lift part of the floor; on looser soil it can soften support or carry soil away. Finding and fixing the leak is part of any lasting repair, because leveling alone doesn't stop the water. ## How does a leak move a foundation? Expansive clay swells when water enters and shrinks when it dries [5]. Most moisture-driven movement starts at the outer walls, but water that reaches the soil under the middle of a house, including from plumbing leaks, can cause movement in the interior too [4]. Structural engineers list leaking pipes among the main causes of uneven moisture under foundations, alongside poor drainage, trees and irrigation [3]. Long-term moisture gain under a slab is linked to **center lift** (also called center heave), where the middle of the floor rises relative to the edges [3]. A leak-driven hump is often more localized than a whole-house center lift; see leak-induced localized heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave) and interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump). ## What are the warning signs of a slab leak? - **A rising area in the floor**, with cracks spreading from it (interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump)). - **Unexplained high water use.** The EPA notes that a family of four using more than 12,000 gallons a month in winter probably has serious leaks [1]. See unexplained high water bill (https://terrabrain.vercel.app/signs/unexplained-high-water-bill). - **Moisture and mold** at the base of walls or under flooring. The EPA lists inside walls around leaking pipes among the places hidden moisture and mold develop [2]. - **Slow drains or sewer backups**, which can point to a damaged drain line (slow drains or sewer backups (https://terrabrain.vercel.app/signs/slow-drains-or-sewer-backups)). ## What simple leak checks does EPA guidance suggest? | Check | How it works | Source | |---|---|---| | Meter test | Read the meter, use no water for two hours, read again; any change suggests a leak | [1] | | Winter usage check | Compare water use in a colder month, when outdoor watering is low | [1] | | Toilet dye test | Food coloring in the tank showing up in the bowl within 10 minutes means the toilet leaks | [1] | Household leaks are common: the EPA estimates that about 9% of homes have leaks wasting 50 gallons or more a day, and that the average household's leaks waste more than 9,300 gallons a year [1]. A meter test only shows that water is escaping somewhere on the supply side; it doesn't locate the leak. Methods for finding leaks under a slab are covered on plumbing leak detection and repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair). ## Why does the order of work matter? Engineering guidance on expansive soils puts dealing with the causes of uneven moisture first, including repairing plumbing leaks and revising site drainage [3]. The same source notes that remedial leveling with piers or injection can produce only temporary leveling when those causes remain [3]. The EPA also advises fixing plumbing leaks as soon as possible and drying wet areas within 24–48 hours to limit mold [2]. Leak-related insurance questions in Oklahoma are covered on plumbing leaks and insurance (https://terrabrain.vercel.app/rules/plumbing-leaks-and-insurance-oklahoma). ## Related - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Lifting Procedure and Restoration (https://terrabrain.vercel.app/guides/lifting-procedure-and-restoration) - Center Heave (Moisture Build-up Under Slab) (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) - Collapsible and Loess Soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils) - Plumbing Leak Detection and Repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair) Sources: [1] Fix a Leak Week, U.S. Environmental Protection Agency (WaterSense) https://www.epa.gov/watersense/fix-leak-week [2] A Brief Guide to Mold, Moisture and Your Home, U.S. Environmental Protection Agency https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home [3] Expansive Soils (The Mystery), STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [4] County Expansive Soils Policy & Procedures (Commercial & Residential Projects), Roanoke County, Virginia, Development Services https://roanokecountyva.gov/DocumentCenter/View/1020 [5] Residential House Foundations on Expansive Soils in Changing Climates, HUD Office of Policy Development and Research (Cityscape, Vol. 25 No. 1) https://www.huduser.gov/PORTAL/periodicals/cityscape/vol25num1/ch10.pdf --- # Can earthquakes damage Oklahoma homes and foundations? URL: https://terrabrain.vercel.app/causes/earthquake-shaking-damage Answer: Yes. Strong shaking can crack chimneys, brick and masonry walls. Most Oklahoma quakes are too small to cause damage, but the larger 2016 events did. In short: Earthquake shaking can crack brittle parts of a house, especially masonry chimneys, brick and unreinforced masonry walls. In Oklahoma, most earthquakes have been too small to cause damage, but the larger events of 2016 did. Unlike soil-driven foundation movement, shaking damage happens at the time of a specific earthquake, so documenting the event and the timing is central to evaluating it. ## How does shaking damage a house? During an earthquake the house is shaken along with the ground, and FEMA guidance identifies brittle masonry elements as the most vulnerable parts of a home [6][7]. - **Chimneys.** FEMA describes masonry chimneys in wood-frame homes as highly susceptible to earthquake shaking, with older unreinforced chimneys that have degraded mortar the most vulnerable [6]. Tall, slender chimneys are the most likely to break and fall [7]. - **Unreinforced masonry walls.** Houses built of brick, hollow clay tile, stone or concrete block without reinforcement are very likely to be damaged, and houses built before 1940 are often a concern [7]. - **Foundations and connections.** Homes that are not bolted to their foundations can slide off them, and unreinforced brick or stone foundations may break apart [7]. Previously damaged chimneys that were rebuilt to their original form remain vulnerable to future shaking, according to FEMA [6]. ## What earthquakes has Oklahoma had? Oklahoma's earthquake rate rose sharply in the last decade, and the USGS links the increase to injection of large volumes of saltwater produced with oil and gas [1]. In the central and eastern United States, the number of magnitude 3 and larger earthquakes went from about 25 a year (1973 to 2008) to a peak in 2015, then declined [1]. | Event | Year | Magnitude | Notes | |---|---|---|---| | Pawnee | 2016 | 5.8 | Largest recorded earthquake in Oklahoma [2] | | Cushing | 2016 | 5.0 | Named by the USGS as a damaging event [1] | Most earthquakes in the region are magnitude 3 to 4, which are usually felt but rarely damaging [1]. The Oklahoma Corporation Commission, which regulates disposal wells, credits reduced injection into the Arbuckle formation with a drop of more than 90% in magnitude 3.0 earthquakes in Oklahoma since 2015, and it has issued directives cutting disposal volumes after later events, such as a 2023 magnitude 4.0 earthquake near Carney [3]. For background, see induced seismicity in Oklahoma (https://terrabrain.vercel.app/guides/induced-seismicity-in-oklahoma) and earthquake claims and law data (https://terrabrain.vercel.app/data/earthquakes-claims-and-law). ## What is the difference between magnitude and intensity? Intensity is different from magnitude: it describes the effects of shaking at a particular place, which the USGS says makes it a more meaningful measure of severity for nonscientists [4]. The Modified Mercalli Intensity scale ranks those effects; its lower levels describe how people felt the shaking and its higher levels are based on observed structural damage [4]. ### How is shaking at an address documented? The USGS "Did You Feel It?" system collects reports from the public and groups them by ZIP code to produce community intensity values that approximate the Modified Mercalli scale [5]. The USGS notes that individual experiences can differ from a community's value because of local ground conditions and building construction [5]. The Oklahoma Geological Survey maintains a recent earthquakes map and a reporting form for Oklahoma events [8]. ## What are the signs of earthquake damage? Signs that appear with shaking damage include: - fresh, clean-edged cracks appearing suddenly (https://terrabrain.vercel.app/signs/fresh-clean-edged-cracks-appearing-suddenly) - a chimney separating or leaning (https://terrabrain.vercel.app/signs/chimney-separating-or-leaning) - diagonal drywall cracks at openings (https://terrabrain.vercel.app/signs/diagonal-drywall-cracks-at-openings) - vertical brick or veneer cracks (https://terrabrain.vercel.app/signs/vertical-brick-or-veneer-crack) Many of these signs also come from ordinary soil movement. The page on seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement) compares the two. ## How is earthquake damage typically addressed? FEMA advises inspecting the firebox and checking the support and anchorage of masonry veneer before chimney repair begins, and recommends lightweight metal flues in place of rebuilding a damaged chimney in its original form [6]. FEMA also notes that building permits are required for this work and recommends consulting the local building department and a licensed engineer or architect before major repairs [6][7]. Where the foundation itself is sound, masonry and drywall repairs are cosmetic; see cosmetic repair only (https://terrabrain.vercel.app/repairs/cosmetic-repair-only). ## Related - Induced Seismicity in Oklahoma (https://terrabrain.vercel.app/guides/induced-seismicity-in-oklahoma) - Seismic Damage vs Soil Movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement) - Chimney Separating or Leaning (https://terrabrain.vercel.app/signs/chimney-separating-or-leaning) - Insurance Claims (https://terrabrain.vercel.app/rules/insurance-claims) - North-Central (Red Prairies & Wheat Belt) (https://terrabrain.vercel.app/regions/north-central-red-prairies-and-wheat-belt) Sources: [1] Induced Earthquakes Overview, U.S. Geological Survey https://www.usgs.gov/programs/earthquake-hazards/science/induced-earthquakes-overview [2] Oklahoma experiences largest earthquake during ongoing regional wastewater injection hazard mitigation efforts, U.S. Geological Survey https://www.usgs.gov/publications/oklahoma-experiences-largest-earthquake-during-ongoing-regional-wastewater-injection [3] Directive Reducing Disposal Volumes in Carney Area, Oklahoma Corporation Commission https://oklahoma.gov/occ/news/news-feed/2023/directive-reducing-disposal-volumes-in-carney-area.html [4] The Modified Mercalli Intensity Scale, U.S. Geological Survey https://www.usgs.gov/programs/earthquake-hazards/modified-mercalli-intensity-scale [5] DYFI Scientific Background, U.S. Geological Survey https://earthquake.usgs.gov/data/dyfi/background.php [6] Repair of Earthquake-Damaged Masonry Fireplace Chimneys (FEMA DR-4193-RA1), Federal Emergency Management Agency https://atcouncil.org/images/ChimneyRecoveryAdvisory.pdf [7] Earthquake Safety Guide for Homeowners (FEMA 530), Federal Emergency Management Agency https://pdp.sjsu.edu/ihouse/docs/fema-530.pdf [8] Recent Earthquakes, Oklahoma Geological Survey, University of Oklahoma https://www.ou.edu/ogs/research/earthquakes/recentearthquakes --- # Can removing a tree make my foundation heave? URL: https://terrabrain.vercel.app/causes/post-tree-removal-heave Answer: Yes. A large tree can dry the clay under a house for years; once it is removed, water returns and the clay slowly swells and pushes up what sits on it. In short: A large tree near a house can dry the clay beneath it over many years. When that tree is removed, rain and the end of root uptake let water return, and the clay swells and pushes up whatever sits on it. The rise is slow, it continues until the soil reaches a new moisture balance, and how long that takes is hard to predict. ## How does heave after tree removal happen? Clay-rich soil shrinks as it dries and swells as it takes on water. This is called shrink-swell behavior. Heave is the upward movement of the ground, mainly in low-permeability soils like clay, as they absorb water and swell [1]. Trees pull water from the ground through their roots. Once a tree is removed, that water slowly returns to the soil, which swells and heaves until it reaches equilibrium [1]. The sequence usually runs like this: 1. A mature tree near the house dries the clay, sometimes deeper than normal seasonal drying reaches [4]. 2. The tree is removed after a storm, disease or by choice. 3. Rain soaks in and roots no longer draw it out. 4. The clay swells and the nearby part of the foundation rises over time [1]. ### How deep tree drying can go Shrink-swell activity usually happens within about the top 3 meters (roughly 10 feet), but tree roots can extend this active zone, the layer of soil whose moisture changes with the seasons [3]. In a Houston case study, tree water demand dried the soil to about 28 feet, far deeper than the 4 to 8 feet usually assumed there [4]. The deeper the dried zone, the more soil there is to rewet after removal. ### When it is more likely Horticultural guidance describes heave after felling as uncommon. It happens where the clay under a tree has a persistent moisture deficit, meaning it never fully rewets between seasons [2]. ## What controls the amount of heave? | Factor | Why it matters | |---|---| | Tree species, size and maturity | Higher-demand, larger trees dry more soil [1] | | Soil permeability | Clay takes on water slowly, so swelling is gradual [1] | | Free water available | Rain, irrigation or leaks speed rewetting [1] | | Shrink-swell rating of the soil | Soils with linear extensibility over 3% can damage buildings as they swell [6] | Linear extensibility is a soil survey measure of how much a soil changes in length between moist and oven-dry; low is under 3%, moderate 3-6%, high 6-9% and very high above 9% [6]. In Oklahoma, clay-rich shales and the soils weathered from them can contain montmorillonite, a swelling clay that can expand to 1.5 to 2 times its dry volume, and more than 75% of the state has bedrock that can source expansive soils [5]. See clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) and shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). ## What does heave after tree removal look like? Heave lifts the part of the house nearest the old tree. Field notes associate it with stair-step brick cracks wider at the bottom (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-bottom), sticking doors and, where the dried zone extended under the slab, an interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump). It can look very similar to perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift). The difference is the history: a tree that stood where the rise is now. The opposite problem, a living tree drying and dropping the foundation, is covered in tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement). ## How is heave after tree removal handled? Because the movement is ongoing, options matched to this mechanism focus on time and moisture rather than lifting: - **Monitoring program (https://terrabrain.vercel.app/repairs/monitoring-program):** repeated elevation readings show whether the area is still rising. - **Drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions):** limit extra water reaching the swelling soil, since free water drives rewetting [1]. - **Chemical soil stabilization:** treatments aimed at reducing the soil's swell. ### Planning a removal UK building-warranty guidance for new homes asks that a site investigation consider the effects of removing trees, that an arboriculturist be consulted, and that foundations near removed trees be designed as if the trees were still present [1]. High-demand species named in that guidance include oak and poplar [7]. Where a tree must stay, crown reduction can lessen ground movement but needs to remove at least 70% of the crown and be repeated about every three years [2]. See tree management. ## Related - Tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) - Perimeter wetting heave (edge lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) - Trees and roots (https://terrabrain.vercel.app/guides/trees-and-roots) - Heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Tree management (https://terrabrain.vercel.app/repairs/tree-management) - Monitoring program (https://terrabrain.vercel.app/repairs/monitoring-program) Sources: [1] Heave: ground recovery following tree removal, LABC Warranty https://www.labcwarranty.co.uk/resource-hub/heave-ground-recovery-following-tree-removal [2] Trees near buildings, Royal Horticultural Society https://www.rhs.org.uk/plants/types/trees/near-buildings [3] Expansive soils (encyclopedia entry, post-review manuscript), NERC Open Research Archive https://nora.nerc.ac.uk/id/eprint/521301/1/EncyclopediaEngGeol_ExpansiveSoils_PostReview.pdf [4] Case Study of Settlement of a Foundation on Expansive Clay Due to Moisture Demand of Trees, American Society of Civil Engineers (Geo-Frontiers 2011) https://ascelibrary.com/doi/10.1061/41165%28397%29249 [5] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [6] Alabama FOTG Section II: Physical Properties of the Soils, USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [7] Technical Update: Foundations, Trees and Clay, LABC Warranty https://www.labcwarranty.co.uk/hubfs/Blog/Blog%20PDFs/labcw-foundation-trees-and-clay.pdf --- # Can slow drains or sewer backups signal foundation movement? URL: https://terrabrain.vercel.app/signs/slow-drains-or-sewer-backups Answer: On expansive clay, soil movement can break buried drain pipes and a leaking drain can make the slab heave, so the two are often checked together. In short: A slow drain or sewer backup on its own is a plumbing symptom, but under a slab on expansive clay, drain lines and foundations affect each other. Soil movement can stress and break buried pipes, and a leaking drain can wet the clay and make the slab heave, so the two are often checked together. ## What does this sign look like? Several fixtures drain slowly, toilets gurgle, or sewage backs up into a low tub or floor drain. On its own this does not point to the foundation. It becomes a foundation question when it shows up with floor cracks, a hump in the floor (https://terrabrain.vercel.app/signs/interior-floor-hump), or an unexplained rise in the water bill (https://terrabrain.vercel.app/signs/unexplained-high-water-bill). It applies mainly to slab-on-grade (https://terrabrain.vercel.app/foundations/slab-on-grade) and post-tensioned houses, where drain lines run in the soil under the slab, and to crawl space homes where lines run through the soil to the street. ## How do soil movement and drain lines interact? ### Moving clay stresses buried pipe Expansive clay swells when it gets wetter and shrinks as it dries. The depth where this seasonal moisture change happens is often called the **active zone**. Shallow plastic pipes that sit in this zone of seasonal moisture change are exposed to large stresses from shrinking soil [1]. A pipe that is bent, separated at a joint or pushed out of its slope can drain slowly or leak. ### Leaking drains make the clay swell The relationship also runs the other way. Broken water or sewage pipes add moisture that can worsen swelling damage to nearby structures [1]. Foundation design guidance names leaking utility lines as a source of water that can wet the soil and cause foundation heave [2]. Building officials in expansive-soil areas point out that a plumbing leak is one way water reaches the soil under a house and causes interior movement, not just movement at the outside walls [4]. Leaking pipes are also listed among the factors that make soil moisture uneven, which is what drives foundation movement [5]. These two paths are described in more detail under leak-induced localized heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave) and center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab). ## How is it documented? | Step | What it shows | |---|---| | Drain line leak test | Whether the sanitary drain system holds water or leaks below the slab [3] | | Water supply test | Whether pressurized supply lines are leaking [3] | | Floor elevation survey | Where the floor is high or low relative to the rest of the house [3] | Engineering repair guidance calls for testing water supply and sanitary drain lines for leaks when jacking or lifting is part of the work, and for repairing leaks that are found; gas lines may also need adjustment [3]. The broader process is covered in plumbing leak detection and repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair) and plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab). ## What order should the work follow? Repair guidance for expansive-soil foundations puts correcting moisture sources, including plumbing leaks and drainage, first, with leveling after [5]. Insurance treatment of leaks and resulting damage in Oklahoma is covered in plumbing leaks and insurance (https://terrabrain.vercel.app/rules/plumbing-leaks-and-insurance-oklahoma). ## Related - Leak-Induced Localized Heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave) - Plumbing Leaks Under Slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) - Unexplained High Water Bill (https://terrabrain.vercel.app/signs/unexplained-high-water-bill) - Plumbing Leak Detection and Repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair) - Plumbing Leaks and Insurance - Oklahoma (https://terrabrain.vercel.app/rules/plumbing-leaks-and-insurance-oklahoma) Sources: [1] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [2] Recommended Practice for the Design of Residential Foundations, Version 2, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Recommended-Practice-for-the-Design-of-Residential-Foundations-V2-2007.pdf [3] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [4] County Expansive Soils Policy & Procedures, Roanoke County Development Services https://roanokecountyva.gov/DocumentCenter/View/1020 [5] The Mystery of Expansive Soils, STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf --- # Can tree roots cause foundation settlement on Oklahoma clay? URL: https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement Answer: Yes. Roots under a foundation can dry and shrink expansive clay, so the side or corner nearest the tree settles, worst in summer and drought. In short: Trees pull large amounts of water from the ground. On expansive clay, roots that reach under a foundation can dry and shrink the soil there, so the side or corner nearest the tree settles. The movement is worst in summer and drought and may partly recover in wet seasons. ## How do tree roots cause settlement? Clay soil shrinks as it loses water. Trees on shrinkable clay can draw moisture from soil under foundations during long dry spells; the soil contracts and the building can sink, often cracking around windows and doors [1]. Roots grow toward water, and where paving or buildings block rain from soaking in, trees may send roots deeper or farther to find it [6]. The typical sequence: 1. A large or high-water-demand tree grows near the house. 2. Its roots draw water from soil under the foundation, especially in summer and drought [1][4]. 3. The drying can extend below the depth of normal seasonal moisture change [2][6]. 4. The side or corner nearest the tree settles, then partly recovers in wet, dormant months [4]. ### Deeper than normal drying Significant shrink-swell activity usually happens within about the top 3 meters (about 10 feet), but tree roots can extend this active zone, the layer whose moisture changes with the seasons [6]. In a Houston case study, long-term moisture loss from trees dried the soil to about 28 feet, compared with the 4 to 8 feet usually assumed in that area; piers 9 feet deep settled 3 to 5 inches and the ground under the floor slab dropped about 8 inches [2]. This is why piers meant to stop tree-related settlement need to reach below the root-dried soil. ## How do season and drought affect it? Texas monitoring of slabs on expansive clay found that settlement grew as the growing season progressed, droughts made it worse, and above-normal rain slowed it [4]. Deciduous trees are less active in winter, and winter dormancy, rain and lower evaporation let slabs partly recover [4]. A North Texas study using soil imaging in May and August found early evidence that roots shifted toward the slab during drought [3]. In UK practice, soil shrinkage typically peaks in late summer [1]. In Oklahoma, soil moisture drops faster during hot, dry periods than during cool, wet ones, and the Oklahoma Mesonet has soil moisture sensors at almost every site across the state [8]. More than 75% of the state has bedrock that can produce expansive soils [7]. See drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) and seasonal movement calendar (https://terrabrain.vercel.app/guides/seasonal-movement-calendar). ## How do tree distance and species matter? | Guideline | What the source says | |---|---| | High-water-demand trees | Soil drying can extend out to about the tree's height [1] | | Intermediate and low demand | Unlikely to reach beyond half the tree's height [1] | | Example high-demand broadleaf trees | Oak, poplar, willow, eucalyptus [1] | | Example high-demand conifers | Cypress and related genera [1] | Larger trees, and trees closer to the building, carry more risk [1]. See trees and roots (https://terrabrain.vercel.app/guides/trees-and-roots). ## What does tree-related settlement look like? Damage concentrates toward the tree rather than around the whole perimeter. Field notes link it to stair-step brick cracks wider at the top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top), soil pulled away from the foundation (https://terrabrain.vercel.app/signs/soil-pulled-away-from-foundation), sticking doors, diagonal drywall cracks at openings (https://terrabrain.vercel.app/signs/diagonal-drywall-cracks-at-openings) and cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally). Look-alikes: perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) affects the edges more generally, while tree drying is localized toward the tree. Fill consolidation settlement is not seasonal and is not tied to where a tree stands. ## What repair and moisture-control approaches are used? - **Root barriers and moisture control:** a Texas case history combined a root and moisture barrier with drainage improvements [4]. Engineering guidance on expansive soil aims to keep soil moisture steady; it notes that lack of watering during drought can be more damaging than overwatering, and that tree roots under a foundation can cause shrinkage and settlement [5]. - **Steel push piers or helical piers:** support set below the root-dried zone; in the Houston case, 9-foot piers still settled because tree drying reached about 28 feet [2]. - **Tree management:** crown reduction must remove at least 70% of the crown and be repeated about every three years to reduce movement, and thinning has been found ineffective [1]. Removal can cause heave on clay; see post-tree-removal heave. - **Monitoring program:** seasonal elevation surveys show whether movement follows the tree's water use. ## Related - Post-tree-removal heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave) - Perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Trees and roots (https://terrabrain.vercel.app/guides/trees-and-roots) - Trees data (https://terrabrain.vercel.app/data/trees) - Root barriers and moisture control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control) - OKC Metro (https://terrabrain.vercel.app/regions/okc-metro) Sources: [1] Trees near buildings, Royal Horticultural Society https://www.rhs.org.uk/plants/types/trees/near-buildings [2] Case Study of Settlement of a Foundation on Expansive Clay Due to Moisture Demand of Trees, American Society of Civil Engineers (Geo-Frontiers 2011) https://ascelibrary.com/doi/10.1061/41165%28397%29249 [3] Tree Root Influence on Building Foundations in Expansive Clay Soils in North Texas, University of Texas at Arlington (honors thesis, 2022) https://mavmatrix.uta.edu/honors_fall2022/6 [4] Cyclical Foundation Movements and Their Remediation, CIGMAT, University of Houston (conference presentation) https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2007/addison.pdf [5] Irrigation, Drainage, and Landscaping for Expansive Soil, Journal of Irrigation and Drainage Engineering (ASCE) https://ascelibrary.com/doi/10.1061/%28ASCE%290733-9437%281992%29118%3A2%28285%29 [6] Expansive soils (encyclopedia entry, post-review manuscript), NERC Open Research Archive https://nora.nerc.ac.uk/id/eprint/521301/1/EncyclopediaEngGeol_ExpansiveSoils_PostReview.pdf [7] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [8] Tracking Drought Using Soil Moisture Information (BAE-1541), Oklahoma State University Extension https://extension.okstate.edu/fact-sheets/tracking-drought-using-soil-moisture-information.html --- # Can trees damage a foundation in Oklahoma clay soil? URL: https://terrabrain.vercel.app/guides/trees-and-roots Answer: Large trees rarely push a foundation. They mainly cause damage by drawing water from clay, which shrinks and lets the nearby part of the house settle. In short: Large trees rarely shove a foundation over. The main way they cause damage is by pulling water out of clay soil, which shrinks and lets the nearby part of the house settle. Removing a big tree can reverse the process, letting the clay swell back up over time. ## How do trees affect a foundation? Oklahoma's expansive clays swell when wet and shrink when dry (see shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone)). A tree adds a strong, local drying force to that cycle. A classic engineering study published by the American Society of Civil Engineers followed brick houses on shallow footings that began cracking about 20 years after construction [1]. The worst damage was where large, deep-rooted trees grew close to the foundations [1]. Soil testing showed the trees had dried and shrunk the clay during the growing season, so the footings in that zone settled unevenly compared with the rest of the house [1]. Selective tree removal, combined with repairs, stopped further noticeable differential settlement in the following year [1]. Roots can also damage a building by lifting it, but University of Florida horticulturists note that many roots grow to a foundation and then turn sideways along it instead of going under it [2]. They also point out that clay soils can shrink and crack buildings in dry weather even when no tree is involved, so a crack near a tree is not proof the tree caused it [2]. This pattern is called tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement). "Desiccation" simply means drying out. ## Where are the roots? OSU Extension describes tree roots as mostly shallow and wide: - Most trees grow a fibrous root system in the upper 24 inches of soil, and the top 12 inches does the most water uptake [3]. - Pecan, walnut, some pines and some oaks also grow a deep taproot [3]. - Roots often extend well past the dripline (the edge of the canopy), up to three times the canopy width, and up to five times in shallow soil with clay a few inches down [3]. Because roots spread so far, a tree well out in the yard can still be drawing water from soil beside a footing. ## Which Oklahoma tree species matter? OSU Extension's tree selection guide describes root and growth traits for common Oklahoma trees [4]: | Species | What OSU notes | |---|---| | Silver maple | Fast growth, brittle wood, shallow root system [4] | | Eastern cottonwood | Grows too large for typical lots; fast growing and weak wooded [4] | | Sweetgum | Needs damp soil, not very drought tolerant, may have shallow roots [4] | | Pecan | Needs deep, moist soil; drops large limbs with age [4] | | Weeping willow | Grows best in moist to wet soil [4] | | Sycamore | Large tree suited to big open areas [4] | | Post oak, blackjack oak | Do not tolerate compaction, construction or grade changes [4] | | Bur oak | Slow growing but eventually very large [4] | | Lacebark elm | Extremely tough and drought tolerant [4] | | Bradford (Callery) pear | Weak branching that leads to storm breakage [4] | The oak note matters for foundation work: digging beside a house for piers or drainage can injure oaks that dislike construction and compaction [4]. Ranking trees by "water demand" is common in building guidance, but one review in the Journal of Arboriculture found that forest studies show broadly similar water use across species and argued that rooting habit may matter as much as species [7]. ## How far from a house should trees be planted? - The City of Oklahoma City's planting guide says medium and large trees should be planted no closer than 30 feet to buildings or structures [5]. - The same guide allows trees listed as suitable near water lines at 5 feet from lines 4 inches in diameter, or 10 feet from larger lines [5]. - OSU Extension advises planting at least half the mature canopy width away from the home, and keeping fast-growing or weak-wooded trees well away from buildings [4]. ## What signs suggest a tree is involved? Field clues that point toward a tree include settlement on the side of the house nearest the tree, cracks that open toward it (for example stair-step cracks wider at the top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top)), and soil pulled away from the foundation (https://terrabrain.vercel.app/signs/soil-pulled-away-from-foundation) near the root zone. Because clay can shrink without trees, these clues are a starting point rather than proof [2]. ## What options do people consider? 1. **Root barriers and moisture control.** A vertical barrier between tree and house, or steady soil moisture, aims to limit drying under the footing. See root barriers and moisture control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control). 2. **Tree management or removal.** See tree management (https://terrabrain.vercel.app/repairs/tree-management). 3. **Piers.** Piers carry the house to soil or rock below the drying zone. See steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers). ### The removal caution When a tree that has dried the clay is removed or heavily cut back, moisture gradually returns to the soil, which can swell and damage nearby foundations, particularly on clay [6]. That upward movement of the ground is called heave. Building guidance also notes that a tree's mature height and type affect how much water it draws, and that trees on clay can call for much deeper foundations [6]. This is described further under post-tree-removal heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave). ## Related - OK Data: Trees in Oklahoma metros (https://terrabrain.vercel.app/data/trees) - Tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) - Post-tree-removal heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave) - Heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Root barriers and moisture control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control) - Shrink-swell and active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) Sources: [1] Foundation Clay Shrinkage Caused by Large Trees, American Society of Civil Engineers, Journal of the Soil Mechanics and Foundations Division (via TRID) https://trid.trb.org/View/38711 [2] Roots damaging buildings, University of Florida IFAS, Environmental Horticulture https://hort.ifas.ufl.edu/woody/roots-buildings.shtml [3] Getting to the root of good tree health, Oklahoma State University Extension https://extension.okstate.edu/articles/2026/getting-to-the-root-of-good-tree-health [4] Selecting Deciduous Trees for Oklahoma, Oklahoma State University Extension https://extension.okstate.edu/fact-sheets/selecting-deciduous-trees-for-oklahoma [5] Trees and Plants for Oklahoma City, City of Oklahoma City https://okc.gov/home/showdocument?id=4954 [6] Building regulations: outbuildings: Foundations, Welsh Government (GOV.WALES) https://www.gov.wales/node/2005 [7] A Critical Analysis of the Role of Trees in Damage to Low Rise Buildings, International Society of Arboriculture, Journal of Arboriculture https://auf.isa-arbor.com/content/isa/21/2/90.full.pdf --- # Can vibration from construction or blasting crack a house? URL: https://terrabrain.vercel.app/causes/vibration-related-cracking-rare Answer: Blasting, pile driving or heavy equipment can stress finishes and lengthen existing cracks, but most Oklahoma home cracking traces to soil movement. In short: Vibration from blasting, pile driving or heavy equipment can stress brittle finishes and may lengthen cracks that were already there. In Oklahoma, most cracking in homes traces back to soil movement instead, so the key questions are when the cracks appeared and whether they change with the seasons. Records of the vibration source are the main evidence. ## What does vibration do to a house? Ground vibration moves a house back and forth for a short time. The parts most likely to show it are brittle finishes: plaster, drywall tape joints, ceramic tile, mortar joints and brick veneer. Where a crack already exists, shaking can extend it. This page treats vibration as a mimic: it can add cracks that look like foundation distress without the foundation having moved up or down. Vibration also matters to the ground itself. The U.S. Geological Survey lists artificial vibration among the human causes of landslides, alongside cutting into slopes and leaking utilities [1]. On a steep or wet lot, ground movement can follow a vibration event; see slope creep and lateral movement (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement). ## What are common sources of vibration? - Quarry and construction blasting. - Pile driving, vibratory compaction and demolition. - Heavy truck or rail traffic close to the house. - Earthquakes, which are a natural or induced source handled separately in earthquake shaking damage (https://terrabrain.vercel.app/causes/earthquake-shaking-damage). ### Earthquakes in Oklahoma Before 2009, Oklahoma averaged about two earthquakes of magnitude 3.0 or larger per year; there were 579 in 2014 and 903 in 2015 [2]. Larger events included the magnitude 5.7 Prague earthquake in November 2011, the magnitude 5.8 Pawnee earthquake in September 2016 and the magnitude 5.0 Cushing earthquake in November 2016 [2]. Researchers describe a scientific consensus that wastewater disposal has induced earthquakes in Oklahoma since at least 2010 [2]. Historically mapped seismic areas include El Reno-Mustang, central Oklahoma, Love and Carter counties and the Arkoma Basin [3]. See induced seismicity in Oklahoma (https://terrabrain.vercel.app/guides/induced-seismicity-in-oklahoma). ## How strong does vibration have to be to damage a house? Ground vibration is measured as peak particle velocity, the top speed at which the ground moves as the wave passes, in inches per second. A U.S. Bureau of Mines study of homes near a large surface coal mine cited historical damage thresholds of 0.5 to 2.0 inches per second [7]. Everyday activity such as walking, closing doors, wind and temperature and humidity cycles strains a house about as much as 0.5 inches per second of ground vibration, so the study treated lower levels as insignificant for houses [7]. Earlier Bureau studies saw cracks in basement block walls at 6 to 11 inches per second [7]. In that study the highest blast vibrations measured at the homes were 0.1 inch per second or less, and the authors concluded that expansive clays and erodible soils, with possible help from drainage and slope problems, were mainly responsible for the foundation-related damage [7]. ## What rules limit blasting near homes? Federal coal-mining rules cap peak particle velocity at the nearest dwelling by distance from the blast [8]: | Distance from blast | Maximum peak particle velocity | |---|---| | 0 to 300 ft | 1.25 in/s | | 301 to 5,000 ft | 1.00 in/s | | More than 5,000 ft | 0.75 in/s | The same rules limit airblast (the air pressure pulse) at homes and require a seismograph record of each blast when this limit method is used [8]. For non-coal mines and quarries, Oklahoma Department of Mines rules use a peak particle velocity limit of 1 inch per second when a seismograph is used [9]. Each blast record must list the date, time and location, the distance and direction to the nearest dwelling within half a mile, the maximum weight of explosives detonated within any 8-millisecond period and any required seismograph readings, and must be kept for at least three years [10]. ## Why is soil movement the usual suspect? Expansive clay moves a house in a slow, repeating cycle. The zone of seasonal moisture change can extend from 3 to 40 feet deep, and the soil swells when wet and shrinks when dry [4]. Texas slab monitoring found out-of-levelness growing through the summer and partly recovering in winter [5]. Cracks from this kind of movement tend to grow over months and years, collect dirt and paint, and change width with the seasons. ## How can vibration and soil cracking be told apart? | Clue | Points toward vibration or a sudden event | Points toward soil movement | |---|---|---| | When cracks appeared | All at once, right after a known event | Gradually over time | | Crack edges | Fresh, clean, no dirt or paint in the crack | Weathered, dirty, painted or caulked over | | Season | No link to wet or dry periods | Open and close with the seasons [5] | | Floor levels | No new tilt on an elevation survey | Measurable tilt toward a low side | | Records | Seismograph or blast logs, earthquake catalog match | Mesonet soil moisture or drought trends | See fresh, clean-edged cracks appearing suddenly (https://terrabrain.vercel.app/signs/fresh-clean-edged-cracks-appearing-suddenly), cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally) and seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement). ## How is a possible vibration claim documented? - Date-stamped photos of cracks with a scale in the frame. - Seismograph readings or quarry blast logs, where they exist for the project. Oklahoma non-coal blast records are kept at least three years and are available to the Department of Mines [10]. - An elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) to show whether the floor has tilted. - A home inspection report. Inspection standards call for reporting signs of possible foundation movement such as drywall cracks, brick cracks, out-of-square door frames and uneven floors [6]. ## How is vibration cracking usually handled? When vibration only extended finish cracks, the matched options are cosmetic repair only (https://terrabrain.vercel.app/repairs/cosmetic-repair-only) and a monitoring program to confirm the cracks are not growing. ## Related - Earthquake shaking damage (https://terrabrain.vercel.app/causes/earthquake-shaking-damage) - Fresh, clean-edged cracks appearing suddenly (https://terrabrain.vercel.app/signs/fresh-clean-edged-cracks-appearing-suddenly) - Nail pops and tape-joint cracks (https://terrabrain.vercel.app/signs/nail-pops-and-tape-joint-cracks) - Seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement) - Earthquakes, claims and law (https://terrabrain.vercel.app/data/earthquakes-claims-and-law) Sources: [1] Landslide Types and Processes (Fact Sheet 2004-3072), U.S. Geological Survey https://pubs.usgs.gov/fs/2004/3072/fs-2004-3072.html [2] Detailed mapping of shallow landslides in eastern Oklahoma and western Arkansas and potential triggering by Oklahoma earthquakes, Geomorphology (Oklahoma Geological Survey authors) https://www.jakewalter.net/papers/Regmi_Walter_2019.pdf [3] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [4] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [5] Cyclical Foundation Movements and Their Remediation, CIGMAT, University of Houston (conference presentation) https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2007/addison.pdf [6] Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [7] Blast Vibrations and Other Potential Causes of Damage in Homes Near a Large Surface Coal Mine in Indiana (Report of Investigations 9455), U.S. Bureau of Mines (D. E. Siskind, S. V. Crum, M. N. Plis), via CDC Stacks https://stacks.cdc.gov/view/cdc/201769/cdc_201769_DS1.pdf [8] 30 CFR 816.67 - Use of explosives: Control of adverse effects, Legal Information Institute, Cornell Law School (Code of Federal Regulations) https://www.law.cornell.edu/cfr/text/30/816.67 [9] Oklahoma Administrative Code 460:10-31-9, Seismographic measurements, Justia (Oklahoma Administrative Code, Department of Mines) https://regulations.justia.com/states/oklahoma/title-460/chapter-10/subchapter-31/section-460-10-31-9 [10] Oklahoma Administrative Code 460:10-31-10, Records of blasting operations, Justia (Oklahoma Administrative Code, Department of Mines) https://regulations.justia.com/states/oklahoma/title-460/chapter-10/subchapter-31/section-460-10-31-10 --- # Do root barriers and moisture barriers protect foundations? URL: https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control Answer: Buried root and moisture barriers keep roots and seasonal drying away from soil under a foundation. They support other repairs but cannot lift a foundation. In short: Root barriers and moisture barriers are walls of sheet material buried beside a foundation to keep tree roots and seasonal drying or wetting away from the soil under it [1][4]. Together with even watering and good landscaping, they aim to keep clay moisture steady so it shrinks and swells less. They are maintenance measures that support other repairs, not a way to lift a foundation, and they have known limits [6]. ## Why does moisture control matter on clay? Oklahoma's expansive clays shrink as they dry and swell as they wet. Uneven moisture around a house — dry under one corner, wet under another — produces uneven movement. An engineering maintenance guide sums up the goal as uniform soil moisture, maintained evenly all the way around the foundation [5]. Trees are a major source of uneven drying. A Texas geotechnical engineer documented about 7 inches of ground settlement under a slab caused by oak trees about 16 feet from a building, with the affected zone reaching about 40 feet beyond the tree's drip line [1]. See tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement). ## How do root barriers work? A **root barrier** is a vertical sheet, such as heavy plastic, set in a trench between a tree and the foundation. Its purpose is to stop roots from growing under the slab and drawing water from the clay there. A geotechnical engineer has noted that a deep, impermeable barrier along the building perimeter can limit roots growing beneath a floor slab [1]. What research and guidance say about limits: - In a University of Florida study, vertical barriers pushed roots deeper, but many roots grew under the barrier and returned toward the surface farther on [2]. - Engineering post-repair guidance lists removing roots that grow past root barriers as an ongoing maintenance task [6]. - The engineering description above calls for a *deep* barrier; the Texas case studies found tree-related drying in clay extending well beyond the canopy, which is why shallow barriers can be bypassed [1]. Trenching near a tree can cut roots the tree depends on, and underground utilities must be located before digging. OSU Extension advises having utility lines marked by a locating company before choosing where to plant a tree [7]. ## How do vertical moisture barriers work? A **vertical moisture barrier** is a deeper buried sheet around the perimeter meant to slow water moving sideways into or out of the soil under the slab edge. This reduces the seasonal wetting and drying that drives perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) and perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift). - An engineering design review describes vertical moisture retarders as more effective at controlling sideways moisture movement than surface options, but costly, hard to inspect and possibly requiring tree roots to be cut [4]. - A five-year Texas field study of vertical moisture barriers beside highways on expansive clay found the greatest benefit in wet and semi-arid climates where the clay is cracked and the root zone is shallow; modeling also identified conditions where barriers would do little [3]. ## Should you water around the foundation? Watering the soil around a foundation in drought is debated because it can help or hurt. Published maintenance guidance for expansive soils says [5]: - In dry weather, irrigate the soil around the foundation where expansive soils are known to occur. - Water at least one to two feet away from the foundation, and do not spray the house. - Do not water directly into a gap where soil has pulled away from the foundation. - Water lightly enough that tree roots are not drawn toward the foundation. The risks are also documented. A design review notes that sprinklers, soaker hoses and drip systems can reduce shrinkage but cause harm if moisture is uneven [4]. Post-repair guidance warns that watering-system sensors can fail, water can run continuously, and overwatering can cause movement; watering systems can also attract roots [6]. See soil pulled away from foundation (https://terrabrain.vercel.app/signs/soil-pulled-away-from-foundation) and drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles). ## What landscaping supports moisture control? The same maintenance guide recommends [5]: - Sloping soil and bed material away from the foundation, or adding swales, so beds do not trap water. - Keeping ground cover uniform around the house and using mulch in unplanted areas out to at least five feet. - Avoiding metal edging or other water-damming borders within five feet of the foundation on expansive soils. - Cutting back or replacing shrubs that grow toward one-story roof height. More on grading is in surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) and drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). ## What are the limits of barriers and moisture control? - Barriers and watering do not lift a foundation or repair existing damage; guidance treats maintenance systems as performance aids, not repairs [6]. - Barriers can be bypassed by roots and must be deep enough for the root zone [2][6]. - Watering must be kept even, and overwatering can itself cause movement [4][6]. ## Related - Trees and Roots (https://terrabrain.vercel.app/guides/trees-and-roots) - Tree Management (https://terrabrain.vercel.app/repairs/tree-management) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Chemical Soil Stabilization (https://terrabrain.vercel.app/repairs/chemical-soil-stabilization) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) Sources: [1] Settlement of Foundations on Expansive Clays Due to Moisture Demand of Trees, CIGMAT, University of Houston https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2008/kenneth.pdf [2] Deflecting roots near sidewalks, University of Florida IFAS (abstract of Arboriculture and Urban Forestry 32(1)) https://hort.ifas.ufl.edu/woody/abstracts/efg/EFG0501.shtm [3] Effectiveness of Controlling Pavement Roughness Due to Expansive Clays with Vertical Moisture Barriers, Texas Transportation Institute / Texas Department of Transportation https://rosap.ntl.bts.gov/view/dot/84929 [4] Foundation Design Options for Residential and Other Low-Rise Buildings on Expansive Soils (FPA-SC-01-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-01-0.pdf [5] Foundation Maintenance and Inspection Guide for Residential and Other Low-Rise Buildings (FPA-SC-07-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-07-0.pdf [6] Post Foundation Repair Performance of Residential and Other Low-Rise Buildings on Expansive Soils (FPA-RC-01-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-RC-01-0.pdf [7] Placement of Trees, Oklahoma State University Extension https://extension.okstate.edu/programs/gardening/grow-gardening-columns/grow-columns-2021/march-28-2021-placement-of-trees.html --- # Do sticking doors or tapered door gaps mean foundation movement? URL: https://terrabrain.vercel.app/signs/doors-binding-or-tapered-gaps Answer: They can. Out-of-square door frames are a listed sign of possible foundation movement, but the pattern across the house and a floor survey decide the cause. In short: Doors that rub, stop latching or show a gap at the top that is wider on one side than the other are recorded as possible signs of foundation movement. They do not identify a cause by themselves. Which doors are affected, which way the gap tapers and how it changes with the seasons, checked against a floor elevation survey, are what point to a specific cause. ## What does this sign look like? - A door that rubs the frame at the top or on the latch side, or needs force to close. - A latch or deadbolt that no longer lines up with the strike plate. - A gap above the door (at the **head**, the top piece of the frame) that is wider at one end than the other. - A door that swings open or shut on its own. Home inspection standards require a representative number of doors to be opened and closed during an inspection [1]. The same standards list out-of-square door frames among indications of possible foundation movement, along with drywall cracks, brick cracks and unlevel floors [1]. ## Why does foundation movement show up at doors? A door frame is a rectangle set into the wall framing. When one part of a foundation moves more than another, the framing above it is pulled out of square. Engineering guidance lists poor door alignment as an indication of movement and notes that foundation deflection can cause racking of door frames [3]. **Racking** means the rectangle is pushed into a slight parallelogram, so the door no longer fits evenly. InterNACHI's guidance on the residential code's soil-support section lists sticking doors or windows among the settlement signs inspectors look for [2]. A homeowner guide from the American Society of Civil Engineers lists sticking doors caused by warped door frames among interior signs of foundation distress on shrink-swell soils [4]. ## How does Oklahoma clay move a house? **Expansive clay** (also called shrink-swell clay) swells when it gets wetter and shrinks when it dries. - Research using Oklahoma Mesonet weather data describes two worst-case slab shapes: **center lift** (also called edge drop), when soil around the perimeter dries and shrinks, and **edge lift**, when soil under the perimeter becomes wetter than under the interior and swells [5]. - The same research describes doors starting to jam and floors tilting as walls move on expansive soil [5]. - On a uniformly loaded rectangular slab, the corners press on the soil with about one-fourth the pressure of the center, so corners tend to lift relative to the middle when clay swells [6]. - Seasonal moisture change in clay can reach from 3 to 40 ft deep, depending on climate and soil [6]. Engineers call this the **active zone**. - Oklahoma State University testing of western Oklahoma benchmark soils found clays dominated by montmorillonite, with Kirkland subsoil rated high for shrink-swell and Bethany and Norge rated moderate [7]. ## How do you read the pattern? | What you see | What it can point to | Check next | |---|---|---| | Binding doors on exterior walls | Perimeter movement, either edge drop from drying or edge lift from wetting [5] | Perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop), perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) | | Binding doors near the middle of the house | Center lift or interior movement [5] | Center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab), interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump) | | Doors near a large tree, or where one was removed | Trees can shrink soil under a foundation; removing a tree can lead to heave as soil moisture rises [3] | Tree-root desiccation (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement), post-tree-removal heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave) | | Doors that work in spring and bind in late summer | Seasonal shrink and swell of clay [6] | Cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally) | | One door, no other signs | Not enough to identify foundation movement; engineering guidance says some listed conditions do not by themselves imply inadequate performance [3] | Floor survey before drawing conclusions | Other mechanisms in this library, such as fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement), pier movement after repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair) and interior support failure in crawl spaces (https://terrabrain.vercel.app/causes/interior-support-and-framing-failure-crawl), are covered on their own pages. ## How is it documented? - Each affected door: wall, floor level, where it rubs, and which end of the head gap is wider. - The date of each observation, since the ASCE homeowner guide advises monitoring existing cracks for progressive or seasonal movement [4]. - Nearby signs: diagonal drywall cracks at openings (https://terrabrain.vercel.app/signs/diagonal-drywall-cracks-at-openings), sticking windows (https://terrabrain.vercel.app/signs/windows-sticking-or-cracked-glass), sloping floors (https://terrabrain.vercel.app/signs/sloping-floors). - A floor elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys). Engineering guidance notes that a single survey shows the shape of the foundation at one moment and should not be the only basis for judging deflection and tilt [3]. Inspection standards state that home inspectors are not required to report on the adequacy of any structural system or to provide engineering services [1]. ## Related - Distress Pattern Library (https://terrabrain.vercel.app/guides/distress-pattern-library) - Symptom Matrix (https://terrabrain.vercel.app/guides/symptom-matrix) - Elevation Surveys (https://terrabrain.vercel.app/guides/elevation-surveys) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Windows Sticking or Cracked Glass (https://terrabrain.vercel.app/signs/windows-sticking-or-cracked-glass) Sources: [1] InterNACHI Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [2] Foundation Fundamentals: Inspecting Load Paths and Water Paths (IRC R401.2 & R401.3), InterNACHI https://nachi.org/foundation-load-water.htm [3] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Residential House Foundations on Expansive Soils in Changing Climates, U.S. Department of Housing and Urban Development, Cityscape https://www.huduser.gov/PORTAL/periodicals/cityscape/vol25num1/ch10.pdf [6] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [7] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf --- # Do you need a permit for foundation repair in Oklahoma? URL: https://terrabrain.vercel.app/rules/codes-and-permits Answer: It depends on the city. Oklahoma uses the 2024 IRC statewide, cities run their own permit offices, and the state does not license foundation repair. In short: Oklahoma uses one statewide minimum residential code, the 2024 International Residential Code (IRC) with Oklahoma amendments, effective September 14, 2026 [1]. Cities enforce it and run their own permit offices, so whether a foundation repair needs a permit depends on the city [5]. The state does not list foundation repair among the trades it licenses [7]. ## What is the statewide code? The Oklahoma Uniform Building Code Commission adopts the IRC for one- and two-family homes. The 2024 edition with Oklahoma amendments took effect September 14, 2026 [1], replacing the 2018 edition that had been effective since September 14, 2022 [2]. The 2024 adoption includes an appendix of residential tornado provisions and a 250 mph design wind speed for storm shelters [1]. ## Which code sections touch foundations? | Section | What it says | |---|---| | R401.3 Drainage | Ground must fall at least 6 inches within the first 10 feet from the foundation, or drains or swales must be built; hard surfaces within 10 feet must slope at least 2% away [3] | | R401.4 Soil tests | Where data suggest expansive, compressible or shifting soils, the building official decides whether a soil test is required [3]; see soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values) | | R403.1.8 Expansive soils | Foundations on expansive soils must be designed under the building code's expansive-soil provisions, unless a proven system is approved [3] | | Table R301.2(1) | Oklahoma leaves the frost line depth blank; each jurisdiction fills in the minimum footing depth [4] | ## What are Oklahoma's foundation amendments? The 2024 Oklahoma rule changes several Chapter 4 provisions [1]: - **R402.2**: interior slabs and enclosed garage slabs do not need air-entrained concrete. - **R403.1**: two #4 reinforcing bars in all footings; #4 bars tie footings to stem walls at each corner and at most 6 feet apart, with 12 inches of embedment. - **R403.1.6**: ½-inch anchor bolts at most 6 feet apart and at least 7 inches into concrete; hand-driven cut or concrete nails are not approved. - **R403.1.7.3** (foundation elevation): deleted. - **R404.1.3.3.7.1.b**: glass-fiber reinforcing bar allowed in foundation walls and footings up to 48 inches high. The earlier 2018 Oklahoma rule added **R403.1.9**, which barred trenches for plumbing, electrical, storm shelters or pools running parallel to a footing from cutting into the soil zone below it, defined by a 45-degree line down from the footing's outside bottom edge [2]. Whether this section carried into the 2024 adoption was not confirmed in the 2024 summary. ## Is a permit needed for foundation repair? Permit requirements are set and enforced locally, and published guidance differs by city: - **Tulsa**: the owner, contractor, architect or owner's agent may apply. Repair permits are applied for in person, and if damage is extensive or structural, construction plans are required; the plans examiner decides at submittal [5]. Electrical, mechanical and plumbing permits can only be pulled by licensed contractors [5]. - **Oklahoma City**: anyone contracting for work that needs a building permit must register as a building contractor, with general liability of at least $50,000 per occurrence and workers' compensation coverage or an exemption form [6]. - **Other cities** (Broken Arrow, Edmond, Norman, Moore and others) set their own requirements. The local permit desk is the authority on whether piering needs a permit, plans or inspections. City-by-city notes: permits, licensing and frost depth (https://terrabrain.vercel.app/rules/permits-licensing-and-frost-depth-oklahoma-cities). ## Does Oklahoma license foundation repair? The Oklahoma Construction Industries Board licenses plumbers, electricians, mechanical contractors, home inspectors and building inspectors, and registers roofing contractors [7]. Engineering is licensed separately: when an engineer prepares a foundation repair plan, Oklahoma's engineering board says it must be signed, sealed and dated [8]. See working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). ## Related - Tolerances and standards (https://terrabrain.vercel.app/guides/tolerances-and-standards) - Surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Freeze-thaw and frost depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) - Contracts, warranties and liens (https://terrabrain.vercel.app/rules/contracts-warranties-liens) - Drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - How to choose a foundation repair contractor in Oklahoma (https://terrabrain.vercel.app/rules/how-to-choose-a-foundation-repair-contractor-in-oklahoma) Sources: [1] Oklahoma Uniform Building Code Commission, Adoption of International Residential Code 2024: Code Changes Summary, Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2024%20IRC%20Code%20Changes%20Summary%20-%20for%20website.pdf [2] 748:20-6-9. IRC 2018 Chapter 4 Foundations (Permanent Rule), Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2022%2009%2014%20IRC%202018%20Permanent%20Rule.pdf [3] Seattle Residential Code 2018, Chapter 4 Foundations (IRC-based text of R401.3, R401.4 and R403.1.8), City of Seattle Department of Construction and Inspections https://seattle.gov/Documents/Departments/SDCI/Codes/SeattleResidentialCode/2018SRCChapter4.pdf [4] Oklahoma Administrative Code 748:20-6-8, IRC 2018 Chapter 3 Building Planning, Justia (Oklahoma Administrative Code) https://regulations.justia.com/states/oklahoma/title-748/chapter-20/subchapter-6/section-748-20-6-8/ [5] Residential Building Permit Process, City of Tulsa Development Services https://www.cityoftulsa.org/media/10918/residential2019.pdf [6] Residential Building Contractor, City of Oklahoma City Development Services https://okc.gov/departments/development-services/business-licensing/contractor-registration/building-contractor [7] About, Oklahoma Construction Industries Board https://oklahoma.gov/cib/about.html [8] The Board's Bulletin, Vol. 21, Issue 4 (2007): Compliance Guidelines for Foundation Repair Companies, Oklahoma State Board of Licensure for Professional Engineers and Land Surveyors https://oklahoma.gov/content/dam/ok/en/pes/documents/bulletin/Newsletter_Volume21_Issue62.pdf --- # Does chemical soil stabilization work on Oklahoma clay? URL: https://terrabrain.vercel.app/data/stabilization-research Answer: Oklahoma highway research found lime cuts swelling in ordinary clay but can cause severe heave in high-sulfate soil; two acid additives did not cut swelling. In short: Oklahoma highway research shows lime can sharply cut swelling in ordinary clay, but it can cause severe heave in soils high in sulfate. Kiln dust raised swelling in every soil tested in one study because the dust itself carried sulfate. Two acid-based additives tested on Oklahoma clays did not reduce swelling or meaningfully raise strength. ## Why does this research matter to homeowners? Chemical soil stabilization means mixing or injecting a material into clay to reduce its tendency to swell and shrink. Most published Oklahoma testing was done for roads by the Oklahoma Department of Transportation (ODOT) and the University of Oklahoma, so it measures mixed-in treatment of subgrade soils rather than injection under a house [1][2]. The results still show how Oklahoma clays respond to common chemicals. For how treatment is used around foundations, see chemical soil stabilization (https://terrabrain.vercel.app/repairs/chemical-soil-stabilization). The common additives are: - **Lime:** hydrated lime or quicklime, calcium-based. - **Fly ash:** a byproduct of burning coal; Class C fly ash contains calcium. - **Cement kiln dust (CKD):** fine dust collected from cement plants. ## What did lime, fly ash and kiln dust tests show? A University of Oklahoma study (FHWA-OK-08-10) measured three-dimensional swell after curing for three Oklahoma soils [1]. | Soil | Sulfate | Untreated swell | 3% lime | 15% fly ash | 15% kiln dust | |---|---|---|---|---|---| | Kingfisher (lean clay, LL ~39, PI ~21) | none detected | 6.1% | swell cut about 95% | swell cut about 54% | swell up 98% [1] | | Vernon (lean clay, PI ~11 to 15) | 15,400 ppm | not stated | swell up 1,237% | swell cut about 145% | swell up 593% [1] | | Carnasaw (fat clay, LL ~58, PI 29) | 267 ppm | not stated | nearly eliminated swell | swell cut about 32% | swell up 113% [1] | Additional findings from the same study: - At 9% lime, Kingfisher soil averaged negative 2.8% swell, meaning it shrank slightly [1]. - Lower fly ash doses on Vernon soil (5% and 10%) reduced swell by about 40% and 75% [1]. - The kiln dust tested carried about 28,133 ppm soluble sulfate, and the report says soil-kiln dust mixes above 2,000 ppm can cause sulfate heave [1]. ### What sulfate heave is When calcium from lime, fly ash or kiln dust reacts with sulfate in soil and water, it can form ettringite, a mineral that takes up a large volume as it grows [1]. The researchers confirmed ettringite in treated samples with electron microscopy and X-ray methods [1]. Sulfate in Oklahoma soils ranges widely. Borings at one McClain County site tested between 38 and 1,300 ppm, and that report stated that levels below 3,000 ppm pose a low risk of harmful reactions in lime stabilization [4]. Vernon soil, at 15,400 ppm, is far above that [1]. Gypsum is a calcium sulfate mineral, and gypsum-rich soil was behind the highway failure described below [3] (see Permian gypsum units (https://terrabrain.vercel.app/geology/permian-gypsum-units-e-g-blaine) and gypsum karst and sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes)). ### A field failure: SH-412 near Woodward In 2004, several miles of State Highway 412 near Woodward failed from sulfate-induced heave [3]. The subbase soil had been lime-treated and came from a borrow source with a large amount of gypsum; the lime reacted with the gypsum to form ettringite, which swelled the subbase and ruined that section of road [3]. ## Do acid-based additives work? A 2013 University of Oklahoma study for ODOT (FHWA-OK-13-06) tested two commercial acid-based liquid additives, described as sulfonated oil products mixed with acid, on three Oklahoma clays: Lela clay (Kay County), Renfrow clay (Logan County) and Vernon soil [2]. They were compared with hydrated lime and Class C fly ash [2]. | Measure | Finding | |---|---| | Strength | No substantial increase in unconfined compressive strength in any soil; neither additive met ODOT's stabilization criteria [2] | | Plasticity | Little effect; Renfrow cured PI was 27.2 untreated vs 27.4 and 25.7 with the two additives [2] | | Swell | No reduction in swelling potential in any soil; lime clearly reduced swell in Lela clay [2] | | Sulfate soil | The additives did not cause the adverse swelling that lime and fly ash produced in Vernon soil [2] | ## What are the limits of the research? - These studies tested road subgrade mixing and lab samples, not injection beneath existing houses [1][2]. - Results vary by soil; a treatment that works on low-sulfate Kingfisher soil behaved very differently on Vernon soil [1]. - Measured soil properties for many Oklahoma soils are listed in soil lab values (https://terrabrain.vercel.app/data/soil-lab-values). ## Related - Chemical soil stabilization (https://terrabrain.vercel.app/repairs/chemical-soil-stabilization) - Soil lab values (https://terrabrain.vercel.app/data/soil-lab-values) - Clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Vernon soil (https://terrabrain.vercel.app/soils/vernon) - Renfrow soil (https://terrabrain.vercel.app/soils/renfrow) - Shrink-swell and active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) Sources: [1] Engineering Properties of Stabilized Subgrade Soils for Implementation of the AASHTO 2002 Pavement Design Guide (FHWA-OK-08-10), Oklahoma Department of Transportation https://www.odot.org/hqdiv/p-r-div/spr-rip/library/reports/fhwa-ok0810.pdf [2] Report FHWA-OK-13-06 (ODOT SP&R Item 2242), University of Oklahoma, Oklahoma Department of Transportation / U.S. DOT ROSA P https://rosap.ntl.bts.gov/view/dot/31441/dot_31441_DS1.pdf [3] Calcium-Based Stabilizer Induced Heave in Oklahoma Sulfate-Bearing Soils (FHWA-OK-11-03), Oklahoma Department of Transportation / U.S. DOT ROSA P https://rosap.ntl.bts.gov/view/dot/23202/dot_23202_DS1.pdf [4] Subsurface Exploration, New ODOT Maintenance and Residency Facilities, Oklahoma Department of Transportation https://oklahoma.gov/content/dam/ok/en/odot/procurement/open/26-FM-0017_Geotech_Report.pdf --- # Does chemical soil stabilization work on Oklahoma clay? URL: https://terrabrain.vercel.app/repairs/chemical-soil-stabilization Answer: Lime can nearly eliminate swell in some Oklahoma soils but make sulfate-rich soils dramatically worse, so soil testing, especially for sulfates, comes first. In short: Chemical soil stabilization adds lime or another chemical to expansive clay to reduce how much it swells and shrinks. Oklahoma highway research shows lime can nearly eliminate swell in some Oklahoma soils and make it dramatically worse in sulfate-rich soils. Testing the soil, especially for sulfates, comes before any treatment decision. ## What is chemical soil stabilization? **Expansive clay** swells when wet and shrinks when dry. Most foundation repair works around it, by placing piers below the moving layer or by controlling water. Chemical stabilization tries to change the clay itself. Engineering guidance for swelling soils lists two ways to deal with the soil directly: remove it to an adequate depth and replace it with compacted non-expansive fill, or treat it chemically on site, noting that adequate amounts of lime or cement can reduce swell potential in most expansive soils [3]. A Texas regulatory bulletin on residential foundations lists stabilizing the soil by chemical dewatering or chemical presaturation (pre-wetting the clay) among alternatives for compressible or shifting soils [5]. Colorado State University Extension describes lime treatment at 2 to 10% mixed 12 to 18 in deep, along with vertical or horizontal moisture barriers installed by builders [4]. ## What approaches are used? | Approach | How it is applied | |---|---| | Lime mixing | Hydrated lime blended into excavated or tilled soil, then compacted; standard on highway subgrades [1] | | Lime slurry injection | Lime mixed with water and pumped under pressure into the ground through probes | | Fly ash or cement | Other calcium-based additives mixed into soil [1] | | Presaturation and moisture barriers | Pre-wetting clay [5]; vertical or horizontal moisture barriers [4] | | Other chemical products | Liquid stabilizers sold for injection | ## What did Oklahoma research find? The University of Oklahoma, working for the Oklahoma Department of Transportation, tested lime, fly ash and cement kiln dust on Oklahoma soils after curing [1]: | Soil | Treatment | Effect on swell | |---|---|---| | Kingfisher (https://terrabrain.vercel.app/soils/kingfisher) | 9% lime | 6.1% swell untreated to -2.8% (net shrink) [1] | | Kingfisher | 3% lime | Swell cut about 95% [1] | | Kingfisher | 15% fly ash | Swell cut about 54% [1] | | Vernon (https://terrabrain.vercel.app/soils/vernon), 15,400 ppm sulfate | 3% lime | Swell increased 1,237% [1] | | Vernon | 15% cement kiln dust | Swell increased 593% [1] | | Vernon | 5% and 10% fly ash | Swell cut about 40% and 75% [1] | | Kingfisher | 15% cement kiln dust | Swell increased 98% [1] | Swell in the lime- and kiln-dust-treated samples was traced to ettringite, confirmed by microscope and X-ray analysis; the kiln dust itself carried about 28,133 ppm sulfate [1]. These were laboratory mixes for highway pavement design, compacted in molds [1]. Pressure injection into undisturbed clay under an existing house is a different process, and the lab numbers do not transfer to it directly. ## What is the sulfate problem? **Ettringite** is a calcium-aluminum-sulfate mineral that forms when lime, soluble sulfate (often from gypsum), aluminum from clay and water combine; it can swell up to 250% of its original volume [2]. In 2004, several miles of State Highway 412 near Woodward failed from sulfate-induced heave after a gypsum-rich subbase was treated with lime, and repairs cost the state millions [2]. Published sulfate limits for lime treatment range from about 700 to 8,000 ppm, and the Oklahoma researchers questioned whether a 3,000 ppm threshold developed in Texas applies to Oklahoma soils [2]. The SH-412 subbase came from a borrow source with large amounts of gypsum [2]; gypsum-bearing rock in Oklahoma is described under Permian gypsum units (https://terrabrain.vercel.app/geology/permian-gypsum-units-e-g-blaine). ## Which Oklahoma soils are candidates? Oklahoma State University testing found montmorillonite-dominated clay in western Oklahoma benchmark soils, with Kirkland showing volume change up to 73% and Bethany up to 66% [6]. The researchers treated shrink-swell values above a set threshold as a sign of substantial smectite and severe limits for engineering use [6]; see clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy). ## What testing is needed before treatment? - Plasticity index and swell tests on samples from the depth to be treated; see soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values). - Soluble sulfate content, because of the ettringite reaction [2]. - Swell tests on treated and untreated samples, the comparison the Oklahoma studies used [1]. - Follow-up elevation and moisture monitoring after treatment. Full study details are summarized in OK Data - Stabilization Research (https://terrabrain.vercel.app/data/stabilization-research). Stabilization is often discussed alongside root barriers and moisture control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control) and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). ## Related - OK Data - Stabilization Research (https://terrabrain.vercel.app/data/stabilization-research) - Clay Mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Soil Testing and Lab Values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Root Barriers and Moisture Control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control) Sources: [1] Engineering Properties of Stabilized Subgrade Soils for Implementation of the AASHTO 2002 Pavement Design Guide (FHWA-OK-08-10), Oklahoma Department of Transportation (Solanki, Khoury and Zaman, University of Oklahoma) https://www.odot.org/hqdiv/p-r-div/spr-rip/library/reports/fhwa-ok0810.pdf [2] Calcium-Based Stabilizer Induced Heave in Oklahoma Sulfate-Bearing Soils (FHWA-OK-11-03), Oklahoma Department of Transportation (Cerato, Miller, Elwood-Madden, Adams and Varnier) https://rosap.ntl.bts.gov/view/dot/23202/dot_23202_DS1.pdf [3] Home Construction on Shrinking and Swelling Soils (Special Publication 11), Colorado Geological Survey (Holtz and Hart, 1978) https://coloradogeologicalsurvey.org/wp-content/uploads/woocommerce_uploads/SP-11.pdf [4] Landscaping on Expansive Soils (Fact Sheet 7.236), Colorado State University Cooperative Extension https://ca-montereypark.civicplus.com/DocumentCenter/View/487 [5] Foundations on Expansive Soils – Residential (IHB TB 10-01), Texas Department of Licensing and Regulation https://tdlr.texas.gov/ihb/pdf/TB1001.pdf [6] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf --- # Does homeowners insurance cover foundation damage in Oklahoma? URL: https://terrabrain.vercel.app/rules/insurance-claims Answer: Standard policies usually exclude settling or soil movement. Earthquake damage needs a separate endorsement, and flood policies exclude earth movement. In short: Standard homeowner policies usually exclude foundation damage caused by settling or soil movement [2]. Earthquake damage needs a separate endorsement or policy [1], and flood policies exclude earth movement even when a flood triggers it [4]. Coverage questions turn on the cause of the damage, which is why documentation and engineering reports matter. ## What do standard policies usually exclude? The standard homeowners form's earth movement exclusion applies no matter what caused the movement, and an insurance coverage analysis applied it to a foundation cracked by drought [2]. Policies also commonly carry a settling, cracking and bulging exclusion [3]. Exact wording varies by insurer, so the policy's own exclusions section controls. ## What if a plumbing leak is involved? Courts are split on whether settlement caused by a plumbing leak falls under the settling exclusion [3]: - Some courts applied the exclusion to leak-caused foundation movement, such as a 1996 federal case in Texas and a 1989 Oregon appeals case. - Others found the exclusion aimed at gradual, natural settlement and found coverage, such as a 1999 Colorado appeals case and a 1974 Florida appeals case. No Oklahoma appellate decision on this point was located for this page. In the claim that article described, settlement was concentrated at the footings nearest the leak, with little or none about 5 feet away [3]. That kind of pattern evidence is what links damage to a leak. More detail: plumbing leaks and insurance in Oklahoma (https://terrabrain.vercel.app/rules/plumbing-leaks-and-insurance-oklahoma). ## How does earthquake coverage work in Oklahoma? According to the Oklahoma Insurance Department [1]: - Typical homeowner and renter policies do not cover earthquakes. - Coverage is sold as an endorsement or a stand-alone policy, though not every insurer offers it. - Deductibles are usually 5 to 10 percent of the insured value, with separate deductibles for the home, other structures and contents. - Most companies will not sell new earthquake coverage for 30 to 60 days after a quake. - Coverage may include costs to stabilize land under structures, but damage to the lot itself, such as sinkholes, is typically excluded, and some insurers exclude brick or stone veneer. In 2015 the department warned insurers not to deny earthquake claims based on an unsupported assumption that a quake was man-made, and said insurers denying claims for pre-existing damage should have inspected the property before coverage began [5]. After the 2016 Pawnee earthquake, 4 of 274 claims reported to the department had been paid by late October 2016; the commissioner said earthquake policies "are meant to only cover damage from catastrophic loss" [6]. See seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement). ## Does flood insurance cover foundation damage? The National Flood Insurance Program pays for direct physical loss by or from flood, but not for loss caused by earth movement, even when a flood causes that movement [4]. In one appeal, an engineer tied exterior foundation cracks to long-term drying shrinkage and differential soil movement, and FEMA upheld the insurer's denial of coverage for the front porch [4]. ## What documentation helps show the cause? - An elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) showing the pattern of movement - Dated photos and a crack log - Plumbing test results when a leak is suspected - A licensed engineer's report when cause is disputed. See working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). ## What if a claim is disputed? The Oklahoma Insurance Department's complaint process asks consumers to contact the insurer first, then file a signed Request for Assistance with copies of the policy and letters; the insurer has 30 days to respond to the department [7]. The department's EAGLE program offers free, voluntary mediation by a court-approved mediator when both sides agree [8]. ## Related - Plumbing leaks and insurance in Oklahoma (https://terrabrain.vercel.app/rules/plumbing-leaks-and-insurance-oklahoma) - Severe weather effects (https://terrabrain.vercel.app/guides/severe-weather-effects) - Induced seismicity in Oklahoma (https://terrabrain.vercel.app/guides/induced-seismicity-in-oklahoma) - Earthquakes, claims and law data (https://terrabrain.vercel.app/data/earthquakes-claims-and-law) - Seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement) - What affects the cost of foundation repair in Oklahoma? (https://terrabrain.vercel.app/guides/what-affects-foundation-repair-cost) Sources: [1] Fast Facts on Earthquake Insurance, Oklahoma Insurance Department https://oid.ok.gov/fast-facts-on-earthquake-insurance [2] Drought and Cracked Foundation, PropertyCasualty360 (FC&S) https://propertycasualty360.com/fcs/2012/12/10/drought-and-cracked-foundation [3] Settling Due to Leaking vs. Natural Causes, PropertyCasualty360 (FC&S) https://propertycasualty360.com/fcs/2010/05/18/settling-due-to-leaking-vs-natural-causes-422-11964 [4] Earth Movement Decision Upheld, FEMA National Flood Insurance Program https://www.floodsmart.gov/recover/how-to-write-your-appeal/earth-movement-decision-upheld [5] Bulletin PC 2015-02: Earthquake Insurance, Excluded Loss, Inspection of Insured Property and Adjuster Training, Oklahoma Insurance Department https://www.oid.ok.gov/wp-content/uploads/2019/10/030415_Earthquake-Bulletin-3-3-15.pdf [6] Much Of Labor Day Weekend 5.8-Magnitude Earthquake Damage Not Covered By Insurance, KGOU https://www.kgou.org/oklahoma-news/2016-10-31/much-of-labor-day-weekend-5-8-magnitude-earthquake-damage-not-covered-by-insurance [7] Filing an Insurance Complaint with the Oklahoma Insurance Department, Oklahoma Insurance Department https://www.oid.ok.gov/wp-content/uploads/2020/01/2020_Filing-Complaint.pdf [8] EAGLE Mediation Program, Oklahoma Insurance Department https://www.oid.ok.gov/consumers/eagle-mediation-program/ --- # Does insurance cover slab leak foundation damage in Oklahoma? URL: https://terrabrain.vercel.app/rules/plumbing-leaks-and-insurance-oklahoma Answer: A slab leak can raise or lower part of a house, but insurance treatment of leak-related settlement is unsettled, with courts split on the settling exclusion. In short: A leak under a slab can raise or lower part of a house, depending on the soil, and in one documented claim the damage lined up with the leaking plumbing [1]. Engineers recommend testing plumbing whenever a foundation is lifted [2]. Insurance treatment of leak-related settlement is unsettled: courts have split on whether the settling exclusion applies [1]. ## How do leaks move foundations? - **On expansive clay**, added water swells the soil, and slab-on-grade foundations on these soils are vulnerable to that volume change [2]. A leak can swell the soil under one area and push up an interior part of the slab, called **heave**. See leak-induced localized heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave). - **Under one side of a slab**, leak water can follow a sloping pipe and soften the ground there, producing localized settlement [1]. See also erosion and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). The location of the damage is the main clue. In one documented claim, settlement was concentrated along the footings nearest the leak, with little or none about 5 feet away, and a sloping drain pipe carried water under one side of the slab [1]. Movement and leaks can also run the other way: forensic engineers note frequent sub-slab plumbing failures on expansive soils, and the model plumbing code now has provisions for plumbing under expansive soils [2]. ## What pipe materials were used in homes of each age? | Material | What sources report | |---|---| | Cast iron drains | In building use for more than 100 years, usually as 4- to 6-inch main drains [3] | | Black ABS plastic drain pipe | Some made in the mid-1980s was defective and failed by cracking [3] | | Copper supply | Can last indefinitely in many areas, but may fail within 20 years in corrosive water or soil [3] | House age helps estimate which materials are under the slab; see construction era by decade (https://terrabrain.vercel.app/guides/construction-era-by-decade). ## How is a leak found? 1. **Water meter check.** Read the meter, use no water for two hours, then read it again; any change probably means a leak [4]. This finds pressurized supply leaks, not drain leaks. 2. **Licensed plumber testing.** Drain and supply testing, camera inspection and electronic leak location are plumbing work. In Oklahoma, plumbers are licensed by the Construction Industries Board [5]. 3. **Elevation survey.** An interior high spot near baths, kitchen or laundry points toward heave rather than settlement. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). After any foundation lift, forensic engineering guidance calls for plumbing tests, repair of any leaks and a new baseline elevation survey [2]. The model plumbing code also bars lifting a slab and its plumbing together to create a void unless the space below is a crawl space with inspection access [2]. Background: plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab). ## How does insurance treat leak-related damage? - **Earth movement and settling.** The standard homeowners form excludes earth movement no matter the cause [6], and policies commonly exclude settling and cracking of foundations [1]. - **Leak-caused settlement.** Courts are split. A 1996 federal case in Texas and a 1989 Oregon case applied the exclusion; a 1999 Colorado case and a 1974 Florida case found coverage [1]. The source's authors read the exclusion as aimed at gradual, natural settlement [1]. No Oklahoma appellate ruling on this point was located for this page. - **Earthquake.** Not covered by typical homeowner policies; endorsements carry deductibles of usually 5 to 10 percent of insured value [7]. The exact policy wording and the documented cause decide each claim. Useful records include the plumber's written test report, repair invoice, dated photos and an elevation survey. ## What are Oklahoma's claim-handling deadlines? Under Oklahoma's Unfair Claims Settlement Practices Act, as summarized by a coverage law firm [8]: - Insurers must respond within 30 days to communications that call for a response. - Insurers must acknowledge a claim within 30 days. - Insurers must accept or deny within 60 days after a properly executed proof of loss, or say within that time that more investigation is needed. - Investigations generally may not exceed 120 days absent specific fraud or arson indicators. Violations do not create a private lawsuit by themselves, but can be evidence in a bad-faith case; the Oklahoma Supreme Court recognized bad faith as a stand-alone tort in 1977 [8]. See insurance claims (https://terrabrain.vercel.app/rules/insurance-claims). ## Related - Plumbing leak detection and repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair) - Unexplained high water bill (https://terrabrain.vercel.app/signs/unexplained-high-water-bill) - Interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump) - Heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Insurance claims (https://terrabrain.vercel.app/rules/insurance-claims) Sources: [1] Settling Due to Leaking vs. Natural Causes, PropertyCasualty360 (FC&S) https://propertycasualty360.com/fcs/2010/05/18/settling-due-to-leaking-vs-natural-causes-422-11964 [2] Beyond the Building Code: Expansive Soils, Journal of the National Academy of Forensic Engineers https://journal.nafe.org/ojs/index.php/nafe/article/download/975/924/4846 [3] Water supply & drain piping, InspectAPedia https://inspectapedia.com/plumbing/Building_Piping_Guide.php [4] Checking Your Water Meter for Leaks, U.S. Environmental Protection Agency, WaterSense (January 2017 archive) https://19january2017snapshot.epa.gov/www3/watersense/our_water/howto.html [5] About, Oklahoma Construction Industries Board https://oklahoma.gov/cib/about.html [6] Drought and Cracked Foundation, PropertyCasualty360 (FC&S) https://propertycasualty360.com/fcs/2012/12/10/drought-and-cracked-foundation [7] Fast Facts on Earthquake Insurance, Oklahoma Insurance Department https://oid.ok.gov/fast-facts-on-earthquake-insurance [8] Wrongful Denial or Delay by Your Insurance Company in Oklahoma? Insurance Companies Have Good Faith Obligations and Can Be Held Accountable, Property Insurance Coverage Law Blog (Merlin Law Group) https://www.propertyinsurancecoveragelaw.com/blog/wrongful-denial-or-delay-by-your-insurance-company-in-oklahoma-insurance-companies-have-good-faith-obligations-and-can-be-held-accountable/ --- # Does insurance pay for Oklahoma earthquake foundation damage? URL: https://terrabrain.vercel.app/data/earthquakes-claims-and-law Answer: Oklahoma quake claims have been paid at a low rate: in 2014 about 100 were filed and eight paid, and masonry veneer and chimneys are often excluded. In short: Oklahoma earthquake insurance claims have historically had a low payment rate; in 2014 about 100 claims were filed and eight were paid. The state Insurance Department responded with a 2015 bulletin telling insurers to inspect homes before coverage if they plan to deny claims as pre-existing damage. The bulletin also notes the common exclusion of masonry veneer walls and chimneys from earthquake coverage. ## How active are earthquakes in Oklahoma? In a 2008 summary, an Oklahoma Geological Survey geologist described four main seismic areas in the state: El Reno-Mustang, central Oklahoma, Love and Carter counties, and the Arkoma Basin [2]. Typical magnitudes were 1.8 to 2.5, with focal depths generally under 3 miles [2]. The same summary listed earthquakes alongside expansive soils, karst and landslides as Oklahoma's main geologic hazards, and noted that over 75% of the state has bedrock that can produce expansive soils [2]. That last point matters for claims: in most of Oklahoma, cracks in a house can come from swelling and shrinking clay as well as from shaking [2]. For the later rise in earthquakes linked to wastewater injection, see induced seismicity in Oklahoma (https://terrabrain.vercel.app/guides/induced-seismicity-in-oklahoma). For how to tell the two causes apart, see seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement). ## What did Oklahoma's larger earthquakes actually damage? ### Prague, November 2011 The magnitude 5.6 earthquake of November 2011, centered in Lincoln County about 45 miles east of Oklahoma City, buckled several roads including Highway 62, and chimneys collapsed through the roofs of some homes [10]. In nearby Shawnee, all four turrets on a 1915 university building were destroyed [9]. ### Pawnee, September 2016 The magnitude 5.8 Pawnee earthquake of September 3, 2016, is the strongest in Oklahoma's recorded history, and it injured one person [7]. Emergency managers reported no building collapses; much of the damage was to older brick and stone buildings from the early 1900s, and stones fell from the facade of a 1902 sandstone bank building downtown [8]. Researchers also found sand blows, surface fractures and lateral spreading, which are signs of liquefaction: water-soaked sand losing strength and flowing like a liquid during shaking [7]. This was unusual for an Oklahoma earthquake. Their imaging showed that loose, young river-channel deposits of sand, gravel, silt and clay were the soils prone to it [7]. Homes on river-bottom soils are discussed in soft soil consolidation in alluvium and wet clays (https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays). ### Cushing, November 2016 The magnitude 5.0 Cushing earthquake started only about 4 km (2.5 miles) deep [6]. Nearby instruments recorded peak horizontal ground accelerations of 0.44 g to 0.58 g, meaning the ground briefly accelerated at roughly half the force of gravity [6]. Century-old unreinforced brick buildings downtown were heavily damaged and some were demolished [6]. A study of newer low-rise buildings in town noted they sat on shallow concrete foundations (grade beams, bell footings and piers) and reported out-of-plumb walls and cracked masonry, but did not report foundation damage [6]. ## What did the 2015 Insurance Department bulletin say? In March 2015 the Oklahoma Insurance Commissioner issued Earthquake Insurance Bulletin No. PC 2015-02 [1]. Its main points: | Topic | What the bulletin said | |---|---| | Claim payment rate | About 100 Oklahoma earthquake claims were filed in 2014 and only eight were paid [1] | | Pre-existing damage | Insurers should inspect a property before coverage begins and keep current information on its condition [1] | | Denials for pre-existing damage | The Commissioner expects an insurer denying on that basis to have inspected before coverage started [1] | | Cause of the quake | Insurers should not deny claims based on an unsupported belief that quakes were caused by fracking or injection wells [1] | | Masonry | The bulletin refers to the common exclusion of coverage for masonry veneer walls and chimneys [1] | | Deductibles | Earthquake deductibles are much larger than typical homeowners deductibles, and more than one deductible may apply to a single loss [1] | | Adjuster training | Insurers should train adjusters in earthquake coverage, which involves complex deductibles and causation questions [1] | | Enforcement | The Commissioner said he was considering market conduct examinations and that unsupported denials could lead to enforcement action [1] | ## How often have Oklahoma earthquake claims been paid? | Period or event | What was reported | |---|---| | 2014 | About 100 claims filed, eight paid [1] | | 2010 to mid-2016 | Insurers collected more than $135 million in earthquake premiums and paid about $4.5 million; just under 18% of about 1,136 residential claims received any payment, with payments typically about $5,500 [4] | | Pawnee 2016 (by early November) | 274 claims filed, four paid, totaling $24,232 [5] | Separate earthquake coverage also became more common: about 10 to 15 percent of Oklahomans had it in 2016, up from about 2 percent in 2011, according to the Insurance Department [5]. Deductibles are typically 5 to 10 percent of the home's value, so damage from smaller quakes often falls below the deductible [4][5]. In April 2021 the Oklahoma Insurance Department announced a $25 million settlement with one insurer over roughly 1,000 earthquake claims that had been denied or not properly paid; the claims were to be reopened and re-evaluated by an independent administrator [3]. ## How have Oklahoma courts treated "earth movement" exclusions? An earth movement exclusion is policy wording that removes coverage for damage caused by the ground shifting, settling or heaving. Oklahoma cases show the outcome can turn on exact policy wording and the cause of the movement: - **2009, Edmond home (federal appeals court):** A burst bathroom pipe soaked the clay under part of a slab, the clay swelled and the slab heaved. The insurer paid for interior water damage but not the foundation. The Tenth Circuit held "earth movement" was not ambiguous and the exclusion barred the foundation claim [11]. - **2019, school property (Oklahoma Supreme Court):** Damage followed a burst underground water pipe. The court found the earth movement and water exclusions ambiguous because they listed natural events but not man-made ones and lacked "however caused" wording [12]. - **2021, wastewater injection (Oklahoma Supreme Court):** In coverage for lawsuits claiming injection wells caused quake damage, the court held the earth movement exclusion in the earlier policies unambiguously barred coverage, since its list covered nearly every event associated with an earthquake [13]. Lawsuits against well operators have also been filed. In 2022 one disposal well operator, which denied a role in the quakes, agreed to an $850,000 settlement with a class of residents covering damage from quakes within 50 miles of Pawnee from 2014 to 2016 [14]. Because a pipe-caused heave and soil-caused settlement can be treated differently, the documented cause of movement matters; see leak-induced localized heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave). ## What does this mean for foundation-related claims? ### Pre-loss condition is central Because insurers are expected to know a home's condition before coverage starts, records of that condition carry weight in a claim [1]. Useful records include dated photos of brick, drywall and slab cracks, and an elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) showing how level the floors were. ### Masonry and chimneys Brick veneer and chimneys are often excluded from earthquake coverage [1]. Brick veneer is the single layer of brick tied to the outside of a wood-framed wall. Damage to it, such as stair-step brick cracks (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top) or a chimney separating or leaning (https://terrabrain.vercel.app/signs/chimney-separating-or-leaning), may fall outside an earthquake policy even when shaking caused it [1]. ### Separating shaking from soil movement Since expansive soils are widespread in Oklahoma [2], adjusters and engineers often have to decide whether cracking came from an earthquake or from clay movement. Signs that point toward ongoing soil movement, such as cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally), are covered in earthquake shaking damage (https://terrabrain.vercel.app/causes/earthquake-shaking-damage) and the guide on seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement). ### General insurance rules See insurance claims (https://terrabrain.vercel.app/rules/insurance-claims) for how homeowners coverage and exclusions are handled in Oklahoma. ## Related - Induced seismicity in Oklahoma (https://terrabrain.vercel.app/guides/induced-seismicity-in-oklahoma) - Seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement) - Earthquake shaking damage (https://terrabrain.vercel.app/causes/earthquake-shaking-damage) - Insurance claims (https://terrabrain.vercel.app/rules/insurance-claims) - Elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) Sources: [1] Earthquake Insurance Bulletin No. PC 2015-02, Oklahoma Insurance Department https://www.oid.ok.gov/wp-content/uploads/2019/10/030415_Earthquake-Bulletin-3-3-15.pdf [2] Abstract: Geologic Hazards in Oklahoma, Geological Society of America (Oklahoma Geological Survey author) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [3] April 5, 2021 news release: earthquake claims settlement, Oklahoma Insurance Department https://www.oid.ok.gov/release_040521/ [4] Insurers reaped $135 million selling quake policies, paid out $4.5 million, The Frontier https://www.readfrontier.org/?p=6978 [5] Rising Earthquake Risks and Oklahoma's Insurance Market, Insurance Journal https://www.insurancejournal.com/magazines/mag-features/2016/11/21/432762.htm [6] Performance of Low-Rise Buildings with No Seismic Design in Unanticipated Earthquakes (17th World Conference on Earthquake Engineering), 17WCEE / NICEE https://wcee.nicee.org/wcee/article/17WCEE/2c-0197.pdf [7] OSU researcher authors paper exploring Pawnee quake damage, Oklahoma State University College of Arts and Sciences https://casnews.okstate.edu/casnews/archives/1268-osu-researcher-authors-paper-exploring-pawnee-quake-damage [8] Overview of building damages after the September 3, 2016 Oklahoma, USA Earthquake, Earthquake Engineering Research Institute, Learning from Earthquakes https://learningfromearthquakes.org/?p=54335 [9] St. Gregory's To Begin Restoration After '11 Quake, Public Radio Tulsa https://www.publicradiotulsa.org/local-regional/2012-12-16/st-gregorys-to-begin-restoration-after-11-quake [10] 5.6 earthquake hits central Oklahoma after earlier shakers, NBC News https://www.nbcnews.com/id/wbna45173167 [11] Order and Judgment, No. 08-6135 (10th Cir. June 25, 2009), U.S. Court of Appeals for the Tenth Circuit https://www.ca10.uscourts.gov/sites/ca10/files/opinions/01018088824.pdf [12] Oklahoma Supreme Court Finds Earth Movement Exclusion Ambiguous While Mississippi Supreme Court Enforces Its Terms, Simpson Thacher & Bartlett LLP, Insurance Law Alert https://www.stblaw.com/about-us/publications/view/2019/03/28/oklahoma-supreme-court-finds-earth-movement-exclusion-ambiguous-while-mississippi-supreme-court-enforces-its-terms [13] Oklahoma Supreme Court Rules That Pollution Exclusion Is Ambiguous in the Context of Earthquake Damage but That Earth Movement Exclusion Unambiguously Bars Coverage, Simpson Thacher & Bartlett LLP, Insurance Law Alert https://www.stblaw.com/about-us/publications/view/2021/12/27/oklahoma-supreme-court-rules-that-pollution-exclusion-is-ambiguous-in-the-context-of-earthquake-damage-but-that-earth-movement-exclusion-unambiguously-bars-coverage [14] Oil company agrees to $850k settlement for 2016 Oklahoma earthquake damages, KGOU https://www.kgou.org/science-technology-and-environment/2022-08-05/oil-company-agrees-to-850k-settlement-for-2016-oklahoma-earthquake-damages --- # How are bowing or cracked basement walls repaired? URL: https://terrabrain.vercel.app/repairs/basement-wall-repair Answer: Repairs strengthen, brace, anchor or replace the wall, paired with drainage, since soil pressure, swelling clay and trapped water cause the damage. In short: Basement walls crack and bow when the sideways push of the soil behind them, plus swelling clay and trapped water, exceeds what the wall can resist. Repairs either strengthen the wall, brace it, anchor it into the yard, or replace it, and they are paired with drainage because water is part of the load. Severe movement is an engineering design question rather than a product choice. ## What loads cause basement wall damage? ### Soil pressure The residential code's basement wall tables assign design soil pressures of 30, 45 or 60 pounds per square foot for each foot of depth, depending on soil type; inorganic clays fall in the 60 psf group [1]. The pressure grows with depth, so a deeper wall carries much more load near its base than near its top. Walls holding 4 ft or more of unbalanced backfill must be laterally supported at the top and bottom before backfilling [1]. ### Swelling clay Clay-rich soils can swell 10% or more by volume when wetted and press on foundations at 20,000 lb per square foot or more [5]. A University of Oklahoma geologist quoted by NPR described Oklahoma's red clay expanding and contracting with moisture and cracking basement walls, which then leak [4]. ### Water Dampproofing resists vapor and incidental moisture but is not built for significant water pressure; waterproofing is required where a high water table or other severe soil-water conditions are known to exist [3]. White residue on the wall, efflorescence, forms when water carries dissolved salts through masonry or concrete and evaporates at the surface [6]. ## What does the damage look like? - Horizontal cracking along a mortar joint or at mid-height of a block wall, with the wall bowing inward (horizontal crack or inward bow (https://terrabrain.vercel.app/signs/horizontal-crack-or-inward-bow-in-basement-wall)). - Cracks that let water in, the pattern described for Oklahoma clay [4]. - Seepage at cracks or at the joint between wall and floor, or white salt deposits left where water has moved through the masonry and evaporated (water at cove joint or efflorescence (https://terrabrain.vercel.app/signs/water-at-cove-joint-or-efflorescence)) [6]. The InterNACHI Standards of Practice require inspectors to report signs of active water penetration and of possible foundation movement, but not to provide engineering services or judge structural adequacy [7]. ## What repair methods are used? Plain-English definitions of the methods named in repair proposals: | Method | What it is | |---|---| | Carbon fiber straps | High-strength fiber strips bonded to the inside face of the wall with epoxy, tied to the floor framing and slab | | Steel wall braces | Vertical steel beams set against the wall, fastened at the floor and at the joists above | | Wall (plate) anchors | Steel rods run through the wall to steel plates buried in the yard; the rods are tightened against the wall | | Helical tiebacks | Screw-type steel anchors installed through the wall at an angle into the soil behind it | | Excavate and rebuild | Digging out the outside of the wall, rebuilding or straightening it, and backfilling with drainage | | Crack injection | Filling individual cracks with epoxy or polyurethane to seal or bond them | The choice depends on how far the wall has moved, whether it has sheared or slid, its material, access to the yard, and the loads described above. Inspection standards leave structural adequacy and engineering out of a home inspection [7], so wall movement is assessed separately; see working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). ## What water control goes with wall repair? - **Footing drains:** required around concrete or masonry walls that retain earth and enclose usable below-grade space, set at or below the top of the footing and discharged by gravity or pump [2]. - **Drain construction:** gravel at least 1 ft beyond the footing and 6 in above it, or perforated pipe on 2 in of washed gravel with 6 in of cover and a filter membrane [2]. - **Waterproofing:** where severe soil-water conditions exist, a waterproofing membrane rather than dampproofing [3]. - **Surface water:** grade falling at least 6 in within 10 ft of the foundation, and gutters and downspouts discharging away from it [8]. These steps reduce the water part of the load; perched water that collects behind walls in wet seasons is explained in groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water), and site water work is covered in drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). ## Related - Basements (https://terrabrain.vercel.app/foundations/basements) - Lateral Earth, Swell and Hydrostatic Pressure on Walls (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls) - Horizontal Crack or Inward Bow in Basement Wall (https://terrabrain.vercel.app/signs/horizontal-crack-or-inward-bow-in-basement-wall) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Working with Engineers (https://terrabrain.vercel.app/guides/working-with-engineers) Sources: [1] 2007/2008 Proposed Changes to the International Residential Code (RB101–RB143), International Code Council https://www.iccsafe.org/cs/codes/Documents/2007-08cycle/ProposedChanges/V2_RB101-143.pdf [2] Inspecting Foundation Drainage: Essential Guidelines for Below-Grade Spaces (IRC R405), InterNACHI https://www.nachi.org/foundation-drainage-below-grade.htm [3] Inspecting Foundation Dampproofing and Waterproofing (IRC R406), InterNACHI https://www.nachi.org/foundation-dampproofing-waterproofing.htm [4] Why Oklahomans Don't Like Basements, NPR (via WFAE 90.7) https://www.wfae.org/2013-05-21/why-oklahomans-dont-like-basements [5] Expansive Soil, Colorado Geological Survey https://coloradogeologicalsurvey.org/hazards/expansive-soil/ [6] Understanding Efflorescence and Spalling: Critical Assessment Points for Home Inspectors, InterNACHI https://www.nachi.org/efflorescence-capillary-osmosis-spalling [7] InterNACHI Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [8] Foundation Fundamentals: Inspecting Load Paths and Water Paths (IRC R401.2 & R401.3), InterNACHI https://nachi.org/foundation-load-water.htm --- # How are foundation problems handled in an Oklahoma home sale? URL: https://terrabrain.vercel.app/rules/real-estate-disclosure-and-inspections-foundation-issues-in-oklahoma Answer: They surface through the seller's disclosure form, the buyer's inspection, the contract's repair window and lender rules; the 2026 form asks about past repairs. In short: In an Oklahoma home sale, foundation issues come up through four channels: the seller's disclosure form, the buyer's home inspection, the contract's inspection and repair window, and the lender's appraisal rules [1][3][5][6]. The 2026 disclosure form asks directly about previous foundation repairs [2]. Lenders can require repair or a professional report before a loan closes [6][7]. ## What does Oklahoma's seller disclosure law require? The Residential Property Condition Disclosure Act (60 O.S. §831 et seq.) covers residential property with one or two dwelling units [1]. Key points [1]: - A **defect** is a condition that would materially lower the property's value or impair the health or safety of future occupants. - The seller gives either a **disclosure statement** or, if the seller never occupied the property and knows of no defects, a **disclaimer statement**. The form must be completed no more than 180 days before the buyer receives it. - It must be delivered before an offer is accepted. A seller who later learns of a defect must promptly deliver an amended statement. - A seller is not liable for defects disclosed before acceptance, or for things outside the seller's actual knowledge. - Real estate licensees must disclose defects they actually know about, but have no duty to inspect. - The buyer's remedy is actual damages, including repair cost, with no punitive damages. Suits must be filed within two years after transfer. - Exemptions include court-ordered and certain foreclosure transfers and newly built, never-occupied homes. ## What does the 2026 disclosure form ask? Questions on the official form that touch foundations and drainage include [2]: | No. | Topic | |---|---| | 3 | Located in a FEMA-defined flood zone | | 7 | Damage from flood, storm run-off, sewer backup, or draining or grading defects | | 8 | Surface or groundwater drainage systems on the property | | 10 | Water seepage, leakage or other draining defects | | 12 | "Are you aware of any previous foundation repairs?" | | 14 | Defects affecting walls, slab or foundation, basement or storm cellar, floors, windows and doors | | 23 | Defects in sewer, septic or lateral lines | | 50 | Warranties covering the property, naming foundation warranties as an example | ## What do home inspections cover? Oklahoma home inspectors are licensed by the Construction Industries Board, need 90 hours of training and at least $50,000 in general liability insurance [4]. An inspector may be disciplined for doing repair work, or being paid by a repair company, on a one- to four-unit property the inspector inspected within the prior year [4]. Under the state standards of practice [3]: - Inspectors must inspect the foundation, including slabs, piers, columns, posts and stem walls, and **describe indicators of foundation or structural movement** (see the symptom matrix (https://terrabrain.vercel.app/guides/symptom-matrix)). - They are not required to enter crawl spaces with less than 18 inches of headroom or an opening smaller than 18 by 24 inches (see pier and beam crawl space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space)). - They are not required to determine causes, repair methods or materials, or to perform engineering. - Reports must recommend that reported conditions be corrected, **further evaluated** or monitored. Further evaluation means analysis by a qualified professional, tradesman or service technician. ## What is the sale contract timeline? On the 2026 state Residential Sale Contract [5]: - The buyer's inspection period is 10 days after the Time Reference Date if left blank. - Buyers may use licensed home inspectors, architects and registered professional engineers; a structural inspection is a listed option. - Within 24 hours after the period ends, the buyer either cancels or delivers a repair list (Treatments, Repairs and Replacements). - The parties then have 7 days, if left blank, to negotiate. Agreed repairs are completed by the seller before closing at the seller's expense unless agreed otherwise. - If the buyer does nothing within the deadlines, the buyer accepts the property regardless of its condition. ## What do lenders require? - **Conventional (Fannie Mae).** Deficiencies affecting safety, soundness or structural integrity make the appraisal "subject to" repair. A property rated C6 is ineligible until repaired. For abnormal settlement, the lender must show it was corrected or provide a professionally prepared report that it poses no threat of structural damage [6]. - **FHA.** HUD appraisal training lists cracked masonry or foundation damage, drainage problems including standing water against the foundation, and structural failure in framing among conditions requiring further inspection or repair by qualified individuals [7]. See working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers) for how engineer letters fit in. ## Related - Contracts, warranties and liens (https://terrabrain.vercel.app/rules/contracts-warranties-liens) - Inspection protocol (https://terrabrain.vercel.app/guides/inspection-protocol) - Legal and real estate data (https://terrabrain.vercel.app/data/legal-and-real-estate) - Construction history data (https://terrabrain.vercel.app/data/construction-history) - Symptom matrix (https://terrabrain.vercel.app/guides/symptom-matrix) Sources: [1] Residential Property Condition Disclosure Act (60 O.S. §831 et seq.), updated 2025, Oklahoma Real Estate Commission https://oklahoma.gov/content/dam/ok/en/orec/documents/contracts-and-forms-page/RPCD%20Act%20Updated%202025%20.pdf [2] 2026 Appendix A: Residential Property Condition Disclosure Statement, Oklahoma Real Estate Commission https://oklahoma.gov/content/dam/ok/en/orec/documents/contracts-and-forms-page/2026-contract-forms/2026%20Appendix%20A%20Residential%20Property%20Condition.pdf [3] OAC 158:70 Home Inspector rules, 158:70-1-3 Standards of workmanship and practice, Oklahoma Construction Industries Board https://oklahoma.gov/content/dam/ok/en/cib/documents/your-industry/home-inspector/title_158_chapter_70.pdf [4] Home Inspection Licensing Act, Title 59 §858-621 et seq., Oklahoma Construction Industries Board https://oklahoma.gov/content/dam/ok/en/cib/documents/your-industry/home-inspector/title_59_home_inspection_licensing_act.pdf [5] 2026 Residential Sale Contract, Oklahoma Real Estate Commission https://oklahoma.gov/content/dam/ok/en/orec/documents/contracts-and-forms-page/2026-contract-forms/2026%20Residential%20Sale.pdf [6] B4-1.3-06, Property Condition and Quality of Construction of the Improvements, Fannie Mae https://selling-guide.fanniemae.com/sel/b4-1.3-06/property-condition-and-quality-construction-improvements [7] Underwriting the FHA Appraisal, U.S. Department of Housing and Urban Development https://www.hud.gov/sites/documents/punder.pdf --- # How are interior slab piers installed by tunneling or coring? URL: https://terrabrain.vercel.app/repairs/interior-piers-tunnel-or-core Answer: Crews reach soil under the slab interior by tunneling from outside or coring through the floor. Interior piers address settlement only, not a heaved center. In short: Interior piers support the inside of a slab foundation, under interior beams or settled floor areas, instead of the outside edge. Crews reach the soil by tunneling under the slab from outside or by coring a hole through the floor. They address interior settlement only; they cannot pull down a center that has heaved upward. ## How do crews reach the soil? | | Tunneling | Coring | |---|---|---| | How | A tunnel is dug from outside the house, under the perimeter beam, to the pier locations | A round hole is cut through the slab at each pier location | | Inside the house | Floors are left in place | Flooring is removed at each hole and the slab patched afterward | | Afterward | The tunnel is backfilled | Holes are filled with concrete | | Main issue | Compacting the tunnel backfill; the code compacts fill under slabs in 8 to 12 in lifts [5] | Cutting the slab where tendons or plumbing may run | **Coring** means cutting a cylinder out of concrete with a diamond-tipped drill. A **tunnel** here is a crawl-height excavation under the slab. ## Where do interior piers go? Slab foundations can have interior footings under bearing walls, cast with the slab; in Seismic Design Categories D0 to D2 the code requires those footings to extend at least 12 in below the top of the slab [2]. Interior piers are typically set under these thickened beams or under areas of the slab that have settled, such as over soft or poorly compacted fill. Oklahoma's 2024 code adoption also sets limits on fill under slabs: compaction in 8 to 12 in lifts, with clean sand or gravel fill up to 48 in and earth fill up to 8 in [5]. ## What do Oklahoma install records show? Steel push piers rely on the weight above them to drive the pier down. Records from Oklahoma steel push pier installations show a clear difference between piers at the slab and at the perimeter footing [1]: | Location | Typical depth reached | Typical final pressure | |---|---|---| | At the interior slab | 8 to 11 ft | 4,000 to 5,000 psi | | At the perimeter footing | 13 to 17 ft | 7,000 to 8,000 psi | The slab readings fall below the 6,000 psi minimum used as the field standard in the same records [1]. One explanation consistent with these numbers is that a slab provides less weight to push against than a loaded perimeter footing, so the pier may stop because the slab lifts rather than because the pier has reached firm bearing. The records alone do not separate those two causes, so low-pressure interior piers are flagged on the installation log. ## What can interior piers not do? Interior piers lift or hold up; they cannot pull a slab down. That matters because a raised center is common on clay: - On a uniformly loaded rectangular slab, corners press on the soil with about one-fourth the pressure of the center, and corners tend to rise relative to the middle when clay swells [3]. - Research on slabs over expansive soil models a center-lift condition after a long dry period, and the effect of a water line leak under the slab center [4]. When the center is high and the edges are low, the movement is either center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) or perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop), and an elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) with heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) analysis is used to tell them apart. Where plumbing runs under the high area, leak testing is part of that analysis; see plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab). ## How do floating slabs and interior walls affect them? Engineering guidance for swelling soils notes that floating slabs are kept isolated from bearing walls, columns, stairs and utilities and that some cracking should be expected [6]. ## Can interior piers be used in post-tensioned slabs? Oklahoma's 2024 code adoption requires post-tensioned slabs on grade to carry a label on the electrical panel door [5]. Post-tensioned slabs contain tendons, steel cables stressed after the pour, so the slab type is identified before coring; see post-tensioned slabs (https://terrabrain.vercel.app/foundations/post-tensioned-slabs). ## Related - Slab on Grade (https://terrabrain.vercel.app/foundations/slab-on-grade) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Center Heave (Moisture Build-up Under Slab) (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) - Fill Consolidation Settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) - Slabjacking and Polyurethane (https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane) Sources: [1] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data [2] Steel Bones: Inspecting the Critical Role of Rebar in Foundation Strength (IRC R403.1-R403.1.6), InterNACHI https://www.nachi.org/footing-stem-wall-reinforcement-rebar.htm [3] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [4] Investigation of a leaking water line beneath residential foundation on expansive soils, American Society of Civil Engineers, Geotechnical Special Publication 147 (Michigan Technological University Digital Commons) https://digitalcommons.mtu.edu/michigantech-p/8670 [5] Adoption of International Residential Code 2024 (IRC 2024), Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2024%20IRC%20Code%20Changes%20Summary%20-%20for%20website.pdf [6] Home Construction on Shrinking and Swelling Soils (Special Publication 11), Colorado Geological Survey (Holtz and Hart, 1978) https://coloradogeologicalsurvey.org/wp-content/uploads/woocommerce_uploads/SP-11.pdf --- # How are manufactured homes set on piers in Oklahoma? URL: https://terrabrain.vercel.app/foundations/manufactured-homes-on-piers Answer: They rest on a steel chassis carried by concrete-block piers on small pads, held by anchors. Shallow pads ride up and down as Oklahoma clay swells and shrinks. In short: Most manufactured homes rest on a steel chassis carried by stacked concrete-block piers on small footing pads, held down by ground anchors and hidden by skirting. New homes in Oklahoma are installed to the federal HUD standard, and used homes to the manufacturer's manual, the state's generic standard or an engineer's plan. Because the pads sit near the surface, they ride up and down with Oklahoma clay as it swells and shrinks. ## How does the support system work? - **Chassis:** two or more steel I-beams running the length of each section. - **Piers:** stacks of 8 x 8 x 16 inch concrete blocks under the I-beams, with hollow cells set vertically [1]. - **Pads (footings):** precast or poured concrete, or solid blocks, under each pier [1][3]. - **Shims:** wedges that fill the last gap between pier cap and beam [1]. - **Anchors:** steel ground anchors and straps that resist wind uplift and sliding [1]. - **Skirting:** a perimeter screen that encloses the crawl space. ## Who sets the installation rules in Oklahoma? Installation of new homes, including site preparation, must follow HUD's Model Manufactured Home Installation Standards (24 CFR Part 3285) or manufacturer instructions approved by a design approval agency [2]. Used (previously occupied) homes may be set using the manufacturer's manual, the generic standard in state rules, or a plan approved by a professional engineer or registered architect [2]. Using an installer not licensed by the Oklahoma Used Motor Vehicle, Dismantler, and Manufactured Housing Commission is an unacceptable procedure for new or used homes [2]. ## What are the key numbers in the rules? | Item | Oklahoma generic standard (used homes) | HUD 24 CFR 3285 | |---|---|---| | Assumed soil bearing | At least 1,500 psf unless tested [3] | 1,500 psf default; high-plasticity clays (CH, MH) rated 1,000 psf [1] | | Footing pad | Three 4x8x16 solid blocks or one 4x16x16, at least 384 sq in [3] | Precast pads 4 in nominal; poured pads at least 6 in thick [1] | | Single-block piers | Under 36 in tall [3] | Frame piers under 36 in [1] | | Double interlocked piers | 36 to 67 in [3] | 36 to 67 in; over 67 in needs an engineer or architect [1] | | Pier spacing | No more than 6 ft on center; end piers within 2 ft of frame ends [3] | Per the HUD support tables, or an engineer's or architect's design [1] | | Shims | 4x6x1 in, in pairs, no more than 1 in total [3] | Same [1] | | Clearance to grade | At least 12 in under the lowest frame member [3] | At least 12 in [1] | | Site drainage | Not addressed in the support-system section [3] | Ground slopes at least 1/2 in per ft for the first 10 ft [1] | | Ground cover | Not addressed [3] | 6-mil polyethylene vapor retarder when skirted, seams lapped 12 in [1] | | Frost | Not addressed [3] | Conventional footings below the local frost line [1] | Under both standards, organic material such as grass and loose topsoil comes out from under each support [3], and HUD requires a registered professional for peat, organic clays or uncompacted fill [1]. ### Anchors HUD requires ground anchors certified by a registered engineer or architect, with a working load equal to the ultimate load divided by 1.5 [1]. Anchors listed before November 10, 2014 had to meet a 3,150 lb working load and 4,725 lb ultimate load [1]. HUD's soil table pairs each soil class with a torque-probe reading, and high-plasticity clays without test data must use anchors rated for the weakest clay class, 4B [1]. ## Why do piers move on Oklahoma clay? Under the generic standard, pads rest on firm undisturbed soil (or fill compacted to at least 90 percent) once grass and loose topsoil are removed [3], so they bear on the soil layer that changes moisture most with the seasons. Seasonal moisture change in clay can extend from 3 to 40 ft deep, and lightly loaded supports in that zone can be lifted in wet seasons and drop in dry ones [5]. Oklahoma State University testing of western Oklahoma benchmark soils found montmorillonite-rich clays, with Kirkland rated severe and Bethany and Norge rated moderate as sites for low buildings because of shrink-swell [4]. The results show up as: - Perimeter piers and center frame piers moving by different amounts, racking the floor [5] (interior support and framing failure (https://terrabrain.vercel.app/causes/interior-support-and-framing-failure-crawl)). - Shims loosening in dry months or the home being pushed up in wet months, the seasonal lift-and-drop cycle described for lightly loaded supports [5]. - Water ponding under skirting where the site was not graded to drain [1]. ## How are manufactured home piers repaired? Re-leveling with shims resets the home on the same shallow pads. Supports that reach below the moving layer, such as helical piers (https://terrabrain.vercel.app/repairs/helical-piers), steel adjustable piers on new footings, and site drainage are covered under crawl space repair (https://terrabrain.vercel.app/repairs/crawl-space-repair), drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) and crawl space encapsulation (https://terrabrain.vercel.app/repairs/crawl-space-encapsulation). Statewide figures are collected in OK Data - Manufactured Homes (https://terrabrain.vercel.app/data/manufactured-homes). ## Related - OK Data - Manufactured Homes (https://terrabrain.vercel.app/data/manufactured-homes) - Crawl Space Repair (https://terrabrain.vercel.app/repairs/crawl-space-repair) - Helical Piers (https://terrabrain.vercel.app/repairs/helical-piers) - Surface Drainage and Grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) Sources: [1] 24 CFR Part 3285 – Model Manufactured Home Installation Standards (Code of Federal Regulations, 2020), U.S. Government Publishing Office https://www.govinfo.gov/content/pkg/CFR-2020-title24-vol5/pdf/CFR-2020-title24-vol5-part3285.pdf [2] Section 765:37-7-1 – Acceptable procedure (Oklahoma Administrative Code), Justia https://regulations.justia.com/states/oklahoma/title-765/chapter-37/subchapter-7/section-765-37-7-1 [3] Okla. Admin. Code § 765:37-7-3 – Support Systems, Legal Information Institute, Cornell Law School https://law.cornell.edu/regulations/oklahoma/OAC-765-37-7-3 [4] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [5] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf --- # How are sagging crawl space floors repaired? URL: https://terrabrain.vercel.app/repairs/crawl-space-repair Answer: Crawl space repair adds supports on proper footings, shims, added beams, reinforced joists and new sill plates, designed to be adjusted as Oklahoma clay moves. In short: Crawl space repair re-supports and strengthens the floor system of a pier and beam or manufactured home. Typical work includes new supports on proper footings, steel or new shims, added beams, reinforced joists and replaced sill plates. In Oklahoma clay, interior supports keep moving with the seasons, so repairs are designed to be adjusted later. ## What gets repaired in a crawl space? | Problem | Typical repair | Notes | |---|---|---| | Sagging floor over settled interior piers | New supports on new footings, set to the corrected height | Shallow pads sit in the seasonal moisture zone [4] | | Crushed or rotted wood shims | Replacement shims, often steel | Wood in contact with or near soil is reported as a defect [2] | | Undersized or cracked beam | Added beam, replacement beam, or a new support at mid-span | Inspectors do not judge beam size or span [2] | | Over-spanned, cut or notched joists | **Sistering**: fastening a new joist alongside the damaged one; or an added beam | Cutting, notching or boring that may be a structural concern is reported [2] | | Rotted sill plate | Temporary shoring, new sill, re-anchoring to the stem wall | Anchor bolt rules below [3] | | Leaning or crumbling brick piers | Rebuilt or replaced supports | Same seasonal movement applies [4] | | Perimeter settlement | Perimeter piers | See the method selection matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix) | **Adjustable supports** are steel posts with a threaded section that lets the height be changed after installation, set on a concrete footing or on a pier. ## Why do interior supports move in Oklahoma? Seasonal moisture change in clay can extend from 3 to 40 ft deep, and lightly loaded supports in that zone can be lifted when clay swells in the wet season, then lose grip and drop when it shrinks in the dry season [4]. Interior piers on small, shallow pads rest in exactly that layer. A crawl space floor can be re-shimmed after such movement, which is not possible under a slab. ## How are shims, caps and anchor bolts used? - **Shim limits:** Oklahoma installation records cap shim stacks at no more than four per support [6]. - **Manufactured homes:** HUD's standard calls for 4 x 6 x 1 in shims used in pairs and driven tight, occupying no more than 1 in of height, with pier caps of solid concrete or masonry at least 4 in thick, lumber at least 2 in nominal, or corrosion-protected steel at least 1/2 in [5]. - **Sill anchoring:** sill plates are held by anchor bolts at least 1/2 in in diameter, no more than 6 ft apart and embedded at least 7 in, with a bolt within 12 in of each end [3]. - **Oklahoma rule:** the state's 2024 code adoption does not approve hand-driven cut nails or concrete nails as sill fasteners [7]. - **Decay protection:** sill plates must be protected against decay and termites where the code requires [3]. ## What moisture work goes with structural repair? Structural repair in a damp crawl space is paired with moisture work such as: - Removing vegetation and organic debris from the crawl floor, which the code requires [1]. - Covering the ground with a vapor retarder; with a Class I retarder, required vent area drops from 1 sq ft per 150 sq ft to 1 per 1,500 [1]. - Correcting grade or adding drainage where groundwater rises within 6 in of the finished floor or surface water drains poorly [1]. - Closing the crawl space as an unvented space under the code's conditions; see crawl space encapsulation (https://terrabrain.vercel.app/repairs/crawl-space-encapsulation). ## What access and safety issues apply? The code requires crawl space access openings of at least 18 x 24 in through a floor or 16 x 24 in through a wall [1]. Inspection standards do not require inspectors to enter crawl spaces that are not readily accessible or could be hazardous [2], so some damage is first found during repair. ## Why are re-checks needed after repair? Because clay keeps cycling with the seasons [4], adjustable supports are re-checked and re-shimmed as needed. Over-correction after a drought lift is covered under over-lift heave after drought lift (https://terrabrain.vercel.app/causes/over-lift-heave-after-drought-lift), and ongoing readings under the monitoring program (https://terrabrain.vercel.app/repairs/monitoring-program). ## Related - Pier and Beam Crawl Space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) - Interior Support and Framing Failure (Crawl) (https://terrabrain.vercel.app/causes/interior-support-and-framing-failure-crawl) - Sagging Floor Between Supports (https://terrabrain.vercel.app/signs/sagging-floor-between-supports) - Bouncy or Soft Floors (https://terrabrain.vercel.app/signs/bouncy-or-soft-floors) - Crawl Space Encapsulation (https://terrabrain.vercel.app/repairs/crawl-space-encapsulation) Sources: [1] Inspecting Under-Floor Crawl Spaces: A Guide for Home Inspectors (2024 IRC Section R408), InterNACHI https://www.nachi.org/under-floor-crawl-space.htm [2] InterNACHI Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [3] Securing the Perimeter: Inspecting Foundation Anchor Bolts and Sill Plate Protocols (IRC R403.1.6), InterNACHI https://www.nachi.org/foundation-anchor-bolts-sill-plate.htm [4] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [5] 24 CFR Part 3285 – Model Manufactured Home Installation Standards (Code of Federal Regulations, 2020), U.S. Government Publishing Office https://www.govinfo.gov/content/pkg/CFR-2020-title24-vol5/pdf/CFR-2020-title24-vol5-part3285.pdf [6] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data [7] Adoption of International Residential Code 2024 (IRC 2024), Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2024%20IRC%20Code%20Changes%20Summary%20-%20for%20website.pdf --- # How are under-slab plumbing leaks found and repaired? URL: https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair Answer: Supply leaks are found with a water-meter check and drain leaks with a hydrostatic test and camera; in Oklahoma the repair is licensed plumbing work. In short: Leaks in water supply lines or sewer drains under a slab add water to the soil, and on expansive clay that water can make the ground swell under the foundation [3]. Supply leaks are usually found with a water-meter check, and drain leaks with a hydrostatic (water-level) test followed by a camera inspection [1][2]. In Oklahoma, the repair itself is licensed plumbing work [4]. ## Why do plumbing leaks matter for foundations? Most Oklahoma homes built on a slab have water supply pipes and sewer drains running in the soil under the concrete. When one leaks, it wets the clay in one area. Expansive clay swells as it takes on water, so a leak can push part of a slab up — called **heave** — while the rest stays put. Engineering research modeling a leaking water line under a slab on expansive soil found that leaks can cause differential movement and added bending stress in the foundation [3]. Leaks are also linked to problems after a foundation has been repaired. An engineering committee review lists leaking sewer or water lines as a cause of renewed movement after mudjacking, foam injection and pressed piles [5]. Leaks can play a part in several movement patterns: - Leak-induced localized heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave) — a wet "bulb" of swollen clay lifts one area. - Center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) — moisture builds up under the middle of the slab. - Erosion and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) — running water carries soil away and leaves gaps. - Hydrocollapse (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil) — some loose, dry soils compact suddenly when soaked. Because adding lift to an area that is already high makes things worse, the water source is typically found and stopped before any lifting is planned. ## How are supply leaks detected? Pressurized water lines leak constantly, so the water meter is the first check. - **Two-hour meter test:** Record the meter, use no water for two hours, then read it again. If the reading changes at all, a leak is likely [1]. - **Winter usage check:** EPA notes that a family of four using more than 12,000 gallons a month in a cold month such as January or February probably has a serious leak [1]. - **Scale of the problem:** EPA estimates that about 9% of homes have leaks wasting 50 gallons or more per day [1]. An unexplained high water bill (https://terrabrain.vercel.app/signs/unexplained-high-water-bill) is often the first clue. Once a leak is confirmed, a plumber narrows down its location before opening the slab. ## How are drain and sewer leaks tested? Drain lines are not under pressure, so they do not move the meter. A **hydrostatic test** is used instead [2]: 1. An inflatable plug seals the main sewer line through a cleanout. 2. The under-slab drain system is filled with water up to slab level. 3. The water level is watched for up to about 15 minutes. A drop suggests a leak. 4. Follow-up uses a video camera in the line and isolation testing of individual branches to pinpoint the leak. Some facts about this test from a city building department bulletin [2]: - There is no general requirement to hydrostatically test existing homes; it is often done during a sale inspection. - Testing is most often requested on older homes with cast-iron drain pipe (generally homes built before the early 1970s) and on homes with earlier foundation repair. - Shallow sewer lines sit under only about 1 to 2.5 psi of water pressure in the test, which is low enough to reveal existing leaks rather than create new ones. - Not every small drain leak releases enough water in normal use to threaten a foundation. Engineering guidelines for underpinning list a hydrostatic leak test report for under-slab sewer and water lines among the records kept for a pier job [7]. See slow drains or sewer backups (https://terrabrain.vercel.app/signs/slow-drains-or-sewer-backups) and plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) for the warning signs. ## What are the repair options? Once a leak is located, the plumber's options range from repairing a single section through the slab, to rerouting a line around the slab, to lining or replacing longer runs of pipe. The choice depends on the pipe material, its age and how many leaks the testing finds. Cost is driven mainly by the number of leaks, how much concrete must be opened or tunneled under, and the length of pipe involved. ## Who may repair leaks in Oklahoma? Oklahoma's plumbing rules state that no person or firm may perform plumbing work without first obtaining the appropriate license or registration [4]. The Construction Industries Board licenses plumbing contractors and journeymen, including residential categories limited to one- and two-family homes and townhouses; journeymen must work for a licensed contractor [4]. ## What ongoing checks help? A foundation maintenance guide suggests checking for dripping faucets, air-conditioner condensate drips (especially from the overflow line) and stoppages, and fixing local moisture sources as soon as possible [6]. Leak coverage and insurance questions are covered in plumbing leaks and insurance in Oklahoma (https://terrabrain.vercel.app/rules/plumbing-leaks-and-insurance-oklahoma). ## Related - Plumbing Leaks Under Slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) - Leak-Induced Localized Heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave) - Unexplained High Water Bill (https://terrabrain.vercel.app/signs/unexplained-high-water-bill) - Plumbing Leaks and Insurance - Oklahoma (https://terrabrain.vercel.app/rules/plumbing-leaks-and-insurance-oklahoma) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) Sources: [1] Fix a Leak Week, U.S. Environmental Protection Agency (WaterSense) https://www.epa.gov/watersense/fix-leak-week [2] Informational Bulletin 15-02: Testing of Drain, Waste, Vent Systems, City of Amarillo Department of Building Safety https://amarillo.gov/home/showpublisheddocument/5292/636421987410570000 [3] Investigation of a leaking water line beneath residential foundation on expansive soils, Geotechnical Special Publication 147, ASCE (via Michigan Technological University) https://digitalcommons.mtu.edu/michigantech-p/8670 [4] Chapter 30. Plumbing Industry Regulations (OAC 158:30), Oklahoma Construction Industries Board https://oklahoma.gov/content/dam/ok/en/cib/documents/your-industry/plumbing-industry/title_158_chapter_30.pdf [5] Post Foundation Repair Performance of Residential and Other Low-Rise Buildings on Expansive Soils (FPA-RC-01-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-RC-01-0.pdf [6] Foundation Maintenance and Inspection Guide for Residential and Other Low-Rise Buildings (FPA-SC-07-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-07-0.pdf [7] Design, Manufacture, and Installation Guidelines of Precast Concrete Segmented Piles For Foundation Underpinning (FPA-SC-08-1), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-08-1.pdf --- # How can Oklahoma Mesonet soil moisture data explain foundations? URL: https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros Answer: The Oklahoma Mesonet is a free statewide network reporting soil moisture. Its shallow readings show whether ground is drier or wetter than usual, as trends. In short: The Oklahoma Mesonet is a free, statewide network of weather stations that reports rainfall, temperature and soil moisture for every county. Its soil moisture readings show whether the ground near a home is drier or wetter than usual, which helps explain why clay soils are shrinking or swelling. The sensors are shallow, so they show trends rather than conditions at foundation or pier depth. ## What is the Oklahoma Mesonet? The Mesonet was officially commissioned on January 1, 1994, and is a joint project of the University of Oklahoma and Oklahoma State University, operated by the Oklahoma Climatological Survey [1]. The current network has 120 stations [1]. Stations are located in all 77 Oklahoma counties at an average spacing of about 18 miles [2]. Rainfall is recorded every 5 minutes and soil moisture every 30 minutes [2]. ## What soil moisture data does it report? ### Sensor depths Most Mesonet sites have four soil moisture sensors, at 2, 4, 10 and 24 inches (5, 10, 25 and 60 cm) below the surface [3]. The 4-inch depth is the only one measured under both grass and bare soil [3]. ### Fractional water index The fractional water index (FWI) is a normalized sensor reading that runs from 0 to 1 [3]. On the Mesonet's maps, 0 means the soil is about as dry as the sensor can read and 1 means it is about as wet as the sensor can read [4]. OSU Extension describes 0 as near the wilting point (plants can't pull water) and 1 as near field capacity (soil holding as much as it can drain to) [3]. A few practical notes from the sources: - Soil moisture can't be measured when the ground is frozen, so winter maps can have gaps [4]. - The rate at which soil moisture falls reflects how hot and dry the air is; it drops faster in hot, dry spells [3]. - Comparing depths after a rain shows how deep the water soaked in [3]. ### Other useful readings - **Rainfall totals** from the 5-minute gauges [2]. - **U.S. Drought Monitor** categories (D0–D4), updated every Thursday and built partly from soil moisture data [5]. ## How does Mesonet data connect to foundations? Expansive clay swells when it gets wet and shrinks when it dries, and uneven moisture under a slab causes differential movement, meaning one part of the house moves more than another [6]. Oklahoma State University researchers have used Mesonet climate data to map long-term soil moisture conditions for foundation design across the state [6]. The limits matter. The deepest standard sensor is about 2 feet down [3], while studies of Houston-area clay sites judged seasonal moisture change to reach about 8–12 feet, deepening by about 2 feet during the 2011 drought [7]. Mesonet readings therefore show whether the near-surface soil is unusually dry or wet, not the moisture at the depth where piers bear. More detail is on the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) page. ### Ways the data is commonly used - Recording the nearest station's soil moisture and drought category on the date of an elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) or repair, so later surveys can be compared under similar conditions. - Explaining why cracks open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally). - Putting lift decisions in context: lifting while soil is at its driest can be followed by swelling when it rewets, as described under over-lift heave (https://terrabrain.vercel.app/causes/over-lift-heave-after-drought-lift). ## Related - Drought and Wet Cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) - Seasonal Movement Calendar (https://terrabrain.vercel.app/guides/seasonal-movement-calendar) - OK Data - Moisture Index by City (https://terrabrain.vercel.app/data/moisture-index-by-city) - Monitoring Program (https://terrabrain.vercel.app/repairs/monitoring-program) Sources: [1] History of the Mesonet, Oklahoma Mesonet https://mesonet.org/about/history-of-mesonet [2] Oklahoma Mesonet, Oklahoma State University Extension https://extension.okstate.edu/programs/mesonet [3] Tracking Drought Using Soil Moisture Information (BAE-1541), Oklahoma State University Extension https://extension.okstate.edu/fact-sheets/tracking-drought-using-soil-moisture-information.html [4] 1-day Average 4-inch Bare Soil Fractional Water Index, Oklahoma Mesonet https://mesonet.org/weather/soil-moisture/1-day-average-4-inch-bare-soil-fractional-water-index [5] U.S. Drought Monitor (USDM), Drought.gov (NOAA National Integrated Drought Information System) https://www.drought.gov/data-maps-tools/us-drought-monitor-usdm [6] Residential House Foundations on Expansive Soils in Changing Climates, HUD Office of Policy Development and Research (Cityscape, Vol. 25 No. 1) https://www.huduser.gov/PORTAL/periodicals/cityscape/vol25num1/ch10.pdf [7] Ground Conditions in the 2011 Drought, CIGMAT Conference, University of Houston https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2012/3.pdf --- # How deep did steel piers go across a large Tulsa apartment complex? URL: https://terrabrain.vercel.app/case-studies/tulsa-apartment-complex-steel-pier-depths Answer: Across 396 logged piers at a 34-building Tulsa complex, refusal depth ranged 2 to 40 ft, median 12 ft, at a median 9,000 psi driving pressure. In short: A large apartment complex in Tulsa, 34 buildings on about 30 acres, was underpinned with several hundred steel push piers plus polyurethane foam and crack stitching in 2025-2026. The engineer's drawings specified galvanized steel piers driven to refusal on bedrock and repeatedly pointed to roof water and drainage; the pier logs show refusal depth varied from 2 to 40 ft across the site [1]. ## What did the buildings show? The engineer's drawings marked pier locations and foam-injection areas building by building, but did not include a written narrative, soil borings or a stated cause [1]. One building next to a retaining wall was described as appearing to subside on its south side "due to bad site drainage and uncontrolled water from roof" [1]. ## What did the engineer find was causing it? No cause was written up. Standard notes on every sheet called for gutters on all eaves and stated that better drainage around each building would improve structural stability. A second engineer, answering a question about the retaining-wall building, specified 16 piers, removal of nearby trees, a French drain behind the retaining walls, and gutters routed to swales away from the walls [1]. ## What repair was specified? - 469 galvanized steel push piers at exterior footings, hydraulically driven to refusal at bedrock; plan spacing typically 3 to 5 ft, with some 6 to 7 ft spans. No pier diameter, capacity, safety factor or minimum depth was given [1]. - About 32,400 sq ft of 1.75 lb/cu ft two-component polyurethane foam under interior slabs, after a passing hydrostatic plumbing test [1]. - Concrete and carbon fiber crack stitching set in structural epoxy [1]. - Slab procedures: plumbing test after repair, probe for utilities after drilling, gradual lift checked with survey equipment, no over-jacking [1]. ## What happened on the job? Work ran in five phases from September 2025 into 2026. Of 469 planned piers, 396 have both a logged depth and pressure. Buildings that first needed siding or wall demolition for access are the ones with missing logs [1]. Logged results [1]: | Measure | Value | |---|---| | Refusal depth, median | 12 ft | | Middle half of depths | 9 to 14 ft | | Full range | 2 to 40 ft | | Driving pressure, median | 9,000 psi | | Pressure range | 2,500 to 10,000 psi | | Piers deeper than 20 ft | 14 | - Phase medians ranged from 10 ft to 20 ft. In one phase every pier went at least 10 ft (median 15 ft); one building's piers ranged from 7 to 40 ft, two of them stopping at 40 ft at 6,000 psi [1]. - In two buildings depths split into two groups: about 4 to 7 ft at 2,500 to 4,500 psi, and about 10 to 13 ft at 7,500 to 9,000 psi [1]. - A few piers refused at 2 to 5 ft at 8,000 to 10,000 psi, flagged in the record for verification [1]. - Where no footing was found and piers were set at the slab, they stopped at 8 to 12 ft and 4,000 to 5,000 psi [1]. - In the last phase, 171 of 192 piers were logged at exactly 10,000 psi; the documents do not state a termination criterion [1]. - Depth and pressure were almost uncorrelated (r = -0.06 across all 396; r = +0.24 excluding piers at 10,000 psi) [1]. - At one building the log notes "foam heaved," and the engineer's table noted a hump in one unit [1]. ## What does this case show about Oklahoma foundations? Depth to a pier-stopping layer is not uniform even within one property. Tulsa-area Pennsylvanian rock is a stack of shales, sandstones and limestones whose thickness changes across short distances; one limestone mapped in the area thins from well over 100 ft to about 8 ft southward [2]. On this site, piers on the same complex stopped anywhere from 2 to 40 ft down [1]. Water was the cause the engineers could point to. Federal building-science guidance notes that a few inches of rain on a roof produces thousands of gallons of runoff and that water pooled near a building can damage foundations on expansive soils [3]. The engineers' standard notes, and their answer for the retaining-wall building, were about controlling that roof water [1]. ## Related - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Slabjacking and Polyurethane (https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane) - Depth to Rock from Borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings) - Bedrock - Tulsa Metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro) - Pennsylvanian Shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) Sources: [1] Project record: engineer's pier and foam drawings, field observation tables, RFI response and pier logs, 2025-2026 (private client records), Licensed professional engineers, Oklahoma; repair contractor field logs [2] The "Oologah" limestone and associated formations in the Tulsa area (Proceedings of the Oklahoma Academy of Science, 1931), Oklahoma Academy of Science https://ojs.library.okstate.edu/osu/index.php/OAS/article/view/2728/2425 [3] Gutters and Downspouts (Building America Solution Center), U.S. Department of Energy / Pacific Northwest National Laboratory https://basc.pnnl.gov/resource-guides/gutters-and-downspouts --- # How deep do foundation piers need to go in Oklahoma shale? URL: https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata Answer: Shale weathers top-down into clay; piers aim for firmer material below the shrink-swell layers, and Oklahoma push pier records run about 8 to 16 feet. In short: Oklahoma shale weathers from the top down: hard rock at depth grades upward into softer, broken shale and then into clay soil. The upper clay and weathered layers are the ones that shrink and swell, so repair piers are meant to reach firmer material below them. Typical push pier depths in Oklahoma installation records run about 8 to 16 feet, but each site differs. ## What does the shale weathering profile look like? From the surface down, a typical shale profile looks like this: 1. **Topsoil or fill**: organic, loose surface material or soil brought in during construction. 2. **Residual clay**: shale that has fully broken down into clay. This is the expansive, moisture-sensitive layer. 3. **Weathered shale**: soft, blocky rock that can still be dug and still reacts to water. Soil surveys call its top a **paralithic contact**. 4. **Competent rock**: firmer shale, sandstone or limestone. Soil surveys call the top of hard rock a **lithic contact**. USDA soil descriptions show how variable this is in Oklahoma: | Soil series | Parent rock | Depth to rock | Source | |---|---|---|---| | Collinsville | Pennsylvanian sandstone | Hard sandstone at about 4–20 in. | [4] | | Eram | Shale with thin sandstone beds | Soft shale at 20–40 in. (about 30 in. typical) | [1] | | Kirkland | Clayey sediments over Permian shale | Weakly cemented siltstone at about 82 in. in the typical profile | [3] | | Dennis | Pennsylvanian shale | Soil layers more than 60 in. thick; no rock depth given | [2] | Eram's weathered layer is described as gray or olive shale or compacted clay beds with thin sandstone [1], and Kirkland's bedrock is described as weakly consolidated shale, clay or siltstone [3]. In other words, the transition from soil to rock is often gradual. The Oklahoma Geological Survey notes that the state's thickest accumulation of strata is of Pennsylvanian age, mainly river, delta and shallow-marine deposits [5]; Pennsylvanian shales and sandstones underlie the Tulsa area. See Pennsylvanian shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales) and Bedrock - Tulsa Metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro). ## Where does the active zone sit? The active zone, the depth of soil whose moisture changes seasonally, mostly lies in the clay and weathered layers. At four studied Houston clay sites it was about 8–10 feet before the 2011 drought and 10–12 feet during it [7]. A structural engineering article on expansive clay describes pier bearing strata as lying below the zone of seasonal moisture variation, typically a minimum of 15 feet or deeper [6]. More detail is on shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). ## Why does bearing depth matter for each pier type? - **Steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers)** are driven until they reach a layer that resists the load; the depth where that happens is the bearing depth. - **Pressed concrete piles (https://terrabrain.vercel.app/repairs/pressed-concrete-piles)** rely on a mix of end bearing and side friction, so stiff, dry clay can produce resistance at shallower depth during drought. - **Helical piers (https://terrabrain.vercel.app/repairs/helical-piers)** are screwed in, and installation torque is used to estimate capacity. - **Drilled bell-bottom piers (https://terrabrain.vercel.app/repairs/drilled-bell-bottom-piers)** are drilled and widened at the base; belled piers anchor against uplift from swelling soil [6]. ### Typical Oklahoma depths Oklahoma steel push pier installation records show depths of roughly 8 to 16 feet, with a median of about 12 feet in Tulsa, at installation pressures around 9,000 psi and a 6,000 psi minimum [8]. These are field records rather than a design rule; each pier's depth and final pressure are normally logged so they can be compared with nearby borings and with the soil series. A pier that stops shallow in known expansive clay may be resting within the active zone rather than below it, which is why refusal depth is compared against site data. See loads, pier spacing and capacity (https://terrabrain.vercel.app/guides/loads-pier-spacing-and-capacity). ## Related - Method Selection Matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix) - Borings - Depth to Rock in Tulsa and OKC (https://terrabrain.vercel.app/data/borings-depth-to-rock-in-tulsa-and-okc) - Pier Uplift or Movement After Repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair) - Oklahoma Geologic Provinces (https://terrabrain.vercel.app/guides/oklahoma-geologic-provinces) - Bedrock - OKC Metro (https://terrabrain.vercel.app/guides/bedrock-okc-metro) Sources: [1] Official Series Description - ERAM Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/E/ERAM.html [2] Official Series Description - DENNIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DENNIS.html [3] Official Series Description - KIRKLAND Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KIRKLAND.html [4] Official Series Description - COLLINSVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COLLINSVILLE.html [5] Structural / Tectonic Map of Oklahoma (GM-46), Oklahoma Geological Survey https://www.ou.edu/content/dam/ogs/documents/GMs/GM-46_Structural_Tectonic_Map_of_Oklahoma.pdf [6] Expansive Soils (The Mystery), STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [7] Ground Conditions in the 2011 Drought, CIGMAT Conference, University of Houston https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2012/3.pdf [8] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # How deep does Oklahoma soil dry out during drought? URL: https://terrabrain.vercel.app/data/active-zone-and-drought-depth Answer: Oklahoma Mesonet research puts the active zone of seasonal moisture change at about 0.5 to 4 meters (1.6 to 13 feet), depending on soil and climate. In short: Research using Oklahoma Mesonet data puts the depth of seasonal soil moisture change, called the active zone, at about 0.5 to 4 meters (roughly 1.6 to 13 feet), depending on the soil and climate. In the severe 2022 drought, Mesonet sensors recorded critically dry soil down to at least 32 inches. Typical steel pier depths in Tulsa sit below most of that range. ## What is the active zone? Clay soil swells as it takes on water and shrinks as it dries. Near the surface, rain, heat and plants change soil moisture all year. Deeper down, moisture stays nearly constant. The **active zone** is the layer in between that goes through seasonal wet-dry change, and it is where most foundation movement starts. A full explanation is in shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). Engineers often track this with **soil suction**, a measure of how tightly dry soil holds onto water. Where suction stops changing with the seasons is the bottom of the active zone. ## How deep is the active zone in Oklahoma? An Oklahoma State University study combined field measurements from the Oklahoma Mesonet and the U.S. Department of Energy's Atmospheric Radiation Measurement network with modeling [1]. Its findings: | Finding | Detail | |---|---| | Active zone depth | About 0.5 to 4 m (1.6 to 13 ft) [1] | | Main controls | Soil diffusion coefficient and saturated hydraulic conductivity (how fast moisture moves through the soil) [1] | | Most climate-sensitive layer | Shallower soil [1] | | Seasonal pattern | Soil suction follows a seasonal cycle [1] | The wide range reflects how differently Oklahoma soils transmit moisture: the study identified the rate at which moisture moves through soil as the key control on how deep seasonal change reaches [1]. ## How do cracks carry drying deeper? When clay shrinks it cracks, and open cracks let air and heat reach soil far below the surface. NRCS Official Series Descriptions record this for Oklahoma-area clays: - **Durant** (type location in Bryan County, Oklahoma): cracks more than 1 cm wide and 30 inches deep form during dry periods [4]. - **Hollister** (type location in Hardeman County, Texas): cracks more than 30 inches (76 cm) deep stay open 150 or more cumulative days in most years [5]. These cracks are one reason drought drying can extend below what normal seasons reach. See Durant (https://terrabrain.vercel.app/soils/durant) and Hollister (https://terrabrain.vercel.app/soils/hollister). ## What do Mesonet drought records show? | Drought | What was measured | |---|---| | August 2011 | 93% of Oklahoma in extreme to exceptional drought (D3 to D4), with 65% in exceptional drought (D4) [3] | | August 2012 | About 97% of the state in D3 to D4, the highest coverage since the Drought Monitor began in 2000 [3] | | September 2022 | Mesonet measured critically dry soils down to at least 32 inches; 64% of the state in D3 to D4 and 94% in severe drought or worse [2] | D-levels come from the U.S. Drought Monitor: D2 is severe, D3 extreme and D4 exceptional drought. For year-by-year history, see drought and wet years (https://terrabrain.vercel.app/data/drought-and-wet-years), and for how to read live soil moisture, see Mesonet for foundation pros (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros). ## How do pier depths compare to the active zone? Oklahoma steel push pier installation records show piers in Tulsa typically reaching 8 to 16 feet, with a median of about 12 feet [6]. That is deeper than most of the 1.6 to 13 foot active zone range estimated for the state [1][6]. A pier that stops at a shallow depth in late summer, when clay near the surface is at its driest and hardest, may be resting within the active zone rather than below it. See steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) and seasonal movement calendar (https://terrabrain.vercel.app/guides/seasonal-movement-calendar). Large trees near a house add their own drying of the clay; see trees and roots (https://terrabrain.vercel.app/guides/trees-and-roots). ## Related - Shrink-swell and active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Drought and wet years (https://terrabrain.vercel.app/data/drought-and-wet-years) - Drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) - Mesonet for foundation pros (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros) - Perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Trees and roots (https://terrabrain.vercel.app/guides/trees-and-roots) Sources: [1] Soil matric suction and active zone depth in Oklahoma, Oklahoma State University (SHAREOK repository) https://shareok.org/handle/11244/54639 [2] Oklahoma Monthly Climate Summary, September 2022, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2022/MCS_September_2022.pdf [3] Extreme to Exceptional Drought Covers Most of Oklahoma, Oklahoma Mesonet https://mesonet.org/images/news/Extreme%20to%20Exceptional%20Drought%20Covers%20Most%20of%20Oklahoma.pdf [4] Official Series Description - DURANT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DURANT.html [5] Official Series Description - HOLLISTER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/H/HOLLISTER.html [6] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # How deep is bedrock in Tulsa and Oklahoma City? URL: https://terrabrain.vercel.app/data/borings-depth-to-rock-in-tulsa-and-okc Answer: Public borings show rock about 9 to 15 feet under upland shale in Tulsa; in Oklahoma City, Hennessey shale ran 2 to 41 feet and Garber sandstone 20 to 95. In short: Public geotechnical borings show rock at roughly 9 to 15 feet under upland shale in Tulsa, which lines up with typical steel pier depths there. Oklahoma City is more variable: Hennessey shale can sit 2 to 41 feet down, and Garber sandstone in the Edmond area was 20 to 95 feet down. Creek bottoms and river banks are the deep cases in both metros. ## What do these boring numbers mean? A boring is a test hole drilled by a geotechnical engineer to log soil and rock. These reports separate two depths: - **Weathered rock:** the top of shale, sandstone or limestone that has broken down and is softer than the rock below. Engineers sometimes call it intermediate geomaterial. - **Competent rock:** hard rock as each report defines it, usually by auger refusal (the drill can't advance), standard penetration test refusal, or a Texas Cone Penetrometer reading. Each report draws these lines a little differently, so treat depths as close guides. For the geology behind them, see shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata). ## What do Tulsa metro borings show? ### East Tulsa shale (S 193rd E Ave, 31st to 41st St) Nine borings for a sewer project found weathered rock at 1 to 8 feet and competent shale or limestone at 4 to 14.5 feet [1]. | Boring | Weathered rock (ft) | Competent rock (ft) | Water at end of drilling (ft) | |---|---|---|---| | B-1 | 7.5 | 9.5 | 7 [1] | | B-2 | 7 | 14.5 | not encountered [1] | | B-3 | 7 | 9.5 | not encountered [1] | | B-4 | 1 | 4 | not recorded [1] | | B-6 | 8 | 9 | not encountered [1] | | B-7 | 7 | 8.5 | not encountered [1] | | B-8 | 7 | 8.5 | 7 [1] | | B-9 | 8 | 11 | 9.5 [1] | | B-10 | 7.5 | 14.5 | not encountered [1] | Rock cores from B-4 tested at 4,880 to 9,560 psi in unconfined compression, and the report expected that a pneumatic hammer or blasting would be needed to excavate [1]. ### South Tulsa, 91st St between Memorial and Mingo Five borings for one retaining wall hit highly weathered Nowata shale at about 13.5 feet and weathered shale at about 18.5 feet, and were dry [2]. Two borings for a second wall found clay all the way to 30 and 35 feet with no shale, and water at 13.5 to 15 feet [2]. Clay samples had liquid limits up to 56 and plasticity index up to 39 [2]. See soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values) for what those numbers mean. ### Central Tulsa, I-44 and US-75 Ten borings in the Holdenville unit reached competent rock at 13.5 to 14.5 feet on one wall and 18.5 to 19.5 feet on the other [3]. Groundwater appeared during drilling in several holes but none was found after drilling [3]. ## What do Oklahoma City metro borings show? ### Hennessey shale, I-35/I-240 interchange The Hennessey unit is red clay shale and mudstone [4]. Depth to bedrock varied widely across three structures: | Structure | Depth to bedrock by boring (ft) | |---|---| | Retaining Wall C2 | 16, 5.5, 2, 2, 2 [4] | | Bridge D | 10.5, 15, 16, 21, 10.5 [5] | | Bridge C (under alluvium) | 35.5, 17.5, 21, 41 [6] | No groundwater was observed at Bridge D or Bridge C, while one Wall C2 boring had water at 20 feet [4][5][6]. The Wall C2 report noted saturated overburden in places as shallow as 3 feet and perched water at the rock contact [4]. ### Garber sandstone, I-35 over Waterloo Road (north Edmond) The Garber unit is described as red clay shales, sandy shales and cross-bedded sandstones [7]. Eight borings found competent rock far deeper than in Tulsa [7]. | Borings | Top of weathered rock (ft) | Top of competent rock (ft) | |---|---|---| | A-1 to A-4 | 40, 60, 90, 85 | 41.5, 60.5, 95, 85 [7] | | B-1 to B-4 | 20, 60, 76, 91.5 | 20.5, 60.5, 85, 91.5 [7] | Water levels after drilling were mostly 30 to 35 feet, and the report notes they change with the seasons [7]. ## What do the summary statistics show? Calculated from the borings above (drilled borings that reached rock, each counted once): | Group | Borings | Median (ft) | Range (ft) | |---|---|---|---| | Tulsa, competent rock, all groups | 19 | 13.5 to 14.5 | 4 to 19.5 [1][3] | | East Tulsa shale only | 9 | 9.5 | 4 to 14.5 [1] | | OKC Hennessey, top of bedrock | 14 | 15.5 | 2 to 41 [4][5][6] | | OKC Garber, competent rock | 8 | about 73 | 20.5 to 95 [7] | ## How do rock depths compare with pier depths? Oklahoma steel push pier installation records show typical pier depths of 8 to 16 feet, with a median of about 12 feet in Tulsa [8]. That sits close to the Tulsa boring medians above [1][3]. A steel push pier (https://terrabrain.vercel.app/repairs/steel-push-piers) is driven until it meets enough resistance to carry the house, which can be rock or dense soil. Where borings found clay to 30 and 35 feet with no rock, as on the second 91st St wall [2], or rock 20.5 to 95 feet down, as at the Garber site [7], a pier may stop on friction in dense soil before reaching rock. For a city-by-city overview, see bedrock in the Tulsa metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro) and bedrock in the OKC metro (https://terrabrain.vercel.app/guides/bedrock-okc-metro). ## What are the limits of this data? - Highway and sewer borings are often on low ground, cuts or fill, so a hilltop lot may be shallower. - Reports sometimes conflict between their summary tables and boring logs; the original PDF is the authority. - Rock depth can change sharply over short distances, as the Bridge C borings show [6]. ## Related - Depth to rock from borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings) - Bedrock - Tulsa metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro) - Bedrock - OKC metro (https://terrabrain.vercel.app/guides/bedrock-okc-metro) - Hennessey shale (https://terrabrain.vercel.app/geology/hennessey-shale-group) - Garber sandstone (https://terrabrain.vercel.app/geology/garber-sandstone) - Loads, pier spacing and capacity (https://terrabrain.vercel.app/guides/loads-pier-spacing-and-capacity) Sources: [1] Report for Subsurface Investigation and Laboratory Testing Services, TMUA Spunky Creek MS South Phase 3, City of Tulsa / Tulsa Metropolitan Utility Authority https://www.cityoftulsa.org/media/31178/tul24r166807_tmua-spunky-creek-ms-south-phase-3-geotech-report.pdf [2] Geotechnical Engineering Report, Retaining Walls A and B Along 91st Street South from South Memorial Drive to South Mingo Road, City of Tulsa https://www.cityoftulsa.org/media/25588/geotechnical-report-retaining-walls.pdf [3] Geotechnical Engineering Report, I-44/US-75 Interchange Reconstruction, Retaining Walls RW-21 & RW-22, Oklahoma Department of Transportation https://www.odot.org/contracts/2024/24091201/geotech/CO166_24091201_GEOTECH/33788(08)%20GEO%20Report%20WP2%20Wall%20RW-21%20&%20RW-22.pdf [4] Report of Geotechnical Engineering Services, Proposed Retaining Wall C2, Crossroads Interchange Reconstruction, I-35/I-240, Oklahoma Department of Transportation https://oklahoma.gov/content/dam/ok/en/odot/business-center/upcoming-major-projects/2026/september/0903206/geotech-reports/0903206%20Geotech%20Retaining%20Wall%20C2,%20Crossroads%20Interchange%20Reconstruction%20I-35%20-%20I-240.pdf [5] Report of Geotechnical Engineering Services, Crossroads Interchange Reconstruction, Bridge D, I-35/I-240 Interchange, Oklahoma Department of Transportation https://oklahoma.gov/content/dam/ok/en/odot/business-center/upcoming-major-projects/2026/september/0903206/geotech-reports/0903206%20Geotech%20Report%20-%20Bridge%20D,%20I-35%20Interchange%20Reconstruction.pdf [6] Geotechnical Engineering Services Report, Crossroads Interchange Reconstruction, Bridge C, I-35/I-240 Interchange, Oklahoma Department of Transportation https://oklahoma.gov/content/dam/ok/en/odot/business-center/upcoming-major-projects/2026/september/0903208/geotech-reports/Geotech%20Report%20-%20Bridge%20C%20I-35%20Interchange%20Reconstruction.pdf [7] Geotechnical Engineering Report, Three Span Bridge, Interstate 35 over Waterloo Road, Oklahoma Department of Transportation https://oklahoma.gov/content/dam/ok/en/odot/business-center/upcoming-major-projects/2026/january/2984304/geotech-reports/Terracon%20Project%20No.%2003205039%20-%20Three%20Span%20Bridge%20-%20I-35%20over%20Waterloo%20Rd%20-%20REVISED.pdf [8] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # How deep is rock under Tulsa and Oklahoma City? URL: https://terrabrain.vercel.app/data/depth-to-rock-from-borings Answer: In upland Tulsa, rock is often 2 to 15 feet down; near creeks and the river, 20 to 35 feet or more. South of OKC, borings hit shale at 15.5 to 25 feet. In short: Under upland ground in Tulsa, shale or limestone is often within about 2 to 15 feet of the surface. Along creeks and the Arkansas River, clay and river deposits can run 20 to 35 feet or more before rock. South of Oklahoma City, borings in McClain County found competent shale at 15.5 to 25 feet. ## Why does depth to rock matter? Rock depth controls how deep foundation piers may go and whether they end on rock or on friction in dense soil. Bedrock here means shale, sandstone or limestone below the soil. "Weathered" rock has partly broken down; "competent" rock is hard enough that drilling stalls. For pier basics, see steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers), and for the full boring-by-boring tables, see borings: depth to rock in Tulsa and OKC (https://terrabrain.vercel.app/data/borings-depth-to-rock-in-tulsa-and-okc). ## What do Tulsa city reports show? | Location | Weathered rock | Competent rock | Notes | |---|---|---|---| | E 91st St, Memorial to Mingo (Nowata unit) | about 13.5 ft | borings stopped in weathered shale near 19 ft | Two other borings found clay to 30 and 35 ft with no shale; water at 13.5 to 15 ft [1] | | S 193rd E Ave, 31st to 41st St | 1 to 8 ft | 4 to 14.5 ft | Rock cores 4,880 to 9,560 psi [2] | | E Pine St and N 71st E Ave | 8.5 ft | 13 to 14.5 ft | Shale with limestone; fat clay (PI 27) at 5 to 7 ft [3] | | S 69th to 71st E Ave, E 9th to 10th St | decomposed shale from 15 in | hand-auger refusal on shale 15 to 23 in below pavement | 4 of 12 holes refused [4] | | Arkansas River corridor | shale about 5 to 10 ft below the river bottom | about 20 to 30 ft below the banks | Nellie Bly, Wewoka and Senora formations [5] | ### Rock strength varies widely Strength is reported as unconfined compressive strength (UCS), the pressure a rock core takes before it crushes. - East Tulsa (S 193rd E Ave) cores: 4,880 to 9,560 psi, and the report expected a pneumatic hammer or blasting would be needed for trenching [2]. - Arkansas River shale at Sand Springs averaged 565 psi over six tests, and at Jenks averaged 737 psi over nine tests [5]. That is more than a tenfold range between the strongest east Tulsa cores and the weakest river-valley shale [2][5]. Weak shale can soften further when wet, a topic covered in shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata). ### Upland vs creek bottom The 91st St report illustrates the pattern: one set of borings hit Nowata shale near 13.5 feet, while the other went through clay to 30 to 35 feet without finding rock and found water at 13.5 to 15 feet [1]. The Arkansas River data shows the same thing on a bigger scale, with overburden (soil above rock) 18 to 35 feet thick in the river banks versus about 4 to 10 feet within the channel at the Sand Springs and South Tulsa/Jenks sites [5]. In practice this means a shallow pier refusal on an upland shale site is consistent with nearby borings, while the same shallow depth near a creek or river terrace is less consistent with the boring record [1][5]. See Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) for those deposits. ## What do borings show in central Oklahoma? ### McClain County (I-35 and SH-59) A state maintenance and residency facility study reported competent shale (standard penetration test refusal) at 15.5 to 25 feet [6]. Above the rock were lean to fat clays, with plasticity index up to 41, that the report classified as expansive, over very weathered shale [6]. No groundwater was found during drilling, though high moisture in several clay samples led the report to expect water in excavations [6]. ### What soil surveys say NRCS Official Series Descriptions record what lies beneath each soil series: - **Kirkland:** the typical profile reaches weakly cemented siltstone at 208 cm, about 82 inches [7]. - **Renfrow** (type location in Kay County, Oklahoma): formed in material weathered from Permian clayey shale, with noncemented shale more than 60 inches down [8]. For more on these soils, see Kirkland (https://terrabrain.vercel.app/soils/kirkland) and Renfrow (https://terrabrain.vercel.app/soils/renfrow). ## What do borings show about groundwater? - Three east Tulsa borings had water at 7 to 9.5 feet at the end of drilling, and groundwater was not observed in four of the nine borings [2]. - The 91st St creek-side borings had water at 13.5 to 15 feet; the upland borings were dry [1]. - Water perched on top of rock is common; see groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water). ## Related - Borings: depth to rock in Tulsa and OKC (https://terrabrain.vercel.app/data/borings-depth-to-rock-in-tulsa-and-okc) - Bedrock - Tulsa metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro) - Bedrock - OKC metro (https://terrabrain.vercel.app/guides/bedrock-okc-metro) - Shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata) - Pennsylvanian shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales) - Tulsa metro region (https://terrabrain.vercel.app/regions/tulsa-metro) Sources: [1] Geotechnical Engineering Report, Retaining Walls A and B Along 91st Street South from South Memorial Drive to South Mingo Road, City of Tulsa https://www.cityoftulsa.org/media/25588/geotechnical-report-retaining-walls.pdf [2] Report for Subsurface Investigation and Laboratory Testing Services, TMUA Spunky Creek MS South Phase 3, City of Tulsa / Tulsa Metropolitan Utility Authority https://www.cityoftulsa.org/media/31178/tul24r166807_tmua-spunky-creek-ms-south-phase-3-geotech-report.pdf [3] Report for Geotechnical Drilling and Laboratory Testing Services, Proposed Jack and Bore Construction, TMUA ES 2025-09, City of Tulsa / Tulsa Metropolitan Utility Authority https://www.cityoftulsa.org/media/28189/tul25l182298_26000483001a_tmua-es-2025-09-geotech-report.pdf [4] Geotechnical Explorations, City of Tulsa Non-Arterial Maintenance Zone 3017, City of Tulsa https://www.cityoftulsa.org/media/27858/cot-namz-3017-geotech-report.pdf [5] Arkansas River Corridor Projects: Existing Geotechnical Resource Review, Tulsa County River Projects https://riverprojectstulsa.info/wp-content/uploads/2014/Appendix_Q_Final_Geotech.pdf [6] Subsurface Exploration, New ODOT Maintenance and Residency Facilities, Oklahoma Department of Transportation https://oklahoma.gov/content/dam/ok/en/odot/procurement/open/26-FM-0017_Geotech_Report.pdf [7] Official Series Description - KIRKLAND Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KIRKLAND.html [8] Official Series Description - RENFROW Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/R/RENFROW.html --- # How did downspouts help crack the foundation of a 2007 Bristow house? URL: https://terrabrain.vercel.app/case-studies/bristow-2007-slab-downspout-erosion-piers Answer: Downspouts discharging at the foundation eroded two corners. The engineer called it a defect and specified piers, slab leveling and downspout extensions. In short: A slab-on-grade house in Bristow built about 2007 had significant stem-wall cracks and interior cracking on its east side. It also had significant erosion at two corners where downspouts discharged at the foundation [1]. The engineer named variations in soil moisture and the downspout discharge, which the report calls a defect. The scope was piers under the footings, polyurethane slab leveling, crack stitching and downspout extensions [1]. ## What did the house show? The engineer inspected the house in February 2026 [1]. It is a one-story timber-frame house with vinyl siding, built about 2007, on a slab-on-grade with continuous perimeter footings and stem walls [1]. Observed conditions [1]: - The site slopes moderately down to the east. - Interior cracks above doors and windows in the **east** part of the house, and baseboard and stem-wall separations in the eastern bedrooms. Doors mostly worked, with minor misalignment. - **Significant stem-wall cracks** on the north and south sides of the eastern portion. - **Significant erosion at the southeast and southwest corners**, caused by downspouts discharging at the foundation. ## What did the engineer find was causing it? The engineer named two factors [1]: - Variations in the moisture content of the soil beneath the footings and slab, described as a mildly active clay. - **Downspouts discharging at the foundation**, which the report itself calls "a defect." ## What repair was specified? - **Piers under the continuous footings** at the locations on the engineer's drawing [1]. - **Polyurethane slab leveling** at marked areas, to "stabilize and partially lift" [1]. - A leak test of the sub-slab supply and drain lines [1]. - After leveling, stitch slab cracks with carbon fiber and epoxy. If a height difference remains, saw-cut at least 6 in. each side and re-pour [1]. - **Downspout extensions at every downspout** so roof water flows away from the house [1]. - Delay cosmetic repairs several weeks after stabilization [1]. ## What happened on the job? The record shows that an updated estimate based on the engineer's recommendations was prepared in March 2026. It does not record whether the work was done [1]. ## What does this case show about Oklahoma foundations? - **Downspouts are a concentrated water source.** ASCE's homeowner guide for shrink-swell soils recommends downspouts that discharge at least 3 feet from the foundation into well-drained areas. It warns that ponding near the foundation can cause localized heave and recommends checking grading and drainage every year [2]. Here the discharge eroded soil at two corners [1]. - **Uneven wetting is the problem.** Researchers writing on expansive-soil damage identify differential water content as the biggest problem in expansive-soil areas [3]. Water dumped at a few points around a house wets the soil unevenly. - **Age is not protection.** The house was under 20 years old when the engineer found significant stem-wall cracks [1]. ## Related - Erosion, Undermining & Washout Voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) - Exposed Slab Edge or Void Under Footing (https://terrabrain.vercel.app/signs/exposed-slab-edge-or-void-under-footing) - Surface Drainage and Grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Slabjacking and Polyurethane (https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane) - Slab on Grade (https://terrabrain.vercel.app/foundations/slab-on-grade) Sources: [1] Engineer's evaluation report, 2026 (private client report), Licensed professional engineer, Oklahoma [2] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, ASCE Geo-Institute, Shallow Foundations Committee https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [3] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers et al.) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf --- # How did Oklahoma's foundation code change for homes in 2022? URL: https://terrabrain.vercel.app/data/construction-history Answer: Oklahoma's 2018 IRC rule, effective September 14, 2022, added rebar to all footings, set anchor bolt spacing and barred trenching into footing support soil. In short: Oklahoma builds houses under the International Residential Code (IRC) with state amendments. The 2018 IRC rule, effective September 14, 2022, added rebar to all footings, set anchor bolt spacing, and barred trenching into the soil zone that supports a footing. A home's construction date tells you which of these rules applied when it was built. ## Why does a home's construction date matter? The rules in force when a house was built shape what is under it: how its footings were reinforced, how the frame was bolted down, and whether later trenching near the foundation was restricted. Older homes predate these amendments. For how building practice changed decade by decade, see construction era by decade (https://terrabrain.vercel.app/guides/construction-era-by-decade). ## What are Oklahoma's 2018 IRC foundation amendments? The Oklahoma Uniform Building Code Commission adopted the 2018 IRC by permanent rule effective September 14, 2022 [1]. Its Chapter 4 (Foundations) amendments include: | Section | Oklahoma amendment | |---|---| | R403.1 Footings | Add two No. 4 rebar to all footings [1] | | R403.1 Cold joints | Tie footings to foundation walls with No. 4 rebar at every corner and no more than 6 ft on center, embedded 12 in into each [1] | | R403.1.6 Anchorage | Sill and sole plates anchored with bolts at least 1/2 in diameter, no more than 6 ft on center, embedded at least 7 in; hand-driven cut or concrete nails not approved [1] | | R402.2 Concrete | Interior slabs on grade and enclosed garage slabs exempt from air-entrainment requirement [1] | | R403.1.7.3 | Foundation elevation section removed [1] | | R403.1.9 (added) | No trenching into the footing bearing plane [1] | A **cold joint** is where concrete poured at different times meets, such as a footing poured first and a stem wall poured later. No. 4 rebar is half-inch reinforcing steel. ### Trenching near footings (R403.1.9) The added section protects the soil that carries a footing's load. Trenching parallel to footings and walls may not extend into the bearing plane, whose upper boundary runs downward at 45 degrees from the outside bottom edge of the footing [1]. The rule expressly covers trenching for plumbing, electrical, storm shelters and pools [1]. This connects to settlement problems described in erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). ### Frost depth is local The state rule leaves the frost depth line in the climate table blank for the local authority having jurisdiction to fill in, and notes that deeper footings than the code figure may be required [1]. City values are discussed in permits, licensing and frost depth (https://terrabrain.vercel.app/rules/permits-licensing-and-frost-depth-oklahoma-cities) and freeze-thaw and frost depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth). ### Storm shelters The same rule requires storm shelters to follow the ICC 500 standard with added requirements, and sets a minimum design wind speed of 250 miles per hour for shelters statewide [1]. In-ground garage shelters must have a rim at least 1 inch above the garage floor [1]. ## When did Oklahoma homes move from crawl spaces to slabs? Slab-on-grade houses were still uncommon in Tulsa in the mid-1950s [5]. A University of Oklahoma survey of Tulsa's Lortondale neighborhood, where 211 homes were built mainly from 1954 to 1956, describes its slab-on-grade foundations as "unusual for Tulsa residential construction at the time" [5]. In those houses the heating and cooling ductwork was laid into the slab, first as sheet metal and later as cardboard pipe to save money [5]. Ducts cast into a slab can be affected when the slab cracks or moves; see slab on grade (https://terrabrain.vercel.app/foundations/slab-on-grade). Older Tulsa neighborhoods predate that shift. The representative listed homes in the Maple Ridge Historic District date from 1913 to 1927, with walls of brick, hollow tile, stucco and stone [8]. For homes of that age, see pier and beam crawl space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space). Today slabs dominate. In 2024, 97.9% of new single-family homes in the West South Central census division (Oklahoma, Texas, Arkansas and Louisiana) were built on slabs, compared with 73% nationally [6]. ## Have any Oklahoma cities set stricter local rules? After the May 20, 2013 tornado, Moore became the first U.S. city to adopt building rules aimed specifically at limiting tornado damage [7]. New homes there must be built to resist winds up to 135 mph, compared with the 90 mph nationally accepted standard cited at the time [7]. The city council approved 11 recommendations drawn from engineers' review of the 2013 damage [7]. ## What rules apply to manufactured homes? Manufactured homes follow a separate set of rules. New homes in Oklahoma must be installed to HUD's federal installation standards (24 CFR Part 3285) or the manufacturer's approved instructions by a state-licensed installer [2]. Used homes follow Oklahoma's generic support standard, which assumes soil bearing of at least 1,500 psf and allows block piers spaced up to 6 feet on center [3]. See manufactured homes data (https://terrabrain.vercel.app/data/manufactured-homes). ## What soils does the code have to deal with? Code footings sit on Oklahoma soils that can be highly expansive. A 1978 Oklahoma Agricultural Experiment Station study described Kirkland soil, sampled in Canadian County, as very plastic and highly expansive, which restricts its use for most engineering purposes [4]. It also found Bethany, Kirkland and Norge soils have enough montmorillonite to make them unstable for many engineering uses [4]. See shrink-swell and active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) and slab on grade (https://terrabrain.vercel.app/foundations/slab-on-grade). ## Related - Construction era by decade (https://terrabrain.vercel.app/guides/construction-era-by-decade) - Codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits) - Original construction deficiency (https://terrabrain.vercel.app/causes/original-construction-deficiency) - Slab on grade (https://terrabrain.vercel.app/foundations/slab-on-grade) - Pier and beam crawl space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) - Additions and mixed foundations (https://terrabrain.vercel.app/guides/additions-and-mixed-foundations) Sources: [1] Title 748, Chapter 20, Subchapter 6, IRC 2018 (Permanent Rule, effective 9-14-2022), Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2022%2009%2014%20IRC%202018%20Permanent%20Rule.pdf [2] Okla. Admin. Code 765:37-7-1, Acceptable procedure, Justia Regulations (Oklahoma Administrative Code) https://regulations.justia.com/states/oklahoma/title-765/chapter-37/subchapter-7/section-765-37-7-1 [3] Okla. Admin. Code 765:37-7-3, Support Systems, Cornell Law School Legal Information Institute https://www.law.cornell.edu/regulations/oklahoma/OAC-765-37-7-3 [4] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma Agricultural Experiment Station, Oklahoma State University https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [5] Intensive Level Historic/Architectural Survey of the Lortondale Neighborhood, Tulsa, Oklahoma, University of Oklahoma, College of Architecture, Urban Design Studio https://www.ou.edu/content/dam/Tulsa/Urban%20Design%20Studio/Archive/2007/LortondaleIntensiveLevelSurvey.pdf [6] Which Foundation Type Is Most Common in Your Region?, National Association of Home Builders https://www.nahb.org/blog/2025/08/foundation-type-by-region [7] Tornado-Ravaged Moore, Oklahoma Toughens Building Codes, NBC News https://www.nbcnews.com/news/us-news/tornado-ravaged-moore-oklahoma-toughens-building-codes-n82996 [8] Maple Ridge Historic District, Tulsa Preservation Commission https://tulsapreservationcommission.org/neighborhoods-districts/nrhp/mapleridge/ --- # How do cherty limestone soils affect NE Oklahoma foundations? URL: https://terrabrain.vercel.app/geology/mississippian-cherty-limestone Answer: Weathered cherty limestone leaves very gravelly soils, dense fragipans and some karst, so foundation concerns center on water, voids and rocky digging. In short: In the far northeast corner of Oklahoma, the Ozark Plateau is underlain by limestone packed with chert, a hard silica rock. As the limestone weathers, the chert is left behind, producing very gravelly soils, dense subsoil layers called fragipans, and in places karst openings. Foundation concerns here center on water, voids and rocky digging more than clay swell. ## What is the rock? **Chert** is a dense, glassy rock made of silica that occurs as nodules and beds inside limestone. USDA soil descriptions for the Ozark region describe soils formed in residuum, or weathered-in-place material, from cherty limestone or cherty dolomite [1][2]. The Oklahoma Geological Survey identifies the Ozark area in the northeast and the Arbuckle Mountains in the south as Oklahoma's main limestone and dolomite karst areas [4]. ## What soils form on cherty limestone? ### Clarksville: very gravelly slopes Clarksville soils formed in hillslope sediments over clayey residuum from cherty dolomite or cherty limestone, on steep side slopes and narrow ridgetops [1]. Key features [1]: - Gravel makes up 10 to 80 percent of the surface layer and 20 to 80 percent of the subsoil. - The soil is somewhat excessively drained, with moderate permeability. - Slopes range from 1 to 70 percent. - The series covers a large area of the Ozark region of Kansas, Missouri, Oklahoma and Arkansas. ### Nixa: a dense fragipan Nixa soils formed in colluvium and loamy residuum from cherty limestone on uplands of the Ozark Highlands [2]. Their defining feature is a **fragipan**, a firm, brittle subsoil layer that starts 14 to 27 inches below the surface [2]. Chert can make up 35 to 75 percent of the middle subsoil and up to 85 percent of the lower subsoil [2]. Permeability is very slow and runoff is high to very high [2]. | Series | Drainage | Key subsoil trait | Slopes | |---|---|---|---| | Clarksville | Somewhat excessively drained [1] | 20–80% chert gravel [1] | 1–70% [1] | | Nixa | Moderately well drained [2] | Fragipan at 14–27 in [2] | 1–35% [2] | ## Is there karst in cherty limestone? **Karst** is ground shaped by dissolving rock, with features such as sinkholes, caves, springs and disappearing streams. In other parts of the Ozarks, soils formed in residuum from cherty limestone are described with karst topography in many areas [3]. The Oklahoma Geological Survey lists sinkholes, caverns, subsidence and collapse as potential hazards in karst terranes, and notes that groundwater contaminants can move rapidly through them [4]. ## What does this mean for foundations? - **Water held up by a fragipan.** A very slowly permeable layer starting 14 to 27 inches down [2] can slow drainage near footings and in crawl spaces after rain. See crawl space moisture (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) and groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water). - **Voids and sudden drops.** In karst areas, sinkholes and caverns can lead to settlement or collapse of the land surface [4], a different problem from seasonal clay movement. See karst subsidence and sinkholes (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes). - **Steep, rocky lots.** Slopes up to 70 percent on Clarksville soils [1] mean hillside cuts and fills are common. See slope creep (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement) and fill consolidation (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). - **Runoff control.** High runoff on Nixa soils [2] makes gutters and grading important. The ASCE homeowner guide suggests sloping soil at least 3 inches in the first 5 feet and discharging downspouts at least 3 feet from the foundation [5]. ## Related - Northeast (Ozark Plateau and Grand Lake) (https://terrabrain.vercel.app/regions/northeast-ozark-plateau-and-grand-lake) - Clarksville soil (https://terrabrain.vercel.app/soils/clarksville) - Nixa soil (https://terrabrain.vercel.app/soils/nixa) - Karst subsidence and sinkholes (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes) - Oklahoma geologic provinces (https://terrabrain.vercel.app/guides/oklahoma-geologic-provinces) Sources: [1] Official Soil Series Description: CLARKSVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/CLARKSVILLE.html [2] Official Soil Series Description: NIXA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/N/NIXA.html [3] Official Soil Series Description: BAXTER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/B/BAXTER.html [4] Mapping of Karst Terranes in Oklahoma to Identify Potential Environmental and Hydrologic Problems, AAPG Search and Discovery / Oklahoma Geological Survey https://www.searchanddiscovery.com/abstracts/html/1995/midcon/abstracts/1403b.htm [5] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # How do drilled bell-bottom piers work on expansive clay? URL: https://terrabrain.vercel.app/repairs/drilled-bell-bottom-piers Answer: A drilled bell-bottom pier is a reinforced concrete column with a widened base set below the active clay and anchored to minimize uplift from swelling clay. In short: A drilled bell-bottom pier is a steel-reinforced concrete column cast in an augered hole, with the bottom widened into a bell. It is designed to bear below the clay that swells and shrinks with the seasons, and the bell anchors it to minimize uplift from swelling clay. Its performance depends on reaching the right depth, which comes from site-specific soil data. ## How does the system work? Trade words used on this page: - **Auger:** a large drill that bores a round shaft into the ground. - **Under-reaming (belling):** widening the bottom of the shaft with a special tool to form the bell. - **Rebar cage:** a bundle of steel reinforcing bars lowered into the shaft before concrete is placed. - **Pier cap:** the top of the pier, on which a beam or footing rests. - **Active zone:** the depth of soil whose moisture, and therefore volume, changes with the seasons. The sequence is to drill the shaft to design depth, form the bell, set the reinforcement, and fill the hole with concrete. The building or a new beam is then supported on the pier caps. ## Why do depth and the bell matter? Engineering guidance for swelling soils calls for piers to extend well below the zone of seasonal moisture change and to be anchored in non-swelling soil against uplift, using belled bottoms, grooved pier holes or greater depth [1]. Researchers report that seasonal moisture change can extend from 3 to 40 ft deep, and that designers should assume the upper part of a pier will lose contact with the soil [2]. **Uplift** is the upward drag that swelling clay puts on the sides of a pier. Corner piers are often lifted during the wet season and can lose side friction and drop when the soil shrinks in the dry season [2]. Six-foot piers that handle normal annual cycles may fail after a multi-year drought followed by a very wet year [2]; see OK Data - Active Zone and Drought Depth (https://terrabrain.vercel.app/data/active-zone-and-drought-depth) for Oklahoma drought depths. ## Where are drilled piers used? - **New construction on swelling soil:** drilled piers with a grade beam are generally recommended for moderately to highly swelling soils, with a 3 to 6 in gap between the soil and the beam [1]. See stem wall and grade beam (https://terrabrain.vercel.app/foundations/stem-wall-and-grade-beam). - **History:** drilled piers have been used on expansive soils in California, Colorado and Texas since the late 1950s [2]. - **Oklahoma research:** an Oklahoma Department of Transportation study built eight drilled shafts at two load-test sites to develop design methods for shafts socketed in weak rock, publishing recommended tip and side resistance relations in 2024 [4]. - **Code basis:** the residential code sends foundations on expansive soil to the building code's expansive-soil design section, and soil survey data from USDA NRCS is the minimum resource for locating expansive soils [5]. ## What can go wrong with drilled piers? | Problem | Effect | Source | |---|---|---| | Improper pier depth or diameter | Listed as a common design problem | [3] | | Mushroom-topped pier | Listed as a common construction problem | [3] | | No or inadequate void under the grade beam | Clay pushes up on the beam directly | [1][3] | | Long drought followed by a very wet year | Six-foot piers that withstand normal annual cycles may not be adequate | [2] | When piers move after construction or repair, the mechanism is described in pier uplift or movement after repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair). ## What practical considerations apply? - **Design input:** depth and bell size come from a site soil investigation, and swelling-soil guidance calls for the foundation to be designed by an engineer who specializes in soil and foundation engineering [1]; depth to rock from borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings) summarizes Oklahoma boring data. - **Engineering:** drilled piers are an engineered system; how homeowners work with an engineer is covered in working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). How drilled piers compare with pressed concrete, steel push and helical piers is laid out in the method selection matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix). ## Related - Stem Wall and Grade Beam (https://terrabrain.vercel.app/foundations/stem-wall-and-grade-beam) - Method Selection Matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix) - Pier Uplift or Movement After Repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Working with Engineers (https://terrabrain.vercel.app/guides/working-with-engineers) Sources: [1] Home Construction on Shrinking and Swelling Soils (Special Publication 11), Colorado Geological Survey (Holtz and Hart, 1978) https://coloradogeologicalsurvey.org/wp-content/uploads/woocommerce_uploads/SP-11.pdf [2] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [3] Expansive Soil, Colorado Geological Survey https://coloradogeologicalsurvey.org/hazards/expansive-soil/ [4] Probabilistic Approach for Design of Drilled Shafts Socketed in Weak Rock in Oklahoma (FHWA-OK-23-02), Oklahoma Department of Transportation and Federal Highway Administration (University of Missouri) https://rosap.ntl.bts.gov/view/dot/89161 [5] Foundations on Expansive Soils – Residential (IHB TB 10-01), Texas Department of Licensing and Regulation https://tdlr.texas.gov/ihb/pdf/TB1001.pdf --- # How do erosion, creeks and slopes threaten Oklahoma foundations? URL: https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes Answer: Runoff can undermine slab edges, creeks can cut into banks, clay on slopes can creep, and underground flow can carry soil away and leave voids. In short: Moving water can remove the soil that holds a foundation up. Runoff can wash out soil under slab edges, creeks can eat into their banks, clay on slopes can creep slowly downhill, and underground flow can carry soil away and leave voids. Steep ground, bare soil and heavy rain all raise the risk. ## How does water take soil away? ### Undermining **Undermining** is the loss of soil from beneath a slab edge or footing, usually from concentrated water such as overflowing gutters, a downspout or a flash flood. It leaves the edge of the foundation unsupported; see exposed slab edge or void under footing (https://terrabrain.vercel.app/signs/exposed-slab-edge-or-void-under-footing). ### Creek-bank retreat Streams cut into their banks during high flows. Oklahoma State University Extension notes that long-term removal of perennial plant cover along streams can cause significant erosion from stream flow, while plant crowns and roots help hold soil in place [2]. A house near a retreating bank can lose the soil that supports it from the side. Flood-plain soils show how active these settings are. Port soils, on narrow flood plains in central Oklahoma, flood occasionally or frequently for very brief periods during March to October [4]. Osage soils lie on flood plains along major streams in eastern Oklahoma [5], and Verdigris soils on flood plains in northeastern Oklahoma are described as subject to flooding [8]. ### Slope creep **Creep** is very slow downhill movement of soil. On clay, wet and dry cycles bring periods of deep near-surface drying; when intense rain follows, water enters the deep cracks and the soil swells [7]. Repeated over years, this helps move soil downslope. Common clues are leaning fences, retaining walls and trees; see tilted retaining walls, fences or trees (https://terrabrain.vercel.app/signs/tilted-retaining-walls-fences-or-trees) and slope creep and lateral movement (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement). ### Piping **Piping** is underground erosion in which flowing water carries fine soil out through a channel, gradually forming a tunnel or void. The USGS notes that piping caves have been reported in relatively unconsolidated sediments, which it maps as a form of pseudokarst (karst-like voids not caused by dissolving rock) [3]. ## What raises the risk? | Factor | Why it matters | Source | |---|---|---| | Slope steepness | Steeper ground has greater potential for erosion | [2] | | Loss of plant cover | Roots and plant crowns hold soil; removing cover along streams leads to erosion | [2] | | Heavy rainfall | 2-inch rain events have increased in Oklahoma since 1985; more are projected, with more erosion | [1] | | Shallow rock on hillsides | Collinsville soils on hillslopes reach sandstone within about 4–20 in. and shed medium to very high runoff | [6] | ## What are other warning signs? Besides exposed slab edges and leaning walls or trees, sign pages on this site cover a sudden depression or sinkhole (https://terrabrain.vercel.app/signs/sudden-depression-or-sinkhole), which can mark underground soil loss, and water ponding near the foundation (https://terrabrain.vercel.app/signs/water-ponding-near-foundation), which shows where runoff collects. ## How are these problems repaired? Because steep slopes, bare ground and heavy rain drive erosion [1][2], repair options focus on the water and the slope as well as the house. They are described on slope and erosion stabilization (https://terrabrain.vercel.app/repairs/slope-and-erosion-stabilization) and drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). Local rules for work near creeks and floodplains are covered under codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits). ## Related - Erosion, Undermining and Washout Voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) - Fill Soils and Lot History (https://terrabrain.vercel.app/guides/fill-soils-and-lot-history) - Gypsum Karst and Sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes) - OK Data - Creeks and Flood History (https://terrabrain.vercel.app/data/creeks-and-flood-history) - Working with Engineers (https://terrabrain.vercel.app/guides/working-with-engineers) Sources: [1] Oklahoma - State Climate Summaries 2022, NOAA National Centers for Environmental Information https://statesummaries.ncics.org/chapter/ok/ [2] Fire Effects: Soil Erosion (NREM-2911), Oklahoma State University Extension https://extension.okstate.edu/fact-sheets/fire-effects-soil-erosion [3] Karst in the United States: A Digital Map Compilation and Database (Open-File Report 2014-1156), U.S. Geological Survey https://pubs.usgs.gov/of/2014/1156/ [4] Official Series Description - PORT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/PORT.html [5] Official Series Description - OSAGE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OSAGE.html [6] Official Series Description - COLLINSVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COLLINSVILLE.html [7] TRB Webinar: Foundations in Shrink Swell Soil: Innovation and State of Practice, Transportation Research Board, National Academies https://www.nationalacademies.org/cdn/materials/a067d915-1c17-4a16-840d-06452b68646c [8] Official Series Description - VERDIGRIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/V/VERDIGRIS.html --- # How do freezes and frost affect Oklahoma foundations? URL: https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth Answer: Frost is a secondary issue in most of Oklahoma; freezes mainly affect porches, steps, driveways and plumbing, more so in the northwest and Panhandle. In short: Frost is a secondary foundation issue in most of Oklahoma because winters are relatively mild and frozen soil is rare and short-lived. Freezing weather matters most for shallow concrete such as porches, steps and driveways, and for plumbing that can freeze and leak. Cold-season effects are stronger in the northwest and Panhandle than in the southeast. ## How does frost move soil? **Frost heave** happens when water in the soil freezes and expands, pushing shallow concrete or footings upward; it settles back, often unevenly, when the ground thaws. The **frost depth** is the depth to which the ground is expected to freeze; footings set below it are out of reach of frost heave. Local frost-depth requirements for Oklahoma cities are covered on the permits, licensing and frost depth (https://terrabrain.vercel.app/rules/permits-licensing-and-frost-depth-oklahoma-cities) page. ## What is Oklahoma's winter climate like? - Winters are shorter and less severe than in the northern Plains states [1]. - The Oklahoma Climatological Survey describes frozen soil as rare and brief [1]. - Temperatures at or below 32°F occur on average about 60 days a year in the southeast [1]. - Snowfall ranges from under 2 inches a year in the far southeast to nearly 30 inches in the western Panhandle [1]. - Freezing rain occurs regularly, especially in the southeast [2]. During the February 9–20, 2021 cold wave, heavy snow of more than 10 inches in many places, severe icing and power outages caused considerable damage across the state [2]. Mesonet soil moisture sensors can't read frozen soil, so winter soil moisture maps often show gaps during hard freezes [3]. ## Where does freezing weather show up on a house? ### Flatwork and porches Driveways, sidewalks, patios and porch or stoop footings are thin or shallow, so they are the parts of a property most exposed to freezing. Uneven lifting at joints is described on the heaved or settled flatwork (https://terrabrain.vercel.app/signs/heaved-or-settled-flatwork) and flatwork and exterior slabs (https://terrabrain.vercel.app/foundations/flatwork-and-exterior-slabs) pages. ### Crawl spaces Crawl spaces with open vents let cold air reach floor framing and pipes. See pier and beam crawl space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space). ### Frozen and burst pipes The larger foundation risk from a freeze is often water, not ice. Leaking pipes are a recognized cause of the uneven soil moisture that moves foundations on clay [6], and expansive clay swells as it takes on water [5]. The EPA advises fixing plumbing leaks as soon as possible and drying water-damaged areas within 24–48 hours to prevent mold [4]. More on leak-related movement is on the plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) page. ## How does frost compare with clay movement? Frost heave is seasonal and limited to the depth that actually freezes. Clay shrink-swell responds to moisture and follows wet and dry cycles rather than cold spells [5], and the depth of seasonal moisture variation is typically 15 feet or more [6]. When cracks change between summer and winter in Oklahoma, moisture is usually the first thing examined; see shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). ## Related - Frost Heave (https://terrabrain.vercel.app/causes/frost-heave) - Seasonal Movement Calendar (https://terrabrain.vercel.app/guides/seasonal-movement-calendar) - Severe Weather Effects (https://terrabrain.vercel.app/guides/severe-weather-effects) - Codes and Permits (https://terrabrain.vercel.app/rules/codes-and-permits) - Panhandle (High Plains) (https://terrabrain.vercel.app/regions/panhandle-high-plains) Sources: [1] Oklahoma Climate, Oklahoma Climatological Survey https://www.ou.edu/ocs/oklahoma-climate [2] Oklahoma - State Climate Summaries 2022, NOAA National Centers for Environmental Information https://statesummaries.ncics.org/chapter/ok/ [3] 1-day Average 4-inch Bare Soil Fractional Water Index, Oklahoma Mesonet https://mesonet.org/weather/soil-moisture/1-day-average-4-inch-bare-soil-fractional-water-index [4] A Brief Guide to Mold, Moisture and Your Home, U.S. Environmental Protection Agency https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home [5] Residential House Foundations on Expansive Soils in Changing Climates, HUD Office of Policy Development and Research (Cityscape, Vol. 25 No. 1) https://www.huduser.gov/PORTAL/periodicals/cityscape/vol25num1/ch10.pdf [6] Expansive Soils (The Mystery), STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf --- # How do helical piers support a foundation? URL: https://terrabrain.vercel.app/repairs/helical-piers Answer: A steel shaft with screw plates is turned into the ground and bracketed to the foundation. It installs without building weight, suiting light loads and uplift. In short: A helical pier is a steel shaft with screw-shaped plates that is turned into the ground by a hydraulic motor and then bracketed to the foundation. Because it is screwed in rather than pushed, it does not need the building's weight to install, which suits light structures and situations that need resistance to upward pull. In Oklahoma clay, its plates have to end up below the soil layer that swells and shrinks. ## How does a helical pier work? Trade words used on this page: - **Shaft:** a square steel bar or round steel pipe, added in sections as it goes deeper. - **Helix (helical plate):** a round steel plate formed into one turn of a screw, welded near the lead end; a pier may have one or several. - **Torque:** the turning force the motor applies, read from a calibrated gauge during installation. - **Bracket:** the steel seat that connects the pier to the footing, slab edge or beam. - **Tension capacity:** the ability to resist being pulled upward. The pier is screwed down until it reaches the planned depth and torque, then the bracket transfers the structure's load to it, and the structure can be lifted from it. ## Why is torque recorded? Turning resistance is used as a measure of soil strength in federal rules: HUD's manufactured home installation standard uses a torque probe, a small screw-tipped rod turned into the soil, to classify soil strength: readings over 550 inch-pounds indicate class 2 soils such as gravel and dense sand, while readings under 175 indicate class 5 soils: uncompacted fill, peat and organic clays [1]. High-plasticity clays without torque probe or blow count data must use anchors rated for class 4B soil [1]. HUD also requires ground anchors to be certified by a registered engineer or architect, with the working load set at the ultimate load divided by a factor of safety of 1.5 [1]. For helical piers, the final torque at each pier is logged as the installation record, and converting it to a design capacity is part of the engineered design. ## How deep must helical piers go in clay? - Expansive soils swell with added moisture and can lift a structure, and shrink with moisture loss and let it settle [4]. - Seasonal moisture change in clay can reach from 3 to 40 ft deep, and the upper part of a pier can lose contact with shrinking soil [3]. - Engineering guidance for swelling soils calls for piers to extend well below the zone of seasonal moisture change and to be anchored in non-swelling soil against uplift [2]. A helical plate set below that zone acts as an anchor, because the swelling clay above it has to pull the plate up through stable soil. A plate set within the zone moves with the clay. For context on bearing depths in Oklahoma, steel push piers in Tulsa installation records typically reached 8 to 16 ft, with a median of 12 ft [5]. ## Where are helical piers used? | Situation | Connection to the sources | |---|---| | Porches, stoops, decks and additions | Light structures; swelling soils lift and crack lightly loaded footings [3] | | Manufactured homes and light crawl space supports | Supports extended beneath the zone of seasonal moisture change, as recommended on swelling soils [3] | | Heave-prone sites | Anchorage below the zone of seasonal moisture change resists uplift [2] | ## What are the limits of helical piers? - Plates that end inside the active zone do not provide reliable anchorage, which depends on soil below the zone of seasonal moisture change [2][3]. - Corner piers on swelling soil can be lifted in wet seasons, then lose skin friction as the soil shrinks in dry seasons and drop [3]. - The design depth depends on site soil data; soil survey reports are the minimum resource for locating expansive soils [4]. ## How do helical piers compare to other piers? Helical piers, steel push piers, pressed concrete piles and drilled piers are compared side by side in the method selection matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix). Spacing and load questions are covered in loads, pier spacing and capacity (https://terrabrain.vercel.app/guides/loads-pier-spacing-and-capacity), and the mechanism behind pier movement after repair in pier uplift or movement after repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair). Light additions that move differently from the main house are covered in differential movement at additions (https://terrabrain.vercel.app/causes/differential-movement-at-additions). ## Related - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Method Selection Matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix) - Loads Pier Spacing and Capacity (https://terrabrain.vercel.app/guides/loads-pier-spacing-and-capacity) - Manufactured Homes on Piers (https://terrabrain.vercel.app/foundations/manufactured-homes-on-piers) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) Sources: [1] 24 CFR Part 3285 – Model Manufactured Home Installation Standards (Code of Federal Regulations, 2020), U.S. Government Publishing Office https://www.govinfo.gov/content/pkg/CFR-2020-title24-vol5/pdf/CFR-2020-title24-vol5-part3285.pdf [2] Home Construction on Shrinking and Swelling Soils (Special Publication 11), Colorado Geological Survey (Holtz and Hart, 1978) https://coloradogeologicalsurvey.org/wp-content/uploads/woocommerce_uploads/SP-11.pdf [3] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [4] Foundations on Expansive Soils – Residential (IHB TB 10-01), Texas Department of Licensing and Regulation https://tdlr.texas.gov/ihb/pdf/TB1001.pdf [5] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # How do mudjacking and polyurethane foam lift a sunken slab? URL: https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane Answer: Both pump material under a slab, cement slurry or expanding foam, to fill gaps and lift it, but they rest on the same soil and do not stop clay movement. In short: Slabjacking raises a sunken concrete slab by pumping material underneath it — either a cement-based slurry (mudjacking) or an expanding polyurethane foam [1]. Both fill gaps and lift the slab, but they rest on the same soil that moved, so they do not stop expansive clay from shrinking or swelling again [1][3]. They are mainly used for flatwork and for filling voids, not for slabs that are heaving. ## What are the two methods? ### Mudjacking (cement grout) Mudjacking pressure-injects a slurry of sand, fly ash or topsoil mixed with cement between the slab and the soil [1]. The slurry fills empty spaces and, as more is pumped in, raises the slab. - Grout can be blocked by roots, pipes or other objects under the slab, which can make the lift uneven [1]. ### Polyurethane foam Foam lifting injects a urethane-based foam under the slab, where it expands to raise low areas; the slab then rests on the foam [1]. - An incorrect mix of the two foam chemicals can cause the repair to fail [1]. - If the mix is too wet, water can seep into expansive soil before the foam hardens and cause local heave [1]. - Oklahoma field practice records include foam with a density of about 1.75 pounds per cubic foot used for slab lifting [6]. ## Where are these methods used? - Driveways, sidewalks, patios, garage slabs and pool decks — see heaved or settled flatwork (https://terrabrain.vercel.app/signs/heaved-or-settled-flatwork) and flatwork and exterior slabs (https://terrabrain.vercel.app/foundations/flatwork-and-exterior-slabs). - Filling voids under slabs after erosion or leak washout — see erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). - Interior slab areas that have settled over loose fill, rather than heaved. ## Why don't they fix clay movement? Expansive clay swells when wet and shrinks when dry, and its shrinkage cracks do not close up perfectly on rewetting [3]. A slab lifted with grout or foam still sits on that soil. An engineering committee review describes both methods as shallow repairs affected by active soil movement and lists these causes of renewed movement after repair [1]: - Changes in soil moisture and seasonal swings - Leaking sewer or water lines under the slab - Nearby trees - Poor drainage This is why slab lifting is not used for perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) as a lasting fix, and why it is harmful for center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) or leak-induced heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave): it adds more lift to an area that is already high. Telling the two apart is covered in heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). ## What are the risks during lifting? The same review lists installation problems for both methods [1]: | Risk | Cause | |---|---| | Bulging or cracking of the slab | Injecting too much material | | Blowouts | Excessive injection pressure | | Plugged drain or water lines | Material entering cracked or broken pipes | | Uneven lift | Material trapped by roots, pipes or objects | ## What should be checked before lifting? **Plumbing.** Grout and foam can enter cracked or broken pipes and plug them [1], so under-slab drains are often checked before lifting. A hydrostatic test plugs the main drain, fills the under-slab system to slab level and watches for a drop in water level for up to 15 minutes [2]. Leaks also matter because sewer leakage is one of the ways expansive soils become saturated [5]. See plumbing leak detection and repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair). **Post-tensioned slabs.** Many newer slabs are **post-tensioned** — reinforced with high-strength steel cables (tendons) stressed after the concrete cures. An engineering design review notes these slabs require specialized expertise and that tendon anchorages need attention [4]. Drilling injection holes into a post-tensioned slab without locating the tendons risks cutting one. ## Can they be combined with other repairs? Foam or grout is sometimes used together with piers: piers carry the foundation beam, and foam fills voids or supports the slab between beams. Cost depends mainly on slab area, how much material is needed and access. ## Related - Void and Compaction Grouting (https://terrabrain.vercel.app/repairs/void-and-compaction-grouting) - Heaved or Settled Flatwork (https://terrabrain.vercel.app/signs/heaved-or-settled-flatwork) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Method Selection Matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix) - Erosion, Creeks and Slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) Sources: [1] Post Foundation Repair Performance of Residential and Other Low-Rise Buildings on Expansive Soils (FPA-RC-01-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-RC-01-0.pdf [2] Informational Bulletin 15-02: Testing of Drain, Waste, Vent Systems, City of Amarillo Department of Building Safety https://amarillo.gov/home/showpublisheddocument/5292/636421987410570000 [3] Chapter C5 – Expansive Soils, Institution of Civil Engineers / British Geological Survey https://nora.nerc.ac.uk/id/eprint/17002/1/C5_expansive_soils_Oct.pdf [4] Foundation Design Options for Residential and Other Low-Rise Buildings on Expansive Soils (FPA-SC-01-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-01-0.pdf [5] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [6] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # How do Oklahoma drought and wet cycles move foundations? URL: https://terrabrain.vercel.app/guides/drought-and-wet-cycles Answer: Oklahoma clay shrinks in drought and swells when wet, so foundations drop at the edges during drought and can be pushed back up when heavy rain returns. In short: Oklahoma swings between multi-year droughts and very wet periods, and its clay soils shrink when they dry and swell when they get wet. Those swings move foundations down at the edges during drought and can push them back up when heavy rain returns. Knowing where the state sits in the cycle helps explain why cracks appear, close and reappear. ## Why does the weather cycle matter to a foundation? Many Oklahoma homes sit on expansive clay, a soil made of very fine clay minerals that swell when water enters and shrink when the soil dries out [6]. When moisture under a house is uneven, the slab bends: the edges can drop while the center stays put, or the edges can rise while the center stays lower [6]. Light houses on shallow slab foundations are especially sensitive to this movement [6]. Researchers at Oklahoma State University note that extreme weather, both heavy rain and drought, makes the shrink-swell problem worse [6]. For background on the mechanics, see shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). ## What are Oklahoma's recent droughts and wet spells? | Period | What happened | Source | |---|---|---| | Fall 2010 – 2011 | Drought began in late 2010 and spread into central and eastern Oklahoma by August 2011 | [1] | | Summer 2011 | Hottest summer on record statewide (86.9°F average) and third driest | [1] | | Year 2011 | 25.71 in. of rain statewide, about 11 in. below normal | [2] | | May 2015 | Wettest month in state history (14.40 in.), which largely ended a drought that had lasted much of five years | [3] | | Year 2015 | Wettest year on record (53.88 in.), beating 1957 | [4] | | 2021 – 2022 | Drought from August 2021; by mid-October 2022, 86% of the state was in extreme or exceptional drought | [5] | The National Weather Service in Tulsa links the 2011 drought to La Niña, a cooling of the equatorial Pacific that shifts the jet stream north and raises the odds of warm, dry weather in the Southern Plains [1]. ## What does each phase do to soil and houses? ### Drought onset As clay near the surface dries, it shrinks and pulls away from the foundation. When the soil under the perimeter dries and shrinks more than the soil under the interior, the outer walls can drop relative to the center [6]. Typical signs include soil pulled away from the foundation (https://terrabrain.vercel.app/signs/soil-pulled-away-from-foundation) and stair-step cracks wider at the top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top). ### Long or deep drought Drying reaches deeper the longer a drought lasts. A study of clay sites during the 2011 Texas drought found the zone of seasonal moisture change, called the active zone, deepened by about 2 feet, from roughly 8–10 feet to 10–12 feet [7]. The same study found the drought increased the clays' potential to heave once they were rewetted [7]. ### The drought breaks When big rains arrive after a long dry spell, dry clay takes on water and swells. Cracks that opened in the drought may close, and some areas can rise. A house that was lifted to level while the soil was at its driest can end up too high once the ground swells back; this is described on the over-lift heave (https://terrabrain.vercel.app/causes/over-lift-heave-after-drought-lift) page. ### Wet periods 2015 was Oklahoma's wettest year on record [4], and in years like that soils can stay wet for long stretches. Wet soil around the edges can raise the perimeter (edge lift (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift)), and water can collect in crawl spaces and basements. ## How can you track where the cycle is? - **U.S. Drought Monitor**: a weekly map, updated every Thursday, that ranks drought from D0 (abnormally dry) to D4 (exceptional) using rainfall, temperature, soil moisture, streamflow and local reports [8]. - **Oklahoma Mesonet soil moisture**: daily readings at several depths from stations statewide; see using Mesonet data (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros). Recording the drought category and soil moisture at the time of an inspection or repair gives a baseline for judging later movement. ## Related - Seasonal Movement Calendar (https://terrabrain.vercel.app/guides/seasonal-movement-calendar) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Lifting Procedure and Restoration (https://terrabrain.vercel.app/guides/lifting-procedure-and-restoration) - OK Data - Drought and Wet Years (https://terrabrain.vercel.app/data/drought-and-wet-years) - Perimeter Drying Settlement (Edge Drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) Sources: [1] 2011 Drought, National Weather Service, Tulsa https://www.weather.gov/tsa/weather-event_2011drought [2] Oklahoma Monthly Climate Summary: December 2011, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2011/MCS_December_2011.pdf [3] Oklahoma Monthly Climate Summary: May 2015, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2015/MCS_May_2015.pdf [4] Oklahoma Monthly Climate Summary: December 2015, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2015/MCS_December_2015.pdf [5] Oklahoma Monthly Climate Summary: October 2022, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2022/MCS_October_2022.pdf [6] Residential House Foundations on Expansive Soils in Changing Climates, HUD Office of Policy Development and Research (Cityscape, Vol. 25 No. 1) https://www.huduser.gov/PORTAL/periodicals/cityscape/vol25num1/ch10.pdf [7] Ground Conditions in the 2011 Drought, CIGMAT Conference, University of Houston https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2012/3.pdf [8] U.S. Drought Monitor (USDM), Drought.gov (NOAA National Integrated Drought Information System) https://www.drought.gov/data-maps-tools/us-drought-monitor-usdm --- # How do Oklahoma river floodplain and terrace soils affect homes? URL: https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces Answer: Floodplain and terrace deposits range from soft wet clay to sandy dunes and expansive claypans, so the soil series, not the river, predicts behavior. In short: Along every major Oklahoma river, the youngest ground is alluvium, sediment the river laid down on its floodplain, with older terraces standing higher on the valley sides. These deposits range from soft, wet floodplain clay to sandy dune ground to dense, expansive claypan soils. The soil series matters more than the river name for predicting how a foundation will behave. ## How do floodplains and terraces differ? **Alluvium** is sediment deposited by flowing water. The present **floodplain** is the low, flat land a river still floods. A **terrace** (or paleoterrace) is an older floodplain surface left higher than today's river as it cut downward. Alluvium can be thick. In Oklahoma County, the North Canadian River alluvial aquifer generally averages about 50 feet thick and may be up to 150 feet thick in the river channel itself, and productive alluvial aquifers are generally within about a mile of either side of the river [7]. Alluvium along Deer Creek can be up to 50 feet thick [7]. ## What soils form on floodplains? | Series | Material | Drainage | Water and flooding | |---|---|---|---| | Osage | Thick clayey alluvium; smectitic [1] | Poorly drained; very slow permeability [1] | Seasonal high water table 6–18 in, Nov–May [1] | | Port | Calcareous loamy alluvium [2] | Well drained [2] | Occasionally or frequently flooded, Mar–Oct [2] | | Verdigris | Silty alluvium [3] | Well drained [3] | Subject to flooding [3] | - **Osage** is a Vertisol, a clay soil defined by shrink-swell, with intersecting slickensides from about 13 to 60 inches deep [1]. It occurs on floodplains along major streams in eastern Oklahoma, southeastern Kansas and southwestern Missouri [1]. - **Port** occurs on floodplains in the eastern Central Rolling Red Plains and the Central Rolling Red Prairies of Oklahoma, Kansas and Texas [2]. - **Verdigris** occurs on floodplains in northeastern Oklahoma, southeastern Kansas and southwestern Missouri [3]. ## What soils form on terraces? | Series | Material | Key trait | |---|---|---| | Kirkland | Clayey sediments over Permian shale, on paleoterraces [5] | Slow permeability; intersecting slickensides [5] | | Tabler | Calcareous loamy or clayey alluvium on paleoterraces [4] | Very slow permeability; slickensides [4] | | Dougherty | Sandy and loamy sediments on Pleistocene terraces [6] | Stabilized dunes; about 20–40 in of sandy surface [6] | An Oklahoma State University study of five western Oklahoma soils found Kirkland had the greatest total shrink-swell across its profile, with a coefficient of linear extensibility up to about 0.090, and found Norge, on uplands of old alluvial origin, reached about 0.066 [8]. The authors linked these values to smectite clay and severe limitations for many engineering projects [8]. ## What does this mean for foundations? ### Soft, wet floodplain clay A thick clay floodplain soil with a water table within 6 to 18 inches for half the year [1] can compress under load and stay wet beneath crawl spaces. See soft soil consolidation (https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays) and crawl space moisture (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay). ### Flooding and scour Port and Verdigris are subject to flooding [2][3]. Floodwater can scour soil from around footings. See creeks and flood history (https://terrabrain.vercel.app/data/creeks-and-flood-history) and erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). ### Expansive terrace clay Kirkland and Tabler subsoils have slickensides [4][5], and lab tests show high shrink-swell in Kirkland-type soil [8]. These lots behave like other expansive clay sites. See perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). ### Sandy terraces Dougherty's thick sandy surface [6] swells little but can wash out under leaks or concentrated runoff. ## Related - Erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Osage soil (https://terrabrain.vercel.app/soils/osage) - Kirkland soil (https://terrabrain.vercel.app/soils/kirkland) - Tulsa metro (https://terrabrain.vercel.app/regions/tulsa-metro) - OKC metro (https://terrabrain.vercel.app/regions/okc-metro) Sources: [1] Official Soil Series Description: OSAGE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OSAGE.html [2] Official Soil Series Description: PORT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/PORT.html [3] Official Soil Series Description: VERDIGRIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/V/VERDIGRIS.html [4] Official Soil Series Description: TABLER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TABLER.html [5] Official Soil Series Description: KIRKLAND Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KIRKLAND.html [6] Official Soil Series Description: DOUGHERTY Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DOUGHERTY.html [7] OK County Groundwater Model (Project 174601), Association of Central Oklahoma Governments https://www.oklahomacounty.org/Portals/0/OK%20County%20Groundwater%20Model.pdf [8] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf --- # How do Oklahoma storms, floods and ice affect foundations? URL: https://terrabrain.vercel.app/guides/severe-weather-effects Answer: Water is the main way severe weather reaches a foundation: floods and heavy rain saturate clay and wash out soil, while wind and tornadoes act on the structure. In short: Water is the main way Oklahoma's severe weather reaches a foundation. Floods and heavy rain saturate clay soils, soften support and can wash soil out from under slab edges, while hard freezes can burst pipes. Wind and tornadoes act mostly on the structure above the foundation rather than the soil beneath it. ## How severe is Oklahoma's weather by the numbers? - From 1985 to 2019 Oklahoma averaged 60 tornadoes a year, with peaks in April and May [1]. - About three-fourths of the state's tornadoes have occurred in April, May and June; autumn is a secondary severe weather season [2]. - Flooding is most frequent in the spring and autumn months that bring the most rain [2]. - 2-inch extreme rainfall events have increased since 1985, and NOAA projects more extreme precipitation, raising flood risk and soil erosion [1]. - Freezing rain occurs regularly, especially in the southeast [1]. ## How does each weather event affect foundations? | Event | How it can affect a foundation | |---|---| | Flood or flash flood | Saturated, swelling clay and soil erosion [1][6] | | Heavy rain after drought | Clay swelling with increased heave potential [5][6] | | Tornado or straight-line wind | Mainly acts on walls, roof and connections above the foundation | | Ice storm or hard freeze | Icing and power outages [1]; any resulting pipe leaks add moisture and mold risk [7] | ### Floods and very wet periods May 2015 was the wettest month in Oklahoma history at 14.40 inches statewide, and the storms brought flooding, more than 60 tornadoes and 11 deaths [3]. In 2019, May and June together averaged 15.52 inches, the fifth-wettest such period on record [4]. Long stretches of saturated soil are when edge lift (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift), wet crawl spaces and basement seepage tend to appear. Soil washed out from under a slab edge is covered under erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) and erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes). After flooding or leaks, the EPA advises drying water-damaged areas and items within 24–48 hours to prevent mold [7]. ### Heavy rain after drought Expansive clay swells when water enters it and shrinks when it dries; extreme weather in both directions intensifies the problem [6]. A study of clay sites found the 2011 drought increased the soils' potential to heave once rewetted [5]. That is why a sudden wet spell after drought can move foundations that were settling only weeks earlier; see drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles). ### Tornadoes and wind Wind loads act on the house frame and how it is tied down to the foundation, rather than on the soil. Oklahoma's deadliest tornado, on April 9, 1947, killed more than 100 people, and the May 3, 1999 outbreak produced more than 60 tornadoes [1]. ### Ice storms and hard freezes During the February 9–20, 2021 cold wave, heavy snow, severe icing and power outages caused considerable damage [1]. Freeze effects on foundations, flatwork and plumbing are on the freeze-thaw and frost depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) page. ## How does weather relate to insurance questions? Storm-related claims often raise the question of whether damage came from the storm or from long-term soil movement. The EPA notes that hidden moisture problems can develop around leaking pipes and inside walls [7], which is one reason documentation of conditions before and after an event matters. See insurance claims (https://terrabrain.vercel.app/rules/insurance-claims) and seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement) for how causes are separated. ## Related - Drought and Wet Cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) - Freeze-Thaw and Frost Depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) - Surface Drainage and Grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - OK Data - Creeks and Flood History (https://terrabrain.vercel.app/data/creeks-and-flood-history) - Insurance Claims (https://terrabrain.vercel.app/rules/insurance-claims) Sources: [1] Oklahoma - State Climate Summaries 2022, NOAA National Centers for Environmental Information https://statesummaries.ncics.org/chapter/ok/ [2] Oklahoma Climate, Oklahoma Climatological Survey https://www.ou.edu/ocs/oklahoma-climate [3] Oklahoma Monthly Climate Summary: May 2015, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2015/MCS_May_2015.pdf [4] Oklahoma Monthly Climate Summary: June 2019, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2019/MCS_June_2019.pdf [5] Ground Conditions in the 2011 Drought, CIGMAT Conference, University of Houston https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2012/3.pdf [6] Residential House Foundations on Expansive Soils in Changing Climates, HUD Office of Policy Development and Research (Cityscape, Vol. 25 No. 1) https://www.huduser.gov/PORTAL/periodicals/cityscape/vol25num1/ch10.pdf [7] A Brief Guide to Mold, Moisture and Your Home, U.S. Environmental Protection Agency https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home --- # How do Oklahoma's geologic regions affect foundations? URL: https://terrabrain.vercel.app/guides/oklahoma-geologic-provinces Answer: Pennsylvanian shales and sandstones in the east and Permian red beds in central and western Oklahoma shape soil, clay content and depth to firm material. In short: Oklahoma's surface is mostly sedimentary rock, with a few uplifted mountain areas. For foundations, the most practical divide is between Pennsylvanian shales and sandstones in the east, around Tulsa, and Permian red beds in the central and western state, around Oklahoma City, with gypsum appearing farther west. The rock underneath shapes the soil, its clay content and how deep firm material lies. ## What are Oklahoma's geologic provinces? The Oklahoma Geological Survey's 2024 structural and tectonic map names the state's major provinces [1]: | Province | Location | Notes from the OGS map | |---|---|---| | Ozark Uplift | Far northeast | Oldest structure in the region, centered in southern Missouri; Oklahoma portion has small extensional faults | | Cherokee Platform | Northeast and east-central, including the Tulsa area | Underlain by ancient crystalline rock and relatively stable through the Paleozoic | | Arkoma Basin | East-central and southeast | Shaped by a late Paleozoic continental collision | | Ouachita Uplift | Southeast | Low-angle, imbricated fault zone with about 100 miles of lateral displacement on the sole fault | | Arbuckle Uplift | South-central | Bounded by upthrust faults | | Ardmore and Marietta basins | South-central | Marietta Basin separated from the Ardmore by significant en-echelon faults | | Wichita Uplift | Southwest | Upthrust faults with an igneous core of Cambrian age | | Anadarko Basin | West-central | Deepest sedimentary basin in North America | | Hollis-Hardeman Basin | Far southwest | Shallower than the Anadarko, with a similar origin | | Nemaha Uplift and fault zone | North-central | Variable; responded to compressional, extensional and wrench events | The map also notes Cretaceous rocks in south-central and southeastern Oklahoma and Mesozoic rocks in the westernmost Panhandle [1]. ## What did eastern and western soils form from? USDA soil descriptions record the rock each soil weathered from, which shows the east-west split clearly: - **Tulsa side (Pennsylvanian rocks):** Dennis formed from Pennsylvanian shale and has its type location near Claremore [2]. Collinsville formed from Pennsylvanian sandstone near Inola and reaches hard rock within about 4 to 20 inches [3]. The OGS describes Pennsylvanian strata as the thickest accumulation on the Cherokee Platform [1]. - **Oklahoma City side (Permian red beds):** Renfrow formed from Permian clayey shale and has vertic properties, meaning strong seasonal cracking [4]. Vernon formed from Permian redbed claystone, with dense bedrock at 20 to 40 inches [5]. - **Western gypsum country:** Cottonwood formed over massive gypsum of the Permian Blaine Formation in southwestern Oklahoma and northwest Texas, with hard gypsum often within 3 to 20 inches of the surface [6]. Details for each metro are on soil series - Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) and soil series - OKC metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro). ## Why do geologic regions matter for foundations? | Setting | Foundation consideration | |---|---| | Shale-derived clays (east and central) | Clay-rich soils that shrink and swell; perched water common in eastern shale soils [2][4] | | Sandstone uplands | Shallow rock; less soil to move, but uneven depth to rock [3] | | Red-bed claystones | High clay content and dense layers at moderate depth [5] | | Gypsum and other soluble rock | Rock that can dissolve, with potential for voids and sinkholes [8] | USGS karst mapping outlines rock units containing significant carbonate or evaporite minerals (gypsum is an evaporite) as soluble rocks that have developed or could develop karst features, such as sinkholes [8]. See gypsum karst and sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes). Climate also changes across the provinces: average annual precipitation ranges from about 17 inches in the far western Panhandle to about 56 inches in the far southeast [7], which affects how deeply soils dry out. Province boundaries are generalized. Specific formations at a site are confirmed from detailed geologic maps and borings. ## Related - Hennessey Shale (Group) (https://terrabrain.vercel.app/geology/hennessey-shale-group) - Pennsylvanian Shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales) - Permian Gypsum Units (e.g., Blaine) (https://terrabrain.vercel.app/geology/permian-gypsum-units-e-g-blaine) - Clay Mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Induced Seismicity in Oklahoma (https://terrabrain.vercel.app/guides/induced-seismicity-in-oklahoma) - Shale Weathering and Bearing Strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata) Sources: [1] Structural / Tectonic Map of Oklahoma (GM-46), Oklahoma Geological Survey https://www.ou.edu/content/dam/ogs/documents/GMs/GM-46_Structural_Tectonic_Map_of_Oklahoma.pdf [2] Official Series Description - DENNIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DENNIS.html [3] Official Series Description - COLLINSVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COLLINSVILLE.html [4] Official Series Description - RENFROW Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/R/RENFROW.html [5] Official Series Description - VERNON Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/V/VERNON.html [6] Official Series Description - COTTONWOOD Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COTTONWOOD.html [7] Oklahoma Climate, Oklahoma Climatological Survey https://www.ou.edu/ocs/oklahoma-climate [8] Karst in the United States: A Digital Map Compilation and Database (Open-File Report 2014-1156), U.S. Geological Survey https://pubs.usgs.gov/of/2014/1156/ --- # How do Ouachita Mountain rocks affect southeast Oklahoma homes? URL: https://terrabrain.vercel.app/geology/ouachita-folded-rocks Answer: Tightly folded sandstone, shale and chert form steep slopes with thin, rocky soils, so slope movement, erosion and fill matter more than clay swell. In short: The Ouachita Mountains of southeast Oklahoma are made of sandstone, shale and chert that were buried deeply and then crumpled into tight folds. Today the hard layers stand as wooded ridges and the soft layers form valleys. Thin, rocky soils on steep slopes mean that slope movement, erosion and fill are more common foundation concerns here than clay swell. ## How did the Ouachita Mountains form? The Ouachita rocks were deeply buried, and the heat and pressure of mountain building squeezed and tightly folded them about 315 million years ago [2]. The wooded mountains now rise roughly 500 to 1,500 feet above nearby valleys [2]. **Folded** rock means layers that were originally flat but are now bent, tilted and in places broken by faults. An early USGS survey of the Atoka area described Ouachita strata as steeply tilted, crushed and faulted, with a major fault along the western edge of the uplift [1]. ## What are the main rock types? The same survey described three kinds of layers that still frame how the region is understood [1]: | Rock | Example unit (Atoka survey) | Landform | |---|---|---| | Sandstone | Jackfork sandstone, fine-grained brown and gray, about 3,800 ft exposed | Forms the Jackfork, Rich and Kiamichi mountains [1] | | Shale | "Standley" (Stanley) shale, mostly green and dark shale with soft sandstone, about 6,000 ft | Nearly level valleys and plains [1] | | Chert | Talihina chert, about 1,200 ft of flint, chert and black shale | Black Knob Ridge [1] | **Chert** is a hard rock made of silica. Hard sandstone and chert resist erosion and hold up ridges, while shale wears down into valleys [1]. ## What soils form on the folded rocks? Ridges and mountainsides commonly carry thin soils over sandstone. The Hector series is an example [3]: - Formed in residuum from sandstone, with some colluvium (soil that has moved downslope) in places. - Hard rock at about 14 to 20 inches, typically about 15 inches. - Rock fragments up to 50 percent of the surface layer and 35 percent of the subsoil. - Well drained, with moderately rapid permeability. - Slopes from 2 to 60 percent, on ridgetops and steep to very steep mountainsides. ## What does this mean for foundations? ### Steep slopes and creep Hector soils occur on slopes up to 60 percent [3]. On slopes like these, soil and fill on the downhill side of a house can creep slowly downslope over years; signs include leaning retaining walls, fences and trees. See slope creep and lateral movement (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement) and tilted retaining walls, fences or trees (https://terrabrain.vercel.app/signs/tilted-retaining-walls-fences-or-trees). ### Thin soil over hard rock With hard sandstone at 14 to 20 inches in soils like Hector [3], footings on a sloping lot may sit partly on rock and partly on soil or fill, which gives the house uneven support. See fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). ### Runoff and erosion Runoff on Hector soils ranges from slow to rapid depending on slope [3]. Concentrated water from roofs and driveways can wash out thin soil at footings. The ASCE homeowner guide recommends discharging downspouts at least 3 feet from the foundation and grading soil away at least 3 inches in the first 5 feet [4]. See erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) and slope and erosion stabilization (https://terrabrain.vercel.app/repairs/slope-and-erosion-stabilization). ### Rapid changes across a site Because steeply tilted sandstone, shale and chert layers alternate [1], bearing conditions can change across a single building footprint. See shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata). ## Related - Southeast (Ouachitas and Red River) (https://terrabrain.vercel.app/regions/southeast-ouachitas-and-red-river) - Hector soil (https://terrabrain.vercel.app/soils/hector) - Slope creep and lateral movement (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement) - Erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Oklahoma geologic provinces (https://terrabrain.vercel.app/guides/oklahoma-geologic-provinces) Sources: [1] Description of the Atoka Quadrangle (Geologic Atlas Folio 79), U.S. Geological Survey https://pubs.usgs.gov/gf/079/text.pdf [2] The Oklahoma Geological Survey and the geology of Oklahoma, USGS National Geologic Map Database (DMT '25) https://ngmdb.usgs.gov/Info/dmt/docs/DMT25_Johnson.pdf [3] Official Soil Series Description: HECTOR Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/H/HECTOR.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # How do Panhandle Ogallala and loess soils affect foundations? URL: https://terrabrain.vercel.app/geology/ogallala-formation-and-loess Answer: Panhandle soils formed in Ogallala deposits capped by loess and sand. They are dry most of the year, so movement follows sudden moisture changes. In short: The Oklahoma Panhandle sits on the High Plains, where the ground is made of Ogallala river deposits capped by wind-blown silt (loess) and sand. Soils here are dry most of the year, often contain calcium carbonate layers, and range from silty and loamy to clayey. Foundation movement tends to follow sudden changes in moisture rather than long wet seasons. ## What layers lie under the Panhandle? ### Ogallala Formation USDA soil descriptions identify the **Ogallala Formation** as calcareous, loamy alluvium (river-laid sediment) of Miocene-Pliocene age [1]. The Potter soil, which formed in this material, occurs in the Southern High Plains and Breaks of western Texas, eastern New Mexico and northwestern Oklahoma, on draws, escarpments and valley sides [1]. Potter soils have calcic horizons, layers enriched in calcium carbonate, with strongly cemented carbonate nodules and calcrete fragments [1]. ### Loess **Loess** is silt that was blown in by wind and settled over the land surface. Two High Plains soils formed in it: - **Richfield** formed in calcareous loess 1 to more than 3 meters thick on tablelands, and its range includes the Oklahoma Panhandle [2]. - **Ulysses** formed in loess on plains and tableland hillslopes in the Central High Tableland, mainly in Kansas, Nebraska and Colorado; USDA removed Oklahoma from its mapped extent [3]. ### Wind-blown sand and younger eolian deposits **Eolian** means wind-deposited. Dalhart soils formed in loamy eolian sediments of Holocene age on interdunes and sand sheets in the Southern High Plains of Kansas, Oklahoma and Texas [4]. Mansker soils formed in calcareous, loamy eolian deposits of the Pleistocene Blackwater Draw Formation in Texas, New Mexico and Oklahoma [5]. ## How do Panhandle soils compare? | Series | Parent material | Texture class | Mean annual precipitation | |---|---|---|---| | Richfield | Loess [2] | Fine, smectitic [2] | 13–22 in (33–56 cm) [2] | | Ulysses | Loess [3] | Fine-silty [3] | 14–24 in [3] | | Dalhart | Eolian sediments [4] | Fine-loamy [4] | 15–23 in [4] | | Potter | Ogallala alluvium [1] | Loamy-skeletal, carbonatic [1] | 16–22 in [1] | ## What do these soils mean for foundations? ### Low rainfall, dry soil Every series above has a mean annual precipitation of roughly 13 to 24 inches [1][2][3][4]. Ulysses notes that most rain falls in high-intensity thunderstorms from late spring through early autumn [3]. Soils that stay dry most of the year can change markedly when they are suddenly wetted by a leak, a downspout or ponding. See hydrocollapse (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil) and collapsible and loess soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils) for how some low-density, dry soils lose volume when first soaked. ### Clay where present Richfield's subsoil is classed as fine and smectitic [2], meaning it has a clay-rich subsoil dominated by swelling clay minerals. Soil scientists rate shrink-swell by linear extensibility, with 3 to 6 percent rated moderate and 6 to 9 percent high [6]. Lot-specific values are listed in the USDA Web Soil Survey. See perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). ### Carbonate layers Secondary carbonates in Richfield begin at about 10 to 24 inches (25 to 61 cm) [2], and calcic horizons in Potter and Mansker begin within roughly the upper 2 to 15 inches [1][5]. These hard, limy layers can affect digging for footings and piers. ### Cold Required footing depth for frost is set locally and differs across Oklahoma. See freeze-thaw and frost depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) and frost heave (https://terrabrain.vercel.app/causes/frost-heave). ## Related - Panhandle (High Plains) (https://terrabrain.vercel.app/regions/panhandle-high-plains) - Collapsible and loess soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils) - Richfield soil (https://terrabrain.vercel.app/soils/richfield) - Dalhart soil (https://terrabrain.vercel.app/soils/dalhart) - Ulysses soil (https://terrabrain.vercel.app/soils/ulysses) - Freeze-thaw and frost depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) Sources: [1] Official Soil Series Description: POTTER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/POTTER.html [2] Official Soil Series Description: RICHFIELD Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/R/RICHFIELD.html [3] Official Soil Series Description: ULYSSES Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/U/ULYSSES.html [4] Official Soil Series Description: DALHART Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DALHART.html [5] Official Soil Series Description: MANSKER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/M/MANSKER.html [6] Linear Extensibility (definition and shrink-swell classes, after NRCS National Soil Survey Handbook), UC Davis California Soil Resource Lab https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html --- # How do Pennsylvanian shale clays affect Oklahoma foundations? URL: https://terrabrain.vercel.app/geology/pennsylvanian-shales Answer: Pennsylvanian shale under Tulsa and eastern Oklahoma weathers into poorly drained clays that hold perched water and often swell and shrink strongly. In short: Thick Pennsylvanian shale underlies the lower ground of the Tulsa metro and much of eastern Oklahoma. Near the surface it weathers into clay soils that drain poorly, hold perched water in winter and spring, and in many cases swell and shrink strongly. These soils are behind much of the seasonal foundation movement in the region. ## What is Pennsylvanian shale? **Shale** is rock made of compacted clay and silt that splits into thin layers. In northeastern Oklahoma, the Nowata is an example: a series of bluish or greenish shales with a few sandstones and at least one coal bed, varying from about 50 to 600 feet thick at Tulsa [1]. Its outcrop is about 8 miles wide east of Tulsa [1]. Farther south in the Arkoma Basin, a USGS study of the Boggy Formation near McAlester described brown to dark-gray shale with numerous thin sandstone beds, 610 to 1,220 meters thick [2]. Key findings from that study [2]: - Fractures were most common at shallow depths, and slickensides were generally visible on fracture surfaces. - About 2 meters of clay-rich soil lay over weathered shale at the test site. - Lab and field tests found very low hydraulic conductivity, meaning water moves through the intact shale very slowly. That last point is why shale acts as an **aquitard**, a layer that holds water up rather than letting it drain. ## What clay soils form on shale? | Series | Parent material | Drainage | Perched water | Notable trait | |---|---|---|---|---| | Dennis | Pennsylvanian shale residuum [3] | Somewhat poorly drained [3] | 12–30 in, Dec–Apr [3] | Solum over 60 in [3] | | Okemah | Alluvium or colluvium from Pennsylvanian shale [6] | Somewhat poorly drained [6] | 2–3 ft, Dec–Apr [6] | Slow permeability [6] | | Parsons | Old alluvium or Pennsylvanian shale residuum [5] | Somewhat poorly drained [5] | 6–18 in, Dec–Apr [5] | Clayey subsoil, 35–60% clay [5] | | Summit | Pennsylvanian shale colluvium or residuum [4] | Moderately well to somewhat poorly drained [4] | 12–36 in, Nov–May [4] | Smectitic; deep summer cracks [4] | | Talihina | Soft Pennsylvanian shale [7] | Poorly drained [7] | 0.5–2 ft, Nov–Apr [7] | Rock at 10–20 in [7] | ### How much they swell Soil scientists rate shrink-swell using the **coefficient of linear extensibility (COLE)**, the fraction a soil's length changes from moist to dry. A COLE of 0.06 to 0.09 is high and 0.09 or more is very high [8]. The Summit description reports deep, wide summer cracks with a COLE of 0.09 or more, and slickensides in the subsoil [4]. Summit's clay is smectitic, meaning dominated by the most swelling clay mineral family [4]. ## What does this mean for foundations? - **Wet-season edge lift.** Perched water from late fall to spring [3][4][5] wets the clay at slab edges and under crawl spaces. See perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) and groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water). - **Summer edge drop.** As perched water disappears and clay dries, deep cracks open in soils like Summit [4]. See perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). - **Crawl space moisture.** A water table 6 to 30 inches below the surface in winter and spring [3][5] is within the depth range of a typical crawl space. See crawl space moisture and wood decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay). - **Shallow shale on slopes.** Talihina, on slopes of 5 to 20 percent and more, reaches shale at 10 to 20 inches [7]. See shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata). ## Related - Tulsa metro (https://terrabrain.vercel.app/regions/tulsa-metro) - East-Central (Arkoma) (https://terrabrain.vercel.app/regions/east-central-arkoma) - Soil series in the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) - Dennis soil (https://terrabrain.vercel.app/soils/dennis) - Summit soil (https://terrabrain.vercel.app/soils/summit) - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) Sources: [1] Geologic Unit: Nowata, USGS National Geologic Map Database (Geolex) https://ngmdb.usgs.gov/Geolex/UnitRefs/NowataRefs_9552.html [2] Geologic and Hydraulic Characteristics of Selected Shaly Geologic Units in Oklahoma (WRI 96-4303), U.S. Geological Survey https://pubs.usgs.gov/wri/1996/4303/report.pdf [3] Official Soil Series Description: DENNIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DENNIS.html [4] Official Soil Series Description: SUMMIT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/S/SUMMIT.html [5] Official Soil Series Description: PARSONS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/PARSONS.html [6] Official Soil Series Description: OKEMAH Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OKEMAH.html [7] Official Soil Series Description: TALIHINA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TALIHINA.html [8] Linear Extensibility (definition and shrink-swell classes, after NRCS National Soil Survey Handbook), UC Davis California Soil Resource Lab https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html --- # How do pressed concrete piles work and what are their limits? URL: https://terrabrain.vercel.app/repairs/pressed-concrete-piles Answer: Short precast concrete cylinders are jacked into the ground until they stop. Refusal does not prove stable soil, and they generally do not resist uplift. In short: Pressed concrete piles are stacks of short precast concrete cylinders pushed into the ground under a foundation with a hydraulic jack, using the building's weight as the reaction, until they will not go further [1]. They are a long-used underpinning method, but stopping point ("refusal") is not the same as proving the pile reached stable soil, and the piles generally do not resist uplift from swelling clay [1][2]. ## How does the system work? A **pile** (or pier) is a column that carries a building's load down to firmer soil. Underpinning means adding piles under an existing foundation. With pressed concrete piles [1]: - Segments are typically cylinders about one foot long. Diameters vary; guidance gives tapering 4-, 6- and 8-inch segments as an example. - One segment at a time is pushed down by a hydraulic jack that pushes against the foundation above. - Each pile is driven to **refusal** — the point where the force needed to drive it exceeds the load it will support. - At refusal, the pile is shimmed under pressure before the jack is removed, to limit rebound. Shims are at least 1/8 inch thick. - A precast cap of the same strength as the segments sits on top. - Steel cable, rebar or rods may run through a center hole as optional reinforcement. If piles are driven at the same time they should be at least 25 feet apart; otherwise one pile is driven at a time [1]. ## What are the installation steps? 1. Dig an access hole at the foundation beam. 2. Press the first segment and keep adding segments under the jack. 3. Continue to refusal and record the depth and driving force or pressure [1]. 4. Set the cap and shims, then raise the foundation toward its target. 5. Backfill and compact the hole. Guidelines call for driving records for each pile (depths, plus driving force or pressure if recorded), elevation surveys before and after, and a plumbing leak test report on under-slab lines [1]. ## What spacing does published guidance show? For lightly loaded homes, one engineering guideline gives prescriptive maximum spacing [1]: | Location | Maximum spacing | |---|---| | Exterior, 1-story wood or brick | 8 ft | | Exterior, 2-story with brick first story only | 7 ft | | Exterior, 2-story brick | 6 ft | | Interior, along beams in stiffened slabs | 10 ft | Homes of three or more stories need an engineered design [1]. Spacing is covered in loads, pier spacing and capacity (https://terrabrain.vercel.app/guides/loads-pier-spacing-and-capacity). ## What are the limitations? ### Refusal is not verified capacity Refusal only shows the jack could not push further at that moment. Guidelines note that piles that do not reach stable soil below the **active zone** — the depth where soil moisture changes with the seasons — may not resist shrink or swell movement [1]. A committee review lists shallow piles losing skin friction (grip along the sides) during drought as a potential problem [2]. Oklahoma research using Mesonet data estimated active zone depths around the state at about 0.5 to 4 meters (roughly 1.5 to 13 feet) [3]. A pile that stops in stiff, dry clay or soft weathered shale near the surface may still be inside that zone; see shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata). When refusal comes before the minimum depth in the plans, the guideline's options include stopping with engineer approval, using a smaller pile at least three diameters away, water jetting, or pre-drilling a new hole [1]. A review notes that water jetting adds moisture that can cause heave [2]. ### No uplift resistance Pressed piles generally do not resist uplift, so where soil touches the foundation they will not stop swelling clay from lifting it [1]. Soils with a **linear extensibility** (an NRCS measure of shrink-swell) of 6% or more are rated high or very high shrink-swell [4]. This is why these piles are not used to fix perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift). ### Segment alignment Without center reinforcement, segments can shift sideways; a committee review lists unreinforced segments moving laterally as a possible problem [2]. ### Fill and debris Guidelines call for removing obstructions encountered during installation, and note that dense granular soils and stiff sandy clay or clayey sand layers can make piles hard to drive [1]. Fill can hold such obstructions above native soil. See fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). ## How do they compare with steel push piers? Steel push piers are installed the same way but use steel pipe, which can often be driven deeper. Oklahoma installation records for steel push piers at one large Tulsa site logged a median depth of about 12 feet, with the middle half between 9 and 14 feet [5]. Details are on the steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) page. Cost for any pier method is driven mainly by the number of piles, depth and access. ## Related - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Method Selection Matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix) - Pier Uplift or Movement After Repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair) - Lifting Procedure and Restoration (https://terrabrain.vercel.app/guides/lifting-procedure-and-restoration) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) Sources: [1] Design, Manufacture, and Installation Guidelines of Precast Concrete Segmented Piles For Foundation Underpinning (FPA-SC-08-1), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-08-1.pdf [2] Post Foundation Repair Performance of Residential and Other Low-Rise Buildings on Expansive Soils (FPA-RC-01-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-RC-01-0.pdf [3] Soil matric suction and active zone depth in Oklahoma, Oklahoma State University (ShareOK) https://shareok.org/handle/11244/54639 [4] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [5] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # How do slab-on-grade foundations move on Oklahoma clay? URL: https://terrabrain.vercel.app/foundations/slab-on-grade Answer: The slab moves as clay under its edges or center gains or loses moisture, and the shape of that movement decides which repair, if any, fits. In short: A slab-on-grade foundation is a concrete floor poured directly on the ground, with its outer edge thickened into a footing. On expansive clay the slab moves when the soil under its edges or center gains or loses moisture, and the shape of that movement decides which repair, if any, fits. ## How is a slab-on-grade foundation built? - **Slab:** the code minimum thickness for a concrete floor on the ground is 3.5 in [1]. - **Base and vapor retarder:** a 4-in base of gravel or crushed stone and a 6-mil polyethylene vapor retarder under the concrete [1]. - **Perimeter beam:** the edge turns down into a thickened footing, also called a grade beam or turn-down. Reinforcement is either one No. 4 bar at top and bottom of that footing, or one No. 5 or two No. 4 bars in its middle third [3]. - **Interior beams:** footings under bearing walls that are cast with the slab extend at least 12 in below the top of the slab [3]. - **Plumbing:** water and drain lines run in the soil under the slab. ### How has Oklahoma's code changed? Oklahoma's adoption of the 2024 International Residential Code, effective September 14, 2026, made these slab-related changes [2]: - Two No. 4 bars added to all footings. - Fill under slabs compacted in 8 to 12 in lifts. - Maximum fill depth raised from 24 to 48 in for clean sand or gravel; earth fill stays at 8 in. - Interior slabs on grade and enclosed garage slabs exempt from air entrainment. - Post-tensioned slabs on grade labeled at the electrical panel door (see post-tensioned slabs (https://terrabrain.vercel.app/foundations/post-tensioned-slabs)). ## Why do slabs move on clay? Foundations on expansive soil fall under the building code's expansive-soil design section, and a soil counts as expansive if, for example, its plasticity index is 15 or more [8]. Swelling soils lift and crack lightly loaded footings and often distress floor slabs [4]. On a uniformly loaded rectangular slab, corners press on the soil with about one-fourth the pressure of the center, so corners tend to lift relative to the middle, and moisture differences at the edge add to it [4]. Seasonal moisture change can reach from 3 to 40 ft deep [4]. Research on a slab-on-ground foundation over expansive soil modeled three base conditions, edge swelling after a wet climate, center lift after a long dry period and edge shrinkage after a dry climate, and then added a water line leak under the slab center to see how it changed movement and bending [5]. ## What are the common movement patterns? | Pattern | What drives it | Typical symptoms | |---|---|---| | Edge drop (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) | Soil at the perimeter dries and shrinks [4][5] | Brick cracks, low corner, exterior doors binding | | Edge lift (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) | Perimeter soil wets and swells [4][5] | High corners, gaps under baseboards near exterior walls | | Center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) | Moisture builds under the middle, or a leak [5] | Interior floor hump, interior door and wall cracks | | Tilt | One side moving more than the other (differential movement) [4] | Whole side lower, sloping floors | | Shrinkage cracks | Concrete shrinking as it dries; extra water increases shrinkage about 20% for 2 gallons per cubic yard [6] | Fine random cracks under flooring | Engineering guidance for swelling soils notes that some cracking of floating slabs should be expected [7]. Whether a crack matters structurally is decided by floor elevations over time, which is covered in elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) and heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). ## Which repairs fit each pattern? - **Edge drop or perimeter settlement:** perimeter underpinning such as steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers), pressed concrete piles, helical piers or drilled piers. - **Interior settlement:** interior piers by tunneling or coring, or slab lifting by injection. - **Moisture-driven movement:** drainage, root barriers and moisture control, and plumbing leak detection (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab). - **Center heave:** lifting is generally not the tool, because piers push up and cannot pull a raised center down; moisture control, leak repair, soil stabilization, or raising the low perimeter to match are the options discussed. ## Related - Post-Tensioned Slabs (https://terrabrain.vercel.app/foundations/post-tensioned-slabs) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Visible Slab Cracks (https://terrabrain.vercel.app/signs/visible-slab-cracks) - Plumbing Leaks Under Slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) - Method Selection Matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix) Sources: [1] Single Family Dwellings – Residential Building Guide, Jersey County (Illinois) Building Division https://jerseycounty-il.gov/wp-content/uploads/2025/01/Residential-Building-Guide-5_22.pdf [2] Adoption of International Residential Code 2024 (IRC 2024), Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2024%20IRC%20Code%20Changes%20Summary%20-%20for%20website.pdf [3] Steel Bones: Inspecting the Critical Role of Rebar in Foundation Strength (IRC R403.1-R403.1.6), InterNACHI https://www.nachi.org/footing-stem-wall-reinforcement-rebar.htm [4] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [5] Investigation of a leaking water line beneath residential foundation on expansive soils, American Society of Civil Engineers, Geotechnical Special Publication 147 (Michigan Technological University Digital Commons) https://digitalcommons.mtu.edu/michigantech-p/8670 [6] Inspecting the Concrete, Cracking, and Water Connection (IRC R406), InterNACHI https://www.nachi.org/concrete-cracking-water-connection.htm [7] Home Construction on Shrinking and Swelling Soils (Special Publication 11), Colorado Geological Survey (Holtz and Hart, 1978) https://coloradogeologicalsurvey.org/wp-content/uploads/woocommerce_uploads/SP-11.pdf [8] Foundations on Expansive Soils – Residential (IHB TB 10-01), Texas Department of Licensing and Regulation https://tdlr.texas.gov/ihb/pdf/TB1001.pdf --- # How do steel push piers fix a settling foundation in Oklahoma? URL: https://terrabrain.vercel.app/repairs/steel-push-piers Answer: Steel pipe is driven down with a hydraulic ram, using the house's weight, until it reaches soil or rock that resists the load. Pressure is recorded per pier. In short: Steel push piers are sections of steel pipe driven straight down beside or under a footing with a hydraulic ram, using the weight of the house as the push-back force, until they reach soil or rock that resists the load [2]. The hydraulic pressure is recorded for every pier, giving a field record of drive resistance at installation. In one large set of Tulsa installation records the median depth was about 12 feet [3]. Push piers carry downward load only; they do not stop swelling clay from lifting a foundation [2]. ## How does the system work? A **pier** is a column that carries a building's load down to firmer ground. A **push pier** (also called a resistance pier) is driven rather than drilled: 1. The soil is dug out at the footing and the footing face is prepared. 2. A steel **bracket** is attached to the footing or grade beam. 3. Pipe sections are pushed down through the bracket by a hydraulic ram. The ram pushes against the house, so the structure's weight is the reaction. 4. Pressure is read at each section. When the pier will not advance under the target force, it has reached its drive resistance. 5. Load is transferred to the piers, the foundation is lifted (often with several rams on one manifold so lifting is even), the pier is locked off and the hole backfilled. ICC Evaluation Service publishes acceptance criteria (AC517) for push pier foundation systems, which set a method for establishing allowable load and deformation capacities for systems that resist axial compression [1]. Many systems are evaluated against these criteria; the specific capacity of a given system comes from its evaluation report and the engineer's design. ## How deep do push piers go in Oklahoma? Oklahoma installation records for 396 steel push piers at a large Tulsa site (2025) show [3]: | Measure | Value | |---|---| | Median depth to refusal | about 12 ft | | Middle half of piers | 9–14 ft | | Full range | 2–40 ft | | Median final installation pressure | about 9,000 psi | | Piers set at the slab | stopped about 8–11 ft at 4,000–5,000 psi | | Piers set at the footing | stopped about 13–17 ft at 7,000–8,000 psi | The wide range reflects changes in soil, weathered shale and rock depth across one site. See depth to rock from borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings) and bedrock in the Tulsa metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro). ## What do push piers address? Push piers are used where the foundation has **settled** — moved down — and firmer soil lies below the zone causing the movement. Typical cases include perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop), tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement), fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) and soft alluvial soils. The aim is to bear below the **active zone**, the depth where soil moisture changes with the seasons. Oklahoma research using Mesonet data estimated active zone depths around the state at about 0.5 to 4 meters (roughly 1.5 to 13 feet) [4]. Soils with an NRCS linear extensibility of 6% or more are rated high or very high shrink-swell [5]. ## What are the limitations? ### Refusal is not a static load test The recorded pressure shows how hard the pier resisted at the time it was driven. Engineering reviews of post-repair performance list two related problems with steel pipe piles: piles not driven deep enough, and loss of skin friction (side grip) at shallow depths during drought [2]. A pier that stops in stiff, dry clay or soft weathered shale near the surface may still be inside the active zone; see shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata). ### No uplift resistance Piers will not prevent uplift from heaving soil unless they are designed to do so; the same review notes heave is generally not considered a pier failure, though it can look like one [2]. For this reason push piers are not a fix for perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) or post-tree-removal heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave). Where the center of a slab has heaved, piers are sometimes used only to raise low perimeter areas toward the high center after the water source is fixed. ### Other installation problems The same review lists piles installed out of plumb and overloading that bends the shaft as potential problems [2]. Other limits: - The structure must be heavy enough to push against; light buildings may not develop enough force, which is one reason helical piers are used. - The bracket sits beside the footing, so it loads the footing off-center; a weak or shallow footing limits what can be done. - Buried steel corrodes. A long-running federal study of underground corrosion found the most corrosive soils were those with high soluble salts (low electrical resistivity) and poor aeration, such as wet, poorly drained clays [7]. - Where soluble rock and cavities are suspected, an engineering investigation comes before piering. ## What records and follow-up are kept? Each pier's depth and final pressure are recorded, and gauge pressure is converted to load using the ram area and calibrated gauges. Monitoring guidelines call for recording elevations at the same reference and monitor points used in earlier surveys, with drainage, plumbing leaks and other moisture problems remedied well before a monitoring period [6]. Cost is driven mainly by the number of piers, their depth and access to the footing. ## Related - Pressed Concrete Piles (https://terrabrain.vercel.app/repairs/pressed-concrete-piles) - Helical Piers (https://terrabrain.vercel.app/repairs/helical-piers) - Loads, Pier Spacing and Capacity (https://terrabrain.vercel.app/guides/loads-pier-spacing-and-capacity) - Pier Uplift or Movement After Repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair) - Method Selection Matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix) - Lifting Procedure and Restoration (https://terrabrain.vercel.app/guides/lifting-procedure-and-restoration) Sources: [1] AC517 Push Pier Foundation Systems, ICC Evaluation Service https://shop.iccsafe.org/ac517-push-pier-foundation-systems-approved-february-2020-editorially-revised-may-2024-pdf-download.html [2] Post Foundation Repair Performance of Residential and Other Low-Rise Buildings on Expansive Soils (FPA-RC-01-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-RC-01-0.pdf [3] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data [4] Soil matric suction and active zone depth in Oklahoma, Oklahoma State University (ShareOK) https://shareok.org/handle/11244/54639 [5] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [6] Guidelines for Evaluating Foundation Performance by Monitoring (FPA-SC-12-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-12-0.pdf [7] Underground Corrosion (Circular 579), National Bureau of Standards (now NIST) https://nvlpubs.nist.gov/nistpubs/Legacy/circ/nbscircular579.pdf --- # How do Tulsa-area sandstone ridges affect Oklahoma foundations? URL: https://terrabrain.vercel.app/geology/pennsylvanian-sandstones Answer: The sandstone forms shallow, loamy, well-drained soils, so slopes, fill, erosion and uneven rock matter more than clay swell on these lots. In short: Pennsylvanian sandstone forms the ridges, hills and ledges of the Tulsa area and much of eastern Oklahoma. It weathers into loamy, well-drained soils that are often only inches to a few feet deep over rock. Lots on this ground deal more with slopes, fill, erosion and uneven rock than with clay swell. ## What is Pennsylvanian sandstone? In northeastern Oklahoma, sandstone beds alternate with shale. In Tulsa County, for example, the Coffeyville Formation was described as five zones, two of sandstone and three of shale, as much as 440 feet thick in all [5]. Sandstone soils such as Collinsville and Coweta occupy ridges, interfluves and hillslopes [1][2]. See Pennsylvanian shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales) for the clay soils between the ridges. ## What soils form on sandstone? | Series | Rock contact | Depth to rock | Drainage | Slopes | |---|---|---|---|---| | Collinsville | Hard (lithic) | 4–20 in; 9 in typical [1] | Well to somewhat excessively drained [1] | 1–35% [1] | | Coweta | Soft (paralithic) | 10–20 in; about 15 in typical [2] | Well to somewhat excessively drained [2] | 1–30% [2] | | Bates | Soft (paralithic) | 20–40 in [3] | Well drained [3] | 1–8% [3] | | Hector | Hard (lithic) | 14–20 in; about 15 in typical [4] | Well drained [4] | 2–60% [4] | A **lithic** contact is hard bedrock; a **paralithic** contact is soft, weathered rock. - Collinsville formed in residuum from Pennsylvanian sandstone on interfluves and hillslopes in Oklahoma, Kansas and Missouri [1]. - Coweta formed in soft sandstone interbedded with shale; in some profiles hard sandstone appears at 24 to 60 inches below the soft layer [2]. - Bates formed in Pennsylvanian sandstone that often includes thin beds of silty or sandy shale, and it is extensive across southeastern Kansas, eastern Oklahoma and southwestern Missouri [3]. - Hector formed in sandstone residuum on ridgetops and steep mountainsides [4]. ## How does rock in the soil survey compare to pier depth? A soil series description covers the soil and the top of the rock, not what lies deeper. Coweta's description shows why that can mislead: soft sandstone at about 15 inches can be followed by hard sandstone farther down, and both are interbedded with shale [2]. In 2025 installation records from Tulsa, steel push piers reached refusal at a median depth of about 12 feet, with most exterior piers between about 8 and 16 feet, including at sites where the survey showed rock within the top 40 inches [7]. Survey rock depth and pier depth are therefore different measurements. See steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) and depth to rock from borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings). ## What does this mean for foundations? ### Hillside lots and fill Slopes up to 30 to 60 percent on Collinsville, Coweta and Hector soils [1][2][4] mean many lots are cut and filled to make a level pad. Fill that was not compacted can settle over time. See fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) and fill soils and lot history (https://terrabrain.vercel.app/guides/fill-soils-and-lot-history). ### Slope creep Soil on steep slopes can move slowly downhill, pulling at the downhill side of a house. See slope creep and lateral movement (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement). ### Erosion and washouts Coweta has medium to very high runoff potential [2], and Bates has saturated hydraulic conductivity in the moderately high to high range [3], so water moves quickly over and through these soils. Leaks and concentrated roof water can carry soil away from footings. The ASCE homeowner guide recommends downspouts discharge at least 3 feet from the foundation [6]. See erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). ## Related - Tulsa metro (https://terrabrain.vercel.app/regions/tulsa-metro) - East-Central (Arkoma) (https://terrabrain.vercel.app/regions/east-central-arkoma) - Bedrock in the Tulsa metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro) - Collinsville soil (https://terrabrain.vercel.app/soils/collinsville) - Coweta soil (https://terrabrain.vercel.app/soils/coweta) - Bates soil (https://terrabrain.vercel.app/soils/bates) Sources: [1] Official Soil Series Description: COLLINSVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COLLINSVILLE.html [2] Official Soil Series Description: COWETA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COWETA.html [3] Official Soil Series Description: BATES Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/B/BATES.html [4] Official Soil Series Description: HECTOR Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/H/HECTOR.html [5] Geolex unit references: Coffeyville, USGS National Geologic Map Database (Geolex) https://ngmdb.usgs.gov/Geolex/UnitRefs/CoffeyvilleRefs_15036.html [6] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [7] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # How do western Oklahoma red beds affect foundation soils? URL: https://terrabrain.vercel.app/geology/western-permian-red-beds Answer: Soft red sandstone and siltstone form shallow silty soils, while claystone and old river clays form expansive clay soils. In short: Much of western Oklahoma is built on Permian red beds, reddish sandstone, siltstone, shale and claystone laid down about 265 million years ago along with salt and gypsum. Soft sandstone and siltstone weather into shallow, silty soils, while claystone and the old river clays washed from it produce expansive clay soils. Which one a house sits on largely decides how it moves. ## What are red beds? **Red beds** are sedimentary rocks colored red by iron oxide. Oklahoma's Permian red beds, about 265 million years old, include red shale and sandstone along with salt and gypsum [1]. The state rock, the rose rock, comes from these Permian red beds [1]. A USGS study at a site near Union City in Canadian County described the Dog Creek Shale as mainly reddish-brown shale with thin siltstone beds, and the underlying Chickasha Formation as shale with siltstone, mudstone conglomerate and sandstone [2]. Gypsum occurred as nodules and veins, and hairline fractures filled with satin spar (a fibrous gypsum) were common in the upper 18 meters [2]. About 1.5 to 2 meters of soil covered the red beds there [2]. ## What soils form from the red beds? ### Shallow loamy and silty soils on soft rock | Series | Parent material | Depth to soft rock | Slopes | |---|---|---|---| | Woodward | Soft, calcareous sandstone or siltstone [6] | 20–40 in [6] | 1–40% [6] | | Quinlan | Soft, calcareous Permian sandstone or siltstone [7] | 10–20 in [7] | 1–50% [7] | Both are well drained and of large extent in western Oklahoma, a few southern Kansas counties and northwestern Texas [6][7]. ### Clay soils on claystone and old terraces | Series | Parent material | Shrink-swell clues | |---|---|---| | Vernon | Clayey residuum from Permian red-bed claystone [3] | Very slow permeability; 0–2% gypsum [3] | | Tillman | Alluvium from Permian red-bed clays and claystone [4] | Cracks deeper than 48 in; COLE above 0.06 in the upper 100 cm [4] | | Hollister | Pleistocene calcareous clays over Permian sediments [5] | Smectitic Vertisol; cracks over 30 in deep [5] | Hollister's cracks remain open for 150 or more cumulative days in most years, and slickensides (polished shear faces) begin 8 to 20 inches down [5]. Hollister and Tillman are both extensive in the Central Rolling Red Plains of Texas and Oklahoma [4][5]. The **coefficient of linear extensibility (COLE)** measures how much a soil shrinks as it dries. Values of 0.06 to 0.09 are rated high and 0.09 or more very high [8]. Tillman's reported COLE above 0.06 [4] places it at least in the high class. ## What does this mean for foundations? ### Expansive clay sites On Hollister, Tillman and Vernon soils, the clay can shrink deeply in dry weather and swell when rain returns [3][4][5]. Cracks reaching 30 to 48 inches or more [4][5] show how deep seasonal drying can go. See perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop), center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). ### Shallow soft rock and runoff Woodward and Quinlan have soft rock within 10 to 40 inches and occur on slopes up to 40 to 50 percent [6][7]. Footings may bear partly on soft rock, and runoff on slopes can erode soil at slab edges. See erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes). ### Gypsum and salt Gypsum within red-bed shale [2] and in some soils [3] links these areas to the dissolving-rock problems described on the Blaine gypsum (https://terrabrain.vercel.app/geology/permian-gypsum-units-e-g-blaine) page. ## Related - Southwest (Lawton and Red Plains) (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains) - Northwest (Gypsum Hills) (https://terrabrain.vercel.app/regions/northwest-gypsum-hills) - Hollister soil (https://terrabrain.vercel.app/soils/hollister) - Tillman soil (https://terrabrain.vercel.app/soils/tillman) - Woodward soil (https://terrabrain.vercel.app/soils/woodward) - Gypsum karst and sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes) Sources: [1] The Oklahoma Geological Survey and the geology of Oklahoma, USGS National Geologic Map Database (DMT '25) https://ngmdb.usgs.gov/Info/dmt/docs/DMT25_Johnson.pdf [2] Geologic and Hydraulic Characteristics of Selected Shaly Geologic Units in Oklahoma (WRI 96-4303), U.S. Geological Survey https://pubs.usgs.gov/wri/1996/4303/report.pdf [3] Official Soil Series Description: VERNON Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/V/VERNON.html [4] Official Soil Series Description: TILLMAN Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TILLMAN.html [5] Official Soil Series Description: HOLLISTER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/H/HOLLISTER.html [6] Official Soil Series Description: WOODWARD Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/W/WOODWARD.html [7] Official Soil Series Description: QUINLAN Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/Q/QUINLAN.html [8] Linear Extensibility (definition and shrink-swell classes, after NRCS National Soil Survey Handbook), UC Davis California Soil Resource Lab https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html --- # How do Wichita granite and outwash affect Lawton-area foundations? URL: https://terrabrain.vercel.app/geology/wichita-granite-and-granite-wash Answer: Around the Wichita Mountains, soils formed in granite outwash over red clay, such as Foard, are sodium-rich, very slowly permeable and prone to shrink-swell. In short: The Wichita Mountains near Lawton are made of ancient granite and related igneous rock, and streams have spread coarse granitic sediment, called granite wash or outwash, over the red-bed plains around them. Soils formed in that outwash over red clay, such as Foard, are sodium-rich, very slowly permeable and prone to shrink-swell. Around the mountains, it is these clay soils rather than the granite that drive most foundation movement. ## What is the Wichita granite? The Wichita Mountains are built of granite and similar igneous rocks that formed about 525 million years ago [1]. They were uplifted into mountains about 315 million years ago, during the same mountain-building episode that raised the Arbuckle and Ouachita ranges [1]. **Igneous** rock forms from cooled molten material; granite and gabbro are common examples. ## What is granite wash? As the mountains eroded, streams carried granitic sand and gravel outward onto the surrounding lowlands. This is called **granitic outwash** or granite wash. USDA soil descriptions record granitic outwash from the Wichita Mountains as part of the parent material of the Foard soil, lying over clayey Permian red-bed sediments [2]. ## What soils are found in the Lawton area? ### Foard | Property | Foard value | |---|---| | Taxonomic class | Fine, smectitic, thermic Vertic Natrustolls [2] | | Parent material | Old alluvium, including granitic outwash, over clayey Permian sediments [2] | | Landform | Broad summits and shoulders of terrace pediments [2] | | Drainage | Well drained; very slow permeability [2] | | Sodium | Natric (high-sodium) horizon from about 22 to 66 in [2] | | Vertic features | Cracks at least 5 mm wide and slickensides within about 4 ft [2] | | Extent | Extensive in the Central Rolling Red Plains of Oklahoma and Texas [2] | A **natric** horizon is a subsoil layer high in exchangeable sodium. In Foard, exchangeable sodium reaches roughly 15 to 25 percent in the lower subsoil [2]. **Smectitic** means the clay is dominated by smectite, the most swelling clay family. **Slickensides** are polished shear faces in clay left by repeated swelling. ### Neighboring clay soils Other extensive clay soils of the same Red Plains area include: - **Hollister**, formed in Pleistocene calcareous clays over Permian sediments, with cracks more than 30 inches deep that stay open 150 or more days in most years [3]. - **Tillman**, formed in alluvium from Permian red-bed clays and claystone, with cracks deeper than 48 inches [4]. ## What does this mean for foundations? ### Strong shrink-swell Smectitic clay with wide cracks and slickensides in Foard and Hollister [2][3], and deeply cracking clay in Tillman [4], shrinks during dry periods and swells when wet [5]. In this setting, slab edges can drop in drought and rise in wet spells. See perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop), perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) and cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally). ### Slow drainage Foard and Hollister have very slow permeability [2][3], so water from roofs, sprinklers or leaks tends to pond at the surface or soak in unevenly. The ASCE homeowner guide recommends sloping soil away at least 3 inches in the first 5 feet, keeping sprinkler heads at least 5 feet from the foundation and watering evenly on all sides [5]. See water ponding near the foundation (https://terrabrain.vercel.app/signs/water-ponding-near-foundation). ### Variable outwash Because outwash was spread by streams over red beds [2], the thickness of sandy or gravelly material over clay can change across a neighborhood. Lot-specific soil maps and, where needed, borings show what is actually under a house. See soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values). ## Related - Southwest (Lawton and Red Plains) (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains) - Foard soil (https://terrabrain.vercel.app/soils/foard) - Western Permian red beds (https://terrabrain.vercel.app/geology/western-permian-red-beds) - Clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Oklahoma geologic provinces (https://terrabrain.vercel.app/guides/oklahoma-geologic-provinces) Sources: [1] The Oklahoma Geological Survey and the geology of Oklahoma, USGS National Geologic Map Database (DMT '25) https://ngmdb.usgs.gov/Info/dmt/docs/DMT25_Johnson.pdf [2] Official Soil Series Description: FOARD Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/F/FOARD.html [3] Official Soil Series Description: HOLLISTER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/H/HOLLISTER.html [4] Official Soil Series Description: TILLMAN Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TILLMAN.html [5] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # How do you choose a foundation repair contractor in Oklahoma? URL: https://terrabrain.vercel.app/rules/how-to-choose-a-foundation-repair-contractor-in-oklahoma Answer: Oklahoma has no state foundation repair license. Check city registration and insurance, permits, an engineer's plan, written scope and warranty, and complaints. In short: Oklahoma does not license foundation repair as a state trade, so the checks that apply are city contractor registration, insurance, local permits and the engineering board's rules for repair plans. A written scope and warranty, Oklahoma's lien rules and federal cancellation rights set the terms of the deal. Complaint records are kept by the Attorney General's Consumer Protection Unit and the Better Business Bureau. ## Is there an Oklahoma license for foundation repair? - The Oklahoma Construction Industries Board licenses plumbers, electricians, mechanical tradespeople, home inspectors and building inspectors, and registers roofing contractors; foundation repair is not on that list [1]. Plumbing or electrical work tied to a repair still falls under those trade licenses [1]. - Oklahoma City requires anyone hired for a change or improvement that needs a building permit to register as a building contractor, with general liability insurance, workers' compensation coverage or an exemption form, and an immigration affidavit where it applies [2]. - Federal consumer guidance says to confirm a contractor's license with the state or county and to ask for proof of insurance [3]. Other cities set their own rules; see permits, licensing and frost depth (https://terrabrain.vercel.app/rules/permits-licensing-and-frost-depth-oklahoma-cities). ## Who pulls the permit? - The FTC lists a contractor asking the homeowner to get the building permits as a warning sign [3]. - Consumer guidance from the Better Business Bureau says to confirm the contractor can obtain the required permits [8]. - In Oklahoma City, contractor registration is tied to work that needs a building permit [2]. Whether a foundation repair needs a permit is set by each city; see codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits). ## Is an engineer's evaluation part of the process? Oklahoma's engineering board published compliance guidelines for foundation repair companies [4]: - A homeowner can start with a repair company that brings in a professional engineer (PE), a company that employs a full-time PE, or an independent engineer who works directly for the owner. - The PE visits the site or directs a technician, then issues a signed, sealed and dated repair plan, or a sealed statement that no repair or a non-pier repair is needed. - The repair company carries out the PE's plan. - A PE may issue an engineering completion letter only after being on site or receiving enough information from a qualified technician. A company's own letter may not be presented as an engineering completion letter. More on this: working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). ## What goes in the written proposal and contract? - The contractor's name, address, phone number and license number, plus estimated start and completion dates [3]. - Written estimates that describe the work, materials and completion date, with any verbal promises written in and no blank spaces left [3]. - Changes to the work agreed in writing before work continues [8]. - No full payment up front, and final payment after the work is complete [3]. - Warranty terms: what is covered, what is excluded, what the owner must maintain, and whether the warranty transfers to a later buyer and how. These are set by the written warranty itself; see contracts, warranties and liens (https://terrabrain.vercel.app/rules/contracts-warranties-liens). How scope, depth and extras shape a proposal is covered in what affects foundation repair cost (https://terrabrain.vercel.app/guides/what-affects-foundation-repair-cost). ## How do Oklahoma lien rules apply? A **mechanic's lien** is a claim against the property by someone who supplied labor or materials and was not paid. Under Title 42 [6]: - Original contractors file within four months after last furnishing labor or materials; subcontractors within 90 days. - A pre-lien notice goes to the original contractor and the owner no later than 75 days after last furnishing. On owner-occupied homes it is required regardless of the claim amount, and a lien is invalid without a timely notice. - Lien statements are filed with the county clerk, who mails notice to the owner. - An owner can discharge a lien by posting a bond or cash for 125% of the claim. ## Can a contract signed at home be cancelled? Under the FTC Cooling-Off Rule [5]: - Covered sales made at the buyer's home can be cancelled for a full refund until midnight of the third business day; Saturdays count as business days. - The seller must explain the right and provide two cancellation forms and a dated contract or receipt. - Sales needed to meet an emergency, and repairs the buyer asked the seller to come to the home to do, are not covered, although extra items bought beyond that request are. - After cancellation, the seller has 10 days to refund payments. ## Where can complaints be checked? - The Oklahoma Attorney General's Consumer Protection Unit mediates consumer complaints and can take legal action over deceptive or unfair practices; complaints are filed by phone or by emailing a complaint form [7]. - Better Business Bureau profiles show ratings, reviews, complaint history and licensing information [8]. - The FTC suggests checking with consumer protection officials and searching the company name with words like "complaint" [3]. Its listed warning signs include door-to-door offers, pressure to decide immediately, and demands for full or cash-only payment up front [3]. ## What can you ask about piers, testing and logs? - What pier or pile type is proposed, and how is final depth decided? See steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers). - Will each pier's depth and final pressure be recorded on an installation log given to the owner? - Is the plan sealed by an engineer, and who issues the completion letter [4]? - Will plumbing be tested after lifting? See plumbing leak detection and repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair). - Will an elevation survey be taken before and after the work? See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). - Are written lien releases provided from subcontractors and suppliers? ## Related - Contracts Warranties Liens (https://terrabrain.vercel.app/rules/contracts-warranties-liens) - Codes and Permits (https://terrabrain.vercel.app/rules/codes-and-permits) - Working with Engineers (https://terrabrain.vercel.app/guides/working-with-engineers) - What affects the cost of foundation repair in Oklahoma? (https://terrabrain.vercel.app/guides/what-affects-foundation-repair-cost) - Real Estate, Disclosure and Inspections (https://terrabrain.vercel.app/rules/real-estate-disclosure-and-inspections-foundation-issues-in-oklahoma) - Insurance Claims (https://terrabrain.vercel.app/rules/insurance-claims) Sources: [1] About, Oklahoma Construction Industries Board https://oklahoma.gov/cib/about.html [2] Residential Building Contractor, City of Oklahoma City Development Services https://okc.gov/departments/development-services/business-licensing/contractor-registration/building-contractor [3] How To Avoid a Home Improvement Scam, Federal Trade Commission https://www.consumer.ftc.gov/articles/0242-hiring-contractor [4] The Board's Bulletin, Vol. 21, Issue 4 (2007): Compliance Guidelines for Foundation Repair Companies, Oklahoma State Board of Licensure for Professional Engineers and Land Surveyors https://oklahoma.gov/content/dam/ok/en/pes/documents/bulletin/Newsletter_Volume21_Issue62.pdf [5] Buyer's Remorse: The FTC's Cooling-Off Rule May Help, Federal Trade Commission https://consumer.ftc.gov/articles/buyers-remorse-ftcs-cooling-rule-may-help [6] To Lien or Not To Lien (and How To Lien): A Summary of Oklahoma's Mechanic's and Materialmen's Lien Laws, Oklahoma Bar Journal (Oklahoma Bar Association) https://www.okbar.org/barjournal/june-2024/to-lien-or-not-to-lien/ [7] Consumer Protection Unit, Oklahoma Office of the Attorney General https://oklahoma.gov/content/sok-wcm/en/oag/about/divisions/cpu [8] BBB Tip: Hiring construction and remodeling services you can trust, Better Business Bureau https://www.bbb.org/article/news-releases/14089-bbb-tip-construction-and-remodeling-services --- # How do you tell foundation heave from settlement? URL: https://terrabrain.vercel.app/guides/heave-vs-settlement Answer: Heave is ground rising, usually as clay takes on water; settlement is ground dropping. Floor surveys over time, the season and water sources tell them apart. In short: Heave is the ground under a foundation rising, usually because clay soil took on water; settlement is the ground dropping, often because clay dried and shrank or soft soil compressed. Both leave a house uneven and can produce similar cracks, so the distinction is made from floor surveys over time, the season, and the water sources around the house. Getting it right matters because the two call for different responses. ## What are heave and settlement? Post-Tensioning Institute (PTI) evaluation guidelines define heave as upward movement of an underlying supporting soil layer and settlement as downward movement of that layer [1]. On expansive clay, heave happens when moisture is added and shrinkage happens when moisture is removed [1]. "Expansive" clay is soil that swells noticeably when wet; the most swelling clays are smectites such as montmorillonite [2]. In Oklahoma, the Oklahoma Geological Survey notes that more than 75 percent of the state has bedrock that can produce expansive soils, and that saturation from rainfall, lawn watering or sewer leaks can damage foundations [6]. ## What drives heave and settlement? | | Settlement (dropping) | Heave (rising) | |---|---|---| | Moisture change | Soil drying and shrinking [1] | Soil wetting and swelling [1] | | Typical drivers | Tree roots drying soil; hot, dry weather and drought [4][5] | Plumbing leaks, overwatering, poor drainage, removal of a large tree [3][4][6] | | Where it tends to show | Near trees and along drying edges [4] | Near the water source; slab corners can lift relative to the center [2][4] | | Season | Dry, hot periods [4][5] | Wet periods and after water is added [2][4] | Some notes on the table: - HUD's soil guide states that vegetation can worsen shrinkage during warm, dry periods because plants draw water from the soil [5]. See tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement). - Lawn and garden watering creates a moist zone along the outside of a foundation, and leaking pipes and pools add water unevenly [2]. See leak-induced localized heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave). - Because corners of a uniformly loaded slab press on the soil with about a quarter of the pressure at the center, corners tend to lift when the soil swells [2]. See perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) and center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab). - ASCE Texas guidelines note that removing a tree can allow soil heave and that a waiting period may be recommended before repair [3]; see post-tree-removal heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave). The greatest expansive-soil hazard is in climates with pronounced wet and dry seasons, and a two-year drought followed by an extremely wet year is cited as a problem case [2]. ## Why is a single survey not enough? An elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) maps high and low areas, but PTI notes that unless a benchmark is used, contours alone do not show whether heave or subsidence occurred [1]. A center that reads high could be a center that rose, or edges that fell. The only absolute way to measure movement is to compare two surveys [1], calculating the change at each matching point [8]. ## Which tests help decide? - **Plumbing tests.** ASCE Texas guidelines list plumbing testing as part of a more detailed investigation and say water supply and drain lines should be tested for leaks if lifting is part of the repair [3]. The ASCE homeowner guide suggests watching for unexplained increases in water bills and confirming leak repairs with pressure tests [4]. See plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab). - **Soil sampling.** Site-specific soil sampling is also listed among detailed investigation tests [3]; see soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values). - **Repeat surveys.** Comparing surveys taken at different times shows whether an area is rising or falling [1][8]. - **Ruling out look-alikes.** Ceiling-wall gaps at interior partitions that open in winter and close in summer are often truss uplift, roof trusses bowing as their lumber dries unevenly, not foundation movement [7]. ## Why does the call matter? Lifting is aimed at raising low areas. If a high area is high because it heaved, raising the surrounding foundation does not address the added water that caused it. ASCE Texas guidelines stress maintaining near-uniform soil moisture and caution against excessive watering [3], and the ASCE homeowner guide notes overwatering itself can cause heave [4]. ## Related - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Distress pattern library (https://terrabrain.vercel.app/guides/distress-pattern-library) - Over-lift heave after drought lift (https://terrabrain.vercel.app/causes/over-lift-heave-after-drought-lift) - Seasonal movement calendar (https://terrabrain.vercel.app/guides/seasonal-movement-calendar) - Perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) Sources: [1] Evaluation Guidelines for the Performance of Slab-on-Ground Foundations (2015 technical session), Post-Tensioning Institute https://www.post-tensioning.org/Portals/13/Files/PDFs/Events/Conventions/TechnicalSessions/2015/042815Brumley.pdf [2] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [3] Guidelines for the Evaluation and Repair of Residential Foundations, Version 2, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2022/05/Guidelines-for-the-Evaluation-and-Repair-of-Residential-Foundations-V2-2008.pdf [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Guide to Use of the FHA Soil PVC Meter (HUD Handbook 4075.15), U.S. Department of Housing and Urban Development https://www.hud.gov/sites/documents/407515hsgh.pdf [6] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [7] Drywall Application (Builders' Series), Canada Mortgage and Housing Corporation https://assets.cmhc-schl.gc.ca/sf/project/archive/research/ca1_mh_90d61.pdf [8] Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings (FPA-SC-13-0), Foundation Performance Association https://www.foundationperformance.org/projects/super/FPA-SC-13-0.pdf --- # How does a pier and beam crawl space foundation work? URL: https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space Answer: The house sits on a raised wood floor over a crawl space, with a perimeter footing and wall and interior piers carrying beams and joists. In short: A pier and beam foundation holds the house on a wood floor system raised above the ground, with a crawl space underneath. The outside edge sits on a continuous footing and wall, and the inside rests on piers that carry beams and floor joists. In Oklahoma the common problems are interior piers moving with clay, crushed or rotted shims and wood, and moisture in the crawl space. ## What are the parts of a pier and beam system? | Part | What it is | |---|---| | Perimeter footing | Concrete strip under the outside wall; code minimum 12 in wide, 6 in thick and 12 in below grade [3] | | Stem wall | Short wall of brick, block or concrete on the footing that encloses the crawl space | | Sill plate | Wood board bolted to the top of the stem wall; the floor framing sits on it | | Interior piers | Columns of brick, block, concrete, wood or steel on small pads | | Beams (girders) | Heavy members spanning from pier to pier | | Joists | Floor framing spanning between beams and the perimeter | | Shims | Wedges between pier tops and beams that set the floor height | The sill plate is held by anchor bolts at least 1/2 in in diameter, no more than 6 ft apart, embedded at least 7 in, with a bolt within 12 in of each plate end [2]. Oklahoma's 2024 code adoption states that hand-driven cut nails or concrete nails are not approved fasteners for sill plates [6]. Sill plates must also be protected from decay and termites where the code requires it [2]. ## What are the code rules for the crawl space? - **Vented crawl spaces:** at least 1 sq ft of net vent area per 150 sq ft of crawl, with one opening within 3 ft of each outside corner; 1 per 1,500 sq ft when a Class I vapor retarder covers the ground [1]. - **Unvented crawl spaces:** a continuous Class I vapor retarder over all exposed earth, seams lapped 6 in, plus mechanical exhaust, conditioned air or dehumidification [1]. - **Access:** floor hatches at least 18 x 24 in; wall openings at least 16 x 24 in [1]. - **Debris:** vegetation and organic material removed from the crawl floor; wood forms removed before occupancy [1]. - **Water:** where groundwater may rise to within 6 in of the finished floor at the perimeter, or surface water drains poorly, the code calls for raising the grade or adding drainage [1]. ## How do pier and beam foundations fail? | Problem | Common cause | Where it is covered | |---|---|---| | Sagging floor between supports | Supports sinking as shrink-swell clay dries and pulls away [4]; crushed or decayed shims and wood | Crawl space repair (https://terrabrain.vercel.app/repairs/crawl-space-repair) | | Perimeter drop | Piers losing support as clay shrinks in the dry season [4] | Perimeter piers | | Corner lift in wet seasons | Corner supports lifted as clay swells, then losing grip as it dries [4] | Monitoring and moisture control | | Rot and termites | Wood in contact with or near soil, which inspectors report as a defect [5] | Framing repair and moisture control | | Bouncy floors | Framing members cut, notched or bored, which inspectors report when it may be a structural concern [5] | Bouncy or soft floors (https://terrabrain.vercel.app/signs/bouncy-or-soft-floors) | | Damp crawl, mold | Groundwater, poor surface drainage or humid air [1] | Crawl space encapsulation (https://terrabrain.vercel.app/repairs/crawl-space-encapsulation) | Seasonal moisture change in clay can reach from 3 to 40 ft deep, so shallow interior pads sit well inside the moving layer [4]. ## Why does pier and beam suit clay country? Engineering guidance for swelling soils notes that structural above-grade flooring is available for consideration under certain conditions [7]. A practical advantage is access: piers, shims, beams and plumbing can all be reached from the crawl space, and the floor can be re-shimmed after the soil moves. In Oklahoma installation records, shim stacks are limited to no more than four shims per support [8]. Inspection standards do not require home inspectors to judge the size, spacing or span of joists, beams or supports [5]; that is engineering or repair-design work. Changes in crawl space construction over time are covered in construction era by decade (https://terrabrain.vercel.app/guides/construction-era-by-decade), and seasonal wet spots in crawl spaces are explained in groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water). ## Related - Crawl Space Repair (https://terrabrain.vercel.app/repairs/crawl-space-repair) - Crawl Space Moisture and Wood Decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) - Sagging Floor Between Supports (https://terrabrain.vercel.app/signs/sagging-floor-between-supports) - Water, Condensation or Mold in Crawl (https://terrabrain.vercel.app/signs/water-condensation-or-mold-in-crawl) - Groundwater and Perched Water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) Sources: [1] Inspecting Under-Floor Crawl Spaces: A Guide for Home Inspectors (2024 IRC Section R408), InterNACHI https://www.nachi.org/under-floor-crawl-space.htm [2] Securing the Perimeter: Inspecting Foundation Anchor Bolts and Sill Plate Protocols (IRC R403.1.6), InterNACHI https://www.nachi.org/foundation-anchor-bolts-sill-plate.htm [3] Inspecting Footings: The Unsung Heroes Beneath a House (IRC R403), InterNACHI https://www.nachi.org/foundation-footings.htm [4] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [5] InterNACHI Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [6] Adoption of International Residential Code 2024 (IRC 2024), Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2024%20IRC%20Code%20Changes%20Summary%20-%20for%20website.pdf [7] Home Construction on Shrinking and Swelling Soils (Special Publication 11), Colorado Geological Survey (Holtz and Hart, 1978) https://coloradogeologicalsurvey.org/wp-content/uploads/woocommerce_uploads/SP-11.pdf [8] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # How does Arbuckle limestone affect Oklahoma foundations? URL: https://terrabrain.vercel.app/geology/arbuckle-carbonates Answer: Hard Arbuckle limestone and dolomite surface in south-central Oklahoma. Shallow rock and karst, not clay swell, are the main foundation questions there. In short: The Arbuckle carbonates are thick, hard limestone and dolomite beds that reach the surface in the Arbuckle Mountains of south-central Oklahoma. Where they are at the surface, houses often sit on or near firm rock, but the rock can dissolve slowly and form karst features such as small cavities and springs. Shallow rock and karst, not clay swell, are the main foundation questions in this setting. ## What is the Arbuckle rock? **Carbonate** rock means limestone (calcium carbonate) and dolomite (calcium-magnesium carbonate). The Arbuckle rocks were deposited in shallow seas [4]. A century-old USGS survey of the area described the Arbuckle limestone as mostly hard bluish-white and cream-colored limestone and dolomite, with some clay beds and with chert and limestone breccia in places [3]. It reported a maximum thickness of nearly 5,500 feet, with the lower part Cambrian and the upper part Ordovician [3]. The Arbuckle Mountains were pushed up about 315 million years ago, and the tilted limestone beds now form rows of outcrops sometimes called "tombstone topography" [4]. ### Arbuckle and Simpson together Hydrologists group the Arbuckle with the overlying Simpson Group as the Arbuckle-Simpson aquifer. It underlies more than 500 square miles of south-central Oklahoma and supplies drinking water to about 39,000 people, including Ada and Sulphur [1]. The rocks are limestone, dolomite and sandstone of Cambrian and Ordovician age, exposed in three uplifts separated by large faults [1]. A USGS model describes the units as highly faulted and fractured and includes 54 faults in its study area [2]. ## What is karst? **Karst** is ground shaped by rock that dissolves in water, producing features such as cavities, sinkholes, caves, disappearing streams and springs. The Oklahoma Geological Survey identifies the Arbuckle Mountains in the south and the Ozark area in the northeast as the state's main limestone and dolomite karst areas [5]. It lists sinkholes, caverns, subsidence and collapse as potential hazards in karst terranes [5]. In the Arbuckle-Simpson outcrop, small karst features occur over much of the area, while caves large enough for people to enter are known at only a few locations [1]. Springs discharge up to 19,000 gallons per minute and feed stream flow [1]. ## What does Arbuckle rock mean for foundations? | Ground condition | Why it matters | |---|---| | Hard rock at or near the surface | The rock is described as uniformly hard [3] and crops out at the surface [4] | | Fractures and faults | The units are highly faulted and fractured [2], and small karst features occur over much of the outcrop [1] | | Small karst openings | Sinkholes and caves can let the ground settle or collapse [5] | | Uplifted, tilted beds | Limestone layers dip down into the ground, forming tombstone topography [4] | - On this ground, the key questions are what lies directly under the footing (sound rock, soil, or a soil-filled opening) and whether roof or yard water is being concentrated into fractures in the rock. - Sudden, localized drops are a sign worth separating from slow seasonal movement. See sudden depressions or sinkholes (https://terrabrain.vercel.app/signs/sudden-depression-or-sinkhole) and karst subsidence (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes). - Because contaminants can move quickly through karst [5], roof and surface drainage that is directed into open rock can also carry contaminants to groundwater. ## How is deep Arbuckle rock tied to earthquakes? The same rock group extends deep underground in other parts of Oklahoma. That deep setting is discussed separately in induced seismicity in Oklahoma (https://terrabrain.vercel.app/guides/induced-seismicity-in-oklahoma) and seismic damage vs. soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement). ## Where can I read more? The South-Central (Arbuckles and Texoma) (https://terrabrain.vercel.app/regions/south-central-arbuckles-and-texoma) region page covers the soils and other rock units around the Arbuckle uplift, and gypsum karst and sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes) explains the different, faster-dissolving karst of western Oklahoma. ## Related - Karst subsidence and sinkholes (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes) - South-Central (Arbuckles and Texoma) (https://terrabrain.vercel.app/regions/south-central-arbuckles-and-texoma) - Oklahoma geologic provinces (https://terrabrain.vercel.app/guides/oklahoma-geologic-provinces) - Gypsum karst and sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes) - Void and compaction grouting (https://terrabrain.vercel.app/repairs/void-and-compaction-grouting) Sources: [1] Karst Aquifers: Arbuckle-Simpson Aquifer, U.S. Geological Survey https://www.usgs.gov/mission-areas/water-resources/science/karst-aquifers-arbuckle-simpson-aquifer?page=1 [2] Three-dimensional geologic model of the Arbuckle-Simpson aquifer, south-central Oklahoma (Open-File Report 2010-1123), U.S. Geological Survey https://pubs.usgs.gov/publication/ofr20101123 [3] Description of the Tishomingo Quadrangle (Geologic Atlas Folio 98), U.S. Geological Survey https://pubs.usgs.gov/gf/098/text.pdf [4] The Oklahoma Geological Survey and the geology of Oklahoma, USGS National Geologic Map Database (DMT '25) https://ngmdb.usgs.gov/Info/dmt/docs/DMT25_Johnson.pdf [5] Mapping of Karst Terranes in Oklahoma to Identify Potential Environmental and Hydrologic Problems, AAPG Search and Discovery / Oklahoma Geological Survey https://www.searchanddiscovery.com/abstracts/html/1995/midcon/abstracts/1403b.htm --- # How does crawl space moisture cause wood rot and sagging floors? URL: https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay Answer: Water and humid air in a crawl space raise wood moisture until decay fungi grow, weakening sills, joists and beams so floors feel soft, bouncy or sag. In short: When water and humid air build up in a crawl space, the wood floor framing absorbs moisture, and once it stays wet enough, decay fungi can break it down. Rotted sills, joists and beams lose strength, which shows up as soft, bouncy or sagging floors. The building code treats moisture control as the main purpose of crawl space rules. ## What happens when a crawl space stays damp? A crawl space is the shallow open area between the ground and the wood floor of a pier-and-beam house. InterNACHI's guide to the International Residential Code (IRC) section R408 states that the main objective of the crawl space rules is moisture control [1]. The common moisture sources are evaporation from bare ground, bulk water from rain or groundwater entering the space, condensation on cool surfaces, and plumbing leaks or HVAC condensate [1]. Left unchecked, that moisture leads to fungal decay, pest problems, poorer insulation performance and poor indoor air quality [1]. ### Summer condensation Humid outdoor air that enters through crawl space vents in summer can condense on cooler surfaces inside the crawl space [2]. This is why a crawl space can show water droplets on ducts and pipes, or damp framing, even during dry weather. ## When does wood start to decay? Wood decay is caused by fungi, and they need four things: food (the wood itself), oxygen, a suitable temperature and enough moisture [4]. The details: | Condition | What research shows | |---|---| | Moisture | Decay generally occurs above about 30% moisture content and not below 20%; 20-30% is a grey area [3] | | Air-dried wood | Usually no more than about 20% moisture content, so decay generally does not occur [4] | | Temperature | Fungi grow between about 50 and 95°F, with an optimum around 75 to 90°F [4] | | Existing decay | Can continue until the wood dries below about 20% [3] | Moisture content is the weight of water in wood compared with the weight of the dry wood. Because decay that has started keeps going until the wood dries below 20%, decay is harder to stop than to prevent [3]. ## How does wood rot affect the floor? As decay fungi break down wood, the wood loses strength [4]. The framing at risk in a crawl space includes the sill plate (the board resting on the foundation wall), the floor joists and the beams or girders that carry them. Weakened framing can lead to bouncy or soft floors (https://terrabrain.vercel.app/signs/bouncy-or-soft-floors) and a sagging floor between supports (https://terrabrain.vercel.app/signs/sagging-floor-between-supports). Visible water, condensation or mold in the crawl space (https://terrabrain.vercel.app/signs/water-condensation-or-mold-in-crawl) is often the first clue. ## What Oklahoma conditions add to crawl space moisture? Oklahoma's climate ranges from humid subtropical in the east to semi-arid in the west [6]. Because humid outdoor air entering vents is itself a moisture source [2], local humidity matters. See the Tulsa metro region page (https://terrabrain.vercel.app/regions/tulsa-metro) and groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) for local conditions. ## What does the building code require? | Approach | Key requirement under IRC R408 | |---|---| | Vented crawl space | At least 1 sq ft of net vent area per 150 sq ft of crawl space, with a vent within 3 ft of each corner [1] | | Vented with ground cover | Vent area can drop to 1 per 1,500 sq ft with a Class I vapor retarder on the soil [1] | | Unvented crawl space | Continuous sealed Class I vapor retarder plus exhaust, conditioned air supply or dehumidification [1] | The code also calls for removing vegetation, organic material and wood forms from the crawl space, and for drainage or a raised grade where groundwater can rise within 6 inches of the floor or the space does not drain [1]. ## How is crawl space moisture typically addressed? - **Remove the water.** Bulk water entering the crawl space is one of the main moisture sources [1], which is why grading and drainage are addressed first; see drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). - **Control humidity.** A sealed vapor retarder with dehumidification is one code-recognized option [1]; Penn State's housing research center also lists sealed vapor retarders and dehumidification among moisture control measures [2]. See crawl space encapsulation (https://terrabrain.vercel.app/repairs/crawl-space-encapsulation). - **Repair the framing.** Texas engineering guidelines for pier-and-beam homes list shimming, framing repairs, added supports, restoring the space under the floor and crawl space moisture control as repair approaches [5]. See crawl space repair (https://terrabrain.vercel.app/repairs/crawl-space-repair). ## Related - Interior Support and Framing Failure (Crawl) (https://terrabrain.vercel.app/causes/interior-support-and-framing-failure-crawl) - Pier and Beam Crawl Space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) - Water, Condensation or Mold in Crawl (https://terrabrain.vercel.app/signs/water-condensation-or-mold-in-crawl) - Crawl Space Encapsulation (https://terrabrain.vercel.app/repairs/crawl-space-encapsulation) - Manufactured Homes on Piers (https://terrabrain.vercel.app/foundations/manufactured-homes-on-piers) Sources: [1] Inspecting Under-Floor Crawl Spaces: A Guide for Home Inspectors (2024 IRC Section R408), InterNACHI https://www.nachi.org/under-floor-crawl-space.htm [2] The Do's and Don'ts of Crawlspace Design and Construction: Revisited!, Pennsylvania Housing Research Center, Penn State University https://www.phrc.psu.edu/assets/docs/Webinars/Crawlspaces_Revisited_HANDOUTS.pdf [3] Limiting Conditions for Decay in Wood Systems, USDA Forest Products Laboratory / International Research Group on Wood Protection https://www.fpl.fs.usda.gov/documnts/pdf2002/morri02a.pdf [4] Strength loss in decayed wood, USDA Forest Products Laboratory https://www.fpl.fs.usda.gov/documnts/pdf2014/fpl_2014_ibach001.pdf [5] Guidelines for the Evaluation and Repair of Residential Foundations, Version 2, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2022/05/Guidelines-for-the-Evaluation-and-Repair-of-Residential-Foundations-V2-2008.pdf [6] Soil Matric Suction and Active Zone Depth in Oklahoma, Oklahoma State University (Er Yue, Ph.D. dissertation, 2017) https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf --- # How does erosion leave voids under a foundation or slab? URL: https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids Answer: Runoff, flooding or a leaking pipe can carry soil from beside or under a foundation, leaving a void where the concrete above can crack or settle. In short: Erosion and washout happen when moving water carries soil away from beside or beneath a foundation, leaving an empty space (a void) where support used to be. The water can come from concentrated roof and yard runoff, flooding, or a leaking pipe under the slab. Once support is lost, the concrete above can crack or settle into the void. ## How does water remove soil from under a foundation? Water that is concentrated, such as at a downspout outlet, along a low spot against the house, or at a broken pipe, can pick up soil particles and move them. The Oklahoma Geological Survey describes sinkholes forming when water flowing underground erodes sediment and creates voids that the ground above eventually collapses into [1]. After the heavy rains of April 2025, the OGS expected more sinkholes in the hardest-hit parts of Oklahoma, most of them small and located where water flowed beneath roads and driveways [1]. The same process can work under slab edges, footings, porches and flatwork. ### Three common routes - **Surface runoff and scour.** Concentrated flow erodes soil at slab edges and footings. Erosion channels are one of the warning signs inspectors look for in crawl spaces [8]. - **Flooding.** Flood exposure adds another source of moving water. In Oklahoma, flood-prone areas are mapped for about a 1-in-100 chance of flooding in any year, and major floods often occur in spring and fall [6]. - **Plumbing leaks.** A leaking supply or drain line under a slab releases water continuously into the soil. The EPA estimates household leaks can waste more than 10,000 gallons a year in an average home [3]. ## Which soils erode easily? Some soils are far more erodible than others. USDA soil surveys rate surface erodibility with the K factor, which ranges from 0.02 to 0.69, with higher values meaning greater susceptibility to sheet and rill erosion; it depends mainly on silt, sand and organic matter content, structure and permeability [4]. A special case is **dispersive clay**, a clay whose particles break apart and wash away readily in water because sodium dominates its pore water [2]. In dispersive soils, a small leak through a crack can enlarge into a pipe or tunnel, and if the tunnel grows large enough its roof can collapse [2]. The USDA Natural Resources Conservation Service documented Oklahoma flood-control dams, including Owl Creek Site 13 and Upper Red Rock Site 20, that failed by this kind of tunnel erosion [2]. Standard index tests do not identify dispersive clays; specialized tests such as the crumb test, double hydrometer and pinhole test are used [2]. ## What are the signs of erosion voids? - an exposed slab edge or void under a footing (https://terrabrain.vercel.app/signs/exposed-slab-edge-or-void-under-footing) - visible slab cracks (https://terrabrain.vercel.app/signs/visible-slab-cracks) over an unsupported area - heaved or settled flatwork (https://terrabrain.vercel.app/signs/heaved-or-settled-flatwork) such as sidewalks and patios - a sudden depression or sinkhole (https://terrabrain.vercel.app/signs/sudden-depression-or-sinkhole) in the yard or under a slab ## How do erosion voids differ from karst sinkholes? Karst sinkholes form when soluble bedrock such as limestone, gypsum or salt dissolves and the ground above collapses into the cavity [7]. Erosion voids form in the soil itself, close to the surface, where water carries particles away [1]. The USGS notes that human changes to natural drainage can also contribute to sinkhole formation [7]. See karst subsidence and sinkholes (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes) for the bedrock-driven version. ## How are erosion voids typically addressed? - **Stop the water first.** Leaks are found with testing; the EPA's meter test (read the meter, use no water for two hours, read again) checks supply lines [3], and Texas engineering guidelines call for testing supply and drain lines whenever a foundation will be lifted [5]. See plumbing leak detection and repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair). - **Control runoff.** Where concentrated surface flow is the source, grading and downspout routing are the related topics; see surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). - **Fill the void.** Texas guidelines list grouting and mudjacking among slab repair methods [5]. See void and compaction grouting (https://terrabrain.vercel.app/repairs/void-and-compaction-grouting). ## Related - Karst Subsidence and Sinkholes (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes) - Erosion, Creeks and Slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Slabjacking and Polyurethane (https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Plumbing Leaks Under Slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) Sources: [1] Hazard Mapping, Oklahoma Geological Survey, University of Oklahoma https://ou.edu/ogs/research/hazard_mapping [2] Dispersive Clays - Experience and History of the NRCS (Formerly SCS), USDA Natural Resources Conservation Service (D. McCook, Tri-Service Infrastructure Conference) https://ndia.dtic.mil/wp-content/uploads/2005/triservice/track5/mccook.pdf [3] WaterSense Challenges Homeowners: Take 10 Minutes to Find and Fix a Leak this Week, U.S. Environmental Protection Agency https://www.epa.gov/node/265001 [4] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [5] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [6] Geologic Hazards in Oklahoma, Geological Society of America (abstract by K. V. Luza, Oklahoma Geological Survey) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [7] Sinkholes, U.S. Geological Survey Water Science School https://www.usgs.gov/special-topics/water-science-school/science/sinkholes [8] Inspecting Under-Floor Crawl Spaces: A Guide for Home Inspectors (2024 IRC Section R408), InterNACHI https://www.nachi.org/under-floor-crawl-space.htm --- # How does Garber Sandstone affect Oklahoma foundations near OKC? URL: https://terrabrain.vercel.app/geology/garber-sandstone Answer: It weathers into loamy, well-drained soils often shallow to soft rock that swell less than red clays, so drainage, erosion and shallow rock matter most. In short: The Garber Sandstone is a Permian sandstone with shale and siltstone layers that reaches the surface on the east side of Oklahoma County. It weathers into loamy, well-drained soils that are often shallow to soft rock. These soils generally swell less than the red clays to the west, so drainage, erosion and shallow rock are the usual foundation questions. ## What is the Garber Sandstone? The Garber Sandstone is an early Permian rock unit, deposited in a delta setting, made of lens-shaped beds of sandstone, shale and siltstone [2]. A regional groundwater study for central Oklahoma describes it as fluvial channel deposits with scour-and-fill sandstones, and the upper Garber in the west as wide, uniform sand sheets [1]. A **lens** is a layer that thins out sideways, so a sandstone bed under one house may be shale under the next. ### Where it is at the surface The rock layers in central Oklahoma dip west at roughly 35 to 80 feet per mile, depending on location [1]. As a result, the Garber is at the surface on the east side of Oklahoma County, while on the west side of the county a well can pass through up to 1,000 feet of Hennessey shale before reaching it [1]. Edmond sits on the northern side of the aquifer, where the sandstones are better sorted [1]. See the Hennessey Shale (https://terrabrain.vercel.app/geology/hennessey-shale-group) page for the clay ground to the west. ### Part of the main aquifer The Garber Sandstone and Wellington Formation form the primary flow system of the Central Oklahoma aquifer, which is why it is often called the Garber-Wellington aquifer [2]. The aquifer covers about 2,000 square miles [1]. ## What soils form on Garber sandstone? | Series | Depth to soft rock | Drainage | Slopes | |---|---|---|---| | Darnell | 10–20 in [3] | Well to somewhat excessively drained [3] | 1–45% [3] | | Lucien | 10–20 in (14 in typical) [6] | Well drained [6] | 1–30% [6] | | Stephenville | 20–40 in [4] | Well drained [4] | 1–25% [4] | | Zaneis | About 40–60 in [5] | Well drained [5] | 0–8% [5] | - Darnell formed in Permian sandstone on ridge crests and upper hill slopes [3]. - Stephenville formed in material weathered from Permian sandstone on hill backslopes [4]. - Zaneis formed in residuum from interbedded Permian sandstone and shale on low hills, and its subsoil is fine-loamy [5]. - Lucien formed in sandstone interbedded with clay, siltstone or sandy shale [6]. Soil surveys record the top of this soft, weathered sandstone as a **paralithic contact**, meaning the soil rests on rock that is weak rather than hard [3][4][6]. ## What does Garber sandstone mean for foundations? ### Lower swell, but not zero The Garber soils above are classed as loamy or fine-loamy, not clayey [3][4][5][6]. However, the Garber itself contains shale and siltstone lenses [2], and Zaneis and Lucien formed partly from shale or clay layers [5][6]. A lot can therefore have a clayey pocket that moves seasonally even in a sandy area. See shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). ### Shallow soft rock Where soft sandstone is within 10 to 40 inches [3][4][6], footings may bear partly on rock and partly on soil. Different support under different parts of a house can show up as differential movement at additions (https://terrabrain.vercel.app/causes/differential-movement-at-additions) or cracks where one support type meets another. ### Erosion and runoff Darnell has very high permeability and medium to rapid runoff, and Lucien has very high runoff [3][6]. On sloping lots, concentrated roof water and leaks can wash out soil beside footings. See erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) and surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). ## Related - OKC metro (https://terrabrain.vercel.app/regions/okc-metro) - Bedrock in the OKC metro (https://terrabrain.vercel.app/guides/bedrock-okc-metro) - Soil series in the OKC metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) - Wellington Formation (https://terrabrain.vercel.app/geology/wellington-formation) - Stephenville soil (https://terrabrain.vercel.app/soils/stephenville) - Zaneis soil (https://terrabrain.vercel.app/soils/zaneis) Sources: [1] OK County Groundwater Model (Project 174601), Association of Central Oklahoma Governments https://www.oklahomacounty.org/Portals/0/OK%20County%20Groundwater%20Model.pdf [2] Review of the general geology and solid-phase geochemical studies in the vicinity of the Central Oklahoma aquifer (Circular 1019), U.S. Geological Survey https://pubs.usgs.gov/publication/cir1019 [3] Official Soil Series Description: DARNELL Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DARNELL.html [4] Official Soil Series Description: STEPHENVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/S/STEPHENVILLE.html [5] Official Soil Series Description: ZANEIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/Z/ZANEIS.html [6] Official Soil Series Description: LUCIEN Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/L/LUCIEN.html --- # How does grouting fill voids under a foundation? URL: https://terrabrain.vercel.app/repairs/void-and-compaction-grouting Answer: Cement-based grout is pumped under pressure to fill voids or densify loose soil; larger voids, fill or sinkholes are normally grouted to an engineer's design. In short: Grouting pumps cement-based material into the ground under pressure to fill empty spaces (voids) or to densify loose soil beneath a foundation. Small, shallow voids from erosion or leaks are often filled directly, while compaction and cap grouting over larger voids, loose fill or sinkholes is normally engineered. Engineering guidance describes the slab tests and soil borings used to investigate a site [3][4]. Grouting does not stop expansive clay from shrinking and swelling. ## What kinds of grouting are there? | Type | What it does | Typical use | |---|---|---| | Void fill | Fills open gaps between slab or footing and soil | Washout voids, leak erosion | | Compaction grouting | Injects a stiff grout that pushes loose soil aside and densifies it | Loose fill, collapsible or soft layers, sinkhole repair | | Permeation grouting | Thin grout soaks into pores of sandy soil | Sands and gravels | | Cap grouting | Seals the top of a sinkhole throat or rock opening | Karst sites | These descriptions are general terms used in ground improvement. Which type fits a site depends on what the investigation finds. ## Where do voids come from? - **Erosion and leaks.** Running water from leaking pipes, downspouts or poor drainage can carry soil away from under a slab edge; see erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) and exposed slab edge or void under footing (https://terrabrain.vercel.app/signs/exposed-slab-edge-or-void-under-footing). - **Loose or decaying fill.** Poorly compacted fill or buried debris can settle or leave gaps; see fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). - **Soluble rock (karst).** Limestone, dolomite, gypsum and salt can dissolve in circulating groundwater, forming caverns and sinkholes [1]. ## Where do sinkholes and karst occur in Oklahoma? A **sinkhole** is a ground depression with no surface drainage outlet, where water drains underground [1]. USGS describes two common types [1]: - **Cover-collapse** sinkholes can open within hours where the overlying soil contains a lot of clay, and can cause severe damage. - **Cover-subsidence** sinkholes develop gradually where the cover is sandy and permeable. Construction, changes to drainage patterns and heavy loads can trigger sinkholes [1]. In Oklahoma, the state geological survey reports limestone and dolomite karst mainly in the Ozark region, the Arbuckle Mountains and the Limestone Hills north of the Wichita Mountains, and gypsum and shallow salt deposits in many areas of western Oklahoma [2]. See gypsum karst and sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes) and karst subsidence and sinkholes (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes). ## How are voids found before grouting? Engineering guidance describes several ways to locate voids under a slab [3]: - **Ground penetrating radar** — radar pulses that commonly detect voids; resolution drops with depth and moisture affects results. - **Hammer sounding** — tapping the slab to outline hollow areas; low cost but does not show depth. - **Impact-echo** — stress waves that can show the presence and extent of voids under a slab-on-ground. - **Electrical resistivity** — a geophysical survey that can reveal caverns, voids, groundwater and the effects of plumbing leaks; it should be checked against soil borings. - **Test openings and borings** — direct looks at the soil, limited to the spots opened. A recommended practice for geotechnical work calls for borings of at least 20 feet for typical residential lots, deeper on wooded lots, and additional depth near slopes [4]. Where soluble rock is mapped near the surface and settlement keeps progressing, this kind of investigation usually comes before any repair. ## What are the risks and limits? Pressure grouting under a slab carries the same installation risks reported for mudjacking: too much material can bulge or crack the slab, excessive pressure can cause blowouts, and grout can enter and plug cracked utility lines [5]. Voids caused by a leak can return if the water source is not fixed, so the plumbing is commonly tested first; see plumbing leak detection and repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair). Grouting improves loose or hollow ground but does not change the shrink-swell behavior of clay. Expansive clays continue to swell when wet and shrink when dry [6]; that movement is addressed by moisture control or by deeper support. Cost is driven mainly by the volume of grout, the depth of injection and whether engineering and subsurface testing are needed. ## Related - Slabjacking and Polyurethane (https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane) - Gypsum Karst and Sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes) - Sudden Depression or Sinkhole (https://terrabrain.vercel.app/signs/sudden-depression-or-sinkhole) - Fill Soils and Lot History (https://terrabrain.vercel.app/guides/fill-soils-and-lot-history) - Hydrocollapse (Collapsible Soil) (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil) Sources: [1] Sinkholes, U.S. Geological Survey Water Science School https://www.usgs.gov/special-topics/water-science-school/science/sinkholes [2] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [3] Test Methods for Evaluating Existing Foundations (FPA-SC-02-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-02-0.pdf [4] Recommended Practice for Geotechnical Explorations and Reports (FPA-SC-04-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-04-0.pdf [5] Post Foundation Repair Performance of Residential and Other Low-Rise Buildings on Expansive Soils (FPA-RC-01-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-RC-01-0.pdf [6] Chapter C5 – Expansive Soils, Institution of Civil Engineers / British Geological Survey https://nora.nerc.ac.uk/id/eprint/17002/1/C5_expansive_soils_Oct.pdf --- # How does limestone north of Tulsa affect Oklahoma foundations? URL: https://terrabrain.vercel.app/geology/pennsylvanian-limestones Answer: Pennsylvanian limestone beds can weather into Apperson soil, a very expansive clay over hard limestone about 3.5 to 5 feet down. In short: Northeastern Oklahoma's prairie country includes Pennsylvanian limestone units that alternate with shale formations. Where limestone is the parent rock, it can weather into Apperson soil, a very expansive smectite clay sitting over hard limestone about 3.5 to 5 feet down. Those lots combine strong seasonal shrink-swell with shallow rock. ## What are the rock layers? In northeastern Oklahoma, Pennsylvanian limestone and shale units alternate: the Oologah limestone is 80 to 145 feet thick, while the Nowata shale above it ranges from 50 to 600 feet [2][4]. Geologists once grouped four formations here as the "Tulsa Group," named from Tulsa County, listed upward as the Claremore, Labette, Oologah and Nowata [3]. That group name is now abandoned [3]. ### Oologah limestone The Oologah was described as blue cherty limestone separated by bands of black shale, 80 to 145 feet thick, in a belt about 10 miles wide running south from the Kansas line toward the Verdigris River [2]. **Cherty** means it contains chert, a hard silica rock. ### Shale above and below The Nowata, directly above the Oologah, is a series of bluish or greenish shales with a few sandstones, reported as 50 to 600 feet thick [4]. It crops out in a narrow band between limestone escarpments near the Kansas line and in a belt about 8 miles wide east of Tulsa [4]. Where shale such as the Nowata crops out [4], lots sit on shale-derived soil instead. See Pennsylvanian shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales). ## What is Apperson clay on limestone? The Apperson series is the main soil formed from this limestone [1]: | Property | Apperson value | |---|---| | Parent material | Calcareous residuum from Pennsylvanian limestone [1] | | Taxonomic class | Fine, smectitic, thermic Aquic Hapluderts (a Vertisol) [1] | | Subsoil | Silty clay with slickensides [1] | | Depth to hard limestone | 40–60 in; about 44 in typical [1] | | Drainage | Somewhat poorly drained, slow permeability [1] | | Perched saturation | December through April [1] | | Typical location | Osage County, north of Foraker [1] | | Mean annual precipitation | About 40 in (36–44) [1] | A **Vertisol** is a soil defined by clay that shrinks and swells enough to crack open in dry seasons and churn itself over time. The Apperson description notes cracks that open and close periodically and **slickensides**, polished shear faces in the clay left by repeated swelling [1]. **Smectitic** means the clay is dominated by smectite, the most swelling clay mineral family. ## What does this mean for foundations? - **Seasonal shrink-swell.** Smectite clay above the rock has cracks that open and close periodically [1], and clayey soils swell as they take on water [6]. Soil under a slab edge can drop in drought and rise when rain returns. See cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally) and perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). - **Perched water in winter and spring.** Saturation from December through April [1] can wet crawl spaces and push on below-grade walls. See crawl space moisture (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) and lateral earth and hydrostatic pressure (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls). - **Shallow hard rock.** Hard limestone at about 3.5 to 5 feet [1] limits how deep the clay goes but can make excavation harder. - **Moisture control.** The ASCE homeowner guide recommends even watering around the house, sloping soil at least 3 inches in the first 5 feet, and keeping trees farther away than their mature height [6]. ## Is karst a concern? Limestone can dissolve and form karst features. The Oklahoma Geological Survey identifies the Ozark area in the northeast and the Arbuckle Mountains in the south as the state's main limestone and dolomite karst areas [5]. See karst subsidence and sinkholes (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes). ## Related - Tulsa metro (https://terrabrain.vercel.app/regions/tulsa-metro) - Northeast (Ozark Plateau and Grand Lake) (https://terrabrain.vercel.app/regions/northeast-ozark-plateau-and-grand-lake) - Apperson soil (https://terrabrain.vercel.app/soils/apperson) - Bedrock in the Tulsa metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro) - Clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) Sources: [1] Official Soil Series Description: APPERSON Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/A/APPERSON.html [2] Geolex unit references: Oologah, USGS National Geologic Map Database (Geolex) https://ngmdb.usgs.gov/Geolex/UnitRefs/OologahRefs_9678.html [3] Geologic Unit: Tulsa (Group, abandoned), USGS National Geologic Map Database (Geolex) https://ngmdb.usgs.gov/Geolex/Units/Tulsa_10978.html [4] Geologic Unit: Nowata, USGS National Geologic Map Database (Geolex) https://ngmdb.usgs.gov/Geolex/UnitRefs/NowataRefs_9552.html [5] Mapping of Karst Terranes in Oklahoma to Identify Potential Environmental and Hydrologic Problems, AAPG Search and Discovery / Oklahoma Geological Survey https://www.searchanddiscovery.com/abstracts/html/1995/midcon/abstracts/1403b.htm [6] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # How does the moisture index change across Oklahoma? URL: https://terrabrain.vercel.app/data/moisture-index-by-city Answer: The Thornthwaite Moisture Index weighs rainfall against evaporation. Oklahoma gets drier east to west, and drier climates generally drive soil drying deeper. In short: The Thornthwaite Moisture Index (TMI) is a single number that describes how wet or dry a climate is by weighing rainfall against the water the climate can evaporate. Oklahoma grows drier from east to west, and state evaporation data shows the western half losing roughly 10 to 16 more inches of water each warm season than the east. Drier climates generally drive seasonal soil drying deeper into clay. ## What is the Thornthwaite Moisture Index? The TMI compares a location's yearly precipitation with its **potential evapotranspiration**, the amount of water that would evaporate from soil and pass through plants if water were always available. - A **positive** TMI means rainfall exceeds that demand (a moist climate). - A value near **zero** means they are roughly balanced. - A **negative** TMI means demand exceeds rainfall (a dry or semi-arid climate). Foundation engineers use the TMI in slab design methods for expansive clay, such as those used for post-tensioned slabs (https://terrabrain.vercel.app/foundations/post-tensioned-slabs), to estimate how far soil moisture will change under and around a slab. The idea connects directly to the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone), the layer of soil whose moisture changes with the seasons. ### Climate classes Thornthwaite's 1948 method computes the index from a yearly moisture balance as TMI = (100R − 60D)/PE, where R is water surplus (runoff), D is moisture deficit and PE is potential evapotranspiration [5]. An ODOT-sponsored study by Oklahoma State University and the University of Oklahoma used these class limits [5]: | Climate class | TMI range | |---|---| | Humid | 20 to 100 [5] | | Moist sub-humid | 0 to 20 [5] | | Dry sub-humid | −20 to 0 [5] | | Semi-arid | −40 to −20 [5] | | Arid | below −40 [5] | The same study notes that TMI is widely used in geotechnical and pavement engineering, and that it has been correlated with equilibrium soil suction (how tightly dry soil holds water) below the zone of seasonal moisture change [5]. ## How does Oklahoma's climate change from east to west? No verified city-by-city TMI table was found for this page. The ODOT-sponsored study instead mapped TMI statewide with three calculation methods and found that the zero TMI line runs across central Oklahoma, so the climate there ranges from moist sub-humid to dry sub-humid [5]. The study describes Oklahoma's climate overall as ranging from humid to semi-arid [5]. Other Oklahoma climate data shows the same east-to-west drying trend. ### Evaporation increases to the west OSU Extension fact sheet BAE-1529 lists average May to October evaporation from shallow water bodies by climate division [1]: | Climate division | May to October evaporation | |---|---| | Southeast (CD-9) | 28.1 inches [1] | | Northeast (CD-3) | 30.1 inches [1] | | Southwest (CD-7) | 40.3 inches [1] | | West-central (CD-4) | 40.9 inches [1] | | Panhandle (CD-1) | 44.4 inches [1] | The fact sheet notes that losses increase moving west and can be higher during drought [1]. That difference of about 10 to 16 inches over six months reflects much higher evaporative demand in western Oklahoma [1]. ### Climate controls drying depth An Oklahoma State University study using Mesonet soil-suction data estimated the depth of seasonal moisture change at about 0.5 to 4 meters across the state, depending on soil properties and climate, with the shallowest soil most sensitive to climate [2]. A drier climate (lower TMI) pushes the soil toward drier conditions more of the year. ### Drought can override the averages Averages hide extreme years. A 1961 study applying Thornthwaite's classification found desert (arid) conditions somewhere in Oklahoma in 1933 to 1937, 1954 and 1956; in 1956 they covered the whole Panhandle and part of northwestern Oklahoma [6]. In August 2012, about 97% of Oklahoma was in extreme or exceptional drought, and north-central Oklahoma had its driest May-to-early-August since 1921 [3]. In May 2015, by contrast, the statewide average rainfall of 14.40 inches set the record for the wettest month in Oklahoma history [4]. Swings like these matter as much as the long-term index for how much clay moves; see drought and wet years (https://terrabrain.vercel.app/data/drought-and-wet-years). ## What does this mean for each region? - **Tulsa and northeast Oklahoma** sit at the wetter, lower-evaporation end of the state [1]. See Tulsa metro (https://terrabrain.vercel.app/regions/tulsa-metro). - **Oklahoma City** lies in central Oklahoma, near the zero TMI line between moist and dry sub-humid climates [5]. See OKC metro (https://terrabrain.vercel.app/regions/okc-metro). - **Southwest Oklahoma and the Panhandle** have the highest evaporation [1]. See southwest Lawton and Red Plains (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains) and Panhandle High Plains (https://terrabrain.vercel.app/regions/panhandle-high-plains). ## Related - Active zone and drought depth (https://terrabrain.vercel.app/data/active-zone-and-drought-depth) - Drought and wet years (https://terrabrain.vercel.app/data/drought-and-wet-years) - Shrink-swell and active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Post-tensioned slabs (https://terrabrain.vercel.app/foundations/post-tensioned-slabs) - Mesonet for foundation pros (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros) Sources: [1] Evaporation Losses from Shallow Water Bodies in Oklahoma (BAE-1529), Oklahoma State University Extension https://extension.okstate.edu/fact-sheets/evaporation-losses-from-shallow-water-bodies-in-oklahoma [2] Soil matric suction and active zone depth in Oklahoma, Oklahoma State University (SHAREOK repository) https://shareok.org/handle/11244/54639 [3] Extreme to Exceptional Drought Covers Most of Oklahoma, Oklahoma Mesonet https://mesonet.org/images/news/Extreme%20to%20Exceptional%20Drought%20Covers%20Most%20of%20Oklahoma.pdf [4] Oklahoma Monthly Climate Summary, May 2015, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2015/MCS_May_2015.pdf [5] Evaluation of the Enhanced Integrated Climatic Model for Specification of Subgrade Soils in Oklahoma (FHWA-OK-14-05), Oklahoma Department of Transportation / Oklahoma State University and University of Oklahoma https://rosap.ntl.bts.gov/view/dot/31435/dot_31435_DS1.pdf [6] Desert Years in Oklahoma During the 1930's and 1950's, Proceedings of the Oklahoma Academy of Science https://ojs.library.okstate.edu/osu/index.php/OAS/article/view/4206/3879 --- # How does the Wellington Formation affect Oklahoma foundations? URL: https://terrabrain.vercel.app/geology/wellington-formation Answer: Wellington layers shift quickly from sand to clay, so soils range from shallow and loamy to deep and highly expansive and must be judged lot by lot. In short: The Wellington Formation is an early Permian mix of sandstone, shale and mudstone in central Oklahoma, lying below and east of the Garber Sandstone. Because its layers change quickly from sand to clay, soils on it range from shallow and loamy to deep and highly expansive. Foundation behavior has to be judged lot by lot from the mapped soil. ## What is the Wellington Formation rock? The Wellington Formation is made of sands, shales and mudstones [2]. A USGS review describes the Wellington and Garber as interbedded, lens-shaped sandstone, shale and siltstone deposited in similar delta environments during the early Permian [1]. A **lens** is a bed that thins and pinches out sideways, which is why the rock under one house can differ from the rock under the next. The Garber Sandstone and Wellington Formation together form the primary flow system of the Central Oklahoma aquifer, often called the Garber-Wellington aquifer [1]. The aquifer covers roughly 2,000 square miles [2]. ### Where it is Rock layers in central Oklahoma tilt west at about 35 to 40 feet per mile in most locations [2]. The USGS lists the aquifer units as the Admire, Council Grove and Chase groups, the Wellington Formation and the Garber Sandstone [1]. See the Garber Sandstone (https://terrabrain.vercel.app/geology/garber-sandstone) and Hennessey Shale (https://terrabrain.vercel.app/geology/hennessey-shale-group) pages. ## What soils form on the Wellington Formation? | Series | Parent material | Depth to rock | Shrink-swell clues | |---|---|---|---| | Renfrow | Weathered Permian clayey shale [3] | More than 60 in [3] | Vertic cracks at least 5 mm wide; slickensides [3] | | Kirkland | Clayey sediments over Permian shale [6] | About 82 in (208 cm) in the typical pedon [6] | Slickensides in the subsoil [6] | | Zaneis | Interbedded Permian sandstone and shale [4] | About 40–60 in [4] | Fine-loamy subsoil [4] | | Lucien | Permian sandstone with clay, siltstone or sandy shale [5] | 10–20 in; 14 in typical [5] | Loamy, shallow [5] | **Vertic** features, such as wide cracks and slickensides (polished shear faces in clay), are the soil survey's signs of strong shrink-swell. Renfrow's description requires cracks at least 5 millimeters wide within about 4 feet of the surface for part of most years [3]. Soil scientists rate shrink-swell by **linear extensibility**, the percent a soil's length changes between moist and dry, with under 3 percent low and 9 percent or more very high [7]. Map-unit values for a specific lot are listed in the USDA Web Soil Survey. ## What does the Wellington Formation mean for foundations? ### Clay sites On Renfrow and Kirkland, slow-draining clay with slickensides [3][6] shrinks in drought and swells when wet. Renfrow has low saturated hydraulic conductivity and high runoff [3], so water tends to run off rather than soak in evenly. See perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) and perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift). ### Sandy and shallow sites On Lucien, rippable sandstone at 10 to 20 inches and very high runoff [5] point toward erosion and uneven bearing. Zaneis, with rock at 40 to 60 inches and moderate permeability [4], sits between the two extremes. See erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). ### Mixed sites Because sand and clay lenses alternate [1], a single house can span both. Differences in support across a footprint can show up as cracking at the transition. See differential movement at additions (https://terrabrain.vercel.app/causes/differential-movement-at-additions) and soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values). ## Related - OKC metro (https://terrabrain.vercel.app/regions/okc-metro) - North-Central (Red Prairies and Wheat Belt) (https://terrabrain.vercel.app/regions/north-central-red-prairies-and-wheat-belt) - Bedrock in the OKC metro (https://terrabrain.vercel.app/guides/bedrock-okc-metro) - Renfrow soil (https://terrabrain.vercel.app/soils/renfrow) - Lucien soil (https://terrabrain.vercel.app/soils/lucien) Sources: [1] Review of the general geology and solid-phase geochemical studies in the vicinity of the Central Oklahoma aquifer (Circular 1019), U.S. Geological Survey https://pubs.usgs.gov/publication/cir1019 [2] OK County Groundwater Model (Project 174601), Association of Central Oklahoma Governments https://www.oklahomacounty.org/Portals/0/OK%20County%20Groundwater%20Model.pdf [3] Official Soil Series Description: RENFROW Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/R/RENFROW.html [4] Official Soil Series Description: ZANEIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/Z/ZANEIS.html [5] Official Soil Series Description: LUCIEN Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/L/LUCIEN.html [6] Official Soil Series Description: KIRKLAND Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KIRKLAND.html [7] Linear Extensibility (definition and shrink-swell classes, after NRCS National Soil Survey Handbook), UC Davis California Soil Resource Lab https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html --- # How does yard drainage and grading affect an Oklahoma foundation? URL: https://terrabrain.vercel.app/guides/surface-drainage-and-grading Answer: On expansive clay, slopes toward the house, downspouts at the wall and sprinklers wet soil unevenly and drive movement; fixing drainage is a first step. In short: On Oklahoma's expansive clay, where water goes around a house largely decides where the foundation moves. Ground that slopes toward the house, downspouts that empty at the wall and sprinklers that soak one side all wet the soil unevenly. Engineering sources treat fixing drainage as one of the first steps in addressing moisture-driven foundation movement. ## Why does surface water matter? Expansive clay swells when water enters it and shrinks when it dries, and uneven moisture under a slab causes differential movement, where one part of the house moves more than another [5]. Movement often happens at a building's outer walls, and water reaching the soil from rain, irrigation or leaks can cause interior movement too [4]. Impermeable surfaces, drainage, vegetation and irrigation all influence how deep and how far moisture changes reach [6]. Structural engineers list poor drainage, irrigation, groundwater, leaking pipes and trees among the causes of differential moisture, and name revising site drainage as a remedy [3]. ## What does the guidance say? ### Grading The EPA advises making sure the ground slopes away from the building foundation so water does not enter or collect around it [1]. Code requirements for new construction are covered on codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits). ### Gutters and downspouts The EPA advises cleaning and repairing roof gutters regularly [1]. Its stormwater program describes redirecting downspouts to a rain barrel or to a lawn or garden where water can soak in, while cautioning that owners should consider local rules and where the water will flow to avoid property damage, and that disconnection may not suit every location [2]. ### Heavier rain events NOAA reports that 2-inch extreme rainfall events in Oklahoma have increased since 1985 and projects more extreme precipitation, which may increase the risk of flooding and soil erosion [7]. Drainage that handles ordinary rain can be overwhelmed by these bursts. ## What drainage problems are common on Oklahoma lots? | Problem | Effect on soil moisture | Source | |---|---|---| | Downspouts emptying beside the wall | Concentrated water at one spot on the perimeter, a form of poor drainage | [3] | | Ground sloping toward the house (built-up beds, settled backfill) | Water collects at the foundation | [1] | | Sprinklers wetting the slab edge | Ongoing extra moisture on one side | [3][4] | | Clogged or damaged gutters | Overflow along the wall line | [1] | | Paving next to the house | Changes how soil under it wets and dries | [6] | Signs that water is collecting include water ponding near the foundation (https://terrabrain.vercel.app/signs/water-ponding-near-foundation) and, after dry spells, soil pulled away from the foundation (https://terrabrain.vercel.app/signs/soil-pulled-away-from-foundation). ## How does drainage connect to foundation movement? - **Edge lift**: when the perimeter gets wetter than the center, the edges can rise; see perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift). - **Edge drop**: when the perimeter dries faster, the edges can fall; see perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). - **Washouts**: concentrated runoff can carry soil from under slab edges; see erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes). Engineering sources note that leveling a foundation without correcting the moisture source can produce only temporary results [3]. Drainage options such as regrading, extensions and subsurface drains are described on drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). ## Related - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Groundwater and Perched Water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Root Barriers and Moisture Control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control) - Inspection Protocol (https://terrabrain.vercel.app/guides/inspection-protocol) Sources: [1] A Brief Guide to Mold, Moisture and Your Home, U.S. Environmental Protection Agency https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home [2] Soak Up the Rain: Disconnect / Redirect Downspouts, U.S. Environmental Protection Agency https://www.epa.gov/soakuptherain/soak-rain-disconnect-redirect-downspouts [3] Expansive Soils (The Mystery), STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [4] County Expansive Soils Policy & Procedures (Commercial & Residential Projects), Roanoke County, Virginia, Development Services https://roanokecountyva.gov/DocumentCenter/View/1020 [5] Residential House Foundations on Expansive Soils in Changing Climates, HUD Office of Policy Development and Research (Cityscape, Vol. 25 No. 1) https://www.huduser.gov/PORTAL/periodicals/cityscape/vol25num1/ch10.pdf [6] TRB Webinar: Foundations in Shrink Swell Soil: Innovation and State of Practice, Transportation Research Board, National Academies https://www.nationalacademies.org/cdn/materials/a067d915-1c17-4a16-840d-06452b68646c [7] Oklahoma - State Climate Summaries 2022, NOAA National Centers for Environmental Information https://statesummaries.ncics.org/chapter/ok/ --- # How far apart are foundation piers in Oklahoma? URL: https://terrabrain.vercel.app/guides/loads-pier-spacing-and-capacity Answer: Spacing depends on wall load, pier capacity and how far the beam can span. Oklahoma steel push piers are commonly set about 7 feet apart. In short: Pier spacing comes from three numbers: how much weight each foot of wall puts on the foundation, how much each pier can safely carry, and how far the concrete beam can bridge between piers. Oklahoma steel push piers are commonly set about 7 feet apart and driven to at least 6,000 psi [1]. Final spacing on any house is an engineering decision: Oklahoma's engineering board expects a professional engineer to be in responsible charge of a foundation repair plan and to sign and seal it [2]. ## Where does the load come from? A house's weight reaches the soil through its perimeter beam or footing. Engineers express this as a **line load**: pounds per linear foot of wall. It adds up from the roof, the walls, the floors and the concrete itself. Brick veneer adds a large share. Oklahoma's engineering board illustrated this with a back-calculation: 10-inch piers spaced 7 feet apart on soil allowing 3,000 pounds per square foot would carry only about 5 feet 10 inches of brick veneer wall height, before any roof, floor or other loads were added [2]. ## How is pier spacing worked out? In plain terms, spacing is limited by whichever of these runs out first: - **Pier capacity.** The load one pier can carry, divided by the line load, gives the longest spacing the pier allows. - **Beam span.** The concrete beam between two piers has to carry the wall like a bridge. A beam with little reinforcing may need closer piers than the pier capacity alone would allow. - **Bracket capacity.** The steel bracket that connects the pier to the beam has its own rating. On Oklahoma steel push pier jobs, exterior piers are placed about every 7 feet in the affected areas [1]. Oklahoma's statewide residential code now requires two #4 reinforcing bars in all new footings [5], so newer foundations generally have more reinforcing to span between supports than many older ones. ## How is pressure read on a pier log? A steel push pier is driven by a hydraulic ram that pushes against the weight of the house. The gauge pressure when the pier stops, multiplied by the ram piston's area, equals the force applied to the pier. That is why the ram size has to be recorded to convert psi into pounds or kips (thousands of pounds). Oklahoma installation data [1]: | Measure | Value | |---|---| | Minimum driving pressure | 6,000 psi | | Median on a large Tulsa job | about 9,000 psi | | Ram rating | 10,000 psi | | Typical exterior spacing | about 7 ft | | Median refusal depth, Tulsa | 12 ft | ## How does frost depth affect shallow systems? Oklahoma's engineering board described common "pier and grade beam" systems: grade beams about 8 to 10 inches wide and 14 to 18 inches deep, on piers 8 to 10 inches in diameter, no more than about 36 inches deep and 6 to 8 feet apart [2]. The board noted that grade beam bottoms were often only 1 to 8 inches below finished grade, and that codes require the bottom to be below frost depth unless perimeter insulation is used. It cited about 18 inches as the Oklahoma City frost depth [2]. More on this: freeze-thaw and frost depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth). ## How does expansive clay cause uplift? The **active zone** is the depth of soil whose moisture changes with the seasons [3]. In that zone, swelling clay can grip a pier shaft and pull up on it. Building codes require foundations placed on or within the active zone to be designed to resist differential volume changes [3], and residential foundations on expansive soil must be designed under the building code's expansive-soil provisions [4]. Resistance to uplift has to come from below the active zone, through depth, a bell or a helix. See shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) and pier uplift after repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair). ## What drives the number of piers? - Length of wall that has settled - Weight of the structure (one or two stories, brick or siding) - Condition and reinforcing of the existing beam - Depth to load-bearing soil or rock, which affects capacity ## Related - Steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Helical piers (https://terrabrain.vercel.app/repairs/helical-piers) - Drilled bell-bottom piers (https://terrabrain.vercel.app/repairs/drilled-bell-bottom-piers) - Working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers) - Bedrock in the Tulsa metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro) Sources: [1] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data [2] The Board's Bulletin, Vol. 21, Issue 4 (2007): Compliance Guidelines for Foundation Repair Companies and Residential Foundation Public Meeting, Oklahoma State Board of Licensure for Professional Engineers and Land Surveyors https://oklahoma.gov/content/dam/ok/en/pes/documents/bulletin/Newsletter_Volume21_Issue62.pdf [3] Beyond the Building Code: Expansive Soils, Journal of the National Academy of Forensic Engineers https://journal.nafe.org/ojs/index.php/nafe/article/download/975/924/4846 [4] Seattle Residential Code 2018, Chapter 4 Foundations (IRC-based text of R403.1.8), City of Seattle Department of Construction and Inspections https://seattle.gov/Documents/Departments/SDCI/Codes/SeattleResidentialCode/2018SRCChapter4.pdf [5] Oklahoma Uniform Building Code Commission, Adoption of International Residential Code 2024: Code Changes Summary, Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2024%20IRC%20Code%20Changes%20Summary%20-%20for%20website.pdf --- # How far out of level can an Oklahoma foundation be? URL: https://terrabrain.vercel.app/guides/tolerances-and-standards Answer: There is no single allowed number. Engineers judge overall tilt, deflection and resulting distress against published guidelines. In short: There is no single "allowed" out-of-level number for an existing house. Engineers judge a foundation by its overall tilt, its deflection (bowing) and the distress it is causing, measured against published engineering guidelines [1]. Oklahoma's building code sets the rules for new foundations and for soils that need testing [2][4]. ## Why is "level" the wrong yardstick? Forensic engineers point out that foundations are not built perfectly level, so a floor-level survey always mixes original construction variation with any movement since [1]. Porches, patios and garages are often built with deliberate slopes for drainage [1]. A difference between the highest and lowest point therefore does not, by itself, prove the foundation has moved or failed. ## What are tilt, deflection and distress? Engineering guidelines separate two kinds of out-of-level [1]: - **Tilt**: a plane sloping evenly across the whole foundation. - **Deflection**: how far the surface bows away from a straight line drawn between two points. **Global deflection** spans the whole foundation; **local deflection** covers a shorter length. Both the Texas Section of ASCE guidelines and the Post-Tensioning Institute guide require local deflection to be analyzed and require an evaluation of distress (cracks, sticking doors, separations) to decide whether a foundation has failed [1]. A survey compared over time shows whether movement is active. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). ## What are the key reference documents? | Document | What it covers | |---|---| | International Residential Code (IRC), Oklahoma edition | Minimum rules for new one- and two-family homes [2] | | Texas Section ASCE, *Guidelines for the Evaluation and Repair of Residential Foundations*, ver. 3 (2022) | Evaluating existing residential foundations [1] | | Post-Tensioning Institute DC10.8-18, *Guide for Performance Evaluation of Slab-on-Ground Foundations* | Evaluating slab performance [1] | | Texas Section ASCE, *Recommended Practice for the Design of Residential Foundations*, ver. 2 (2007) | Design of new residential foundations [1] | ## What does Oklahoma's residential code cover? The Oklahoma Uniform Building Code Commission adopts the IRC statewide. The 2024 IRC with Oklahoma amendments took effect September 14, 2026 [2]. The prior 2018 edition with Oklahoma amendments had been effective since September 14, 2022 [3]. Foundation-related Oklahoma amendments in the 2024 adoption include [2]: - two #4 reinforcing bars in all footings - #4 bars tying footings to stem walls at corners and at no more than 6 feet apart - ½-inch anchor bolts at no more than 6 feet apart - permission to use glass-fiber-reinforced polymer (GFRP) reinforcing bar in foundation walls and spread footings not more than 48 inches high The 2018 Oklahoma rule also barred trenching parallel to a footing from cutting into the zone beneath it defined by a 45-degree line from the footing's bottom edge [3]. ## What does the code say about expansive soil? Where data suggest expansive, compressible or shifting soils, the building official decides whether a soil test is required [4]. Soil counts as expansive when all four of these are met, though the first three need not be tested if the fourth is run [4]: | Test | Threshold | |---|---| | Plasticity index (how wide a moisture range the soil stays plastic) | 15 or more | | Passing a No. 200 sieve | more than 10% | | Particles finer than 5 micrometers | more than 10% | | Expansion index | more than 20 | Foundations on expansive soil must be designed under the building code's expansive-soil provisions, unless a system that has performed well on similar soils is approved [4]. Texas practice commonly treats about 4.5 inches of potential vertical movement as a general limit for slab-on-grade design [1]. See soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values). ## Does a repair plan need an engineer's seal? In Oklahoma, a foundation repair plan prepared by an engineer must be signed, sealed and dated, and the engineer keeps a design file with criteria, calculations and the cause of the damage [5]. See working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). ## Related - Codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits) - Elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) - Lifting procedure and restoration (https://terrabrain.vercel.app/guides/lifting-procedure-and-restoration) - Post-tensioned slabs (https://terrabrain.vercel.app/foundations/post-tensioned-slabs) - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) Sources: [1] Beyond the Building Code: Expansive Soils, Journal of the National Academy of Forensic Engineers https://journal.nafe.org/ojs/index.php/nafe/article/download/975/924/4846 [2] Oklahoma Uniform Building Code Commission, Adoption of International Residential Code 2024: Code Changes Summary, Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2024%20IRC%20Code%20Changes%20Summary%20-%20for%20website.pdf [3] 748:20-6-9. IRC 2018 Chapter 4 Foundations (Permanent Rule), Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2022%2009%2014%20IRC%202018%20Permanent%20Rule.pdf [4] Seattle Residential Code 2018, Chapter 4 Foundations (IRC-based text of R401.4 and R403.1.8), City of Seattle Department of Construction and Inspections https://seattle.gov/Documents/Departments/SDCI/Codes/SeattleResidentialCode/2018SRCChapter4.pdf [5] The Board's Bulletin, Vol. 21, Issue 62 (Fourth Quarter 2007): Compliance Guidelines for Foundation Repair Companies, Oklahoma State Board of Licensure for Professional Engineers and Land Surveyors https://oklahoma.gov/content/dam/ok/en/pes/documents/bulletin/Newsletter_Volume21_Issue62.pdf --- # How far should trees be planted from a house in Oklahoma City? URL: https://terrabrain.vercel.app/data/trees Answer: Oklahoma City's planting guide keeps medium and large trees at least 30 feet from buildings; most roots are shallow but spread well beyond the canopy. In short: About a fifth of the Oklahoma City metro is under tree canopy, with eastern redcedar, slippery elm and western soapberry the most common species. Oklahoma City's planting guide keeps medium and large trees at least 30 feet from buildings. Most tree roots are shallow but spread well beyond the canopy, which is why trees can dry clay soil next to a footing. This page collects Oklahoma tree data that matters for foundations. For how trees dry clay and cause settlement, see trees and roots (https://terrabrain.vercel.app/guides/trees-and-roots). ## How much tree canopy does the OKC metro have? The Association of Central Oklahoma Governments (ACOG) commissioned a canopy assessment of the Oklahoma City metropolitan area in 2019 [1]. | Measure | Value | |---|---| | Study area | 536.4 square miles (343,314 acres) [1] | | Tree canopy cover | 22.4% (76,903 acres) [1] | | Estimated number of trees | About 65 million [1] | | Species recorded | 74 [1] | ### Most common species | Species | Share of trees | |---|---| | Eastern redcedar | 13.2% [1] | | Slippery elm | 9.7% [1] | | Western soapberry | 9.6% [1] | ## What are the official planting distances? The City of Oklahoma City's planting guide sets these distances [2]: - Medium and large trees: no closer than 30 feet to buildings or structures [2]. - Trees listed as suitable near water lines: 5 feet from lines 4 inches in diameter, or 10 feet from larger lines [2]. - Medium and large trees should never be planted under overhead utility lines [2]. - Street trees: at least 10 feet from overhead lines and power poles (15 feet recommended) and at least 5 feet from underground utility lines [2]. Oklahoma State University (OSU) Extension gives a rule based on tree size: plant at least half the mature canopy width away from the home, and keep fast-growing or weak-wooded trees well away from buildings [3]. ## Where do tree roots grow? | Fact | Source | |---|---| | Most trees grow a fibrous root system in the upper 24 inches of soil | OSU Extension [4] | | The top 12 inches of soil does the most water and mineral uptake | OSU Extension [4] | | Pecan, walnut, some pines and some oaks develop a deep taproot | OSU Extension [4] | | Roots often spread up to 3 times the canopy width | OSU Extension [4] | | In shallow soil over clay, roots may spread up to 5 times the canopy width | OSU Extension [4] | | Studies show roots spreading 4 to 7 times the dripline radius | Iowa State Extension [5] | | Roots rarely grow below about 4 feet, though deeper reports exist | Iowa State Extension [5] | The dripline is the outer edge of a tree's canopy. Because roots reach far past it, a tree that looks well clear of the house can still draw water from soil along the foundation, a process described in tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement). ## What species traits does OSU Extension list? OSU Extension's selection guide lists these traits for trees common in Oklahoma yards [3]: - **Silver maple:** fast growth, brittle wood and a shallow root system [3]. - **Eastern cottonwood:** grows too large for typical landscapes and has surface roots [3]. - **Sweetgum:** needs damp, rich soil, is not very drought tolerant and may have shallow roots [3]. - **Pecan:** needs deep, rich, moist soil and drops large limbs as it ages [3]. - **Post oak and blackjack oak:** do not tolerate compaction or nearby construction; post oak is also listed as not tolerating grade changes [3]. - **Bur oak:** tolerates dry clay soils but eventually grows very large [3]. - **Lacebark elm:** described as extremely tough and drought tolerant [3]. The oak traits are relevant when excavation is planned beside a house, such as for steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) or drainage work, since digging and compaction near the root zone can injure these species [3]. ## Why do trees matter on Oklahoma clay? Clay soils across central and eastern Oklahoma swell and shrink with moisture (see shrink-swell and active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone)). A tree concentrated near one side of a house adds uneven drying on that side, and removing a large tree can lead to post-tree-removal heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave) as the soil rewets. ## Related - Trees and roots (https://terrabrain.vercel.app/guides/trees-and-roots) - Tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) - Post-tree-removal heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave) - Tree management (https://terrabrain.vercel.app/repairs/tree-management) - Root barriers and moisture control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control) - OKC metro region (https://terrabrain.vercel.app/regions/okc-metro) Sources: [1] Oklahoma City Metropolitan Area Tree Canopy Assessment (Executive Summary), Association of Central Oklahoma Governments https://www.acogok.org/wp-content/uploads/2020/02/Tree-Canopy-Executive-Summary-1.pdf [2] Trees and Plants for Oklahoma City, City of Oklahoma City https://okc.gov/home/showdocument?id=4954 [3] Selecting Deciduous Trees for Oklahoma, Oklahoma State University Extension https://extension.okstate.edu/fact-sheets/selecting-deciduous-trees-for-oklahoma [4] Getting to the root of good tree health, Oklahoma State University Extension https://extension.okstate.edu/articles/2026/getting-to-the-root-of-good-tree-health [5] Tree Root Systems, Iowa State University Extension and Outreach https://yardandgarden.extension.iastate.edu/article/1992/4-1-1992/treeroot.html --- # How is a foundation elevation survey done? URL: https://terrabrain.vercel.app/guides/elevation-surveys Answer: Floor heights are measured from one reference point and mapped as contours, then tilt and deflection are checked against limits such as L/360 and 1 percent. In short: An elevation survey measures relative floor heights across a house from a single reference point and turns them into a contour map of the foundation's shape. Engineering guidelines use it to check deflection (bowing) and tilt against limits such as L/360 and 1 percent, always alongside visible distress. Because slabs are not built perfectly level, comparing surveys taken at different times is the clearest way to measure actual movement. ## What does an elevation survey show? A floor elevation survey records the shape of a foundation at one instant [2]. Post-Tensioning Institute (PTI) evaluation guidelines describe it as one of the most common tools for judging foundation performance, and note that the only absolute way to measure movement is to compare changes between two surveys [3]. In the ASCE Texas Section guidelines, a "Level B" investigation adds relative foundation elevations, taken with floor finishes considered, in enough detail to show the foundation's shape, plus a drawing of those elevations [2]. ## How are readings taken? ### Instruments The Foundation Performance Association (FPA) guideline calls for a level-measuring device accurate to plus or minus 1/8 inch or better, and says a spirit level should not be used to measure slab slope [1]. The guidelines set an accuracy requirement rather than naming specific tools, and PTI notes that contour intervals should match the instrument's accuracy [1][3]. ### Reference point The survey starts from a reference point set to 0.0, ideally a spot that is easy to find again, such as a corner or a point near the center of the house [1]. PTI notes the reference is typically near the center of the foundation and may be an arbitrary point rather than a true benchmark [3]. The FPA guideline recommends returning to the reference during the survey to confirm the instrument still reads the same [1]. ### Spacing FPA recommends a reading every 30 to 100 square feet where practical, with more in large rooms [1]. PTI notes that a span needs at least three elevations to describe its shape [3]. ### Floor coverings Tile, wood and carpet have different thicknesses, so readings on top of finishes are either corrected for covering thickness or flagged [1]. PTI distinguishes a raw "survey elevation plan" from an "adjusted elevation plan" corrected for coverings and steps, which shows the true distortion [3]. At a flooring change, FPA suggests several readings on each side, averaged [1]. ## How are the results read? ### Tilt versus deflection - **Tilt** is the whole foundation sloping one way, like a tabletop with short legs at one end. - **Deflection** is bending, where the middle is higher or lower than a straight line between two points, giving a dome or dish shape. The deflection ratio is the largest departure from a straight line between two points divided by the distance between them [2]. ### Common limits | Measure | Guideline value | Source | |---|---|---| | Deflection | L/360 (span length / 360) | FPA, ASCE Texas, PTI [1][2][3] | | Minimum span for deflection checks | 20 ft or foundation width, whichever is less | FPA [1] | | Tilt | 1% or less over length, width or diagonal | FPA, PTI [1][3] | ASCE Texas treats L/360 as a screening benchmark: below it, material deflection is unlikely unless distress shows otherwise; above it with few symptoms, more information is needed; above it with enough symptoms, an engineer is generally justified in finding excessive deflection [2]. That guideline also notes that slopes over 1 percent are usually noticeable to occupants [2]. ### Houses are not built flat FPA cites the ACI 117 concrete tolerance of 1.5 inches overall (plus or minus 3/4 inch) and reports that most residential slabs are built within about 1.0 inch of level [1]. PTI likewise notes that a 1.5-inch spread can be original construction [3]. Without an as-built survey, the original shape is unknown, so deflection and tilt from a single survey are approximations [2]. ### Heave or settlement? Without a fixed benchmark, PTI notes, contours alone do not show whether an area heaved or subsided [3]. See heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). Crack and distress locations are compared against the contour map using the distress pattern library (https://terrabrain.vercel.app/guides/distress-pattern-library). ## Why repeat a survey? Time-change elevations are calculated by subtracting the older reading from the newer one at each point, using equivalent plans and the same locations [1]. PTI notes time-change contours are typically drawn at 0.5-inch increments [3]. Clay soils move with seasonal moisture [5], so survey dates matter; the Oklahoma Mesonet runs 120 weather stations with at least one in every county, a public record of local rainfall around each survey date [4]. Follow-up surveys after repair are part of a monitoring program (https://terrabrain.vercel.app/repairs/monitoring-program). ## Related - Inspection protocol (https://terrabrain.vercel.app/guides/inspection-protocol) - Tolerances and standards (https://terrabrain.vercel.app/guides/tolerances-and-standards) - Working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers) - Sloping floors (https://terrabrain.vercel.app/signs/sloping-floors) - Mesonet for foundation pros (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros) Sources: [1] Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings (FPA-SC-13-0), Foundation Performance Association https://www.foundationperformance.org/projects/super/FPA-SC-13-0.pdf [2] Guidelines for the Evaluation and Repair of Residential Foundations, Version 2, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2022/05/Guidelines-for-the-Evaluation-and-Repair-of-Residential-Foundations-V2-2008.pdf [3] Evaluation Guidelines for the Performance of Slab-on-Ground Foundations (2015 technical session), Post-Tensioning Institute https://www.post-tensioning.org/Portals/13/Files/PDFs/Events/Conventions/TechnicalSessions/2015/042815Brumley.pdf [4] About the Mesonet, Oklahoma Mesonet (University of Oklahoma and Oklahoma State University) https://www.mesonet.org/about [5] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf --- # How is a foundation protected from slope creep and creek erosion? URL: https://terrabrain.vercel.app/repairs/slope-and-erosion-stabilization Answer: By combining grading and drainage, erosion protection, engineered retaining walls and, in some cases, supports designed for sideways load. In short: When a house sits near a slope or creek bank, the soil can slowly creep downhill or be carried away by flowing water, undermining the foundation. Stabilization combines grading and drainage to control water, erosion protection and engineered retaining walls [1][2], and in some cases supports designed for sideways load. This work usually involves a licensed engineer and, for taller walls or floodplain sites, permits [1]. ## What problems does this address? **Slope creep** is slow, downslope movement of soil. Expansive clay swells when wet and shrinks and cracks when dry, and these cycles are not fully reversible [4], which helps loosen and move soil on a slope over time. Signs include tilted retaining walls, fences or trees (https://terrabrain.vercel.app/signs/tilted-retaining-walls-fences-or-trees) and cracking concentrated on the downhill side of a house. See slope creep and lateral movement (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement). **Bank erosion** happens where a creek or drainage channel cuts into the soil next to a lot, especially during floods. In Oklahoma, major floods frequently occur in spring and fall [3]. See erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) and creeks and flood history (https://terrabrain.vercel.app/data/creeks-and-flood-history). The Oklahoma Geological Survey reports that most landslides in the state occur in the eastern third, where the wetter climate and steeper terrain favor them [3]. ## Why does investigation come first? A recommended practice for geotechnical work states that on sloped lots where the foundation is closer than four times the slope height to the toe of an embankment, borings should extend at least twice the slope height, and that reports should recommend earthwork stabilization and slope stability requirements [2]. Fill on the downhill side of a lot is a common contributor; see fill soils and lot history (https://terrabrain.vercel.app/guides/fill-soils-and-lot-history). ## What stabilization methods are used? ### Grading and surface drainage Controlling water is the base of most slope work. Drainage guidelines note that [1]: - Ground next to a foundation should fall 6 inches within the first 10 feet (citing IRC R401.3). - Bare soil erodes easily and should be covered with sod in the drainage area. - Swales — shallow, gently sloped grass channels — should have a minimum slope of about 0.5%; overly steep swales can erode. - Water spilling over terrace edges, or roof runoff from eaves without gutters, can erode soil unless the area is protected. - Gutters are required by the model residential code next to foundations on expansive or collapsible soils, with discharge at least 5 feet from the foundation or into an approved drainage system. More detail is on drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) and surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). ### Retaining walls A **retaining wall** holds back soil where the ground level changes. Drainage guidelines describe these points [1]: - A permit is required for walls over 4 feet tall measured from the bottom of the footing, and for any wall supporting a surcharge, regardless of height (IBC/IRC 105.2). - Walls that may collect water on the uphill side need drainage, such as gravel backfill with drain pipes through the wall or a French drain. - Dry-stacked block walls typically lean back 7 to 15 degrees; small walls without such features, even 18 to 24 inches tall, can lean outward within a few years. ### Bank protection Along creeks, armoring such as rock (riprap) or wire baskets filled with stone (gabions) is used to resist scour. Work in a mapped floodplain is regulated; flood maps delineate areas with a 1-in-100 chance of flooding in any year [3], and new construction floors in floodplains must be above the base flood elevation [1]. ### Lateral supports Standard foundation piers support load vertically. Engineering reviews note that steel pipe piles installed at the wrong angle can lay over or bend under load [5], and soil moving sideways adds forces that vertical piers are not designed for. Sites with active creep are typically designed by an engineer using walls, tiebacks or other elements meant to resist lateral load, with piers addressing only the vertical part. See steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) and helical piers. ## What are the limitations? - Usually requires an engineer's design and may require permits [1][2]. - Cost is driven by wall height and length, access for equipment, the extent of bank protection and engineering and permitting needs. ## Related - Erosion, Creeks and Slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Slope Creep and Lateral Movement (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Codes and Permits (https://terrabrain.vercel.app/rules/codes-and-permits) - Tilted Retaining Walls, Fences or Trees (https://terrabrain.vercel.app/signs/tilted-retaining-walls-fences-or-trees) Sources: [1] Drainage Guidelines (FPA-SC-17-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-17-0.pdf [2] Recommended Practice for Geotechnical Explorations and Reports (FPA-SC-04-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-04-0.pdf [3] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [4] Chapter C5 – Expansive Soils, Institution of Civil Engineers / British Geological Survey https://nora.nerc.ac.uk/id/eprint/17002/1/C5_expansive_soils_Oct.pdf [5] Post Foundation Repair Performance of Residential and Other Low-Rise Buildings on Expansive Soils (FPA-RC-01-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-RC-01-0.pdf --- # How is a settled foundation lifted, and what happens after? URL: https://terrabrain.vercel.app/guides/lifting-procedure-and-restoration Answer: Piers raise settled areas toward original height, aiming for the best practical lift, not flat, followed by plumbing checks, a new survey and pier records. In short: Lifting raises the settled parts of a foundation back toward their original height using the piers that now support it. Because no foundation is built perfectly level [1], the target is the best practical lift the structure will tolerate, not a flat floor. A lift is followed by plumbing checks, a new elevation survey and a written record of every pier [1][2]. ## What does "lifting" mean? Once piers are installed under a settled section, hydraulic jacks set on the pier brackets push the foundation up. A **pier** is a steel or concrete column driven or drilled down to firmer soil or rock so the house no longer rests only on the shallow clay. On Oklahoma steel push pier jobs, each pier is first driven until it reaches at least 6,000 psi of hydraulic pressure, and a large Tulsa job logged a median of about 9,000 psi [2]. Those same records keep shims, the steel spacers between the bracket and the pipe, to no more than three per pier [2]. Lifting is only appropriate where the foundation has actually **settled** (dropped). If part of the house has **heaved** (risen because clay swelled), raising the low areas up to the high spot spreads damage instead of fixing it. See heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) before any lift is planned. ## Why is "level" not the goal? Forensic engineers note that foundations are not constructed perfectly level, so a survey reflects as-built variation plus movement since construction [1]. Engineers evaluate a foundation by **tilt** (an overall slope across the whole foundation) and **deflection** (how far the surface bows away from a straight line between two points), together with visible distress, rather than by one high-to-low number [1]. See tolerances and standards (https://terrabrain.vercel.app/guides/tolerances-and-standards). During a lift, crews watch for signs that the structure is resisting: - cracks closing (expected) versus new cracks opening - doors and windows changing how they fit - the foundation binding or "fighting" in one area When those signs appear, lifting stops. The final height is whatever the house allows without new harm. ## What checks follow the lift? Expansive-soil guidance from forensic engineers recommends three steps after any lifting or lowering [1]: 1. **Plumbing tests** to find leaks that the movement may have caused, especially in drain lines under the slab. 2. **Repair of any leaks found**, since a leak under a slab can cause new movement. 3. **A new baseline elevation survey**, so later movement can be measured against a known starting point. The model plumbing code also limits lifting: a slab and its plumbing may not be lifted together to create a void underneath unless the space below is a crawl space with inspection access [1]. More on testing: plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab). ## Which records matter later? Each pier's depth, final pressure and final elevation are recorded on Oklahoma installation logs [2]. These records serve several later uses: | Record | Later use | |---|---| | Pier log (depth, pressure, location) | Engineer review, warranty file | | Before-and-after elevation survey | Shows what was recovered; baseline for monitoring | | Dated photos of cracks | Shows condition before cosmetic repair | | Warranty document | Sale of the home | Oklahoma's seller disclosure form asks directly, "Are you aware of any previous foundation repairs?" and separately asks about warranties covering the foundation [4]. Mortgage rules also matter: when an appraisal shows abnormal settlement, the lender must show the condition was corrected or provide a professionally prepared report that it poses no threat of structural damage [5]. If an engineer is involved, only that licensed engineer can issue an engineering completion letter. Oklahoma's engineering board allows a repair company to send its own completion letter, but not to call it an engineering completion letter [3]. See working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). ## What restoration work follows? After the structure stops moving, cosmetic work can follow: brick mortar repair (tuckpointing), drywall patching, and door and trim adjustment. Doing this work before the house has settled into its new position risks re-cracking. A monitoring program (https://terrabrain.vercel.app/repairs/monitoring-program) with repeat surveys shows whether movement has stopped. ## Related - Steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) - Heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Over-lift heave after a drought lift (https://terrabrain.vercel.app/causes/over-lift-heave-after-drought-lift) - Contracts, warranties and liens (https://terrabrain.vercel.app/rules/contracts-warranties-liens) - Cosmetic repair only (https://terrabrain.vercel.app/repairs/cosmetic-repair-only) Sources: [1] Beyond the Building Code: Expansive Soils, Journal of the National Academy of Forensic Engineers https://journal.nafe.org/ojs/index.php/nafe/article/download/975/924/4846 [2] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data [3] The Board's Bulletin, Vol. 21, Issue 4 (2007): Compliance Guidelines for Foundation Repair Companies, Oklahoma State Board of Licensure for Professional Engineers and Land Surveyors https://oklahoma.gov/content/dam/ok/en/pes/documents/bulletin/Newsletter_Volume21_Issue62.pdf [4] 2026 Appendix A: Residential Property Condition Disclosure Statement, Oklahoma Real Estate Commission https://oklahoma.gov/content/dam/ok/en/orec/documents/contracts-and-forms-page/2026-contract-forms/2026%20Appendix%20A%20Residential%20Property%20Condition.pdf [5] B4-1.3-06, Property Condition and Quality of Construction of the Improvements, Fannie Mae https://selling-guide.fanniemae.com/sel/b4-1.3-06/property-condition-and-quality-construction-improvements --- # How is foundation movement monitored in Oklahoma? URL: https://terrabrain.vercel.app/repairs/monitoring-program Answer: Repeat elevation surveys, crack gauges and soil-moisture records taken over at least a year show whether a foundation is still moving or has stabilized. In short: A monitoring program measures a foundation repeatedly over months to learn whether it is still moving, which direction it is moving, and whether the movement follows the seasons. Engineering guidelines call for at least a year of readings, because repairs made after movement has stopped are less likely to see distress return [1]. In Oklahoma's expansive clays, monitoring is often the first step when a slab may be heaving rather than settling. ## What is a monitoring program? Monitoring is observation, not a repair. It combines three kinds of records taken on a schedule: - **Floor elevation surveys** — relative heights measured at the same marked points on each visit [1]. - **Crack and distress records** — new or widening cracks, sticking doors and similar signs noted on a plan of the house [1][3]. - **Moisture and rainfall records** — soil moisture, rainfall and drainage conditions around the foundation, so movement can be matched to weather [1]. The goal set out in engineering guidance is to determine whether excessive movement is happening, whether it has likely stopped, and why it happened [1]. ## Why does monitoring matter on Oklahoma clay? Expansive clay swells when wet and shrinks when dry. The depth where this seasonal moisture change happens is called the **active zone**. A study using Oklahoma Mesonet field data estimated active zone depths across the state at roughly 0.5 to 4 meters (about 1.5 to 13 feet), with shallower soil reacting most to weather [7]. Because the soil moves up and down with the seasons, a single visit can mislead. A slab edge that looks low in a dry August may rise again after spring rain. Monitoring separates two patterns [1]: | Pattern seen over time | What it suggests | |---|---| | Points rise and fall in step with seasonal rainfall | Cyclical movement, typical of expansive soil | | Points trend steadily in one direction | Non-cyclical movement that has not stabilized | | Cracks reopen in the same place after repair | Continuing movement rather than seasonal cycling | This is why monitoring is often the first step for perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift), post-tree-removal heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave) and leak-related heave: the soil may need time to reach moisture balance before anyone can tell what, if anything, needs lifting. See heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) for how the two are told apart. ## How are the measurements taken? ### Elevation surveys - Readings are taken about every 30 to 100 square feet, including room corners and near heavy loads such as masonry fireplaces [2]. - The instrument should read to about 1/8 inch or better; a spirit or carpenter's level is not considered accurate enough [2]. - Each survey uses the same points and the same reference point so that a "time-change" plan (later reading minus earlier reading) can be drawn [2]. - A **benchmark** is a reference assumed not to move. Guidelines warn that trees, curbs and manhole covers usually make poor benchmarks [1]. - Manometer-style levels are accurate to about ±0.1 inch, and operator error can add about ±0.1 inch more, so isolated changes of about 0.2 inch may fall within measurement error unless nearby points or new cracks agree [1]. More on the method is in elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). ### Crack monitoring Simple gauges show whether a crack is still active. Federal preservation guidance describes three approaches: two pencil marks on tape across the crack measured on a schedule, a glass slide epoxied across the crack that breaks if movement continues, and a two-plate sliding crack monitor with a printed scale [3]. Measurements are charted at regular intervals and kept on file with photographs [3]. Seasonal opening and closing is covered in cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally). ### Soil moisture records The Oklahoma Mesonet reports soil moisture at most of its stations at depths of 2, 4, 10 and 24 inches [4]. Its Fractional Water Index runs from 0 (near the wilting point, very dry) to 1 (near field capacity, wet) [4]. The Mesonet website publishes daily values and graphs of recent readings [4][5]. Recording the nearest station and its reading with each survey lets a later reader see whether the soil was wet or dry at the time. See Mesonet for foundation pros (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros). ## How often are readings taken and when is movement stable? Guidelines from a Texas engineering group working on similar expansive clays set out these points [1]: - Monitor for at least one year. - Complete at least three time-change surveys, with the first and last in the same season. - Ideally, record elevations every three months. - Correct drainage, plumbing leaks and other moisture sources at least six months before the monitoring period being judged. The same guidelines treat movement as generally stabilized when the largest differential change is about 0.3 inch or less over three to four months (0.4 inch or less over six to eight months), no new functional or structural distress appears, and the movement lines up with climate and rainfall [1]. The authors note the guidance was written for Southeast Texas and should be applied with care elsewhere [1]. For ongoing homeowner checks, a companion guide suggests inspecting the site and structure twice a year and after extreme wet or dry weather, comparing results with earlier photos and records [6]. ## What are the limitations of monitoring? - Monitoring takes at least a year and only shows whether movement has stopped; it does not stop movement itself [1]. - Results depend on repeating the same points, the same reference and comparable instruments [2]. - Newly built foundations commonly go through a 12- to 24-month adjustment period, which can look like movement [2]. ## Related - Elevation Surveys (https://terrabrain.vercel.app/guides/elevation-surveys) - Seasonal Movement Calendar (https://terrabrain.vercel.app/guides/seasonal-movement-calendar) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Tolerances and Standards (https://terrabrain.vercel.app/guides/tolerances-and-standards) - Mesonet for Foundation Pros (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros) - Drought and Wet Cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) Sources: [1] Guidelines for Evaluating Foundation Performance by Monitoring (FPA-SC-12-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-12-0.pdf [2] Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings (FPA-SC-13-1), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-13-1.pdf [3] Monitoring And Evaluating Cracks In Masonry, U.S. General Services Administration https://gsa.gov/real-estate/historic-preservation/historic-preservation-policy-tools/preservation-tools-resources/technical-procedures/monitoring-and-evaluating-cracks-in-masonry [4] Tracking Drought Using Soil Moisture Information (BAE-1541), Oklahoma State University Extension https://extension.okstate.edu/fact-sheets/tracking-drought-using-soil-moisture-information.html [5] Soil Moisture, Oklahoma Mesonet https://www.mesonet.org/weather/soil-moisture [6] Foundation Maintenance and Inspection Guide for Residential and Other Low-Rise Buildings (FPA-SC-07-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-07-0.pdf [7] Soil matric suction and active zone depth in Oklahoma, Oklahoma State University (ShareOK) https://shareok.org/handle/11244/54639 --- # Is a concrete crack from shrinkage or foundation movement? URL: https://terrabrain.vercel.app/causes/material-shrinkage-and-thermal-cracking-mimic Answer: Many cracks come from materials shrinking or moving with temperature, not the foundation; a floor elevation survey and crack pattern tell them apart. In short: Many cracks in concrete and finishes are caused by the materials themselves shrinking as they dry or expanding and contracting with temperature, not by the foundation moving. Many of them appear early in a building's life and are usually cosmetic. A floor elevation survey and the crack pattern are what separate them from cracks caused by real foundation movement. ## Why do materials crack on their own? Concrete changes volume as its moisture and temperature change [1]. As freshly placed concrete dries, it shrinks; as the seasons change, it expands and contracts. When that movement is restrained, for example by a footing, a wall or the ground, the concrete cracks [1][3]. Concrete industry guidance states that cracks form when designs and construction do not allow for these movements [1]. These are sometimes called "mimic" cracks because they can look like signs of foundation movement even though the foundation has not shifted. ### Common types | Type | What it looks like | Cause | |---|---|---| | Drying shrinkage cracks | Random cracks in slabs, often appearing early | Concrete shrinking as it dries while restrained [1] | | Crazing | Fine, shallow surface cracks in a roughly hexagonal pattern, up to about 1.5 inches across | Shrinkage of a paste-rich top layer [2] | | Corner cracks in basement walls | Diagonal cracks from window and door corners | Drying shrinkage [3] | | Thermal cracks | Cracks tied to temperature swings | Expansion and contraction under restraint [1][3] | Crazing is rarely deeper than about 1/8 inch, usually appears by the day after placement or within the first week, and does not affect structural integrity [2]. ## How is concrete detailed to control cracking? Concrete slabs are given contraction joints, grooves that create a planned weak line so the slab cracks there instead of randomly. Industry guidance calls for grooves about one-quarter to one-third of the slab thickness, spaced 24 to 36 times the slab thickness, with a maximum spacing of about 15 feet often recommended and panels kept nearly square [1]. Isolation joints separate slabs from walls, columns and footings where movement may be restrained [1]. Most cracking traces to design and construction factors such as missing or poorly placed joints, poor subgrade preparation, too much water in the mix, improper finishing and inadequate curing [1]. Random early-age cracks are unsightly but rarely affect the structural integrity or service life of concrete [1]. ## When is a crack more than cosmetic? The concrete industry states that cracking is not necessarily a sign of poor materials, poor workmanship or a structural problem [3]. For basement walls, typical warranties call for repair when cracks leak, show measurable vertical displacement or exceed 1/8 inch (3 mm) in width, and cracks that continue widening call for professional evaluation [3]. The Foundation Performance Association classifies distress as architectural, functional or structural, and notes that separations in drywall and stucco typically become noticeable at about 0.02 inch [4]. Texas engineering guidelines add that signs such as cracked drywall or racked door frames do not necessarily mean a foundation is performing inadequately [5]. ### Checking for actual movement Cracks alone do not prove the foundation moved. Without a baseline elevation survey, movement cannot be determined accurately, and most residential slabs are built only to within about 1 inch of level [4]. Repeated surveys over months or years show whether the foundation's shape is changing [5]. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) and the distress pattern library (https://terrabrain.vercel.app/guides/distress-pattern-library). ## What are the signs of shrinkage or thermal cracking? - visible slab cracks (https://terrabrain.vercel.app/signs/visible-slab-cracks), especially fine random cracks in a newer slab - nail pops and tape-joint cracks (https://terrabrain.vercel.app/signs/nail-pops-and-tape-joint-cracks) in drywall - vertical brick or veneer cracks (https://terrabrain.vercel.app/signs/vertical-brick-or-veneer-crack) without offset Compare these with movement-related patterns such as stair-step brick cracks wider at the top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top), which are associated with perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). ## How are shrinkage cracks typically addressed? Where the foundation is sound, the cracks are treated as finish repairs. Texas guidelines note that an owner may choose periodic cosmetic repairs and door adjustments rather than structural work [5]. See cosmetic repair only (https://terrabrain.vercel.app/repairs/cosmetic-repair-only). ## Related - Cosmetic Repair Only (https://terrabrain.vercel.app/repairs/cosmetic-repair-only) - Visible Slab Cracks (https://terrabrain.vercel.app/signs/visible-slab-cracks) - Distress Pattern Library (https://terrabrain.vercel.app/guides/distress-pattern-library) - Tolerances and Standards (https://terrabrain.vercel.app/guides/tolerances-and-standards) - Original Construction Deficiency (https://terrabrain.vercel.app/causes/original-construction-deficiency) Sources: [1] CIP 4 - Cracking Concrete Surfaces, National Ready Mixed Concrete Association https://www.prairie.com/wp-content/uploads/sites/4/2024/12/04p_CrackingConcreteSurfaces.pdf [2] CIP 3 - Crazing Concrete Surfaces, National Ready Mixed Concrete Association https://www.nrmca.org/wp-content/uploads/2021/01/03pr.pdf [3] CIP 7 - Cracks in Residential Basement Walls, National Ready Mixed Concrete Association https://www.nrmca.org/wp-content/uploads/2021/01/07pr.pdf [4] Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings (FPA-SC-13-1), Foundation Performance Association https://inspectapedia.com/structure/Foundation-Movement-Evaluation-Guidelines-FPA-TX.pdf [5] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf --- # Is a vertical crack in brick veneer a foundation problem? URL: https://terrabrain.vercel.app/signs/vertical-brick-or-veneer-crack Answer: A vertical crack near a corner, offset or long wall is often brick expansion. Tapered cracks, or ones at an addition, more likely involve the foundation. In short: A vertical crack of fairly even width in brick veneer, especially near a corner or along a long wall, is often caused by the brick itself expanding rather than by the foundation moving. Cracks that taper, wider at one end, or that sit where an addition meets the house, are more likely to involve foundation movement. ## What does a vertical brick crack look like? The crack runs straight up and down, through brick units or along the vertical (head) joints, with roughly the same width from top to bottom. It is common near outside corners, at offsets in the wall, and partway along long uninterrupted walls. ## Why does brick crack vertically? ### Brick grows and does not shrink back Fired clay brick absorbs moisture from the air and expands permanently; most of that growth happens in the first weeks after firing, with a slower rate for years [1]. Brick is the only common building material listed with this kind of irreversible moisture expansion [1]. It also expands and contracts with temperature, at about 4 millionths of an inch per inch for each degree Fahrenheit [1]. Brick industry guidance puts the total unrestrained movement of brick veneer at about 0.0009 times the wall length, combining moisture expansion (0.0005) and temperature (0.0004) [1]. Over a 25-foot section, that is roughly a quarter inch. Concrete and concrete block behave the opposite way: they shrink as they dry, so they use control joints, while brick uses expansion joints [4]. ### What happens without enough expansion joints An **expansion joint** is a deliberate vertical gap filled with a flexible sealant that lets brick grow without cracking. Brick industry guidance states that an expansion joint prevents cracking by dividing brick into segments, reducing the cumulative movement [2]. It calls for joints near corners, preferably within about 2 feet, at offsets and wall intersections, and spaced no more than 25 feet apart on walls without openings or about 20 feet on walls with several openings [2]. Walls expand toward their ends, which can cause distress where they meet at a corner [2]. Brickwork pushing toward a corner can crack the first head joint on one side, and offset walls can rotate and crack without a joint at the inside corner [1]. If joints are too narrow or too far apart, diagonal cracks can form between windows or doors [1]. Inspection guidance notes that vertical cracking at corners of brick veneer can be caused by thermal movement of the wall [3]. This group of causes is described under material shrinkage and thermal cracking (https://terrabrain.vercel.app/causes/material-shrinkage-and-thermal-cracking-mimic). ## When does a vertical crack point to the foundation? | Feature | Reading | |---|---| | Near a corner, first head joint from the corner | Brick expansion or thermal movement [1][3] | | Tapers, wide at top or bottom | Settlement or deflection [1] | | Nearly vertical crack where a porch, bay window or addition joins | Differential settlement at the joint [3] | | Vertical crack at a wall offset with no joint | Rotation of the offset from brick expansion [1] | Settlement and deflection cracks have a tapering shape [1]. Nearly vertical settlement cracks are described at the joints of bay windows, porches and additions [3]; see differential movement at additions (https://terrabrain.vercel.app/causes/differential-movement-at-additions). For tapered patterns, see stair-step crack wider at top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top). Cracking after ground shaking is a separate topic covered in seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement). ## How is a vertical crack documented? - **Width along the length.** Measure at the top, middle and bottom. Even width supports expansion; taper supports movement. - **Activity.** A clean crack suggests recent movement, while a dirty or previously filled crack may be inactive [3]. - **Location.** Note the distance to the nearest corner, opening or existing sealant joint. - **Floor survey.** If the crack tapers, compare with an elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys). ## Related - Material Shrinkage & Thermal Cracking (Mimic) (https://terrabrain.vercel.app/causes/material-shrinkage-and-thermal-cracking-mimic) - Differential Movement at Additions (https://terrabrain.vercel.app/causes/differential-movement-at-additions) - Earthquake Shaking Damage (https://terrabrain.vercel.app/causes/earthquake-shaking-damage) - Induced Seismicity in Oklahoma (https://terrabrain.vercel.app/guides/induced-seismicity-in-oklahoma) - Stair-Step Brick Crack Wider at Top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top) Sources: [1] Volume Changes – Analysis and Effects of Movement (Technical Note 18), Brick Industry Association https://gobrick.com:443/media/file/18-tn18.pdf [2] Accommodating Expansion of Brickwork (Technical Note 18A), Brick Industry Association https://www.gobrick.com/media/file/18a-tn18a.pdf [3] Inspecting Foundation Walls and Piers, International Association of Certified Home Inspectors (InterNACHI) https://www.nachi.org/documents2012/Inspecting_Foundation_Walls_and_Piers-revised-January-2013.pdf [4] Movement Joints in Masonry, Masonry Advisory Council https://masonryadvisorycouncil.org/wp-content/uploads/2019/03/Movement-Joints-in-Masonry-March-2019.pdf --- # Is it earthquake damage or soil movement in my Oklahoma home? URL: https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement Answer: Earthquake damage appears at a set moment tied to a recorded event; expansive clay damage builds over months or years and changes with the seasons. In short: Earthquake damage appears at a specific moment, tied to a recorded event with enough shaking at the address. Expansive clay damage builds over months or years, changes with the seasons and matches the shape the foundation has been bent into. Comparing the earthquake record, the shaking intensity and an elevation survey of the house is the usual way to separate the two. ## Why does this question come up in Oklahoma? Oklahoma has had far more earthquakes since 2009 than before [1], and much of the state has expansive clay soil that moves with moisture [6]. Both can crack drywall, brick and slabs, so homeowners and insurers often need to know which one did it. Background on the earthquakes is on the induced seismicity (https://terrabrain.vercel.app/guides/induced-seismicity-in-oklahoma) page. ## What does each cause tend to look like? | Evidence | Points toward an earthquake | Points toward soil movement | |---|---|---| | Timing | Damage first noticed right after an event listed in the earthquake catalog [3] | Builds gradually; changes with seasonal or short-term moisture swings [6] | | Shaking at the address | Intensity reports show meaningful shaking (around MMI VI or more for minor damage) [1][2] | Little or no shaking reported nearby | | Progression | Damage tied to one event | Progresses from cracks to sticking doors and sloping floors [5] | | Shape of the house | Damage not explained by floor elevations | Elevations show a center-lift or edge-lift shape [5][6] | | Neighborhood | Similar damage reported over a wide area after the same event [2] | Linked to drainage, leaking pipes, trees or irrigation [6] | ### Shaking intensity Intensity, measured on the Modified Mercalli (MMI) scale, describes how strongly shaking was felt at a location. The Oklahoma Geological Survey describes MMI VI as minor damage such as falling plaster and a few cracks; MMI VII, reached in the 2011 Prague earthquake, involves more significant damage [1][7]. Central U.S. earthquakes are felt over areas more than ten times larger than similar West Coast quakes, so a distant event can still be felt [4]. ### Soil movement patterns Uneven moisture under a slab bends it into a center-lift or edge-lift shape [5]. Center lift is associated with long-term moisture gain, while edge lift and edge drop come from seasonal or short-term changes [6]. Common causes include poor drainage, leaking pipes, trees, irrigation and wet or dry periods [6]. See heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) and cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally). ## What are the typical documentation steps? 1. **Pull the earthquake record.** The OGS catalog lists date, location and magnitude for Oklahoma events [3]; Did You Feel It? maps reported shaking [2]. 2. **Establish when damage was first seen.** Dated photos help place it before or after a specific quake. 3. **Survey floor elevations** and map cracks against them; see elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) and the distress pattern library (https://terrabrain.vercel.app/guides/distress-pattern-library). 4. **Record soil, drainage, trees and past repairs**, the common drivers of moisture-related movement [6]. The OGS has noted that the 2016 USGS hazard report does not address cumulative damage from multiple small-to-moderate earthquakes over time [1], so the effect of repeated small quakes on a specific house is not captured by that assessment. For how engineers use field documentation, see working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). ## Related - Earthquake Shaking Damage (https://terrabrain.vercel.app/causes/earthquake-shaking-damage) - Fresh, Clean-Edged Cracks Appearing Suddenly (https://terrabrain.vercel.app/signs/fresh-clean-edged-cracks-appearing-suddenly) - Insurance Claims (https://terrabrain.vercel.app/rules/insurance-claims) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - OK Data - Earthquakes Claims and Law (https://terrabrain.vercel.app/data/earthquakes-claims-and-law) Sources: [1] Statement on USGS Hazard Assessment for Sites with Induced Seismicity, Oklahoma Geological Survey https://www.ou.edu/content/dam/ogs/documents/statements/OGS_Statement_USGS_Hazard_Assessment_2016-03-28.pdf [2] Did You Feel It? (DYFI), U.S. Geological Survey https://earthquake.usgs.gov/data/dyfi/ [3] Earthquake Catalogs, Oklahoma Geological Survey https://www.ou.edu/ogs/research/earthquakes/catalogs.html [4] Fact Sheet: Pawnee Earthquake, September 3, 2016, Oklahoma Geological Survey https://www.ou.edu/content/dam/ogs/documents/statements/OGS-Fact_Sheet_Pawnee_Earthquake_2016-09-03.pdf [5] Residential House Foundations on Expansive Soils in Changing Climates, HUD Office of Policy Development and Research (Cityscape, Vol. 25 No. 1) https://www.huduser.gov/PORTAL/periodicals/cityscape/vol25num1/ch10.pdf [6] Expansive Soils (The Mystery), STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [7] Information (Top Ten Oklahoma Earthquakes), Oklahoma Geological Survey https://www.ou.edu/ogs/research/earthquakes/Information.html --- # Should I remove a tree near my foundation in Oklahoma? URL: https://terrabrain.vercel.app/repairs/tree-management Answer: Trees dry clay under foundations and can cause settling, but removing a large tree on expansive clay can let soil rewet and swell for years afterward. In short: Trees pull large amounts of water from clay soil, and when that drying reaches under a foundation the clay shrinks and the foundation can settle [3][5]. Tree management — pruning to reduce water use, removal, or replacing a tree with a smaller one — is one way to address this, but removing a large tree on expansive clay can let the soil rewet and swell for years afterward [1][4]. ## How do trees affect clay under a house? Trees draw water from the soil to replace water lost through their leaves. In clay, that drying makes the soil shrink, and if the shrinkage reaches beneath a foundation, the foundation can subside [3]. A Texas geotechnical engineer reported that large oaks can pull more than 55 gallons a day from the subsoil in dry summers, and documented about 7 1/4 inches of ground settlement below a slab from oaks planted about 16 feet from a building [5]. Clay soils with high shrink-swell — an NRCS **linear extensibility** of 6% or more — react most strongly to this drying [7]. Shrink-swell ratings for individual Oklahoma soils are listed in the soil series index (https://terrabrain.vercel.app/soils/soil-series-index). Foundation maintenance guidance from a Texas engineering group states that trees in or near a foundation's footprint cause the majority of foundation problems requiring repair in its area, and that significant subsidence distress from newly planted trees usually appears 10 to 20 years later as the trees mature [1]. The related movement pattern is described in tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement). ## How close is too close? Published rules of thumb differ: | Source | Guidance | |---|---| | Foundation maintenance guide | Broadleaf trees no closer than a distance equal to the tree's height; for conifers, use the canopy radius [1] | | OSU Extension | Plant at least half the tree's mature width from a building; roots can extend two to three times beyond the canopy width [2] | | UK building guidance | Foundations closer to a tree need to be deeper; taller trees generally take up more water [3] | ## Which tree species use the most water? UK building guidance lists oak, poplar and eucalyptus among high-water-demand trees and notes that hardwoods have broad, spreading roots while conifers have a more local effect [3]. Arboriculture researchers have challenged published water-demand tables, arguing that differences between species come as much from rooting depth and habit as from water use [6]. Mature size is the factor both point to: more leaf area generally means more water drawn [3]. ## What are the tree management options? ### Crown reduction and pruning Reducing a tree's crown cuts its leaf area and so its water use. A foundation maintenance guide recommends a pruning program where a tree is too close, with a reasonable interval of every two to three years [1]. It also recommends removing new trees that sprout next to the foundation and cutting back shrubs that approach one-story roof height [1]. ### Removal Removal stops new drying but creates a different risk. When a tree is removed, water slowly returns to the clay, which swells and can cause **heave** — upward movement of the ground and foundation [4]. - Guidance notes that trees removed around construction tend to cause heave of expansive soils during the first few years [1]. - UK guidance says it is often difficult to know how long the ground will take to recover, and the amount of heave depends on the tree's species, maturity and water demand, the soil's permeability and how much water is available [4]. - Heave after removal is a particular issue in low-permeability soils such as clay [4]. Because of this, the heave risk is usually noted before a large tree on high-swell clay is removed. See post-tree-removal heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave). ### Replacement and placement Replacing a large tree with a smaller species planted farther away reduces future drying. A geotechnical engineer has noted that placing trees far enough from buildings is generally more economical than designing foundations to tolerate tree-related settlement, and that trees in larger open landscape areas, where rain and irrigation recharge the soil, affect a smaller zone [5]. ### Combining with other measures Tree management is often paired with root barriers and moisture control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control) and with monitoring (https://terrabrain.vercel.app/repairs/monitoring-program) of the foundation over seasons. Before any lifting, a period of observation helps show whether the soil is still drying or has begun to rewet. ## What are the limits of tree management? - Removal on clay can cause years of heave [1][4]. - Pruning must be repeated as the tree regrows [1]. - These steps do not raise a foundation that has already settled. ## Related - Trees and Roots (https://terrabrain.vercel.app/guides/trees-and-roots) - Tree-Root Desiccation Settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) - Post-Tree-Removal Heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave) - Root Barriers and Moisture Control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control) - OK Data - Trees (https://terrabrain.vercel.app/data/trees) Sources: [1] Foundation Maintenance and Inspection Guide for Residential and Other Low-Rise Buildings (FPA-SC-07-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-07-0.pdf [2] Placement of Trees, Oklahoma State University Extension https://extension.okstate.edu/programs/gardening/grow-gardening-columns/grow-columns-2021/march-28-2021-placement-of-trees.html [3] Foundations, Trees and Clay, LABC Warranty https://www.labcwarranty.co.uk/hubfs/Blog/Blog%20PDFs/LABCW%20Foundation%2c%20Trees%2c%20and%20Clay.pdf [4] Heave: ground recovery following tree removal, LABC Warranty https://www.labcwarranty.co.uk/resource-hub/heave-ground-recovery-following-tree-removal [5] Settlement of Foundations on Expansive Clays Due to Moisture Demand of Trees, CIGMAT, University of Houston https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2008/kenneth.pdf [6] A Critical Analysis of the Role of Trees in Damage to Low Rise Buildings, Journal of Arboriculture (International Society of Arboriculture) https://auf.isa-arbor.com/content/isa/21/2/90.full.pdf [7] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf --- # What affects the cost of foundation repair in Oklahoma? URL: https://terrabrain.vercel.app/guides/what-affects-foundation-repair-cost Answer: Scope drives cost: the cause of movement, foundation type, number and depth of supports, access, drainage and plumbing work, engineering, permits and follow-up. In short: The cost of foundation repair follows its scope, and scope is set by what is causing the movement, the type of foundation, how many support points are needed and how deep they must go. Access, drainage and plumbing work, engineering, permits, restoration, monitoring and warranty terms add to or change that scope. Standard homeowners policies usually exclude damage from soil movement, so insurance rarely changes who pays. ## What sets the scope of a foundation repair? Repair options for foundations on expansive clay fall into two groups [1]: - **Non-structural**: watering programs, vegetation changes, root barriers, gutters and downspouts, grading, subsurface drains and moisture barriers. - **Structural**: underpinning (adding supports under the foundation), grouting, mudjacking, crack injection and, for post-tensioned slabs, re-stressing tendons. Within underpinning, methods range from mudjacking and foam injection to spread footings, drilled piers, pressed concrete piles, steel pipe piles and helical piers [2]. Which of these fits depends on the root cause, because drainage, vegetation and soil conditions each call for different fixes [1]. See the method selection matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix). | Factor | Why it changes the scope | |---|---| | Cause of movement | Settlement, heave and leaks call for different repairs [1][2] | | Foundation type | Slabs and pier-and-beam floors are repaired differently [1] | | Repair method | Options range from pads and slab lifting to deep piers and piles [2] | | Depth to bearing soil or rock | Piers are installed until they reach resistance or firm strata [2][8] | | Drainage and plumbing | Leaks and poor drainage keep soil moisture changing [2] | | Engineering and permits | Sealed plans and permit submittals are separate steps [5][6] | | Monitoring and restoration | Finish repairs are timed to when movement stops [4] | ## Why does the cause of movement matter? - **Settlement or heave.** Settlement is the foundation sinking; heave is clay swelling and pushing it up. Piers stop settlement where they are placed, but those areas can still heave, and a slab supported only in part can both heave and settle [1]. Piers not tied into the grade beams generally cannot prevent uplift from swelling soil [2]. See heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). - **Leaks and drainage.** Leaking water or sewer lines can change soil moisture and cause movement, and continuously saturated soil is harmful to the foundation and its piers [2]. Plumbing leaks, drainage and vegetation removal may not be covered in a geotechnical report and are handled separately by the contractor or owner [3]. - **Depth of the investigation.** Evaluation guidelines describe three levels. Level A is a visual walk-through; Level B adds document review and elevation-based tilt and deflection analysis; Level C adds hydrostatic plumbing leak testing, soil sampling and groundwater monitoring under a forensic engineer [3]. ## How do foundation type and support points change the work? - **Slab on grade**: structural options include underpinning, grouting, mudjacking and crack injection [1]. - **Pier and beam**: repair can involve shimming the floor, framing repairs, added supports and crawl space moisture control [1]. - **Interior support points**: in Oklahoma installation records, piers pushed at the interior slab stopped at about 8 to 11 feet and 4,000 to 5,000 psi, while piers at the perimeter footing reached about 13 to 17 feet and 7,000 to 8,000 psi [8]. How crews reach soil under the floor is covered in interior piers (https://terrabrain.vercel.app/repairs/interior-piers-tunnel-or-core). ## Why does depth to bearing soil or rock matter? A bearing stratum is a layer of soil or rock firm enough to carry the load. Piers are built to a bearing stratum where possible, and the depth needed is often governed by uplift from swelling clay in the **active zone** (the upper soil layer whose moisture changes with the seasons) plus enough embedment below it to resist that uplift [1]. Steel pipe piles are pressed until they meet resistance or reach load-capable strata, and helical piers are screwed in to a specified torque [2]. The final depth is therefore found during installation. Oklahoma steel push pier records show typical exterior depths of 8 to 16 feet; across 396 logged piers on one Tulsa site, the median was 12 feet, the middle half fell between 9 and 14 feet, and the full range was 2 to 40 feet [8]. ## What other work can be part of the job? - **Engineering.** Under Oklahoma's engineering board guidelines, a professional engineer visits the site or directs a technician, then issues a signed, sealed and dated repair plan or a sealed statement that no pier repair is needed; the repair company carries out that plan [5]. See working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). - **Permits.** In Tulsa, repair permits are applied for in person, and construction plans are required when damage is extensive or structural, as decided by the plans examiner [6]. See codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits). - **Drainage.** Stormwater is directed away from the foundation [2]; gutters, grading and subsurface drains are the usual non-structural measures [1]. - **Plumbing.** After any lifting or lowering, plumbing is tested for leaks and any leaks are repaired [1]. - **Restoration.** Cracks and finishes are repaired after movement; in one guideline case study, cosmetic repairs followed about two years of continued movement after trees were removed [3]. - **Monitoring.** Monitoring guidelines call for at least three elevation surveys over at least one year, ideally every three months, with the first and last in the same season [4]. A baseline elevation survey after repair gives a reference for later comparison [1]. See monitoring program (https://terrabrain.vercel.app/repairs/monitoring-program). ## How do warranty terms and insurance fit in? - **Warranty.** Foundation performance after repair is judged against the standard written into the contract or warranty [1]. Repair-performance guidance notes that heave alone is not usually considered a pier failure, and that movement can continue after repair if soil moisture keeps changing [2]. What a warranty covers, excludes and whether it transfers to a buyer are set by its written terms; see contracts, warranties and liens (https://terrabrain.vercel.app/rules/contracts-warranties-liens). - **Insurance.** The standard homeowners form excludes earth movement regardless of whether nature or another cause triggered it, and an insurance coverage analysis found no coverage for a foundation wall cracked by drought-driven soil movement [7]. See insurance claims (https://terrabrain.vercel.app/rules/insurance-claims). ## Related - How to choose a foundation repair contractor in Oklahoma (https://terrabrain.vercel.app/rules/how-to-choose-a-foundation-repair-contractor-in-oklahoma) - Working with Engineers (https://terrabrain.vercel.app/guides/working-with-engineers) - Method Selection Matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Contracts Warranties Liens (https://terrabrain.vercel.app/rules/contracts-warranties-liens) - Insurance Claims (https://terrabrain.vercel.app/rules/insurance-claims) Sources: [1] Beyond the Building Code: Expansive Soils, Journal of the National Academy of Forensic Engineers https://journal.nafe.org/ojs/index.php/nafe/article/download/975/924/4846 [2] Post Foundation Repair Performance of Residential and Other Low-Rise Buildings on Expansive Soils (FPA-RC-01-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-RC-01-0.pdf [3] Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings (FPA-SC-13-1), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-13-1.pdf [4] Guidelines for Evaluating Foundation Performance by Monitoring (FPA-SC-12-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-12-0.pdf [5] The Board's Bulletin, Vol. 21, Issue 4 (2007): Compliance Guidelines for Foundation Repair Companies, Oklahoma State Board of Licensure for Professional Engineers and Land Surveyors https://oklahoma.gov/content/dam/ok/en/pes/documents/bulletin/Newsletter_Volume21_Issue62.pdf [6] Residential Building Permit Process, City of Tulsa Development Services https://www.cityoftulsa.org/media/10918/residential2019.pdf [7] Drought and Cracked Foundation, PropertyCasualty360 (FC&S) https://propertycasualty360.com/fcs/2012/12/10/drought-and-cracked-foundation [8] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # What are loess and collapsible soils in western Oklahoma? URL: https://terrabrain.vercel.app/guides/collapsible-and-loess-soils Answer: Loess is wind-deposited silt, found mainly on Oklahoma Panhandle tablelands. Loose, dry wind-laid soils can collapse when wetted, the reverse of swelling clay. In short: Loess is wind-deposited silt, and in Oklahoma it is mainly found on the Panhandle's high tablelands, where the Richfield soil formed in loess 3 to more than 10 feet thick [1]. Loose, dry wind-laid soils are associated with collapse on wetting. That is the reverse of expansive clay, which swells when wet [4]. In both cases water is the trigger, so water sources matter. ## What are loess and eolian soils? **Loess** is silt that wind picked up and dropped in sheets across the landscape. **Eolian** simply means wind-deposited, and covers sandy deposits as well as silt. Oklahoma examples from USDA official soil descriptions: | Soil series | Parent material | Setting | |---|---|---| | Richfield | Calcareous loess, 1 to more than 3 meters (3 to 10+ ft) thick [1] | Nearly flat tablelands at 2,600 to 4,600 ft; 13 to 22 inches of rain a year; includes the Oklahoma Panhandle [1] | | Dalhart | Loamy wind-deposited sediments [3] | Sand sheets and interdunes on Southern High Plains tablelands; type location in Cimarron County; 15 to 23 inches of rain a year [3] | | Ulysses | Loess [2] | Central High Tableland; Oklahoma was removed from the series' range in 2016 [2] | Richfield's subsoil is a silty clay loam or silty clay with 35 to 42 percent clay and a smectitic mineral class [1], so a loess soil can also contain swelling clay in its subsoil. See the Richfield soil (https://terrabrain.vercel.app/soils/richfield) page for details. ## How does collapse differ from swell? A **collapsible soil** is a loose, low-density soil that holds its shape while dry but loses volume when water soaks in under the weight of a building. The result is settlement, often sudden and concentrated where water entered. The mechanism is described on the hydrocollapse (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil) page. Expansive clay does the opposite: clay minerals such as montmorillonite swell substantially when wet [4], and Oklahoma's Permian clay soils owe their shrink-swell to water absorbed between the layers of 2:1 clays [6]. Over 75% of Oklahoma contains bedrock units that can serve as sources for expansive soils [4], so most of the state deals with swelling clay, while collapse is a narrower concern tied to particular soils. | | Expansive clay | Collapsible soil | |---|---|---| | Trigger | Water | Water | | Movement | Swells (rises), then shrinks when dry | Loses volume (drops) | | Where it comes from in Oklahoma | Clay soils weathered from bedrock, over most of the state [4] | Loose wind-deposited soils; in Oklahoma, wind-deposited soils occur on the Panhandle tablelands [1][3] | ## Which water sources matter? Because wetting triggers collapse, the source of water matters: plumbing leaks, roof runoff, irrigation and poor grading. A simple supply-leak check is to read the water meter, use no water for two hours, and read it again; any change probably means a leak [5]. See plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) and surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). ## How are collapsible soils repaired? Repair options on collapsible ground are compared on the method selection matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix). They include piers taken through the loose layer to firmer support, such as steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) or helical piers (https://terrabrain.vercel.app/repairs/helical-piers), void and compaction grouting in some cases, and drainage control. ## Related - Ogallala Formation and loess (https://terrabrain.vercel.app/geology/ogallala-formation-and-loess) - Panhandle (High Plains) region (https://terrabrain.vercel.app/regions/panhandle-high-plains) - Hydrocollapse (collapsible soil) (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil) - Oklahoma geologic provinces (https://terrabrain.vercel.app/guides/oklahoma-geologic-provinces) - Clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) Sources: [1] Official Series Description - RICHFIELD Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/R/RICHFIELD.html [2] Official Series Description - ULYSSES Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/U/ULYSSES.html [3] Official Series Description - DALHART Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DALHART.html [4] Geologic Hazards in Oklahoma, Geological Society of America (abstract by K. V. Luza, Oklahoma Geological Survey) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [5] Checking Your Water Meter for Leaks, U.S. Environmental Protection Agency, WaterSense (January 2017 archive) https://19january2017snapshot.epa.gov/www3/watersense/our_water/howto.html [6] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf --- # What are Oklahoma's pier and anchor rules for manufactured homes? URL: https://terrabrain.vercel.app/data/manufactured-homes Answer: New homes follow the federal standard or maker's instructions. Used homes need block footings, piers no more than 6 feet apart, limited shims and anchor ties. In short: New manufactured homes in Oklahoma must be installed to the federal HUD installation standard or the manufacturer's approved instructions by a state-licensed installer. Previously occupied (used) homes follow Oklahoma's own rules: block footings, frame piers no more than 6 feet apart, limited shims, and diagonal anchor ties. These supports sit near the surface, where Oklahoma clay swells and shrinks the most. ## Who sets the installation rules? Manufactured home installation in Oklahoma falls under Title 765, Chapter 37 of the Oklahoma Administrative Code, administered by the Oklahoma Used Motor Vehicle, Dismantler, and Manufactured Housing Commission [1]. - **New homes:** installation, including site preparation, must follow HUD's Manufactured Home Model Installation Standards (24 CFR Part 3285) or the manufacturer's approved installation instructions [1]. - **Licensed installers:** using an installer not licensed by the Commission at the time of installation is an unacceptable procedure, and a dealer who hires one may face penalties [1]. - **Frost line:** for permanent installations, the installer determines the frost line from the manufacturer's instructions or the local building authority [1]. See freeze-thaw and frost depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth). - **Storage:** a new home held more than 30 days by a retailer, installer or manufacturer must be temporarily supported per the manufacturer's instructions [1]. For how these homes are built and supported, see manufactured homes on piers (https://terrabrain.vercel.app/foundations/manufactured-homes-on-piers). ## What are the support rules for used homes (OAC 765:37-7-3)? ### Footings A footing is the pad that spreads a pier's load onto the soil. | Item | Requirement | |---|---| | Footing options | Three 4x8x16 solid concrete blocks, or one solid 4x16x16 block [2] | | Minimum footing area | 384 square inches [2] | | Minimum tested capacity | 6,000 pounds load-bearing per footing [2] | | Assumed soil bearing | At least 1,500 psf unless site conditions call for less [2] | | Soil under footing | Organic material removed; firm undisturbed soil or fill compacted to at least 90% [2] | If site conditions suggest a lower bearing value, the rule says to consult a professional engineer, registered architect or licensed geologist, and soil testing such as penetrometer readings can change the assumed value [2]. Soil bearing and plasticity are explained in soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values). ### Piers | Pier location and height | Allowed construction | |---|---| | Frame piers under 36 in | Single 8x8x16 blocks, or rated steel piers up to 36 in [2] | | Frame piers 36 to 67 in, and corner piers over three blocks | Double interlocked blocks [2] | | Mate-line, perimeter and opening piers up to 54 in | Single blocks [2] | | Mate-line, perimeter and opening piers over 54 to 67 in | Double interlocked blocks [2] | ### Spacing, clearance and shims - Piers under each main frame beam: no more than 6 feet on center [2]. - Where an open span exceeds 10 feet, intermediate piers no more than 10 feet on center [2]. - End piers: centered no more than 2 feet from the frame ends [2]. - Clearance: at least 12 inches between the lowest frame member and the ground [2]. - Shims: nominal 4x6x1 shims used in pairs, driven tight, taking up no more than one inch of height [2]. ## What are the anchoring rules for used homes (OAC 765:37-7-4)? Anchors and ties hold the home down and resist sideways movement in wind. - Diagonal ties: spaced no more than 11 feet apart on a side; an individual spacing may exceed that by 10% as long as the average stays within 11 feet [3]. - End ties: the diagonal tie nearest each end must be within 2 feet of that end [3]. - Anchor strength: a minimum total load of 4,725 pounds and a working capacity of 3,150 pounds [3]. - Lateral stability: anchors are installed per the manufacturer, which may include stabilizer plates or poured concrete collars 10 inches across and 18 inches deep [3]. ## Why do surface piers move on Oklahoma clay? The rules above place block footings on firm undisturbed soil or compacted fill after organic material is removed [2]. Where that soil is expansive clay, it swells when wet and shrinks when dry. An Oklahoma State University study of soil suction across the state found that the depth affected by seasonal moisture change (the active zone) is roughly 0.5 to 4 meters, and that shallower soil is the most sensitive to climate [4]. Because piers rest in that zone, the home can move as the soil does: - **Uneven heave and settlement:** perimeter piers near drip lines and downspouts can rise or drop differently from interior frame piers. See heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). - **Drainage:** water pooling under a skirted home wets the clay under the footings. See surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). - **Shim limits:** shims may take up no more than one inch of height [2], which limits how much releveling shims alone can do. The shrink-swell and active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) guide explains why moisture changes are greatest near the surface. ## Related - Manufactured homes on piers (https://terrabrain.vercel.app/foundations/manufactured-homes-on-piers) - Shrink-swell and active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Freeze-thaw and frost depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) - Codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits) Sources: [1] Okla. Admin. Code 765:37-7-1, Acceptable procedure, Justia Regulations (Oklahoma Administrative Code) https://regulations.justia.com/states/oklahoma/title-765/chapter-37/subchapter-7/section-765-37-7-1 [2] Okla. Admin. Code 765:37-7-3, Support Systems, Cornell Law School Legal Information Institute https://www.law.cornell.edu/regulations/oklahoma/OAC-765-37-7-3 [3] Okla. Admin. Code 765:37-7-4, Anchoring for previously occupied manufactured homes, Justia Regulations (Oklahoma Administrative Code) https://regulations.justia.com/states/oklahoma/title-765/chapter-37/subchapter-7/section-765-37-7-4 [4] Soil matric suction and active zone depth in Oklahoma, Oklahoma State University (SHAREOK repository) https://shareok.org/handle/11244/54639 --- # What are stem wall and grade beam foundations? URL: https://terrabrain.vercel.app/foundations/stem-wall-and-grade-beam Answer: A stem wall is a short wall on a continuous footing. A grade beam spans drilled piers set below swelling clay, with a gap under it so clay cannot lift it. In short: A stem wall foundation is a short wall built on a continuous footing, used under crawl spaces, on sloped lots and around some slabs. A grade beam foundation is a concrete beam spanning between drilled piers that reach below the clay that swells and shrinks, with a gap under the beam so the clay cannot lift it. Both can move in Oklahoma clay, but for different reasons. ## What is a stem wall on a footing? A **footing** is the wide concrete base that spreads the house's weight onto the soil. A **stem wall** is the vertical wall of concrete or masonry that rises from it. - **Footing size:** code minimum 12 in wide and 6 in thick, with larger sizes from the code tables for heavier loads [1]. - **Footing depth:** at least 12 in below the ground surface, and below the frost line where frost applies [1]. - **Sloped lots:** footing bottoms may slope up to 10%; steeper ground requires stepped footings with level tops [1]. - **Reinforcement where the code's seismic provisions apply:** vertical No. 4 bars at no more than 4 ft, hooked into the footing and extending at least 14 in into the wall, plus a horizontal No. 4 bar within 12 in of the top [2]. - **Oklahoma additions:** the state's 2024 code adoption adds two No. 4 bars to all footings and requires cold joints between footing and stem wall to be tied with No. 4 bars at each corner, no more than 6 ft apart, with 12 in of embedment [3]. - **Anchor bolts:** at least 1/2 in diameter, no more than 6 ft apart and embedded at least 7 in, tying the wood sill to the wall [4]. A **cold joint** is the seam where concrete poured on one day meets concrete poured later, such as a stem wall cast on a footing that has already set. ## What is a grade beam on drilled piers? A **drilled pier** is a concrete column cast in an augered hole. A **grade beam** is a reinforced concrete beam that spans from pier to pier at the ground surface and carries the walls. Engineering guidance for swelling soils describes this system as the general choice for moderately to highly swelling soils [5]: - Piers extend well below the zone of seasonal moisture change [5]. - Piers are anchored in non-swelling soil to resist uplift, by belled bottoms, grooved holes or extra depth [5]. - A gap of 3 to 6 in is left between the soil and the grade beam so swelling soil cannot push up on it [5]. Cardboard void forms that hold this space during the pour are commonly called void boxes. Drilled piers have been used for houses on expansive soil in California, Colorado and Texas since the late 1950s [7]. Seasonal moisture change can extend from 3 to 40 ft deep, and the upper part of a pier can lose contact with the soil as clay shrinks [7]. ## How do these foundations fail? | Problem | What happens | Source | |---|---|---| | Void space missing or too small | Swelling clay pushes directly on the grade beam | [6] | | Piers too short or wrong diameter | Pier rides up and down with the clay | [6][7] | | Mushroom-topped piers | Listed as a construction defect behind swelling-soil damage | [6] | | Corner piers lifting | Wet-season swell lifts corners; dry-season shrink can let them drop | [7] | | Long drought then a wet year | Six-foot piers that handle normal years can fail | [7] | | Stem wall on shallow footing | Footing moves with the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) like any shallow foundation | [7] | When piers move after construction or repair, the mechanism is covered in pier uplift or movement after repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair). Underpinning brackets bear on the stem wall or grade beam itself; spacing and load questions are covered in loads, pier spacing and capacity (https://terrabrain.vercel.app/guides/loads-pier-spacing-and-capacity). ## How are these foundations repaired? - Deeper or belled supports: drilled bell-bottom piers (https://terrabrain.vercel.app/repairs/drilled-bell-bottom-piers) - Steel underpinning on the stem wall: steel push piers or helical piers - Moisture control around the perimeter: drainage and root barriers - Mixed foundations where an addition meets the original house: additions and mixed foundations (https://terrabrain.vercel.app/guides/additions-and-mixed-foundations) ## Related - Drilled Bell-Bottom Piers (https://terrabrain.vercel.app/repairs/drilled-bell-bottom-piers) - Pier and Beam Crawl Space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) - Pier Uplift or Movement After Repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair) - Loads Pier Spacing and Capacity (https://terrabrain.vercel.app/guides/loads-pier-spacing-and-capacity) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) Sources: [1] Inspecting Footings: The Unsung Heroes Beneath a House (IRC R403), InterNACHI https://www.nachi.org/foundation-footings.htm [2] Steel Bones: Inspecting the Critical Role of Rebar in Foundation Strength (IRC R403.1-R403.1.6), InterNACHI https://www.nachi.org/footing-stem-wall-reinforcement-rebar.htm [3] Adoption of International Residential Code 2024 (IRC 2024), Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2024%20IRC%20Code%20Changes%20Summary%20-%20for%20website.pdf [4] Securing the Perimeter: Inspecting Foundation Anchor Bolts and Sill Plate Protocols (IRC R403.1.6), InterNACHI https://www.nachi.org/foundation-anchor-bolts-sill-plate.htm [5] Home Construction on Shrinking and Swelling Soils (Special Publication 11), Colorado Geological Survey (Holtz and Hart, 1978) https://coloradogeologicalsurvey.org/wp-content/uploads/woocommerce_uploads/SP-11.pdf [6] Expansive Soil, Colorado Geological Survey https://coloradogeologicalsurvey.org/hazards/expansive-soil/ [7] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf --- # What bedrock is under Oklahoma City homes? URL: https://terrabrain.vercel.app/guides/bedrock-okc-metro Answer: Mainly Permian red-bed Hennessey shale and Garber sandstone; the clay soils formed from these rocks, not the rock itself, cause most shrink-swell movement. In short: The Oklahoma City metro sits on Permian "red beds": mainly the Hennessey shale and the Garber sandstone [1][3]. Where Hennessey shale is near the surface, public borings found rock within a few feet to about 16 feet [2]; on Garber sandstone at a north Edmond site, soil extended 20 to more than 90 feet down [3]. The clay soils formed from these rocks, not the rock itself, cause most shrink-swell movement [1][4]. ## What are the main rock units? | Unit | What it is | Example site | |---|---|---| | **Hennessey Group** | Red-brown shale interbedded with siltstone, with some greenish-gray shale, sandstone beds and gypsum lenses [1] | Lake Hefner area (northwest OKC) [1]; I-35/I-240 interchange [2] | | **Garber Sandstone** | Red, massive, cross-bedded sandstones in lens shapes, with red clay shales and sandy shales [3] | I-35 over Waterloo Road, north Edmond [3] | | **Alluvium** | River-laid sand, silt and clay over rock | Covers Hennessey shale at the I-35/I-240 site [2] | The Hennessey is about 90 meters (roughly 300 feet) thick in the USGS study area, and its near-surface layers in western Oklahoma County dip gently west-southwest toward the Anadarko Basin [1]. An ODOT geotechnical report describes the Hennessey unit as red, platy to blocky clay shales and mudstones about 400 feet thick [2]. See the geology pages for the Hennessey shale (https://terrabrain.vercel.app/geology/hennessey-shale-group) and Garber sandstone (https://terrabrain.vercel.app/geology/garber-sandstone). ## How deep is rock? **On Hennessey shale (I-35/I-240):** soil of lean clay, silt and sand extended about 2 to 16 feet, and bedrock was reached at 16, 5.5, 2, 2 and 2 feet in five borings [2]. The report notes that shale weathering is erratic and can change over short distances [2]. **On Garber sandstone (I-35 at Waterloo Road):** soil of sand and moderate- to high-plasticity clay extended about 20 to 91.5 feet [3]. Competent rock was found at depths from 20.5 to 95 feet across eight borings [3]. | Setting | Depth to rock in public borings | |---|---| | Hennessey shale, south OKC | about 2 to 16 ft [2] | | Garber sandstone, north Edmond | about 20 to 95 ft [3] | These are highway sites, so they show the range rather than the depth under any particular house. More boring data: depth to rock in Tulsa and OKC (https://terrabrain.vercel.app/data/borings-depth-to-rock-in-tulsa-and-okc). ## Where do groundwater and perched water occur? At the Hennessey site, most borings were dry, but lab tests showed high saturation in some soil as shallow as 3 feet, and the report warns of perched water in the soil or at the soil-rock contact that changes with the seasons [2]. At the Garber site, water levels after drilling ranged from about 15 to 35 feet [3]. **Perched water** is water held up on top of a tight layer, above the main water table. See groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water). ## How does the rock differ from the soil on top? The Hennessey shale in a USGS core taken below the soil was mostly illite and kaolinite, clay minerals with low shrink-swell potential [1]. The soils that form on Permian shales tell a different story. An Oklahoma State University study of central and western Oklahoma soils found high proportions of 2:1 swelling clays, with Bethany and Kirkland soils reaching shrink-swell (COLE) values of 0.095 and 0.090; Kirkland's fine clay was mainly montmorillonite [4]. Statewide, more than 75% of Oklahoma contains bedrock units that can serve as sources for expansive soils [5]. This is why the weathered soil zone, not the rock, drives most shrink-swell movement (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). ## What does it mean for foundations? - Shallow Hennessey rock usually means shorter piers, but rock depth can change sharply between neighboring borings [2]. - On thick soil over Garber sandstone, competent rock at the boring site (20.5 to 95 feet) [3] lay well below the 8 to 16 foot depths typical of Oklahoma push pier installation records [6], so piers there may stop in dense soil rather than on rock. - At the I-35/I-240 site, alluvium lies over the Hennessey shale [2]. ## Related - Soil series in the OKC metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) - OKC metro region (https://terrabrain.vercel.app/regions/okc-metro) - Oklahoma geologic provinces (https://terrabrain.vercel.app/guides/oklahoma-geologic-provinces) - Shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata) - Western Permian red beds (https://terrabrain.vercel.app/geology/western-permian-red-beds) Sources: [1] Geologic and Hydraulic Characteristics of Selected Shaly Geologic Units in Oklahoma (Water-Resources Investigations Report 96-4303), U.S. Geological Survey, with the Oklahoma Geological Survey https://pubs.usgs.gov/wri/1996/4303/report.pdf [2] Report of Geotechnical Engineering Services, Proposed Retaining Wall C2, Crossroads Interchange Reconstruction, I-35/I-240, Oklahoma Department of Transportation https://oklahoma.gov/content/dam/ok/en/odot/business-center/upcoming-major-projects/2026/september/0903206/geotech-reports/0903206%20Geotech%20Retaining%20Wall%20C2,%20Crossroads%20Interchange%20Reconstruction%20I-35%20-%20I-240.pdf [3] Geotechnical Engineering Report: Three Span Bridge, Interstate 35 over Waterloo Road, Oklahoma Department of Transportation https://oklahoma.gov/content/dam/ok/en/odot/business-center/upcoming-major-projects/2026/january/2984304/geotech-reports/Terracon%20Project%20No.%2003205039%20-%20Three%20Span%20Bridge%20-%20I-35%20over%20Waterloo%20Rd%20-%20REVISED.pdf [4] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [5] Geologic Hazards in Oklahoma, Geological Society of America (abstract by K. V. Luza, Oklahoma Geological Survey) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [6] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # What bedrock is under Tulsa, Oklahoma homes and how deep is it? URL: https://terrabrain.vercel.app/guides/bedrock-tulsa-metro Answer: Mostly Pennsylvanian shale with sandstone and limestone; upland borings usually hit rock within 4 to 20 feet, river banks have 18 to 35 feet of sediment. In short: Tulsa sits on layered Pennsylvanian-age rock, mostly gray shale with sandstone and thin limestone [1][2][4]. On upland shale, public borings usually reach rock within about 4 to 20 feet [2][3][4], while river corridors have 18 to 35 feet of sand and clay on the banks [1]. Tulsa steel push piers stop at a median of about 12 feet [5]. ## What rock layers are under Tulsa? Engineering reports across the metro describe the same basic pattern: clay soil over shale, with sandstone and limestone layers mixed in. | Unit named in reports | Description | Example location | |---|---|---| | **Nowata** | Clay shales and sandy shales, minor lens-shaped sandstone, a few limestones usually under 1 foot thick; about 60 ft thick near Kansas, thickening to about 200 ft near Broken Arrow [2] | 91st St S, Memorial to Mingo [2] | | **Holdenville** | Mainly shale with minor sandstone, siltstone and limestone, about 50 to 180 ft thick [4] | I-44/US-75 interchange [4] | | **Nellie Bly, Wewoka, Senora** | Predominantly gray, thinly bedded shale, weathered and fractured in zones [1] | Arkansas River corridor [1] | | Unnamed shale and limestone | Dark gray to gray shale and limestone, extremely weak to strong [3] | East Tulsa, Spunky Creek [3] | Formation names change across the metro, so the map for a specific quadrangle is the reference for any one address. See Pennsylvanian shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales) and Pennsylvanian sandstones (https://terrabrain.vercel.app/geology/pennsylvanian-sandstones). ## How deep is rock in public borings? | Setting | Finding | |---|---| | East Tulsa shale and limestone | Weathered rock at 1 to 8 ft; competent rock at 4 to 14.5 ft in nine borings [3] | | South Tulsa, 91st St (Nowata) | Weathered shale at about 13.5 ft along one wall; lean clay with no shale found along the other [2] | | I-44/US-75 (Holdenville) | Competent rock at about 13.5 to 19.5 ft [4] | | Arkansas River channel | Rock about 5 to 10 ft down [1] | | Arkansas River banks | 18 to 35 ft of alluvium over shale [1] | At I-44/US-75, one boring hit a well-cemented sandstone layer near the surface with a significant thickness of sandy lean clay beneath it, and the report said it should not be considered competent rock [4]. A hard layer near the surface is not always the bottom. ## What is under Tulsa's river corridors? **Alluvium** is sediment laid down by rivers. Along the Arkansas River it is mostly poorly graded sand to silty sand with infrequent clay seams and low gravel content, very loose to loose, with clay layers that are very soft to soft [1]. Groundwater on the banks is presumed to be near the river level [1]. See Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces). ## What clay sits on top of the rock? The soil over Tulsa shale can be highly plastic. Lab tests on the 91st Street walls found fat clay with plasticity indices up to about 39 [2], and east Tulsa samples ranged from 23 to 34 [3]. **Plasticity index** is a lab measure of how much water a clay can take on while staying moldable; building codes treat a value of 15 or more as one sign of expansive soil [7] (see soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values)). Statewide, more than 75% of Oklahoma contains bedrock units that can serve as sources for expansive soils [6]. ## How does water behave on the shale? Five of nine east Tulsa borings recorded water at some point, at depths from 3.5 to 18.5 feet, with end-of-drilling readings of 7 to 9.5 feet; the others were dry [3]. The 91st Street report found water at 13.5 to 15 feet along one wall and dry borings along the other [2]. Water held on top of tight rock or clay is called **perched water**. See groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water). ## How deep do Tulsa piers go? On one large Tulsa site, 396 logged steel push piers refused at a median of 12 feet, with the middle half between 9 and 14 feet and a range of 2 to 40 feet, at a median pressure of about 9,000 psi [5]. Depth varied by building: one phase had a median of 15 feet, another 10 feet, and one building ran 17 to 40 feet [5]. A single building's depths are not a reliable guide for an entire site. ## Related - Soil series in the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) - Tulsa metro region (https://terrabrain.vercel.app/regions/tulsa-metro) - Depth to rock in Tulsa and OKC (https://terrabrain.vercel.app/data/borings-depth-to-rock-in-tulsa-and-okc) - Shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata) - Steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) Sources: [1] Existing Geotechnical Resource Review Technical Memorandum (Arkansas River Corridor Projects, Appendix Q), Tulsa County River Projects https://riverprojectstulsa.info/wp-content/uploads/2014/Appendix_Q_Final_Geotech.pdf [2] Geotechnical Engineering Report, Retaining Walls A and B Along 91st Street South from South Memorial Drive to South Mingo Road, City of Tulsa https://www.cityoftulsa.org/media/25588/geotechnical-report-retaining-walls.pdf [3] Report for Subsurface Investigation and Laboratory Testing Services, TMUA Spunky Creek MS South Phase 3, City of Tulsa / Tulsa Metropolitan Utility Authority https://www.cityoftulsa.org/media/31178/tul24r166807_tmua-spunky-creek-ms-south-phase-3-geotech-report.pdf [4] Geotechnical Engineering Report, I-44/US-75 Interchange Reconstruction, Retaining Walls RW-21 & RW-22, Oklahoma Department of Transportation https://www.odot.org/contracts/2024/24091201/geotech/CO166_24091201_GEOTECH/33788(08)%20GEO%20Report%20WP2%20Wall%20RW-21%20&%20RW-22.pdf [5] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data [6] Geologic Hazards in Oklahoma, Geological Society of America (abstract by K. V. Luza, Oklahoma Geological Survey) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [7] Seattle Residential Code 2018, Chapter 4 Foundations (IRC-based text of R403.1.8.1), City of Seattle Department of Construction and Inspections https://seattle.gov/Documents/Departments/SDCI/Codes/SeattleResidentialCode/2018SRCChapter4.pdf --- # What causes a hump in the middle of a slab floor? URL: https://terrabrain.vercel.app/signs/interior-floor-hump Answer: Usually heave: soil under the area swells and pushes the slab up, from slow moisture build-up, a plumbing leak or removal of a large tree on expansive clay. In short: A hump in an interior slab floor is usually a sign of **heave**, meaning the soil under that area has swollen and pushed the slab up, rather than settlement. On Oklahoma's expansive clays the common sources of that extra moisture are slow build-up under the slab over years, a plumbing leak, or the loss of a large tree that had been drying the soil. ## What does a floor hump look like? The floor rises toward a point or area away from the outside walls, so the perimeter sits lower than the middle. Interior doors may rub at the top, and tile or wood flooring over the high spot may crack. This sign applies to slab-on-grade (https://terrabrain.vercel.app/foundations/slab-on-grade) and post-tensioned (https://terrabrain.vercel.app/foundations/post-tensioned-slabs) houses. ## Why do slab floors hump? Expansive clay swells when it gains water and shrinks when it loses it, and most of Oklahoma has these soils [1]. Soil only moves when its moisture changes unevenly across the site, and leaking pipes, poor drainage, irrigation and trees are listed contributors [1]. Whether a floor humps or settles depends on where the soil gets wetter or drier. ### Long-term moisture build-up (center heave) A slab covers the soil and slows evaporation, so moisture can collect under the middle of the house over time. Engineers call the resulting shape **center lift**, and it is attributed to long-term moisture gain and associated with older foundations [1]. Foundation design practice requires soils reports to give movement values for both center lift and edge lift [2]. See center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab). ### Plumbing leaks Leaking utility lines are named as a water source that can wet the soil and cause foundation heave [2]. Broken water or sewer pipes add moisture that worsens swelling under nearby structures [4]. Building officials in expansive-soil areas note that a plumbing leak is one way water gets under a house and causes interior movement, not just movement at the outside walls [5]. A localized hump near a bathroom, kitchen or water heater fits this pattern; see leak-induced localized heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave) and plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab). ### Tree removal Trees draw water out of the soil. Soil near trees removed shortly before construction may be drier and subject to localized heave [2]. Removing a tree can also halt or partly reverse settlement, but it can cause heave, especially for trees that were there before the house was built [3]. See post-tree-removal heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave). ## How is it documented? - **Elevation survey.** A relative floor elevation survey, drawn as a map, is the step engineering guidance uses beyond a visual first impression [3]. A hump shows as a high zone with lower readings toward the perimeter. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). - **Short-distance caution.** Over distances under about 20 feet, built-in unevenness from original construction can dominate the readings [3]. - **Deflection check.** Guidance compares the curve of the floor to a ratio of L/360 (the span length divided by 360). Below that, damaging deflection is unlikely unless visible distress says otherwise; above it with enough symptoms, an engineer is generally justified in calling the deflection excessive [3]. - **Plumbing tests.** Where lifting is part of a repair, guidance calls for testing water supply and drain lines for leaks [3]. ## Why does the cause matter for repair? Repair guidance for expansive soils puts correcting the moisture source, such as plumbing leaks and drainage, ahead of leveling, and notes that leveling measures mainly mitigate distress [1]. Whether a floor is high in the middle or low at the edges changes which approach fits; the comparison is laid out in heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). ## Related - Center Heave (Moisture Build-up Under Slab) (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) - Leak-Induced Localized Heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave) - Over-Lift Heave After Drought Lift (https://terrabrain.vercel.app/causes/over-lift-heave-after-drought-lift) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Plumbing Leak Detection and Repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair) - Gaps Under Baseboards (https://terrabrain.vercel.app/signs/gaps-under-baseboards) Sources: [1] The Mystery of Expansive Soils, STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [2] Recommended Practice for the Design of Residential Foundations, Version 2, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Recommended-Practice-for-the-Design-of-Residential-Foundations-V2-2007.pdf [3] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [4] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [5] County Expansive Soils Policy & Procedures, Roanoke County Development Services https://roanokecountyva.gov/DocumentCenter/View/1020 --- # What causes a sudden sinkhole or depression near an Oklahoma house? URL: https://terrabrain.vercel.app/signs/sudden-depression-or-sinkhole Answer: It can be a sinkhole over dissolving gypsum or limestone, found in parts of western, northeastern and southern Oklahoma, or a washout where water removed soil. In short: A round or sudden depression in the yard or near a house can be a sinkhole over dissolving rock or a washout where flowing water has carried soil away. Parts of Oklahoma, especially the gypsum country of the west and the limestone areas of the northeast and south, have rock that dissolves, and the Oklahoma Geological Survey maps sinkholes statewide. ## What does this sign look like? A circular or bowl-shaped low spot appears in the yard, under a driveway or next to the foundation, sometimes over days and sometimes overnight. Nearby slabs may crack or drop. Any foundation type can be affected, including slab-on-grade (https://terrabrain.vercel.app/foundations/slab-on-grade), crawl space and flatwork (https://terrabrain.vercel.app/foundations/flatwork-and-exterior-slabs). ## What is a sinkhole? A sinkhole is an area of ground with no natural surface drainage, so rainwater collects in it and drains underground [1]. Sinkholes range from a few feet to hundreds of acres across [1]. They are common where groundwater can dissolve the rock below, including limestone, dolomite, gypsum and salt [1]. Ground underlain by this kind of rock is called **karst** [2]. USGS describes three basic types [1]: - **Dissolution sinkholes:** water gradually dissolves and carries away the rock until a depression forms. - **Cover-subsidence sinkholes:** sandy cover soil gradually sifts down into openings in the rock. - **Cover-collapse sinkholes:** where the cover contains significant clay, the ground can collapse abruptly, sometimes within hours. About a quarter of the United States is underlain by rock that can dissolve to form caves and sinkholes [6]. ## Where do sinkholes occur in Oklahoma? | Rock type | Main Oklahoma areas | |---|---| | Limestone and dolomite | Ozark area of the northeast; Arbuckle Mountains in the south [3] | | Gypsum and salt | Many parts of western Oklahoma [3] | Gypsum and anhydrite lie within about 30 meters of the surface across roughly 4 percent of Oklahoma, including the Permian Blaine gypsum of western Oklahoma [4]. Gypsum karst can develop fast enough, on a human time scale, to threaten highways and other structures [4]. Evaporite karst (karst in gypsum and salt) can form in days, weeks or years and can damage homes, buildings and roads [5]. See gypsum karst and sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes) and Permian gypsum units (https://terrabrain.vercel.app/geology/permian-gypsum-units-e-g-blaine). The Oklahoma Geological Survey reports that sinkholes can form slowly or within hours or days, that more were expected in the parts of the state most affected by heavy April 2025 rain, mostly small ones where water flowed under roads and driveways, and that it is mapping sinkhole locations and asking residents to report them [2]. ## What are washouts and other human causes? Not every depression is karst. Human activities linked to sinkholes include groundwater pumping, construction, and changes to natural drainage [1], as well as leaking pipes beneath roads and buildings [7]. Leaking water mains and faulty drains can erode soil around footings, and underground water scouring one side of a footing can rotate it and displace the wall above [8]. These are covered under erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). ## How is it investigated? - **Probing and drilling** locate soft zones and voids directly. - **Geophysics.** Researchers in western Oklahoma combined electrical resistivity, electromagnetic and seismic methods to map solution cavities in gypsum [4]. - **Reporting.** Sinkhole locations can be reported to the Oklahoma Geological Survey [2]. Filling options for voids under slabs are described in void and compaction grouting (https://terrabrain.vercel.app/repairs/void-and-compaction-grouting). ## Related - Karst Subsidence & Sinkholes (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes) - Gypsum Karst and Sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes) - Erosion, Undermining & Washout Voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) - Northwest (Gypsum Hills) (https://terrabrain.vercel.app/regions/northwest-gypsum-hills) - Exposed Slab Edge or Void Under Footing (https://terrabrain.vercel.app/signs/exposed-slab-edge-or-void-under-footing) Sources: [1] Sinkholes, U.S. Geological Survey, Water Science School https://www.usgs.gov/special-topics/water-science-school/science/sinkholes [2] Hazard Mapping, Oklahoma Geological Survey https://ou.edu/ogs/research/hazard_mapping [3] Mapping of Karst Terranes in Oklahoma to Identify Potential Environmental and Hydrologic Problems, AAPG Search and Discovery (Oklahoma Geological Survey author) https://www.searchanddiscovery.com/abstracts/html/1995/midcon/abstracts/1403b.htm [4] Integrated Subsurface Imaging Techniques for Detecting Cavities in Oklahoma Evaporite Karst, Geological Society of America https://gsa.confex.com/gsa/2002AM/webprogram/Paper45070.html [5] Evaporite Karst and Engineering/Environmental Problems in the United States (Circular 109), Oklahoma Geological Survey https://wipp.energy.gov/library/CRA/CRA-2019/N%20-%20S/Powers%20%202003%20%20OGS%20Circular%20109.pdf [6] How many sinkholes open up in a year?, U.S. Geological Survey https://www.usgs.gov/faqs/how-many-sinkholes-open-a-year [7] Sinkholes, American Geosciences Institute https://profession.americangeosciences.org/collections/geoscience-intersections/sinkholes/ [8] Inspecting Foundation Walls and Piers, International Association of Certified Home Inspectors (InterNACHI) https://www.nachi.org/documents2012/Inspecting_Foundation_Walls_and_Piers-revised-January-2013.pdf --- # What causes center heave in an Oklahoma slab foundation? URL: https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab Answer: Center heave happens when expansive clay under the middle of a slab gains moisture, often from a plumbing leak, swells and pushes the floor up. In short: Center heave is when the clay soil under the middle of a slab-on-grade house slowly gains moisture, swells, and pushes the center of the floor up. It is driven by expansive clay plus a water source such as a plumbing leak, and it can look almost identical to the edges of a house sinking. Elevation surveys over time and a check for leaks are how the two are told apart. ## What is center heave? A slab-on-grade foundation is a concrete floor poured directly on the ground. These slabs are flexible enough that they tend to follow the shape of the soil beneath them as it moves [1]. When the middle of the slab rises, engineers call it "center lift" or center heave, and they link it to a long-term gain in soil moisture, typically seen in older foundations [1]. The soil involved is expansive clay: clay that swells when it takes on water and shrinks when it dries. Clay soils do not move if their moisture stays constant, but in practice moisture rarely stays constant, and it is the change in moisture that causes damage [1]. ## How does center heave develop? - **The slab covers the soil.** Soil under a house is shielded from the weather, so its moisture can differ from soil that is exposed outside [2]. - **Water reaches the soil under the center.** Common sources include leaking pipes, landscape irrigation, poor drainage and groundwater [1]. Leaking water or sewage pipes add water to nearby soil and can worsen swelling damage [2]. - **The clay swells.** As the soil under the slab swells, the slab moves with it, and because the swelling is uneven the movement is differential, meaning one area rises more than another [1]. - **The house distorts.** Differential movement of a slab causes wallboard and brick cracking and skewed door and window frames [1]. This kind of movement is usually slow. It builds over years rather than a single season, unlike edge movement, which engineers tie to seasonal or temporary moisture changes [1]. ## Why are Oklahoma soils prone to center heave? A 2017 Oklahoma State University study using USDA soil survey data found that nearly all of Oklahoma has medium or high swelling potential, and that more than 75% of the state's bedrock units are possible sources of expansive soils [3]. The same study estimated the active zone in Oklahoma, the depth of soil whose moisture changes with the climate, at roughly 0.5 to 4 meters (about 1.5 to 13 feet) [3]. Earlier OSU testing of five western Oklahoma benchmark soils found their fine clays dominantly montmorillonite, a smectite clay that swells strongly when wet, with the Kirkland subsoil dominated by it and rated high in shrink-swell potential [4]. Soil surveys rate this behavior using linear extensibility, the percent change in length of a soil clod as it dries: | Shrink-swell class | Linear extensibility | |---|---| | Low | less than 3% | | Moderate | 3% to 6% | | High | 6% to 9% | | Very high | more than 9% | The USDA notes that above 3%, shrinking and swelling can damage buildings and roads and special design is commonly needed [5]. You can read more about soil types in the shrink-swell and active zone guide (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). ## What signs often go with center heave? Signs that commonly appear include: - an interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump) near the middle of the house - ceiling-wall separation at interior walls - diagonal drywall cracks at door and window openings (https://terrabrain.vercel.app/signs/diagonal-drywall-cracks-at-openings) - floor tile cracks running in a line (https://terrabrain.vercel.app/signs/floor-tile-cracks-in-a-line) - an unexplained high water bill when a supply leak is feeding the soil ## Is it center heave or edge settlement? Center heave and perimeter drying settlement can both leave a floor that is high in the middle. The difference is which part actually moved. | Question | Center heave | Edge drop | |---|---|---| | What moved? | The center rose | The perimeter fell | | Typical timing | Long-term moisture gain, often older homes [1] | Seasonal moisture loss [1] | A single elevation survey shows the foundation's shape at one moment; repeated surveys over months or years show how that shape is changing, and an original-construction survey is useful when one exists [7]. Without a baseline survey, the amount of movement cannot be determined accurately, partly because most residential slabs are built only to within about 1 inch of level [8]. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) for how this is done, and compare with perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). ## How is the water source found? The U.S. EPA describes a simple whole-house leak check: read the water meter, use no water for two hours, and read it again; a change suggests a leak [6]. The EPA also notes that a family of four using more than 12,000 gallons a month in winter probably has a leak [6]. Texas engineering guidelines call for water supply and sanitary drain lines to be tested for leaks whenever lifting is part of a foundation repair [7]. ## How is center heave typically addressed? - **Remove the water source.** Leaks found during testing are repaired [7]. - **Monitor.** The Texas ASCE guidelines note that non-structural measures followed by monitoring may be prudent before, or instead of, structural repairs [7]. - **Cosmetic repairs.** An owner may choose periodic cosmetic repairs and door adjustments rather than full underpinning [7]. - **Underpinning and lifting.** Where lifting is used, the guidelines say it is governed by field judgment and is unlikely to produce a perfectly level foundation [7]. Lifting methods such as mudjacking adjust foundation elevations [7]; they raise low areas rather than lower an area that is already high. The plumbing leak detection and repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair) and monitoring program (https://terrabrain.vercel.app/repairs/monitoring-program) pages cover these steps in more detail. ## Related - Leak-Induced Localized Heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave) - Perimeter Drying Settlement (Edge Drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Plumbing Leaks Under Slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) - Slab on Grade (https://terrabrain.vercel.app/foundations/slab-on-grade) - Interior Floor Hump (https://terrabrain.vercel.app/signs/interior-floor-hump) Sources: [1] The Mystery of Expansive Soils, STRUCTURE magazine (NCSEA / CASE / SEI) https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [2] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers et al.) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [3] Soil Matric Suction and Active Zone Depth in Oklahoma, Oklahoma State University (Er Yue, Ph.D. dissertation, 2017) https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf [4] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [5] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [6] WaterSense Challenges Homeowners: Take 10 Minutes to Find and Fix a Leak this Week, U.S. Environmental Protection Agency https://www.epa.gov/node/265001 [7] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [8] Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings (FPA-SC-13-1), Foundation Performance Association https://inspectapedia.com/structure/Foundation-Movement-Evaluation-Guidelines-FPA-TX.pdf --- # What causes common foundation symptoms in Oklahoma homes? URL: https://terrabrain.vercel.app/guides/symptom-matrix Answer: Most foundation symptoms have more than one possible cause; in Oklahoma, clay soil that shrinks and swells with moisture is widespread. In short: Most foundation symptoms can come from more than one cause, so this table starts from what you can see and points to the causes that usually produce it. In Oklahoma, much of the bedrock can weather into clay soil that shrinks and swells with moisture [4]. A single symptom is a clue, not a diagnosis [1]. ## How do you use this table? Start with the symptom you see, then read the matching sign and cause pages; for example, a stair-step crack wider at the top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top) usually leads to perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop), and an interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump) often leads to center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) or leak-induced heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave). Look for two or three symptoms that point to the same cause. Forensic engineering guidance evaluates distress together with tilt and deflection measurements to decide whether a foundation has failed [3]. Some useful background: - More than 75% of Oklahoma contains bedrock units that can be sources of expansive soils, which swell when wetted [4]. - Drought dries soil under homes, and commonly reported signs include widening cracks in brick or drywall, stair-step brick cracks, sloped floors, sticking doors or windows, trim pulling away, and a visible gap between soil and house [1]. - A single crack does not necessarily mean serious structural damage; photographing cracks over time shows whether they are growing [1]. - Home inspectors in Oklahoma must describe indicators of foundation or structural movement, but are not required to determine the cause or the repair method [2]. ## What do exterior symptoms point to? | What you see | Usually points to | Also possible | |---|---|---| | Stair-step brick crack wider at top | Perimeter drying settlement, tree-root drying, fill settlement | Soft soils, slope creep, karst | | Stair-step brick crack wider at bottom | Perimeter wetting heave, heave after tree removal | Movement after repair | | Vertical brick crack | Material shrinkage (not movement) | Earthquake shaking | | Chimney separating | Concentrated load settlement | Soft soils, earthquake | | Soil pulled away from foundation | Perimeter drying, tree-root drying | — | | Water ponding near foundation | Perimeter wetting heave | — | | Tilted retaining walls, fences or trees | Slope creep | — | | Sudden depression or sinkhole | Karst subsidence | Erosion voids | ## What do interior symptoms point to? | What you see | Usually points to | Also possible | |---|---|---| | Diagonal drywall cracks at openings | Settlement or heave of any kind | Framing problems | | Ceiling-wall separation | Center heave, truss uplift | Leak heave | | Nail pops and tape-joint cracks | Material shrinkage | Vibration (rare) | | Sloping floors | Perimeter drying, fill or soft-soil settlement | Framing failure, karst | | Interior floor hump | Center heave, leak heave | Over-lift after a drought lift | | Floor tile cracks in a line | Center heave, leak heave | — | | Bouncy or soft floors | Crawl space wood decay, framing failure | — | | Horizontal crack or bow in basement wall | Lateral earth and swell pressure | — | | Unexplained high water bill | Leak heave | Center heave | | Fresh, clean-edged cracks appearing suddenly | Earthquake shaking | Vibration (rare) | ## Why do symptom patterns matter? The location of damage relative to a water source can separate causes. In one documented claim, settlement was concentrated along the footings nearest a plumbing leak, with little or none about 5 feet away [5]. In a federal flood-insurance appeal, an engineer separated interior cracks linked to soaked soil from exterior cracks caused by long-term drying shrinkage and differential soil movement [7]. Lenders also treat some symptoms as conditions that need further inspection: federal appraisal training lists cracked masonry or foundation damage and standing water against the foundation among them [6]. ## Related - Distress pattern library (https://terrabrain.vercel.app/guides/distress-pattern-library) - Heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Inspection protocol (https://terrabrain.vercel.app/guides/inspection-protocol) - Elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) - Mechanism-method matrix (https://terrabrain.vercel.app/repairs/mechanism-method-matrix) Sources: [1] Is Oklahoma's drought damaging your foundation? Warning signs to watch for, News 9 (KWTV) https://www.news9.com/oklahoma-city-news/is-oklahomas-drought-damaging-your-foundation-warning-signs-to-watch-for [2] OAC 158:70 Home Inspector rules, 158:70-1-3 Standards of workmanship and practice, Oklahoma Construction Industries Board https://oklahoma.gov/content/dam/ok/en/cib/documents/your-industry/home-inspector/title_158_chapter_70.pdf [3] Beyond the Building Code: Expansive Soils, Journal of the National Academy of Forensic Engineers https://journal.nafe.org/ojs/index.php/nafe/article/download/975/924/4846 [4] Geologic Hazards in Oklahoma, Geological Society of America (abstract by K. V. Luza, Oklahoma Geological Survey) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [5] Settling Due to Leaking vs. Natural Causes, PropertyCasualty360 (FC&S) https://propertycasualty360.com/fcs/2010/05/18/settling-due-to-leaking-vs-natural-causes-422-11964 [6] Underwriting the FHA Appraisal, U.S. Department of Housing and Urban Development https://www.hud.gov/sites/documents/punder.pdf [7] Earth Movement Decision Upheld, FEMA National Flood Insurance Program https://www.floodsmart.gov/recover/how-to-write-your-appeal/earth-movement-decision-upheld --- # What causes foundation problems in the Tulsa, Oklahoma metro? URL: https://terrabrain.vercel.app/regions/tulsa-metro Answer: Most Tulsa foundation movement comes from shale clays that swell and shrink with about 41 inches of yearly rain; sandstone hills and floodplains add others. In short: Most foundation movement in the Tulsa metro comes from clay soils weathered from shale that swell when wet and shrink when dry, set against about 41 inches of rain a year. Sandstone hills bring shallow rock, fill and slope problems instead, and river corridors bring soft, wet floodplain clay. Knowing which of the three settings a house sits on explains most of what it does. ## What is the Tulsa climate like? Tulsa's 1991–2020 normal precipitation is about 40.96 inches a year [1]. May is the wettest month at about 5.73 inches, and January and February are the driest at about 1.6 inches each [1]. That pattern matters because clay soil changes volume as its moisture changes. Uneven wetting and drying around a house does more harm than uniform change, and south and west sides dry fastest in hot weather [7]. ## What are the three ground settings in the metro? ### Shale lowlands: clay and perched water Much of the gently rolling ground in the metro has soils formed from Pennsylvanian shale, an old layered mudrock. Examples include: - **Dennis** — somewhat poorly drained, formed in shale residuum, solum more than 60 inches thick, with a perched water table 12 to 30 inches deep, usually December through April [2]. - **Summit** — a smectite clay (the most swelling clay mineral family) that forms deep, wide cracks in summer and has slickensides, the polished shear faces left by repeated swelling [3]. - **Parsons** — a soil with an abrupt change to a clay subsoil of 35 to 60 percent clay in the subsoil and perched water 6 to 18 inches deep from December through April [4]. A **perched water table** is a shallow, temporary layer of water held up by tight clay or shale below it. It can wet a crawl space and swell soil at slab edges in winter and spring, then disappear in summer. This setting drives perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift), edge drop during drought (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) and crawl space moisture (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay). ### Sandstone hills: shallow rock and slopes Sandstone ridges and bluffs in the metro carry thin soils over rock. Collinsville soils, for instance, reach hard rock at 4 to 20 inches (9 inches in the typical profile) and occur on slopes up to 35 percent [5]. Hillside lots in this setting are often built up with fill, and the common problems are fill settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) and slope creep (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement) rather than clay swell. ### River corridors: soft floodplain clay Along the Arkansas and Verdigris corridors, floodplain soils can be thick, poorly drained clay. Osage soils, for example, formed in thick clayey alluvium on floodplains, have very slow permeability and a seasonal high water table 6 to 18 inches deep from November to May [6]. See soft soil consolidation (https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays). ## Which soil series are common in Tulsa? | Series | Setting | Key trait | |---|---|---| | Dennis | Shale uplands | Perched water 12–30 in, Dec–Apr [2] | | Summit | Shale uplands | Smectite clay, deep summer cracks [3] | | Parsons | Shale plains, old terraces | Abrupt clay subsoil, perched water 6–18 in [4] | | Collinsville | Sandstone ridges | Hard rock at 4–20 in [5] | | Osage | Floodplains | Thick clay, high water table [6] | The Tulsa soil series guide (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) covers more series, including Okemah, Coweta, Bates and Apperson. ## How does rock in the soil survey compare to pier depth? Soil surveys only describe roughly the top 5 feet, so "depth to rock" in a survey is not where a deep foundation pier stops. In 2025 installation records from Tulsa, steel push piers reached refusal at a median depth of about 12 feet, with most exterior piers between about 8 and 16 feet and a full range of roughly 2 to 40 feet [8]. Piers stopped well below the shallow rock that surveys show on some sandstone soils [8]. See depth to rock from borings (https://terrabrain.vercel.app/data/borings-depth-to-rock-in-tulsa-and-okc). ## Which moisture practices matter in Tulsa? Because so much Tulsa movement is moisture-driven, the ASCE homeowner guide lists practical steps for clay sites [7]: - Slope soil away from the house at least 3 inches over the first 5 feet [7]. - Discharge downspouts at least 3 feet from the foundation [7]. - Keep sprinkler lines and heads at least 5 feet from the foundation and water next to all sides of the foundation [7]. - Plant trees farther from the house than their mature height [7]. ## Related - Soil series in the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) - Bedrock in the Tulsa metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro) - Pennsylvanian shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales) - Pennsylvanian sandstones (https://terrabrain.vercel.app/geology/pennsylvanian-sandstones) - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) Sources: [1] Local Climatological Data Annual Summary with Comparative Data, Tulsa, Oklahoma (KTUL), 2023, NOAA National Centers for Environmental Information https://www.ncei.noaa.gov/pub/access/cebrequests/2023lcdannual/01202313TUL.pdf [2] Official Soil Series Description: DENNIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DENNIS.html [3] Official Soil Series Description: SUMMIT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/S/SUMMIT.html [4] Official Soil Series Description: PARSONS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/PARSONS.html [5] Official Soil Series Description: COLLINSVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COLLINSVILLE.html [6] Official Soil Series Description: OSAGE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OSAGE.html [7] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [8] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # What causes sinkholes and karst subsidence in Oklahoma? URL: https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes Answer: Groundwater dissolves gypsum, salt or limestone, forming cavities the soil above can sag or collapse into. Oklahoma has karst in the west, northeast and south. In short: Karst is ground shaped by rock that dissolves in water, such as gypsum, salt, limestone and dolomite. As groundwater dissolves the rock, cavities form, and the soil above can slowly sag into them or collapse suddenly as a sinkhole. In Oklahoma, gypsum and salt karst is found in the west, and limestone and dolomite karst in the northeast and south. ## How do karst sinkholes form? Sinkholes form where groundwater moving through soluble rock dissolves it and creates underground cavities [1]. The ground above may hold for a time, then fail when a cavity grows too large to support it [1]. The rock types involved are evaporites (salt, gypsum and anhydrite) and carbonates (limestone and dolomite) [1]. The USGS describes three main types [1]: | Type | How it develops | |---|---| | Dissolution | Rock dissolves where water first reaches it, forming a gradual depression | | Cover-subsidence | Sandy, permeable cover soil gradually sifts down into openings | | Cover-collapse | Clay-rich cover bridges a growing cavity, then fails abruptly, sometimes within hours | Natural triggers include rainfall soaking through rock, changes in the water table and surface drainage concentrating in low spots [1]. Human changes to drainage, groundwater pumping and heavy new loads can also contribute [1]. The Oklahoma Geological Survey adds that karst sinkholes can form when floodwater rises to a cavern's ceiling and then recedes [7]. ## Where is karst found in Oklahoma? | Rock type | Main Oklahoma areas | |---|---| | Gypsum and shallow salt | Many areas of western Oklahoma [3][4] | | Limestone and dolomite | Ozark region (northeast), Arbuckle Mountains (south) and Limestone Hills [3][4] | ### Western gypsum Gypsum beds of Permian age crop out in parts of 15 Oklahoma counties [5]. The thickest gypsum is in the southwest, mainly across about 600 square miles in Beckham, Greer and Jackson Counties, where the Blaine Formation is about 200 feet thick, about 150 feet of it massive gypsum [5]. Near Watonga in northwestern Oklahoma, Blaine gypsum beds lie about 40 to 140 feet below the surface [6]. Gypsum is highly soluble and forms karst features much like limestone does; gypsum karst in the U.S. has been linked to highway subsidence, dam failure and foundation cracking [6]. An Oklahoma Geological Survey circular notes that evaporite karst can damage or collapse homes, buildings, roads and dams [2]. See gypsum karst and sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes), Permian gypsum units (https://terrabrain.vercel.app/geology/permian-gypsum-units-e-g-blaine) and the Northwest (Gypsum Hills) region (https://terrabrain.vercel.app/regions/northwest-gypsum-hills). ### Eastern and southern limestone In the Ozark region and the Arbuckle Mountains, karst forms in limestone and dolomite [3]. See Arbuckle carbonates (https://terrabrain.vercel.app/geology/arbuckle-carbonates) and Mississippian cherty limestone (https://terrabrain.vercel.app/geology/mississippian-cherty-limestone). ## What are the signs of karst subsidence? - a sudden depression or sinkhole (https://terrabrain.vercel.app/signs/sudden-depression-or-sinkhole) in the yard or under a slab - sloping floors toward one area - stair-step cracks in brick that are wider at the top - visible slab cracks over a settling zone Sinkholes and caverns can cause land to settle or collapse [3]. ## How does karst differ from shallow erosion voids? Not every sinkhole is karst. The OGS notes that most of the sinkholes expected after Oklahoma's heavy April 2025 rains were small ones where water flowed beneath roads and driveways, eroding soil rather than dissolving bedrock [7]. Karst sinkholes are controlled by soluble bedrock and range from under 1 foot to more than 100 feet deep [1]. See erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). ## How is karst evaluated? In a 2010 study of gypsum karst risk in northwestern Oklahoma, geologists recommended gathering subsurface data from petroleum test records and core borings and surveying local landowners about past sinkholes or collapses [6]. They judged gypsum 80 feet or deeper to be low risk and shallower gypsum to be medium or high risk [6]. The OGS is building a statewide subsidence map and accepts sinkhole reports from the public [7]. Repair options for void-related settlement discussed on this site include void and compaction grouting (https://terrabrain.vercel.app/repairs/void-and-compaction-grouting). ## Related - Gypsum Karst and Sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes) - Sudden Depression or Sinkhole (https://terrabrain.vercel.app/signs/sudden-depression-or-sinkhole) - Erosion, Undermining and Washout Voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) - Drilled Bell-Bottom Piers (https://terrabrain.vercel.app/repairs/drilled-bell-bottom-piers) - Southwest (Lawton and Red Plains) (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains) Sources: [1] Sinkholes, U.S. Geological Survey Water Science School https://www.usgs.gov/special-topics/water-science-school/science/sinkholes [2] Evaporite Karst and Engineering/Environmental Problems in the United States (Circular 109), Oklahoma Geological Survey https://wipp.energy.gov/library/CRA/CRA-2019/N%20-%20S/Powers%20%202003%20%20OGS%20Circular%20109.pdf [3] Mapping of Karst Terranes in Oklahoma to Identify Potential Environmental and Hydrologic Problems, AAPG Search and Discovery (K. S. Johnson, Oklahoma Geological Survey) https://www.searchanddiscovery.com/abstracts/html/1995/midcon/abstracts/1403b.htm [4] Geologic Hazards in Oklahoma, Geological Society of America (abstract by K. V. Luza, Oklahoma Geological Survey) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [5] Stratigraphy of the Blaine Formation in Beckham County, Oklahoma, Proceedings of the Oklahoma Academy of Science https://ojs.library.okstate.edu/osu/index.php/OAS/article/view/3971/3645 [6] Gypsum Karst and Potential Problems in Siting Wind Turbines in Northwest Oklahoma, Geological Society of America (Abstracts with Programs, 2010) https://gsa.confex.com/gsa/2010AM/webprogram/Paper179331.html [7] Hazard Mapping, Oklahoma Geological Survey, University of Oklahoma https://ou.edu/ogs/research/hazard_mapping --- # What causes sloping floors in an Oklahoma house? URL: https://terrabrain.vercel.app/signs/sloping-floors Answer: Causes range from a drying slab edge to settling interior piers; slopes over about 1 percent are usually noticeable, and an elevation survey finds the cause. In short: Sloping floors are one of the most common signs of foundation movement on expansive clay, but they have many possible causes, from a drying slab edge to settling interior piers. A slope over about 1 percent is usually noticeable, and the cause is pinned down by measuring the whole floor with an elevation survey rather than by feel. ## What does this sign look like? Floors run downhill toward one wall or corner, doors swing open or shut on their own, and furniture or cabinets sit out of level. Research from Oklahoma State University lists tilting floors, jamming doors and wall cracks among the visible effects of expansive soil movement on houses [2]. Inspectors read sloping floors, sticking doors and warped openings as indicators of **differential settlement**, meaning one part of the house has moved more than another [4]. ## How much slope is noticeable? Engineering guidance gives these reference points [1]: | Floor slope | What the guidance says | |---|---| | Over 1% (about 1/8 inch per foot) | Usually noticeable to occupants | | 2% | Considered too large under the Americans with Disabilities Act | These are comfort and usability benchmarks. Structural significance is judged separately, using deflection (how much the floor curves between two points) and the distress visible in the house [1]. ## What causes sloping floors? | Possible cause | How it produces slope | |---|---| | Perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) | Clay under the slab edge shrinks as it dries, and the perimeter drops [3] | | Tree-root desiccation (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) | Trees and large shrubs withdraw water, causing downward foundation movement [5] | | Differential movement at additions (https://terrabrain.vercel.app/causes/differential-movement-at-additions) | Settlement cracks form at the joints of bay windows, porches and additions [4] | | Slope creep (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement) | Clay soils on slopes can slowly drift downhill, causing settlement [4] | | Interior support failure (crawl) (https://terrabrain.vercel.app/causes/interior-support-and-framing-failure-crawl) | Settling or rotating interior piers drop, and the wood frame sags to follow [4] | | Karst subsidence (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes) | Sinkholes and caverns in soluble rock can cause land settlement or collapse [6] | Other listed mechanisms, such as fill consolidation and soft soil consolidation, are covered in the causes section of this library. ### The Oklahoma clay connection Most of Oklahoma has expansive soils [3]. Seasonal wetting and drying can make a slab perimeter rise when the soil swells and drop when it shrinks [3]. Oklahoma State University researchers have used Oklahoma Mesonet climate data to map the long-term soil moisture conditions that drive this movement across the state [2]. ### Karst areas of Oklahoma Limestone and dolomite karst is found mainly in the Ozark area of the northeast and the Arbuckle Mountains in the south, while gypsum and salt karst occurs in many parts of western Oklahoma [6]. Karst means rock that groundwater can dissolve, leaving voids. ## How are sloping floors measured? - **Elevation survey.** A relative floor elevation survey, with readings drawn on a floor plan, is the level of evaluation engineering guidance uses beyond a first impression [1]. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). - **Short-distance caution.** Over distances under about 20 feet, built-in unevenness from construction can dominate the readings [1]. - **Deflection ratio.** The survey is checked against a deflection of L/360 (span divided by 360). Below it, damaging deflection is unlikely unless visible distress says otherwise; above it with enough symptoms, an engineer is generally justified in calling the deflection excessive [1]. ## Related - Elevation Surveys (https://terrabrain.vercel.app/guides/elevation-surveys) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Tolerances and Standards (https://terrabrain.vercel.app/guides/tolerances-and-standards) - Perimeter Drying Settlement (Edge Drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Symptom Matrix (https://terrabrain.vercel.app/guides/symptom-matrix) - Gaps Under Baseboards (https://terrabrain.vercel.app/signs/gaps-under-baseboards) Sources: [1] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [2] Residential House Foundations on Expansive Soils in Changing Climates, U.S. Department of Housing and Urban Development, Cityscape https://www.huduser.gov/PORTAL/periodicals/cityscape/vol25num1/ch10.pdf [3] The Mystery of Expansive Soils, STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [4] Inspecting Foundation Walls and Piers, International Association of Certified Home Inspectors (InterNACHI) https://www.nachi.org/documents2012/Inspecting_Foundation_Walls_and_Piers-revised-January-2013.pdf [5] Recommended Practice for the Design of Residential Foundations, Version 2, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Recommended-Practice-for-the-Design-of-Residential-Foundations-V2-2007.pdf [6] Mapping of Karst Terranes in Oklahoma to Identify Potential Environmental and Hydrologic Problems, AAPG Search and Discovery (Oklahoma Geological Survey author) https://www.searchanddiscovery.com/abstracts/html/1995/midcon/abstracts/1403b.htm --- # What Cretaceous rocks and soils lie under southern Oklahoma? URL: https://terrabrain.vercel.app/geology/cretaceous-shales-clays-and-sandstones Answer: Layers of clay, shale, marl, limestone and sand; the clay and shale weather into very expansive soils, while sand layers give loose, well-drained soils. In short: Southern Oklahoma's Cretaceous rocks are alternating layers of clay, shale, marl, limestone and sand. Clay and shale layers weather into some of the most expansive soils in the state, while sand layers weather into loose, well-drained soils. The same neighborhood can have both, so foundation behavior depends on which layer a lot sits on. ## What are these rocks and where are they? The Cretaceous Period ran from about 145 to 66 million years ago, and in the Late Cretaceous most of Oklahoma was covered by a shallow sea [3]. Rocks from that time are preserved in southern Oklahoma, including the Tishomingo and Atoka areas [1][2]. Early USGS mapping of the Tishomingo and Atoka areas described the Cretaceous section as about 1,000 feet of nearly flat layers dipping gently to the south [1][2]. From oldest to youngest, the units named included [1][2]: | Unit | Main material | |---|---| | Trinity sand | Friable sand, 300–400 ft, with a basal conglomerate [1] | | Goodland limestone | Hard white limestone forming terraces, benches and bluffs [1] | | Kiamichi | About 30 ft of blue clay marl with oyster beds [1] | | Caddo limestone | About 150 ft of marly limestone and clay [1] | | Bokchito | About 140 ft of clays, sandy beds and shell limestone [1] | | Bennington limestone | Thin hard limestone, 10 ft or less [1] | | Silo sandstone | Soft brown sand and sandy clay [1] | **Marl** is a soft, limy clay. Hard limestones tend to form ridges and terraces, while softer clays and sands form valleys, slopes and rolling uplands [1]. ## Why do they form two very different soils? ### Durant: clay that cracks deeply The Durant soil formed in clayey material weathered from Cretaceous shale and claystone, with its typical profile in Bryan County, Oklahoma [4]. Its clay is **smectitic**, meaning it is dominated by smectite, the clay mineral family that swells most when it takes up water [4]. In dry periods Durant develops cracks wider than 1 centimeter that reach about 30 inches deep [4]. Permeability is very slow and runoff is high [4]. Soil scientists rate shrink-swell by **linear extensibility**, the percent a soil's length changes between moist and oven-dry. Values of 6 to 9 percent are rated high and 9 percent or more very high [6]. Map-unit values for a specific lot are listed in the USDA Web Soil Survey. For a house, that means the soil under the slab edge can shrink away in summer and swell back in a wet spring. See perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) and cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally). ### Bernow: sandy and well drained Bernow soils formed in sandy and loamy residuum from Cretaceous sandstone, mainly in eastern Oklahoma [5]. They are well drained with moderate permeability and occur on slopes up to 12 percent [5]. Sandy soils like this swell little but are easier for running water to carry away, so leaks and roof runoff matter more than seasonal swell. See erosion and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). ## What are the practical points for homeowners? - Look up the soil series for the lot. A clay series like Durant and a sandy series like Bernow call for different explanations of the same crack [4][5]. - On the clay soils, keeping moisture even around the foundation is the main lever. See root barriers and moisture control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control). - On sandy soils, watch for soil loss at slab edges and downspouts. See surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). ## Related - South-Central (Arbuckles and Texoma) (https://terrabrain.vercel.app/regions/south-central-arbuckles-and-texoma) - Southeast (Ouachitas and Red River) (https://terrabrain.vercel.app/regions/southeast-ouachitas-and-red-river) - Durant soil (https://terrabrain.vercel.app/soils/durant) - Bernow soil (https://terrabrain.vercel.app/soils/bernow) - Clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) Sources: [1] Description of the Tishomingo Quadrangle (Geologic Atlas Folio 98), U.S. Geological Survey https://pubs.usgs.gov/gf/098/text.pdf [2] Description of the Atoka Quadrangle (Geologic Atlas Folio 79), U.S. Geological Survey https://pubs.usgs.gov/gf/079/text.pdf [3] The Oklahoma Geological Survey and the geology of Oklahoma, USGS National Geologic Map Database (DMT '25) https://ngmdb.usgs.gov/Info/dmt/docs/DMT25_Johnson.pdf [4] Official Soil Series Description: DURANT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DURANT.html [5] Official Soil Series Description: BERNOW Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/B/BERNOW.html [6] Linear Extensibility (definition and shrink-swell classes, after NRCS National Soil Survey Handbook), UC Davis California Soil Resource Lab https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html --- # What did an engineer specify for a previously piered Sand Springs house? URL: https://terrabrain.vercel.app/case-studies/sand-springs-two-story-additions-perimeter-and-interior-piers Answer: 21 perimeter steel piers at least 10 ft below the footing, 10 to 15 interior helical piers with foam, and a duct camera check, for active clay and additions. In short: A two-story brick-veneer house in Sand Springs had brick cracks on three sides, a chimney separating from the walls and cracks throughout the interior. It had been piered before, with no records available [1]. The engineer attributed the movement to active clay, insufficient earlier piering, and differential movement between the original house and its additions. The scope was 21 perimeter steel piers, 10 to 15 interior helical piers with foam injection, and plumbing and duct checks [1]. ## What did the house show? The engineer inspected the house in May 2025 [1]. It is a two-story wood-frame house with brick veneer. The garage is an addition, and a former garage was converted to living space. The foundation is a slab-on-grade with continuous perimeter footings and a floating floor slab [1]. Observed conditions [1]: - Brick cracks from hairline to 1/4 in., and previously patched cracks, on the north, south and east walls and the northeast and southeast corners. - The **chimney separating** from the walls. - **Previous piering, with no records available.** - Interior cracks throughout, at doors, closets and the living room. - Uneven upstairs floors from minor framing sag, with no repair specified for that. ## What did the engineer find was causing it? The engineer named three factors [1]: - Shrink-swell of active clay. - Earlier piering that was not enough. - Differential movement between the additions and the original house. ## What repair was specified? **Perimeter (item 1).** **21 perimeter piers**, shown at 9 ft dimensions on the plan, with equal spacing where none is given [1]. The engineer's pier specification requires [1]: - steel piers only, unless another system is approved by the engineer - penetration at least **10 ft below the bottom of the foundation** into firm, stable strata - a detail showing the steel pier driven to refusal on bedrock (blue shale) - a **pier log** for every pier: depth, type, diameter, driving pressure and amount of lift - mortar removed from patched cracks near piers before lifting - a **6x6x1/2 in. angle iron** under the footing where a pier falls near a crack - a call to the engineer if old shallow concrete piers are found Locations and count may change for footing conditions [1]. **Interior (item 2).** **Helical piers under load-bearing walls**, about 6 ft on center, with **foam injection** elsewhere on a roughly 6 ft port grid. The foam is to be warranted. The engineer estimated **10 to 15 interior piers**, with cracks stitched at 18 in. [1]. **Other items.** A plumbing test before and after the work, a **camera inspection of the in-slab ducts**, and replacement of fiberboard attic flooring with plywood or OSB [1]. ## What does this case show about Oklahoma foundations? - **Shale is both the problem and the target.** A federal survey of expansive materials identifies clay-rich sediments and shales as the most troublesome expansive materials [2]. In this specification, the piers are driven through the active soil to refusal on shale bedrock [1]. - **Clay moves with moisture.** ASCE's homeowner guide explains that clay expands when wet and shrinks when dry, and that uneven moisture changes cause more damage than uniform ones [3]. The engineer's diagnosis here was shrink-swell of active clay [1]. - **Undocumented earlier repairs complicate the next one.** The house had been piered before, but with no records the engineer could not tell how deep or how hard those piers were driven [1]. - **Additions move on their own.** The engineer expected independent movement at the joints between the original house and its additions [1]. ## Related - Additions and Mixed Foundations (https://terrabrain.vercel.app/guides/additions-and-mixed-foundations) - Differential Movement at Additions (https://terrabrain.vercel.app/causes/differential-movement-at-additions) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Helical Piers (https://terrabrain.vercel.app/repairs/helical-piers) - Chimney Separating or Leaning (https://terrabrain.vercel.app/signs/chimney-separating-or-leaning) - Shale Weathering and Bearing Strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata) Sources: [1] Engineer's evaluation report, 2025 (private client report), Licensed professional engineer, Oklahoma [2] An Occurrence and Distribution Survey of Expansive Materials in the United States by Physiographic Areas (FHWA-RD-76-82), U.S. Federal Highway Administration https://rosap.ntl.bts.gov/view/dot/58199 [3] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, ASCE Geo-Institute, Shallow Foundations Committee https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What did an engineer specify for a south Tulsa slab with failing walls? URL: https://terrabrain.vercel.app/case-studies/south-tulsa-two-story-slab-piers-and-retaining-walls Answer: 4 perimeter steel piers, 10 to 15 interior helical piers with foam, crack stitching, new retaining walls and channel drains, for active clay movement. In short: A two-story brick-veneer house in south Tulsa had brick cracks at its bay windows and corners, uneven floors downstairs, and failing timber and block retaining walls [1]. The engineer attributed the foundation movement to shrink-swell of active clay under the perimeter and slab, plus ineffective drainage at the back. The engineer also found sagging floor framing upstairs. The scope was 4 perimeter steel piers, 10 to 15 interior helical piers with foam injection, crack stitching, framing repair, new retaining walls and new channel drains [1]. ## What did the house show? The engineer inspected the house in January 2026 [1]. It is a two-story wood-frame house with brick veneer, an attached two-car garage and a partly converted attic. The lot has a pool and retaining walls. The foundation is a slab-on-grade with continuous perimeter footings and a floating floor slab [1]. Observed conditions [1]: - Brick cracks from hairline to 1/4 in. at the north and south bay windows, the northwest corner of the house and the garage. - Interior cracks and uneven floors downstairs from slab and foundation movement. - Uneven floors upstairs above the garage from **sagging floor framing**. - **Railroad-tie retaining walls** on the south and west at the end of their life, and **concrete block retaining walls** cracked and leaning. - Downspouts connected and discharging at the northwest of the property. - Pool **channel drains damaged and painted over**, so they were ineffective. - Water pooling on the patio, and a flat yard to the south and west. ## What did the engineer find was causing it? The engineer named shrink-swell of active clay under the perimeter and slab, and ineffective surface drainage at the back of the house [1]. ## What repair was specified? **Perimeter piers.** **4 perimeter steel piers** at spacings of 2 to 7 ft shown on the plan. They must penetrate **at least 10 ft below the bottom of the foundation** into firm, stable strata, and be driven to refusal on bedrock (blue shale) per the detail [1]. The pier specification also requires [1]: - a pier log for every pier: depth, type, diameter, driving pressure and lift - angle iron under the footing where a pier lands near a crack - mortar removed from patched cracks before lifting **Interior slab.** Helical piers under load-bearing walls at about 6 ft on center (for a 4 to 5 in. slab), taken to firm strata with augering if needed [1]. The engineer estimated **10 to 15 interior piers**. Foam injection on a roughly 6 ft port grid elsewhere is acceptable only if warranted against all slab movement. The engineer noted that foam rests on existing soil, not on bedrock. Voids over 3 in. are to be filled with low-pressure grout [1]. **Cracks.** Stitch the remaining large slab cracks with #3 rebar or carbon fiber staples at 18 in., sealed with epoxy [1]. **Other items** [1]: - a plumbing test **before and after** the repair - strengthening and re-leveling the upstairs floor framing (double joists or added beams) - replacing the railroad-tie and block retaining walls with designed, permitted walls - replacing the channel drains with **4 in. channel drains** placed to stop the patio pooling ## What does this case show about Oklahoma foundations? - **Ponding near a slab matters on clay.** ASCE's homeowner guide for shrink-swell soils warns that ponding water near a foundation can cause localized heave. It recommends checking grading and drainage every year [2]. Here water was pooling on the patio because the drains had failed [1]. - **Tulsa's clay drainage problems are long documented.** The Tulsa Geological Society's 1972 volume on the city's physical environment includes a chapter on drainage problems in clay soils under Tulsa buildings, along with chapters on soils and construction conditions [3]. - **Different floor problems, different causes.** On the same house the engineer separated slab movement downstairs, which got piers and foam, from framing sag upstairs, which got joist and beam work [1]. ## Related - Helical Piers (https://terrabrain.vercel.app/repairs/helical-piers) - Interior Piers (Tunnel or Core) (https://terrabrain.vercel.app/repairs/interior-piers-tunnel-or-core) - Slabjacking and Polyurethane (https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane) - Tilted Retaining Walls, Fences or Trees (https://terrabrain.vercel.app/signs/tilted-retaining-walls-fences-or-trees) - Water Ponding Near Foundation (https://terrabrain.vercel.app/signs/water-ponding-near-foundation) - Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro) Sources: [1] Engineer's evaluation report, 2026 (private client report), Licensed professional engineer, Oklahoma [2] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, ASCE Geo-Institute, Shallow Foundations Committee https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [3] Tulsa's Physical Environment (1972), contents: 'Drainage Problems in Clay Soils Under Buildings in Tulsa' and related chapters, Tulsa Geological Society (AAPG Datapages archive) https://archives.datapages.com/data/browse/tulsa-geological-society/tulsas-physical-environment-1972/ --- # What did an engineer specify for an 80-year-old Tulsa basement house? URL: https://terrabrain.vercel.app/case-studies/tulsa-1930s-basement-house-settlement-and-failed-stairwell-wall Answer: 15 exterior steel piers, a rebuilt stairwell wall, new beams and posts, porch foam and a new sump pump, for age-related settlement and basement water. In short: A Tulsa house about 80 years old had settled at a dining-room wall and at the corners of its wraparound porch. Its basement stairwell wall had buckled inward and its sump pump had failed [1]. The engineer attributed the problems to age-related settlement, long-term sagging of the wood framing, poor maintenance and basement water. The scope covered 15 exterior steel piers, a rebuilt stairwell wall, new beams and posts, foam leveling under the porch, and basement water control [1]. ## What did the house show? The engineer inspected the house in January 2014 [1]. It is a two-level timber house with brick veneer and a basement. The stem walls are clay vitreous tile, the basement walls are brick masonry on spread footings, and the floor is framed with 2x10 joists at 16 in. on center [1]. Observed conditions [1]: - Foundation settlement at the south dining-room wall. - Settlement at the northeast, north and northwest corners of the wraparound porch. - **Evidence of past foundation repair** at the west kitchen wall, with no records found. - The **south basement stairwell wall had failed and buckled inward**, and a north landscape retaining wall was rotating. - Dips in the floors, a living-room floor sloping from east to west, out-of-square doors, a deflected wall, and deflection in the upper floor. - In the basement, the **sump pump was not working**, water was seeping in at the walls and floor, and pipe columns had been added at some point. ## What did the engineer find was causing it? The engineer described the movement as age-related settlement plus long-term deflection of the timber framing, typical of a house of this age. Poor maintenance and basement water added to it [1]. ## What repair was specified? The report was a ten-item scope [1]: - **Item 1: 15 exterior steel piers.** Verify the foundation construction first, since a supplemental footing may be required. Then lift and level, repair the brick cracks, and remove and replace pavement where needed. - **Item 2:** Excavate behind the buckled basement stairwell wall and rebuild it. - **Item 3:** Level the wraparound porch with **urethane foam**. - **Items 4 to 6:** Jack, shim and level the basement posts and beams. Add **4x4 treated posts** at the stairwell corners and **two 1-3/4 x 11-1/4 in. LVL beams** on posts. The engineer expected only partial recovery of the framing deflection. - **Item 7:** Re-hang doors after leveling. - **Item 8:** Install a new sump pump, apply hydraulic cement to the basement walls, and paint the basement floor with epoxy. - **Item 9:** Rebuild the north retaining wall. - **Item 10:** Replace decayed sill and soffit material. ## What does this case show about Oklahoma foundations? - **Old houses need the footing checked before piering.** Clay tile stem walls are an older construction type. The engineer made verifying the footing part of the pier scope and noted that a supplemental footing may be required [1]. - **Basement water is part of the structural picture.** Building-science guidance for basements says groundwater should be drained away rather than allowed to saturate the soil around the foundation. It also says roof and surface runoff should be collected and carried away, with grade sloping away from the building [2]. In this house a dead sump pump and seepage sat alongside a buckled below-grade wall [1]. - **Drainage in Tulsa clay has long been studied.** A 1972 Tulsa Geological Society volume on the city's physical environment includes a chapter titled "Drainage Problems in Clay Soils Under Buildings in Tulsa; Causes, Symptoms, and Solutions," alongside chapters on soils and construction conditions [3]. - **Not every floor problem is a soil problem.** Several items in this scope were framing and maintenance items: sagging beams, decayed sills and added posts. They were not pier items [1]. ## Related - Basement Wall Repair (https://terrabrain.vercel.app/repairs/basement-wall-repair) - Basements (https://terrabrain.vercel.app/foundations/basements) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Interior Support & Framing Failure (Crawl) (https://terrabrain.vercel.app/causes/interior-support-and-framing-failure-crawl) - Horizontal Crack or Inward Bow in Basement Wall (https://terrabrain.vercel.app/signs/horizontal-crack-or-inward-bow-in-basement-wall) - Construction Era by Decade (https://terrabrain.vercel.app/guides/construction-era-by-decade) Sources: [1] Engineer's evaluation report, 2014 (private client report), Licensed professional engineer, Oklahoma [2] Understanding Basements, Building Science Digest 103, Building Science Press (J. Lstiburek) https://www.greenbuildingadvisor.com/sites/default/files/Basement%20-%20Understanding%20Basements.pdf [3] Tulsa's Physical Environment (1972), contents: 'Drainage Problems in Clay Soils Under Buildings in Tulsa' and related chapters, Tulsa Geological Society (AAPG Datapages archive) https://archives.datapages.com/data/browse/tulsa-geological-society/tulsas-physical-environment-1972/ --- # What did an engineer specify when old piers stopped holding in south Tulsa? URL: https://terrabrain.vercel.app/case-studies/south-tulsa-repressurize-old-garage-piers Answer: Cracks reopened along a previously piered garage wall; the engineer said to repressurize those piers or replace them, add 3 new piers, and level the slab. In short: A south Tulsa slab home that had been piered before, including its garage wall, showed reopening veneer cracks and new floor cracks. The engineer attributed this to active clay and to the old garage piers no longer holding, and specified repressurizing (or replacing) those piers, 3 new piers at the southeast corner, slab piers or foam for the floor, and plumbing tests before and after [1]. ## What did the house show? - Stone veneer separations at the southeast corners of both the house and the garage [1]. - Hairline to 1/8 in. cracks on the south, east and west walls and on the chimney [1]. - Hairline to 1/4 in. interior cracks throughout, and floor cracks in the entry, kitchen, living room and hall bath [1]. - Evidence of earlier piering, including along the garage's south wall, where cracks had reopened [1]. ## What did the engineer find was causing it? Shrink-swell movement of active clay soil, together with loss of support from the existing piers along the garage's south wall, which were no longer holding [1]. ## What repair was specified? 1. 3 new piers at the southeast corner, shown at about 3 ft spacing near the corner, at least 10 ft below the bottom of the foundation [1]. 2. Repressurize the existing piers on the garage's south wall (about 9 ft spacing on the plan); if they would not repressurize, replace them with new piers [1]. 3. For the slab, steel slab piers about 6 ft on center, or foam injection on about a 6 ft grid with a warranty, or a combination, after consulting the engineer. Floor cracks to be stitched with #3 rebar or carbon fiber staples at 18 in. [1]. 4. A plumbing test before and after the repair [1]. The engineer's standard pier specification applied: steel piers only unless the engineer approved another system; refusal on firm strata, with the detail showing bedrock (blue shale); a log for each pier listing depth, type, diameter, driving pressure and lift; mortar removed from patched cracks before lifting; a 6 x 6 x 1/2 in. angle iron under the footing where a pier lands near a crack; and a call to the engineer if old shallow concrete piers turned up [1]. ## What happened on the job? The record shows the repair contractor's proposal was checked against the engineer's requirements, a plumbing leak test was provided, and an updated scope was sent in early 2026 [1]. ## What does this case show about Oklahoma foundations? This house had already been piered, yet it was moving again. The old piers were along one garage wall, and the new distress appeared at an unpiered corner, in reopened cracks along the old pier line, and in the interior slab [1]. Clay soils shrink when they dry and swell when they wet, the uplift is usually uneven, and floor slabs often show the distress [2], which matches the floor cracks recorded throughout this house [1]. The engineer's answer to the old piers was graded: first try to restore load by repressurizing them, and replace only if that fails. The engineer also required plumbing tests both before and after the work [1]. ## Related - Pier Uplift or Movement After Repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Slabjacking and Polyurethane (https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane) - Interior Piers (Tunnel or Core) (https://terrabrain.vercel.app/repairs/interior-piers-tunnel-or-core) - Plumbing Leak Detection and Repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair) - Visible Slab Cracks (https://terrabrain.vercel.app/signs/visible-slab-cracks) Sources: [1] Engineer's evaluation report, 2025 (private client report), Licensed professional engineer, Oklahoma [2] Shrink-Swell Subsidence (Hazard Information Profile), UN Office for Disaster Risk Reduction / British Geological Survey https://www.undrr.org/understanding-disaster-risk/terminology/hips/gh0310 --- # What do diagonal drywall cracks at door corners mean? URL: https://terrabrain.vercel.app/signs/diagonal-drywall-cracks-at-openings Answer: Diagonal cracks from door and window corners are a common sign of uneven foundation movement, since corners concentrate stress. In short: Diagonal cracks that start at the corners of doors and windows are one of the most common signs that a wall has been distorted by uneven foundation movement. The corners of openings concentrate stress, so cracks begin there. The crack's direction, width and timing, plotted against floor levels, help narrow down which way the house moved and why. ## Why do cracks start at openings? A wall with a door or window is weakest at the corners of the opening, where the solid wall meets the gap. When one part of the foundation moves up or down relative to another, the wall is pulled out of square, and that distortion concentrates at those corners. The crack then runs at an angle from the corner. On shrinkable clay, settlement often shows first as cracking around windows and doors, and cracks usually need about 5 to 10 millimeters of movement before they appear [1]. Home inspection standards list drywall cracks, brick cracks, out-of-square door frames and uneven floors as signs of possible foundation movement [2]. ## What does the crack direction tell you? In foundation diagnosis, the working rule is that a diagonal crack tends to run toward the relatively low side of the wall. A crack that rises from a door corner toward an outside wall suggests the outer side dropped (edge settlement) or the interior rose (center heave). Because both can make similar cracks, the direction is checked against an elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) rather than read alone. See heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). ## What causes can produce these cracks? | Mechanism | What else usually shows up | |---|---| | Perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) | Cracks near outside walls that widen in late summer | | Perimeter wetting heave (edge lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) | Edges high after wet periods | | Center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) | Interior floor high; interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump) | | Tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) | Cracking concentrated toward a large tree | | Fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) | Steady, non-seasonal settlement over a filled area | | Slope creep and lateral movement | Downhill side low; tilted fences or walls | | Earthquake shaking damage | Fresh, clean cracks appearing at once | | Differential movement at additions | Cracks where old and new sections meet | Less often, interior support failure in crawl spaces or an original construction deficiency is the cause. ### Expansive clay is the common background More than 75% of Oklahoma has bedrock that can produce expansive soils [5]. These soils produce two broad shapes of movement: edges wetter and higher than the center (called end or edge lift) or the center higher than the edges (center lift) [6]. Both distort walls and openings. Swelling soils also lift and crack lightly loaded strip footings, frequently distress floor slabs and can distress framing [3]. Texas monitoring found slab out-of-levelness growing through the growing season and recovering during winter as the soil rehydrated, which is why many of these cracks change width through the year [4]. ### Earthquakes Oklahoma's earthquake rate rose from about two magnitude 3.0+ events per year before 2009 to 903 in 2015 [7]. Cracks that appear together right after a felt earthquake, with clean edges, point toward shaking rather than soil; see seismic damage vs soil movement. ## How do you document these cracks? 1. Note which corner the crack starts at and which way it runs. 2. Measure the widest point and mark the crack ends with pencil and date. 3. Photograph with a ruler or crack gauge in view. 4. Mark every crack on a floor plan and compare with an elevation survey. 5. Re-measure every month or two to see whether it is growing or cycling. ## What are the next steps? Use the distress pattern library to compare crack maps and the symptom matrix to weigh mechanisms. ## Related - Stair-step brick crack wider at top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top) - Cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally) - Nail pops and tape-joint cracks (https://terrabrain.vercel.app/signs/nail-pops-and-tape-joint-cracks) - Heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) - Doors binding or tapered gaps (https://terrabrain.vercel.app/signs/doors-binding-or-tapered-gaps) Sources: [1] Trees near buildings, Royal Horticultural Society https://www.rhs.org.uk/plants/types/trees/near-buildings [2] Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [3] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [4] Cyclical Foundation Movements and Their Remediation, CIGMAT, University of Houston (conference presentation) https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2007/addison.pdf [5] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [6] Expansive soils (encyclopedia entry, post-review manuscript), NERC Open Research Archive https://nora.nerc.ac.uk/id/eprint/521301/1/EncyclopediaEngGeol_ExpansiveSoils_PostReview.pdf [7] Detailed mapping of shallow landslides in eastern Oklahoma and western Arkansas and potential triggering by Oklahoma earthquakes, Geomorphology (Oklahoma Geological Survey authors) https://www.jakewalter.net/papers/Regmi_Walter_2019.pdf --- # What do foundation crack patterns in a house mean? URL: https://terrabrain.vercel.app/guides/distress-pattern-library Answer: Stair-step brick cracks, cracks at door and window corners, sticking doors and sloping floors are movement clues, checked against floor elevation surveys. In short: Foundation movement shows up as recognizable patterns: stair-step cracks in brick, cracks running from door and window corners, sticking doors, sloping floors and separations between materials. Engineering guidelines treat these as clues to be checked against floor elevation measurements, not as proof of failure on their own. Crack width, the number of cracks and whether they are growing are the main ways distress is graded. ## How do engineers treat distress signs? The Texas Section of the American Society of Civil Engineers (ASCE) lists 12 visible indications of foundation movement, including cracking or separating of exterior walls, rotating or buckling brick veneer, cracking of concrete foundation elements, cracking of drywall, walls separating from ceilings or floors, racking of door and window frames, and cracking or buckling of floor coverings [1]. The same guideline says that observing some of these does not necessarily mean inadequate structural performance, and that most cracks do not compromise structural integrity [1]. Post-Tensioning Institute evaluation guidelines make a similar point: distress such as drywall and brick cracks or out-of-square doors needs to correlate with out-of-tolerance floor measurements, and minor cracking alone is not a sign of foundation failure [7]. That is why distress is read together with an elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys). The Foundation Performance Association sorts observed "phenomena" into three classes: architectural (appearance), functional (things that stop working properly, like doors) and structural [2]. Its guideline calls for recording where each one is, including its position relative to doors and windows, whether it is on a ceiling or floor, any evidence of earlier repair, and optionally the crack or separation width [2]. ## What patterns show up in each part of a house? ### Brick and exterior - **Stair-step cracks** that follow mortar joints in brick are one of the exterior signs listed in the ASCE homeowner guide [4]. See stair-step cracks wider at the top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top). - **Gaps between window frames and brick walls** are another listed sign [4]; see brick separating from window or door frames (https://terrabrain.vercel.app/signs/brick-separating-from-window-or-door-frame). - **Separation of driveways or patios** from the house is also listed [4]. - **Rotating, buckling or deflecting veneer panels** appear on the ASCE Texas list of indications [1]. ### Interior walls and ceilings - **Cracks above doors and windows** are listed interior signs [4]; see diagonal drywall cracks at openings (https://terrabrain.vercel.app/signs/diagonal-drywall-cracks-at-openings). - **Walls separating from ceilings or floors** are on the ASCE Texas list [1]. A seasonal ceiling-wall gap at interior partitions is often truss uplift instead, covered below. - **Cracked drywall** is one of the possible movement indications that home inspection standards say should be reported [6]. ### Floors, doors and windows - **Sloping floors** and **concrete floor cracks 1/16 inch or wider** are listed signs in the ASCE homeowner guide [4]. See sloping floors (https://terrabrain.vercel.app/signs/sloping-floors). - **Sticking doors and windows** are listed in the ASCE homeowner guide [4], **racking of door and window frames** is on the ASCE Texas list [1], and inspection standards include out-of-square door frames and unlevel floors [6]. - **Cracking, buckling or separating floor coverings** are on the ASCE Texas list [1]. The ASCE homeowner guide adds that the likelihood of foundation movement rises with the number of signs, how often they appear and where they are located [4]. ## What is truss uplift, a common look-alike? Canada Mortgage and Housing Corporation explains truss uplift: roof trusses bow upward when the warmer, drier bottom chord (buried in attic insulation) shrinks more than the top chord [5]. Ceilings fastened to the trusses lift with them, and cracks at the ceiling-partition joint may open in winter and close in summer [5]. The effect is generally worse in a new house's first year as lumber dries [5]. See truss uplift (https://terrabrain.vercel.app/causes/truss-uplift-mimic) and ceiling-wall separation (https://terrabrain.vercel.app/signs/ceiling-wall-separation-at-interior-walls). ## How is crack width graded? The Foundation Performance Association guideline allows crack widths to be recorded but does not set a severity scale [2]. The UK Building Research Establishment (BRE) publishes damage categories for houses based on crack width [3]: | Category | Typical crack width | Meaning | |---|---|---| | 0 | Under 0.1 mm (hairline) | Negligible | | 1 | Up to 1 mm | Treated with normal decoration | | 2 | Up to 5 mm (about 3/16 in) | Easily filled | | 3 | 5-15 mm, or several around 3 mm | Doors and windows may stick | | 4 | 15-25 mm | Sections of wall may need replacing | | 5 | Over 25 mm (about 1 in) | Structural; major repair | Categories 0-2 are considered aesthetic, 3-4 affect serviceability, and 5 affects stability [3]. BRE notes that the number of cracks matters as well as width, and that cracks widening over time can change the category [3]. ## Related - Heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Inspection protocol (https://terrabrain.vercel.app/guides/inspection-protocol) - Symptom matrix (https://terrabrain.vercel.app/guides/symptom-matrix) - Cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally) - Seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement) Sources: [1] Guidelines for the Evaluation and Repair of Residential Foundations, Version 2, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2022/05/Guidelines-for-the-Evaluation-and-Repair-of-Residential-Foundations-V2-2008.pdf [2] Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings (FPA-SC-13-0), Foundation Performance Association https://www.foundationperformance.org/projects/super/FPA-SC-13-0.pdf [3] Assessing cracks in houses, BRE Group https://wpe.bregroup.com/insights/assessing-cracks-in-houses/ [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Drywall Application (Builders' Series), Canada Mortgage and Housing Corporation https://assets.cmhc-schl.gc.ca/sf/project/archive/research/ca1_mh_90d61.pdf [6] Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [7] Evaluation Guidelines for the Performance of Slab-on-Ground Foundations (2015 technical session), Post-Tensioning Institute https://www.post-tensioning.org/Portals/13/Files/PDFs/Events/Conventions/TechnicalSessions/2015/042815Brumley.pdf --- # What do lab tests show about Oklahoma clay soils? URL: https://terrabrain.vercel.app/data/soil-lab-values Answer: Oklahoma subsoil clays mostly test with plasticity index in the high 20s to low 40s, and some western soils carry very high sulfate that affects lime treatment. In short: Lab tests on Oklahoma clays show plasticity index values mostly in the high 20s to low 40s in the subsoil, with the strongest shrink-swell found below the surface layer. Some western soils with modest plasticity carry very high sulfate, which changes how they react to lime treatment. These measured values give a firmer picture than general labels like "high PI." ## What do the key lab terms mean? - **Liquid limit (LL):** the water content at which clay starts to flow like a liquid. Higher LL usually means more clay activity. - **Plasticity index (PI):** the range of water content over which the soil stays moldable. Higher PI generally means more swelling and shrinking. - **COLE (coefficient of linear extensibility):** how much a soil clod shrinks in length from moist to dry. A COLE of 0.09 means about 9% shrinkage. - **Swell:** how much a sample grows when soaked, reported as a percentage. - **Sulfate (ppm):** soluble sulfate, which matters if lime or cement is added. More background is in soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values) and clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy). ## What do statewide soil tests show? An Oklahoma Geological Survey geologist reported that over 75% of Oklahoma has bedrock units that can produce expansive soils, and that montmorillonite clay can swell to roughly 1.5 to 2 times its dry volume when wet [7]. ## What do soil tests show in central Oklahoma? | Soil and location | LL | PI | Clay | Other measured values | |---|---|---|---|---| | Kirkland subsoil (B horizons), Canadian Co. | 52 to 53 | 30 to 32 | about 38 to 40% | COLE 0.076 to 0.090 [1] | | Kirkland surface (Ap) | 26 | 4 | about 17% | COLE 0.016 [1] | | Bethany subsoil (B21t), Canadian Co. | 47 | 27 | 31 to 38% in B horizons | COLE 0.095 [1] | | Renfrow clay, Logan Co. | 59.4 | 33.2 (27.2 after 14-day cure) | 35% | Sulfate 262 ppm [2] | | Kingfisher soil (lean clay) | about 39 | about 21 | not given | Swell 6.1%, no soluble sulfate detected [3] | | Clays at I-35 and SH-59, McClain Co. | about 46 to 52 | 29 to 36 in logs, up to 41 | not given | Sulfate 38 to 1,300 ppm [4] | ### What the numbers show - **The swell is in the subsoil.** Kirkland's surface layer tested at PI 4, while its subsoil tested at PI 30 to 32 [1]. The study described Kirkland as an "inherently unstable soil" because of its high, montmorillonite-dominated clay content [1]. - **Shrink-swell is measurable.** Kirkland and Bethany subsoils had COLE values up to 0.090 and 0.095 [1]. - **Predicted heave.** The McClain County report estimated a potential vertical rise of 2.8 inches, against a commonly tolerated maximum of 0.75 inch [4]. Potential vertical rise is an estimate of how far the ground surface could heave if the clay became fully wet. ### The rock vs the soil The USGS cored Hennessey shale at Lake Hefner after drilling through about 6.4 meters (21 feet) of soil and surface clay [6]. The principal clay minerals in the shale were illite and kaolinite, both with low shrink-swell potential [6]. Thin gypsum lenses appeared at about 19 to 24 meters [6]. By contrast, the soils studied in Canadian County had fine clays dominated by montmorillonite [1]. This contrast is why the Hennessey shale (https://terrabrain.vercel.app/geology/hennessey-shale-group) page treats the weathered soil zone and the rock below separately. ## What do soil tests show in the Tulsa area? City of Tulsa boring reports provide measured values on weathered shale ground: - E 91st St between Memorial and Mingo: LL about 27 to 56 and PI about 9 to 39 across the borings [5]. - The highest single sample tested at LL 56 and PI 39 [5]. For more Tulsa borings, see depth to rock from borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings). ## What do soil tests show in southern and western Oklahoma? - **Durant (south-central):** the NRCS series description says upper subsoil horizons are 40 to 60% clay and that cracks more than 1 cm wide and 30 inches deep form during dry periods [8]. See Durant (https://terrabrain.vercel.app/soils/durant). - **Vernon soil (Major County):** lean clay with PI about 11 to 15 but soluble sulfate of 15,400 ppm [3]. Adding 3% lime increased its swell by 1,237%, which the researchers attributed to formation of the expansive mineral ettringite [3]. See Vernon (https://terrabrain.vercel.app/soils/vernon). - **Carnasaw (southeast):** fat clay with LL about 58 and PI 29 [3]. The Vernon result shows why sulfate, not just PI, matters when chemical treatment is considered. More on that in stabilization research (https://terrabrain.vercel.app/data/stabilization-research). ## Related - Soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values) - Shrink-swell and active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Stabilization research (https://terrabrain.vercel.app/data/stabilization-research) - Kirkland soil (https://terrabrain.vercel.app/soils/kirkland) - Renfrow soil (https://terrabrain.vercel.app/soils/renfrow) Sources: [1] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma Agricultural Experiment Station, Oklahoma State University https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [2] Report FHWA-OK-13-06 (ODOT SP&R Item 2242), University of Oklahoma, Oklahoma Department of Transportation / U.S. DOT ROSA P https://rosap.ntl.bts.gov/view/dot/31441/dot_31441_DS1.pdf [3] Engineering Properties of Stabilized Subgrade Soils for Implementation of the AASHTO 2002 Pavement Design Guide (FHWA-OK-08-10), Oklahoma Department of Transportation https://www.odot.org/hqdiv/p-r-div/spr-rip/library/reports/fhwa-ok0810.pdf [4] Subsurface Exploration, New ODOT Maintenance and Residency Facilities, Oklahoma Department of Transportation https://oklahoma.gov/content/dam/ok/en/odot/procurement/open/26-FM-0017_Geotech_Report.pdf [5] Geotechnical Engineering Report, Retaining Walls A and B Along 91st Street South from South Memorial Drive to South Mingo Road, City of Tulsa https://www.cityoftulsa.org/media/25588/geotechnical-report-retaining-walls.pdf [6] Geologic and Hydraulic Characteristics of Selected Shaly Geologic Units in Oklahoma (WRI 96-4303), U.S. Geological Survey https://pubs.usgs.gov/wri/1996/4303/report.pdf [7] Abstract: Geologic Hazards in Oklahoma, Geological Society of America (Oklahoma Geological Survey author) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [8] Official Series Description - DURANT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DURANT.html --- # What do soil test numbers for expansive clay mean? URL: https://terrabrain.vercel.app/guides/soil-testing-and-lab-values Answer: The plasticity index from Atterberg limits is a common quick indicator of shrink-swell, while swell tests measure movement and pressure directly. In short: Lab tests show how much a clay soil can shrink and swell. The plasticity index from the Atterberg limits test is a common quick indicator, while swell tests measure movement and pressure directly. Results only describe the samples tested, so the number and depth of borings matter as much as the lab values. ## What are the main soil tests? | Test | What it measures | Notes | |---|---|---| | Atterberg limits | Liquid limit and plastic limit; the difference is the plasticity index (PI) | One of the listed methods for identifying expansive clay [1] | | Activity | PI compared with clay content | Used to identify swelling clays [1] | | Free swell, swell pressure, expansion index | How much a sample swells and how hard it pushes | Swell pressure tests are seldom run; designers often use correlations instead [1] | | Coefficient of linear extensibility (COLE) | Change in length between wet and dry states | Used in soil surveys and research [1][3] | | Potential vertical rise (PVR) | Estimated inches of heave at the surface | A method used in Texas practice [2][6] | | Borings with lab samples | Soil layers, depth to rock, samples for testing | Basis of a geotechnical report [4] | ### Plain-English definitions - **Liquid limit**: the moisture content at which a soil starts to flow like a thick liquid. - **Plastic limit**: the moisture content below which the soil crumbles instead of rolling into a thread. - **Plasticity index (PI)**: liquid limit minus plastic limit. A higher PI means the clay can hold more water while still moldable, which generally means more swell. ## How do you read the plasticity index? A commonly cited structural engineering rule of thumb [2]: - PI below about 20: only marginally expansive - PI above about 40: highly expansive Regional correlations link PI to swell pressure. In TRB material, expected swell pressure rises from about 2.0 to 5.0 kips per square foot as PI goes from 30 to 60 for the Houston area, and from 3.0 to 6.0 for Dallas, San Antonio and Austin [1]. Oklahoma-specific correlations should come from local engineering data. ## What do Oklahoma lab results show? An Oklahoma State University study of benchmark soils measured liquid limits, plasticity and swell [3]: | Soil | Lab finding | Building-site rating | |---|---|---| | Kirkland | Subsoil liquid limit above 50%; very plastic and highly expansive | Severe for low buildings | | Bethany | About medium liquid limits and plasticity; appreciable but not extreme swelling clays | Moderate | | Norge | Liquid limit above 30%; relatively low in swelling clays | Moderate | | Sandy soils (Grandfield, Nobscot) | Little or no plasticity; low shrink-swell | Slight | The same study found the fine clays were dominantly montmorillonite, a swelling clay, and that calcium carbonate in the lower Bethany horizons may have depressed natural shrink-swell [3]. See the Kirkland (https://terrabrain.vercel.app/soils/kirkland) and Bethany (https://terrabrain.vercel.app/soils/bethany) soil pages. ## Why does the moisture state matter? The same clay can show different behavior depending on how dry it is when tested. A study of clay sites during the 2011 drought found the drought increased the soils' potential vertical rise, meaning more possible heave once they rewet [6]. Researchers at Oklahoma State University describe newer design methods based on soil suction, a measure of how strongly dry soil pulls in water [5]. ## How many borings and samples are needed? How a site is sampled shapes what the lab can report. As one example of a written requirement, a Virginia county policy for expansive soil areas calls for [4]: - at least two borings within the building footprint; - borings at least 5 feet deep, or to refusal on non-expansive material, and at least 12 inches below planned footing depth; - a lab sample from the weakest soil within 12 inches below the footing; and - a signed report with boring logs, a site sketch and lab results. Oklahoma cities set their own rules; see codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits). For how engineers use these results, see working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). ## Related - Clay Mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - OK Data - Soil Lab Values (https://terrabrain.vercel.app/data/soil-lab-values) - Chemical Soil Stabilization (https://terrabrain.vercel.app/repairs/chemical-soil-stabilization) - Inspection Protocol (https://terrabrain.vercel.app/guides/inspection-protocol) Sources: [1] TRB Webinar: Foundations in Shrink Swell Soil: Innovation and State of Practice, Transportation Research Board, National Academies https://www.nationalacademies.org/cdn/materials/a067d915-1c17-4a16-840d-06452b68646c [2] Expansive Soils (The Mystery), STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [3] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma Agricultural Experiment Station, Oklahoma State University https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [4] County Expansive Soils Policy & Procedures (Commercial & Residential Projects), Roanoke County, Virginia, Development Services https://roanokecountyva.gov/DocumentCenter/View/1020 [5] Residential House Foundations on Expansive Soils in Changing Climates, HUD Office of Policy Development and Research (Cityscape, Vol. 25 No. 1) https://www.huduser.gov/PORTAL/periodicals/cityscape/vol25num1/ch10.pdf [6] Ground Conditions in the 2011 Drought, CIGMAT Conference, University of Houston https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2012/3.pdf --- # What does a full foundation inspection include? URL: https://terrabrain.vercel.app/guides/inspection-protocol Answer: It covers desk research, a homeowner interview, exterior and interior walks, a floor elevation survey, a crawl space or basement check and a report. In short: A full foundation assessment moves from background research to an interview about the home's history, a walk around the outside and inside, a floor elevation survey, a crawl space or basement check where present, and a written report. Engineering guidelines describe these steps in levels, from a walk-through "first impressions" visit up to one with soil sampling and plumbing tests. Each step feeds the main question: what is moving, and why. ## What are the levels of investigation? The Texas Section of the American Society of Civil Engineers (ASCE) defines three levels of residential foundation investigation [1]: | Level | What it adds | |---|---| | A | Interview, document review, visual walk-through, factors affecting performance; a "report of first impressions" | | B | Level A plus relative floor elevations (accounting for floor finishes) and a drawing of them | | C | Levels A and B plus tests such as soil sampling, plumbing testing and detailed distress or tree surveys | The Foundation Performance Association (FPA) uses a similar structure, with a survey elevation plan and a plan of observed distress at Level B [2]. ## 1. What desk research happens before the visit? Background on the lot can be gathered before anyone arrives: - **Soil map.** Web Soil Survey, the USDA soil map, shows the mapped soil series, soil data and use ratings for a chosen area of interest [4]. See the Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index). - **Flood map.** FEMA's Flood Map Service Center can be searched by address for the flood map panel and a printable flood map for that location [5]. - **Weather.** The Oklahoma Mesonet runs 120 automated weather stations with at least one in every county, giving local rainfall records for the weeks before a visit [6]. See Mesonet for foundation pros (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros). ## 2. What is asked in the homeowner interview? ASCE Texas guidelines call for interviewing the occupant, owner and client, where possible, about the property's history and the structure's performance, and reviewing any documents such as construction drawings or geotechnical reports [1]. Topics that bear on soil moisture and movement include: - Whether cracks show progressive or seasonal movement [7] - Water bills, known leaks and plumbing work; the ASCE homeowner guide recommends monitoring water bills along with foundation performance [7] - Sprinkler location and watering habits [7] - Trees planted or removed near the house [1][7] - Earlier repairs and their records [2] ## 3. What is checked on the exterior walk? The exterior walk records cracks in brick, gaps at windows and doors, and separation of flatwork from the house [7]. The ASCE homeowner guide recommends checking that the ground within 5 feet of the foundation drains water away [7]. Home inspection standards likewise include grading, surface drainage and retaining walls where they may affect the structure through moisture [3]. See surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). ## 4. What is checked on the interior walk? FPA's guideline calls for recording distress on every interior level and the exterior, noting whether it is on a wall, ceiling or floor, its position relative to doors and windows, and any sign of earlier repair; crack widths may also be recorded [2]. A crack width scale such as the UK Building Research Establishment categories grades cracks from hairline to over 25 mm, and also weighs the number of cracks and whether they are growing [8]. Patterns are explained in the distress pattern library (https://terrabrain.vercel.app/guides/distress-pattern-library). ## 5. How is the elevation survey done? The floor elevation survey is the Level B step [1]. FPA calls for an instrument accurate to 1/8 inch or better, a repeatable reference point and readings about every 30 to 100 square feet, corrected for floor coverings [2]. Details are on elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). ## 6. What is checked in the crawl space or basement? Home inspection standards require describing the foundation type and the crawl space access, and reporting active water penetration, wood in contact with soil and signs of possible foundation movement [3]. Inspectors are not required to enter crawl spaces that are not readily accessible or where entry could endanger them [3]. ## 7. How are the findings analyzed? Distress locations are compared with the elevation contour map, the likely mechanism is identified (see heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement)), and moisture sources are listed. Level C adds tests the engineer considers appropriate, such as soil sampling and plumbing testing [1]. ASCE Texas guidelines call for testing water and drain lines when lifting is part of the repair [1]. ## 8. What goes in the written report? ASCE Texas guidelines list possible report contents such as the authorization and scope, property description, information sources, collected data, assumptions, analysis, conclusions, recommendations and limiting conditions [1]. FPA adds a list of reviewed documents, the survey elevation plan and the distress plan for a Level B report [2]. ### Home inspection versus engineering evaluation Home inspection standards require reporting possible foundation movement, such as cracked drywall or brick, out-of-square door frames and unlevel floors, but state that inspectors are not required to provide engineering services or report on the adequacy of structural systems [3]. See working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). ## Related - Elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) - Heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Method selection matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix) - Real estate, disclosure and inspections (https://terrabrain.vercel.app/rules/real-estate-disclosure-and-inspections-foundation-issues-in-oklahoma) - Symptom matrix (https://terrabrain.vercel.app/guides/symptom-matrix) Sources: [1] Guidelines for the Evaluation and Repair of Residential Foundations, Version 2, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2022/05/Guidelines-for-the-Evaluation-and-Repair-of-Residential-Foundations-V2-2008.pdf [2] Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings (FPA-SC-13-0), Foundation Performance Association https://www.foundationperformance.org/projects/super/FPA-SC-13-0.pdf [3] Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [4] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [5] FEMA Flood Map Service Center, Federal Emergency Management Agency https://msc.fema.gov/portal/search [6] About the Mesonet, Oklahoma Mesonet (University of Oklahoma and Oklahoma State University) https://www.mesonet.org/about [7] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [8] Assessing cracks in houses, BRE Group https://wpe.bregroup.com/insights/assessing-cracks-in-houses/ --- # What does a gap at the frieze board above brick mean? URL: https://terrabrain.vercel.app/signs/frieze-board-or-trim-separation Answer: A gap between the top of the brick and the frieze board often means the foundation edge carrying the brick has dropped, commonly as perimeter clay dries. In short: A gap opening between the top of the brick and the frieze board under the eaves, or at exterior trim corners, often means the foundation edge carrying the brick has dropped. On Oklahoma's expansive clay, this is commonly tied to soil drying and shrinking at the perimeter. A gap that is wider at one corner and grows in late summer points that way. ## How does the gap form? On a brick home, the brick veneer is a single layer of brick standing on the outer ledge of the foundation, while the roof, soffit and frieze board are attached to the wood framing. The frieze board covers the joint where the top of the brick meets the framing. When the foundation edge settles, the brick goes down with it, but the roof and trim stay where they are, so a gap opens under the frieze board. The gap is usually widest above the corner or section that dropped the most. ## What is edge drop? This site links the sign to perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). Expansive clay shrinks as it dries [2]. Engineering guidance on expansive soil notes that lack of watering during drought, which dries out the clay, can be more damaging than overwatering, and that tree roots extending under a foundation can cause shrinkage and settlement [4]. Texas monitoring found that slabs on expansive clay settled through the growing season, that drought made it worse, and that winter brought partial recovery [3]. In Oklahoma, more than 75% of the state has bedrock that can produce expansive soils [5]. See shrink-swell and active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) and drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles). ## What signs usually come with it? - Stair-step brick cracks wider at the top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top) on the same wall. - Brick separating from window or door frames (https://terrabrain.vercel.app/signs/brick-separating-from-window-or-door-frame). - Soil pulled away from the foundation (https://terrabrain.vercel.app/signs/soil-pulled-away-from-foundation) in dry weather. - Cracks around interior doors and windows on that side; on shrinkable clay, cracks typically need about 5 to 10 millimeters of movement to appear [6]. Home inspection standards list brick cracks and out-of-square door frames among signs of possible foundation movement to report [1]. ## When might it not be the foundation? A gap at trim does not always come from the foundation. Signs pointing away from the foundation include a gap that is even along a whole wall, no cracking in the brick below, and no matching interior signs. Signs pointing toward the foundation include a gap that tapers, wider at one corner, plus brick cracks and sticking openings on the same side. ## How do you document it? 1. Measure the gap at evenly spaced points along each wall, and at every corner. 2. Photograph each point with a ruler in view. 3. Note which corner has the widest gap and check the brick below it for cracks. 4. Repeat through a summer and a winter; monitoring of slabs on expansive clay found settlement through the growing season and partial recovery in winter [3]. 5. Add the corners to an elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys). ## What are the next steps? Compare with the distress pattern library (https://terrabrain.vercel.app/guides/distress-pattern-library) and the symptom matrix. ## Related - Perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Stair-step brick crack wider at top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top) - Brick separating from window or door frame (https://terrabrain.vercel.app/signs/brick-separating-from-window-or-door-frame) - Cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally) - Root barriers and moisture control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control) Sources: [1] Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [2] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [3] Cyclical Foundation Movements and Their Remediation, CIGMAT, University of Houston (conference presentation) https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2007/addison.pdf [4] Irrigation, Drainage, and Landscaping for Expansive Soil, Journal of Irrigation and Drainage Engineering (ASCE) https://ascelibrary.com/doi/10.1061/%28ASCE%290733-9437%281992%29118%3A2%28285%29 [5] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [6] Trees near buildings, Royal Horticultural Society https://www.rhs.org.uk/plants/types/trees/near-buildings --- # What does a gap under the baseboard mean for my foundation? URL: https://terrabrain.vercel.app/signs/gaps-under-baseboards Answer: It shows the floor and the bottom of a wall have moved apart, a listed sign of foundation movement on shrink-swell clay. A floor survey shows which part moved. In short: A gap opening between the floor and the bottom of a baseboard, or a baseboard that has been pushed up, shows that the floor and the wall have moved by different amounts. On Oklahoma's shrink-swell clay that can come from the floor rising or from it dropping. The gap alone does not say which; a floor elevation survey and the pattern of other signs do. ## What does this sign look like? - A visible gap between the floor and the bottom edge of a baseboard, often wider at one end of the wall. - Flooring that has dropped away from the trim, leaving the baseboard hanging above it. - A baseboard that has been pushed up, with its top joint or caulk line cracked. - Gaps on exterior walls, interior walls, or both. A homeowner guide from the American Society of Civil Engineers lists the bottom of a wall separating from the floor among interior signs of foundation distress on shrink-swell soils, along with sloping floors and cracks in walls or ceilings [1]. Texas civil engineering guidance lists walls separating from ceilings or floors as a visible sign of inadequate foundation performance [2]. ## Why does the floor pull away from the wall? Baseboards are nailed to the wall, and the wall and floor are separate parts of the house. When the soil under one part of the foundation moves more than under another, the floor surface and the bottom of the wall shift relative to each other, and the joint between them opens or closes. **Expansive clay** (also called shrink-swell clay) is the main reason this happens in Oklahoma. Soil with high moisture swells and lifts a building, while soil that dries out shrinks and lets it settle [4]. Oklahoma State University testing of western Oklahoma benchmark soils found clays dominated by montmorillonite, with Kirkland subsoil rated high for shrink-swell and Bethany and Norge rated moderate [7]. ## Which movements can open the gap? - **Edge lift** (perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift)): soil under the perimeter becomes wetter than under the interior and swells [3]. - **Center lift or edge drop** (perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop), center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab)): soil around the perimeter dries and shrinks [3]. - **Corner lift**: on a uniformly loaded rectangular slab, the corners press on the soil with about one-fourth the pressure of the center, so corners tend to lift relative to the middle when clay swells [5]. - **Heave after tree removal** (post-tree-removal heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave)): removing a tree may cause upheaval as soil moisture increases, especially if the tree predates the house [2]. | Where the gap is | What it can point to | Check next | |---|---|---| | Along exterior walls | Perimeter movement, either edge lift or edge drop [3] | Soil pulled away from foundation (https://terrabrain.vercel.app/signs/soil-pulled-away-from-foundation), drainage near the wall | | On interior walls near the middle | Center lift or interior movement [3] | Interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump) | | Near where a large tree was removed | Soil moisture rising after removal [2] | Floor survey around that side | | Changes between wet and dry months | Seasonal shrink and swell; seasonal moisture change in clay can reach 3 to 40 ft deep [5] | Cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally) | Engineers call the depth where seasonal moisture change happens the **active zone** [5]. ## How is it documented? - Gap width at each location, the wall it is on and the date. - Repeat readings over time, since the ASCE homeowner guide advises monitoring existing cracks for progressive or seasonal movement [1]. - Nearby signs: sloping floors (https://terrabrain.vercel.app/signs/sloping-floors), doors binding or tapered gaps (https://terrabrain.vercel.app/signs/doors-binding-or-tapered-gaps), diagonal drywall cracks at openings (https://terrabrain.vercel.app/signs/diagonal-drywall-cracks-at-openings). - A floor elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys). Engineering guidance notes a single survey shows the foundation's shape at one moment and should not be the only basis for judging deflection and tilt [2]. Engineering guidance also notes that seeing some listed conditions does not necessarily mean the foundation is performing inadequately [2]. Home inspection standards require inspectors to report possible foundation movement, including unlevel floors, but not to report on the adequacy of any structural system [6]. ## Related - Distress Pattern Library (https://terrabrain.vercel.app/guides/distress-pattern-library) - Symptom Matrix (https://terrabrain.vercel.app/guides/symptom-matrix) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Elevation Surveys (https://terrabrain.vercel.app/guides/elevation-surveys) Sources: [1] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [2] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [3] Residential House Foundations on Expansive Soils in Changing Climates, U.S. Department of Housing and Urban Development, Cityscape https://www.huduser.gov/PORTAL/periodicals/cityscape/vol25num1/ch10.pdf [4] Foundations on Expansive Soils – Residential (IHB TB 10-01), Texas Department of Licensing and Regulation https://tdlr.texas.gov/ihb/pdf/TB1001.pdf [5] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [6] InterNACHI Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [7] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf --- # What does a horizontal crack at the brick ledge or slab edge mean? URL: https://terrabrain.vercel.app/signs/horizontal-crack-at-brick-ledge-or-slab-edge Answer: It can come from brick and concrete moving against each other, the slab edge lifting or dropping, or frost or soil pressure; a floor survey helps tell which. In short: A horizontal crack along the base of brick veneer or the outside edge of a slab can come from the brick and concrete moving against each other, from the slab edge lifting or dropping with the soil, or from frost or soil pressure on shallow walls. The crack alone does not tell you which; its width, any offset, and an elevation survey of the floor do. ## What does this crack look like? The **brick ledge** is the narrow shelf at the outside edge of a slab or grade beam (a thickened concrete beam around the perimeter) where the first row of brick sits. This sign is a crack that runs roughly level along that line, either through the top of the concrete edge or in the mortar joint just above it. It is common on slab-on-grade (https://terrabrain.vercel.app/foundations/slab-on-grade) and post-tensioned (https://terrabrain.vercel.app/foundations/post-tensioned-slabs) houses and also appears on stem walls (https://terrabrain.vercel.app/foundations/stem-wall-and-grade-beam) and basement walls. ## Why does it happen? ### Brick and concrete move in opposite directions Fired clay brick takes on moisture and expands permanently, with most of that growth in the first weeks after firing and a slower rate for years [1]. Concrete does the opposite and shrinks as it cures [1]. Where brick bears directly on concrete, that mismatch creates shear stress that can crack the concrete or pull the brick away at a corner unless a bond break or flashing separates them [1]. Brick industry guidance calls for a bond break, such as flashing, building paper or polyethylene sheeting, between foundations and brick walls for this reason [2]. This is a materials issue, not soil movement; see material shrinkage and thermal cracking (https://terrabrain.vercel.app/causes/material-shrinkage-and-thermal-cracking-mimic). ### The slab edge lifts or drops with the soil Oklahoma sits in a region where expansive clay is widespread [3]. Expansive clay swells when it gets wetter and shrinks when it dries. Under a slab, the perimeter can rise as the soil swells and fall as it shrinks, so the edge may move up or down through the seasons [3]. Because the corners of a uniformly loaded slab press on the soil with about one-fourth the pressure of the center, they tend to rise relative to the middle when clay swells [4]. A slab edge that rotates or rises this way can open a horizontal crack at the ledge. This pattern is described under perimeter wetting heave (edge lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift). ### Frost and soil pressure on shallow walls Swelling or frost heaving of saturated soil can bend shallow masonry or block walls and produce horizontal cracks [5]. Inspection guidance suggests suspecting frost heave (https://terrabrain.vercel.app/causes/frost-heave) when damage sits above the local frost depth or appeared after a cold snap, and checking for broken downspouts or poor drainage when expansive soil is suspected [5]. On basement or stem walls, the same horizontal crack can come from soil pushing inward; see lateral earth and hydrostatic pressure (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls). ## How are the causes told apart? | What you see | Points toward | |---|---| | Thin crack at the ledge, little or no offset, brick fairly new | Brick expansion against concrete shrinkage [1] | | Crack with the slab edge visibly higher than nearby floor | Edge lift from soil swelling [3] | | Crack that appeared after a hard freeze, in shallow masonry | Frost heave [5] | | Horizontal crack in a shallow or below-grade wall that is bent | Swelling or frozen saturated soil pressing on the wall [5] | ## How is it documented? - **Width and offset.** Record the crack width and whether one side sits higher or farther out than the other. A clean crack edge suggests recent movement, while a dirty or previously filled crack may be inactive [5]. - **Change over time.** A crack monitor can record movement; cyclical movement may take six months or more to measure [5]. - **Floor elevations.** Engineering guidance treats a relative floor elevation survey as the step that goes beyond a visual first impression [6]. A plotted survey shows whether the edge is high or low compared with the interior. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). ## Related - Perimeter Wetting Heave (Edge Lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) - Frost Heave (https://terrabrain.vercel.app/causes/frost-heave) - Freeze-Thaw and Frost Depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) - Distress Pattern Library (https://terrabrain.vercel.app/guides/distress-pattern-library) - Symptom Matrix (https://terrabrain.vercel.app/guides/symptom-matrix) Sources: [1] Volume Changes – Analysis and Effects of Movement (Technical Note 18), Brick Industry Association https://gobrick.com:443/media/file/18-tn18.pdf [2] Accommodating Expansion of Brickwork (Technical Note 18A), Brick Industry Association https://www.gobrick.com/media/file/18a-tn18a.pdf [3] The Mystery of Expansive Soils, STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [4] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [5] Inspecting Foundation Walls and Piers, International Association of Certified Home Inspectors (InterNACHI) https://www.nachi.org/documents2012/Inspecting_Foundation_Walls_and_Piers-revised-January-2013.pdf [6] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf --- # What does a horizontal crack or bow in a basement wall mean? URL: https://terrabrain.vercel.app/signs/horizontal-crack-or-inward-bow-in-basement-wall Answer: It usually means soil outside is pushing the wall harder than it was built to resist, from wet soil, swelling clay, frozen soil or poor backfill. In short: A horizontal crack or inward bow in a basement wall usually means the soil outside is pushing the wall sideways harder than it was built to resist. Wet soil, swelling clay, frozen soil and poor backfill are the common sources of that pressure, and water control is part of every fix. ## What does this sign look like? The crack runs roughly level along a poured concrete or concrete block wall, often near mid-height, and the wall above or below it may lean or bulge into the room. In block walls the crack can also follow the mortar joints in a stair-step line before turning horizontal. Inspection guidance describes this kind of horizontal or "sweeping" crack as potentially serious because the wall has been bent or broken [1]. It applies to basements (https://terrabrain.vercel.app/foundations/basements) and, less often, to below-grade crawl space walls [2]. ## Why do basement walls get pushed in? A basement wall works like a retaining wall: soil presses against the outside face, and the wall must resist it. The general name for this is **lateral pressure**, meaning sideways force. When that force grows, the wall cracks and moves inward. The mechanism is covered in lateral earth, swell and hydrostatic pressure on walls (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls). ### Saturated soil and water pressure **Hydrostatic pressure** is the push of water held in the soil. Saturated soil against the outside of a foundation wall pushes it inward, producing a horizontal crack wider than a hairline, usually with signs of water coming through [2]. Clogged drains let that water pressure build up against the wall [1]. ### Swelling clay and frost Swelling or frost heaving of saturated soil is listed as a cause of horizontal wall cracks, and frozen soil exerts more force than wet soil [1]. Expansive clay is widespread across much of Oklahoma [5], and building guidance advises against using silt, heavy clay or expansive clay as backfill against basement walls, favoring granular soil instead [3]. ### Backfill and vibration Improper backfilling and vibration from heavy equipment nearby are also listed causes [1]. Poor backfill matters for water too: guidance states that most damp foundations come from improper surface drainage and poor backfill procedures [3]. ## How is it documented? - **Crack pattern and width.** Note whether the crack is horizontal, stair-stepped or both, and whether water stains or white mineral deposits are present. A clean crack suggests recent movement, while a dirty or filled crack may be older [1]. - **Amount of bow or lean.** Measure how far the wall is out of plumb at its worst point. A common rule says a wall is usually considered unsafe if a plumb line through its center of gravity falls outside the middle third of its base, and that a structural engineer should be consulted in that case [1]. - **Change over time.** Crack monitors can record movement; seasonal movement may take six months or more to show [1]. - **Outside conditions.** Check downspouts, grading and drains, since broken downspouts and poor drainage are tied to these cracks [1]. ## What repair approaches exist? Inspection guidance lists careful jacking, interior buttresses, epoxy grout injection, and lowering the outside grade to reduce pressure as repair approaches [1]. Large bulges are described as needing to be tied back to the structure, while small ones may be pinned or rebuilt [1]. On the water side, basement walls on wet sites are described as needing waterproofing and a sump pump, and below-grade space should not sit below the highest seasonal water table [3]. Typical construction practice was found to produce some water problem in as many as 1 in 3 basements within two years [4]. See basement wall repair (https://terrabrain.vercel.app/repairs/basement-wall-repair) and drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). ## Related - Basements (https://terrabrain.vercel.app/foundations/basements) - Lateral Earth, Swell & Hydrostatic Pressure on Walls (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls) - Water at Cove Joint or Efflorescence (https://terrabrain.vercel.app/signs/water-at-cove-joint-or-efflorescence) - Basement Wall Repair (https://terrabrain.vercel.app/repairs/basement-wall-repair) - Groundwater and Perched Water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) Sources: [1] Inspecting Foundation Walls and Piers, International Association of Certified Home Inspectors (InterNACHI) https://www.nachi.org/documents2012/Inspecting_Foundation_Walls_and_Piers-revised-January-2013.pdf [2] Foundation Crack from Lateral Movement and Hydrostatic Pressure, International Association of Certified Home Inspectors (InterNACHI) https://nachi.org/gallery/settlement-and-cracks/lateral-movement-foundation-cracks [3] A Professional's Guide to Durable Home Design: Durability by Design, 2nd Edition, U.S. Department of Housing and Urban Development https://www.HUDUser.gov/portal/sites/default/files/pdf/Guide-Durability-by-Design.pdf [4] Durability by Design: A Guide for Residential Builders and Designers, U.S. Department of Housing and Urban Development https://www.huduser.gov/publications/pdf/durability_by_design.pdf [5] The Mystery of Expansive Soils, STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf --- # What does a stair-step brick crack wider at the bottom mean? URL: https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-bottom Answer: It suggests the wall was pushed apart from below, often as swelling clay lifted part of the foundation. An elevation survey confirms heave or settlement. In short: A stair-step crack in brick that is wider at the bottom than the top suggests the wall has been pushed apart from below. On Oklahoma's expansive clay, that often means part of the foundation has risen as the soil swelled, but a neighboring section settling can look similar, so the reading is confirmed with a floor elevation survey. ## What does this crack look like? The crack steps through the mortar joints in a staircase line, usually from a corner, window or door, and it opens widest near its lower end, closing to a hairline higher up. Stair-step cracking in brick veneer is a well-documented distress pattern on expansive soils [1]. ## What does the taper tell you? Movement cracks in brick taper, wide at one end and hairline at the other [3][4]. The wide end marks where the wall has separated most. When the bottom is wider, the base of the wall has spread apart, which fits the area under one side of the crack pushing up, or the area on the other side dropping. Neither source gives a single rule for taper direction, so the floor survey decides. For the opposite pattern see stair-step crack wider at top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top). ## What are the common causes? ### Edge lift from swelling clay **Heave** is upward movement of a foundation caused by soil swelling. Expansive clay absorbs water and swells, and upward movements of 6 to 8 inches or more have been reported in central Texas clays [1]. Under a slab, the perimeter can rise when the soil swells and drop when it shrinks [1]. Because the corners of a uniformly loaded slab press down on the soil less than the middle, they tend to lift relative to the center [2]. Poor drainage and lawn watering that wet the soil unevenly are named contributors [1][2]. See perimeter wetting heave (edge lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) and water ponding near the foundation (https://terrabrain.vercel.app/signs/water-ponding-near-foundation). ### Heave after a tree is removed Trees draw water out of clay. Soil where a tree was removed shortly before construction may be drier than its surroundings and subject to localized heave [5]. Repair guidance notes that removing a tree can halt or partly reverse settlement but can also cause heave, especially for trees that predate construction, and that a waiting period may be recommended [6]. See post-tree-removal heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave). ### Movement after a pier repair Inadequately anchored piers can be lifted by swelling clay, and insufficient vertical reinforcement can let uplift pull a pier apart; even the full weight of the structure is usually not enough to resist expansive forces [1]. A crack that reopens after a repair is covered under pier uplift or movement after repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair). ## How is heave or settlement confirmed? | Survey result near the crack | Reading | |---|---| | Area under the narrow end is high compared with the rest of the house | Heave of that area | | Area on the other side is low | Settlement of the neighboring area | | Floor high near the crack and a recent tree removal or leak nearby | Localized heave | - **Elevation survey.** A relative floor elevation survey, drawn on a plan, is the engineering step beyond a visual first impression [6]. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). - **Crack activity.** A clean crack edge suggests recent movement; a dirty or previously filled crack may be inactive [4]. - **Monitoring.** Cyclical movement may take six months or more to measure with a crack monitor [4]. The distinction matters because the two are managed differently; see heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). ## Related - Stair-Step Brick Crack Wider at Top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top) - Perimeter Wetting Heave (Edge Lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) - Post-Tree-Removal Heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Cracks That Open and Close Seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally) Sources: [1] The Mystery of Expansive Soils, STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [2] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [3] Volume Changes – Analysis and Effects of Movement (Technical Note 18), Brick Industry Association https://gobrick.com:443/media/file/18-tn18.pdf [4] Inspecting Foundation Walls and Piers, International Association of Certified Home Inspectors (InterNACHI) https://www.nachi.org/documents2012/Inspecting_Foundation_Walls_and_Piers-revised-January-2013.pdf [5] Recommended Practice for the Design of Residential Foundations, Version 2, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Recommended-Practice-for-the-Design-of-Residential-Foundations-V2-2007.pdf [6] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf --- # What does a stair-step brick crack wider at the top mean? URL: https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top Answer: It usually points to settlement: part of the foundation below dropped. On Oklahoma clay, soil drying under the slab edge, often near trees, is most common. In short: A stair-step crack in brick that is wider at the top than the bottom usually points to settlement, meaning part of the foundation below the crack has dropped and the wall has pulled apart above it. On Oklahoma clay, the most common reason is soil drying and shrinking under the slab edge, often near trees, but the crack is read together with a floor elevation survey before drawing conclusions. ## What does this crack look like? The crack follows the mortar joints in a staircase line, usually starting near a corner, window or door, and it is visibly wider at its upper end and closes to a hairline lower down. Stair-step cracking in brick veneer is among the damage that differential movement on expansive soils causes [3]. ## What does the taper tell you? Brick industry guidance states that foundation settlement, especially on unstable or expansive soils, can cause diagonal or stepped cracks in brick and mortar directly above the foundation, and that settlement and deflection cracks have a tapering shape [1]. Inspection guidance adds that rapid settlement produces tapering cracks, wide at one end and hairline at the other, often along mortar joints near corners and openings [2]. The wide end marks where the two parts of the wall have separated most. When the top is wider, the section of wall on one side has typically rotated down and away, which is the pattern associated with the foundation dropping under the lower end of the crack. Because neither source sets a fixed rule for reading taper direction, the pattern is confirmed by measuring the floor. A crack that is wider at the bottom is covered on its own page: stair-step crack wider at bottom (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-bottom). ## What commonly causes this crack? | Cause | How it drops part of the foundation | |---|---| | Perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) | Clay under the slab edge shrinks and the perimeter drops [3] | | Tree-root desiccation (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) | Trees and large shrubs withdraw soil water, causing downward movement [4] | | Differential movement at additions (https://terrabrain.vercel.app/causes/differential-movement-at-additions) | Settlement cracks form at joints with porches, bay windows and additions [2] | | Slope creep (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement) | Clay on slopes can slowly drift downhill, causing settlement [2] | | Karst subsidence (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes) | Sinkholes and caverns in soluble rock can cause land settlement [6] | | Pier movement after repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair) | Inadequately anchored piers can move with the soil [3] | Settlement from fill, soft alluvial soil and collapsible soil are other listed mechanisms, covered in the causes section. ### Oklahoma context Most of Oklahoma has expansive soils, and seasonal drying lets a slab perimeter drop [3]. Karst, meaning rock that groundwater can dissolve, occurs in limestone in the northeast Ozark area and the Arbuckle Mountains and in gypsum and salt in many parts of western Oklahoma [6]. ## How is this crack documented? - **Width at both ends.** Measure the crack at the top and bottom with a crack-width card, and photograph it with a scale in the frame. - **Age and activity.** A clean crack edge suggests recent movement; a dirty or previously filled crack may be inactive [2]. Width is read against building age: a half-inch crack in a new building may mean rapid settlement, while in a 50-year-old building it may reflect about 1/100 inch of movement per year [2]. - **Monitoring.** Crack monitors can record movement over time; cyclical movement may take six months or more to measure [2]. - **Elevation survey.** A relative floor elevation survey is the engineering step beyond a visual first impression [5]. A low area near the bottom end of the crack supports a settlement reading. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). ## Related - Stair-Step Brick Crack Wider at Bottom (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-bottom) - Perimeter Drying Settlement (Edge Drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Distress Pattern Library (https://terrabrain.vercel.app/guides/distress-pattern-library) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) Sources: [1] Volume Changes – Analysis and Effects of Movement (Technical Note 18), Brick Industry Association https://gobrick.com:443/media/file/18-tn18.pdf [2] Inspecting Foundation Walls and Piers, International Association of Certified Home Inspectors (InterNACHI) https://www.nachi.org/documents2012/Inspecting_Foundation_Walls_and_Piers-revised-January-2013.pdf [3] The Mystery of Expansive Soils, STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [4] Recommended Practice for the Design of Residential Foundations, Version 2, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Recommended-Practice-for-the-Design-of-Residential-Foundations-V2-2007.pdf [5] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [6] Mapping of Karst Terranes in Oklahoma to Identify Potential Environmental and Hydrologic Problems, AAPG Search and Discovery (Oklahoma Geological Survey author) https://www.searchanddiscovery.com/abstracts/html/1995/midcon/abstracts/1403b.htm --- # What does it mean when clean-edged cracks appear suddenly? URL: https://terrabrain.vercel.app/signs/fresh-clean-edged-cracks-appearing-suddenly Answer: Several new, sharp-edged cracks at once point to a sudden cause such as an earthquake, blasting or an impact, rather than slow seasonal clay movement. In short: Cracks with sharp, clean faces and no dirt, paint or caulk inside them are new. When several appear at once, the timing points toward a sudden cause, such as an earthquake, nearby blasting or an impact, rather than the slow, seasonal movement of clay soil. Recording exactly when they appeared is the most useful thing a homeowner can do. ## What does a "fresh" crack look like? - Crack faces are sharp and bright, with no rounding. - No dust, cobwebs or debris inside the crack. - No paint, caulk or patching compound bridging it. - Drywall paper or tape is freshly torn rather than yellowed. - Earlier photos of the same wall show no crack. Older cracks tend to collect dirt, get painted over, and show edges worn by repeated opening and closing. ## What causes can it point to? | Cause | Notes | |---|---| | Earthquake shaking damage (https://terrabrain.vercel.app/causes/earthquake-shaking-damage) | Cracks appear together right after a felt earthquake | | Vibration-related cracking (https://terrabrain.vercel.app/causes/vibration-related-cracking-rare) | Near blasting, pile driving or heavy equipment; may extend existing cracks | | Impact | A vehicle, falling tree or heavy object striking the structure | ### Earthquakes in Oklahoma Oklahoma averaged about two earthquakes of magnitude 3.0 or larger per year before 2009; there were 579 in 2014 and 903 in 2015 [1]. Larger events include the magnitude 5.7 Prague earthquake in November 2011, the magnitude 5.8 Pawnee earthquake in September 2016 and the magnitude 5.0 Cushing earthquake in November 2016 [1]. Researchers describe a scientific consensus that wastewater disposal has induced earthquakes in Oklahoma since at least 2010 [1]. Before that increase, the Oklahoma Geological Survey described four main seismic areas: El Reno-Mustang, central Oklahoma, Love and Carter counties, and the Arkoma Basin [2]. See induced seismicity in Oklahoma (https://terrabrain.vercel.app/guides/induced-seismicity-in-oklahoma) and earthquakes, claims and law (https://terrabrain.vercel.app/data/earthquakes-claims-and-law). ### Vibration The U.S. Geological Survey lists artificial vibration among the human causes of landslides [3], which shows that vibration can affect ground as well as buildings. For houses, the evidence is usually the timing of the cracks against records of the vibration source. ## How does it differ from soil-movement cracks? Expansive clay moves on a seasonal cycle. Texas monitoring found slabs settling through the growing season and partly recovering in winter [4], so cracks from soil movement tend to grow, open and close over months. On shrinkable clay, cracks typically need about 5 to 10 millimeters of movement before they appear [5], which means a soil crack can also seem to appear suddenly once that threshold is passed. A single new crack is weaker evidence than a group of new cracks that all appeared at the same time. | Clue | Sudden event | Soil movement | |---|---|---| | Number appearing at once | Many, in different rooms | Usually one area at a time | | Edges | Fresh and clean | Often weathered or painted | | Seasonal change | None | Settles in the growing season, partly recovers in winter [4] | | Floor tilt on survey | Unchanged | Measurable low side | See seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement) and cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally). ## How should it be documented? 1. Write down the date and time the cracks were first noticed, and anything that happened just before (a felt earthquake, blasting, a storm). 2. Take close-up photos of each crack with a ruler or coin for scale, showing the clean faces. 3. Photograph wider views so each crack's location is clear. 4. Find older photos of the same walls for comparison. 5. Have a floor elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) done to check whether the foundation has tilted. Home inspection standards list drywall cracks, brick cracks, out-of-square door frames and uneven floors as signs of possible foundation movement [6]. ## What are the next steps? Compare with the distress pattern library (https://terrabrain.vercel.app/guides/distress-pattern-library) and the symptom matrix. For insurance questions, see insurance claims. ## Related - Earthquake shaking damage (https://terrabrain.vercel.app/causes/earthquake-shaking-damage) - Vibration-related cracking (rare) (https://terrabrain.vercel.app/causes/vibration-related-cracking-rare) - Seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement) - Induced seismicity in Oklahoma (https://terrabrain.vercel.app/guides/induced-seismicity-in-oklahoma) - Insurance claims (https://terrabrain.vercel.app/rules/insurance-claims) Sources: [1] Detailed mapping of shallow landslides in eastern Oklahoma and western Arkansas and potential triggering by Oklahoma earthquakes, Geomorphology (Oklahoma Geological Survey authors) https://www.jakewalter.net/papers/Regmi_Walter_2019.pdf [2] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [3] Landslide Types and Processes (Fact Sheet 2004-3072), U.S. Geological Survey https://pubs.usgs.gov/fs/2004/3072/fs-2004-3072.html [4] Cyclical Foundation Movements and Their Remediation, CIGMAT, University of Houston (conference presentation) https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2007/addison.pdf [5] Trees near buildings, Royal Horticultural Society https://www.rhs.org.uk/plants/types/trees/near-buildings [6] Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm --- # What drainage fixes protect a foundation on Oklahoma clay? URL: https://terrabrain.vercel.app/repairs/drainage-solutions Answer: Grading, gutters, buried downspout lines and other drainage work move water away and keep clay at a steady moisture level rather than bone dry. In short: Drainage work moves water away from a foundation and keeps the soil around it at a steadier moisture level. On Oklahoma's expansive clay, water piling up at one spot causes swelling and soft soil, while drying causes shrinkage, so the goal is consistent moisture rather than bone-dry soil. The building code sets minimum slopes, and the rest of the toolkit includes gutters, buried downspout lines, swales, French drains and irrigation changes. ## Why does water control matter on clay? Expansive clay swells when it takes on water and shrinks when it dries [7]. Lawn watering, leaking pipes and pools can create the moisture differences that damage foundations, and engineering guidance calls for positive surface drainage away from all sides of a foundation [6]. A Texas regulatory bulletin on foundations over expansive soil notes that surface drainage, plant selection, sprinkling practices and long-term maintenance all help limit soil moisture swings, and that homeowners are warned damage can occur if drainage is changed [7]. ## What are the code minimums? - **Grade:** the ground must fall at least 6 in within the first 10 ft from the foundation (IRC R401.3) [1]. - **When that is not possible:** drains or swales carry water away instead [1]. A 2007/2008 code change proposal set the alternative at a 5% slope away from the foundation, with swales at 2% and impervious surfaces at 2% within 10 ft [2]. - **Paved surfaces:** concrete or asphalt within 10 ft of the foundation must slope at least 2% away [1]. - **Manufactured homes:** the ground must slope at least 1/2 in per foot away for the first 10 ft, or other methods, such as a drain tile and automatic sump pump, must remove water that collects under the home [8]. - **Below-grade walls:** footing drains are required around concrete or masonry walls enclosing usable below-grade space, discharging by gravity or pump [3]. ## What drainage methods are used? | Method | What it is | Notes from sources | |---|---|---| | Regrading | Reshaping soil so it falls away from the house | Expansive-soil guidance suggests 12 in of fall over 10 ft, steeper than the code minimum [4][5] | | Gutters and downspouts | Collecting roof water and releasing it away from the house | Release points at least 5 ft away [5] to at least 10 ft away [4] | | Buried downspout lines | Solid pipe carrying roof water to a lower outlet | Carries discharge away from the foundation, as inspection guidance calls for [1] | | Swales | Shallow, shaped channels in the yard | Code alternative where 6 in in 10 ft is not possible [1][2] | | French or curtain drain | Gravel trench with perforated pipe in filter fabric | Collects subsurface or perched water; outlet to daylight or a sump | | Footing drain | Perforated pipe on 2 in of washed gravel with 6 in of cover at the footing | Required for many below-grade spaces [3] | | Sprinkler changes | Re-aiming heads and adjusting schedules | Keep sprinklers at least 5 ft from the foundation; repair broken heads that throw water back toward the building [5] | **Perched water** is a temporary saturated layer that sits on top of tighter clay or rock after heavy rain; it is explained in groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water). ## Why should Oklahoma clay stay consistently moist, not dry? Colorado State University Extension notes that both overwatering and underwatering near foundations can damage structures, and that drip irrigation near a foundation can be acceptable if well maintained [5]. In droughts, clay dries and shrinks [6]; at the foundation edge, this is the mechanism behind perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop); in wet spells, concentrated water causes perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift). Drainage removes the concentrated water; moisture management for drought is covered under root barriers and moisture control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control). Plants also matter: guidance for expansive soils keeps shrubs, flowers and sprinklers at least 5 ft from the foundation and trees at least 15 ft, or 20 ft for large water-loving species [4]. ## What signs point to drainage work? - Water standing near the foundation after rain; see water ponding near foundation (https://terrabrain.vercel.app/signs/water-ponding-near-foundation). - Flatwork that no longer slopes at least 2% away from the house [1]. - Erosion, washed-out soil under slab edges, or sediment fans below downspouts. - Gutters and downspouts that do not discharge away from the foundation [1]. Water from plumbing rather than the surface is handled under plumbing leak detection and repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair). ## Related - Surface Drainage and Grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Groundwater and Perched Water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Water Ponding Near Foundation (https://terrabrain.vercel.app/signs/water-ponding-near-foundation) - Root Barriers and Moisture Control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control) - Erosion, Undermining and Washout Voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) Sources: [1] Foundation Fundamentals: Inspecting Load Paths and Water Paths (IRC R401.2 & R401.3), InterNACHI https://nachi.org/foundation-load-water.htm [2] 2007/2008 Proposed Changes to the International Residential Code (RB101–RB143), International Code Council https://www.iccsafe.org/cs/codes/Documents/2007-08cycle/ProposedChanges/V2_RB101-143.pdf [3] Inspecting Foundation Drainage: Essential Guidelines for Below-Grade Spaces (IRC R405), InterNACHI https://www.nachi.org/foundation-drainage-below-grade.htm [4] Home Construction on Shrinking and Swelling Soils (Special Publication 11), Colorado Geological Survey (Holtz and Hart, 1978) https://coloradogeologicalsurvey.org/wp-content/uploads/woocommerce_uploads/SP-11.pdf [5] Landscaping on Expansive Soils (Fact Sheet 7.236), Colorado State University Cooperative Extension https://ca-montereypark.civicplus.com/DocumentCenter/View/487 [6] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [7] Foundations on Expansive Soils – Residential (IHB TB 10-01), Texas Department of Licensing and Regulation https://tdlr.texas.gov/ihb/pdf/TB1001.pdf [8] 24 CFR Part 3285 – Model Manufactured Home Installation Standards (Code of Federal Regulations, 2020), U.S. Government Publishing Office https://www.govinfo.gov/content/pkg/CFR-2020-title24-vol5/pdf/CFR-2020-title24-vol5-part3285.pdf --- # What foundation does my Oklahoma house have, by year built? URL: https://terrabrain.vercel.app/guides/construction-era-by-decade Answer: Older Oklahoma homes more often have crawl spaces or basements, while postwar and later homes are mostly on slabs or pier-and-beam. In short: A home's age is a useful first clue to what is under the floor, what pipes run beneath it and which building rules applied when it was built [2][3][4]. Older Oklahoma homes are more likely to have crawl spaces or basements, while postwar and later homes are mostly on slabs or pier-and-beam [2]. Age is only a clue: even some homes built within the past five years have developed foundation issues [8]. ## Why does the construction era matter? - It suggests the **foundation type** before anyone crawls under or measures the floor. - It suggests the **pipe materials** under a slab, which matters when a leak is suspected. - It tells which **code rules** were in force, such as footing reinforcement. ## What was built in each era? | Era | What sources describe | Things to check | |---|---|---| | Early 1900s to 1930s (oil-boom era) | In Tulsa, older central-city homes often have original or updated systems and aging basements or crawl spaces [2] | Wood decay and moisture in crawl spaces; basement walls | | Postwar and mid-century | In Tulsa, slab and pier-and-beam foundations that respond visibly to expansive clay [2] | Perimeter settlement; under-slab drain lines | | 1980s | Some black ABS plastic drain pipe made in the mid-1980s was defective and cracked [3] | Drain line condition | | Mid-2000s (2007 report) | Oklahoma's engineering board reported common shallow pier-and-grade-beam systems with grade beams only 1 to 8 inches below grade [6] | Frost depth and water under the foundation | | Since Sept 14, 2022 | Oklahoma amendments: two #4 bars in all footings, footing-to-stem-wall ties, ½-inch anchor bolts at 6 ft, and no trenching into a footing's bearing plane [4] | Permits and inspections on file | | Since Sept 14, 2026 | 2024 residential code with Oklahoma amendments, including the footing rebar rules and a tornado appendix [5] | Same | Newer suburban homes have fewer age-related defects but builder-grade components [2], and some homes built within the past five years have already developed foundation issues [8]. ## Why are basements rare in Oklahoma? Oklahoma has few basements. The director of the Oklahoma Geological Survey has tied this to a high water table and red clay that expands and contracts with soil moisture, which cracks basement walls and lets water in [1]. See basements (https://terrabrain.vercel.app/foundations/basements). ## What pipes run under the slab? | Material | What sources report | |---|---| | Cast iron | Used in buildings for more than 100 years, usually as the 4- to 6-inch main drain; early hub joints sealed with lead [3] | | Black ABS plastic | Some mid-1980s pipe was defective and failed by cracking [3] | | Copper supply | May last indefinitely in many areas, but can fail within 20 years in corrosive water or soil [3] | Mixed ABS and PVC drain piping in older installations can indicate amateur work and leak-prone joints [3]. See plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab). ## What are post-tensioned slabs? A **post-tensioned (PT) slab** is reinforced with steel cables tightened after the concrete cures. No Oklahoma source located for this page dates when PT slabs came into local use. Forensic engineers list tendon stressing as a structural repair option when a foundation is post-tensioned [7]. See post-tensioned slabs (https://terrabrain.vercel.app/foundations/post-tensioned-slabs). ## Related - Construction history data (https://terrabrain.vercel.app/data/construction-history) - Additions and mixed foundations (https://terrabrain.vercel.app/guides/additions-and-mixed-foundations) - Slab on grade (https://terrabrain.vercel.app/foundations/slab-on-grade) - Pier and beam crawl space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) - Codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits) Sources: [1] Why Oklahomans Don't Like Basements, NPR (via WFAE) https://www.wfae.org/2013-05-21/why-oklahomans-dont-like-basements [2] Home Inspection Tulsa: A Buyer's Hiring Guide, InspectandTest.net https://inspectandtest.net/guides/home-inspection-tulsa/ [3] Water supply & drain piping, InspectAPedia https://inspectapedia.com/plumbing/Building_Piping_Guide.php [4] 748:20-6-9. IRC 2018 Chapter 4 Foundations (Permanent Rule), Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2022%2009%2014%20IRC%202018%20Permanent%20Rule.pdf [5] Oklahoma Uniform Building Code Commission, Adoption of International Residential Code 2024: Code Changes Summary, Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2024%20IRC%20Code%20Changes%20Summary%20-%20for%20website.pdf [6] The Board's Bulletin, Vol. 21, Issue 4 (2007): Residential Foundation Public Meeting, Oklahoma State Board of Licensure for Professional Engineers and Land Surveyors https://oklahoma.gov/content/dam/ok/en/pes/documents/bulletin/Newsletter_Volume21_Issue62.pdf [7] Beyond the Building Code: Expansive Soils, Journal of the National Academy of Forensic Engineers https://journal.nafe.org/ojs/index.php/nafe/article/download/975/924/4846 [8] Is Oklahoma's drought damaging your foundation? Warning signs to watch for, News 9 (KWTV) https://www.news9.com/oklahoma-city-news/is-oklahomas-drought-damaging-your-foundation-warning-signs-to-watch-for --- # What happens when a post-tension slab tendon is cut or fails? URL: https://terrabrain.vercel.app/causes/post-tension-tendon-failure Answer: That part of the slab loses the compression that helps it resist cracking from soil movement, and cutting a stressed tendon releases a dangerous force. In short: A post-tensioned slab is held in compression by steel cables called tendons. When a tendon is cut during a remodel or corrodes at its anchor, that part of the slab loses the squeeze that helps it resist cracking from soil movement. A stressed tendon also stores a large force, so cutting one is a safety hazard as well as a structural one. ## What is a post-tensioned slab? A post-tensioned (PT) slab is a concrete foundation with steel cables cast inside it. Each tendon is wrapped in plastic and greased so it does not bond to the concrete. A few days after the pour, a hydraulic ram stretches each tendon, which puts the slab and its footings into compression [3]. A typical residential tendon is tensioned to about 33,000 pounds, stretching a half-inch cable roughly 4 inches over a 50-foot run [3]. Standard tendons are seven-wire steel strands with an ultimate strength of 270 ksi [4]. In homes, tendons are typically spaced 3 to 4 feet apart, and the outermost tendons sit within 2 feet of the slab edge [3]. Each tendon ends in a cast anchor that transfers its force into the concrete [4]. ### Why do builders use them on clay? The Post-Tensioning Institute describes PT slabs as a residential foundation for shrink-swell soils: the compression offsets tension caused by soil movement, and the added stiffness helps the slab resist bending [1]. Residential PT slabs on expansive soil are designed under the PTI DC10.5 standard, and millions have been built in the U.S. [2]. Oklahoma State University researchers note that DC10.5 is widely recognized across many states [7]. The 2024 International Residential Code added Section R506.2, which requires PT slabs to be designed to DC10.5 [1]. That matters in Oklahoma because more than 75% of the state has bedrock that can produce expansive soils [8]. For background, see shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) and post-tensioned slabs (https://terrabrain.vercel.app/foundations/post-tensioned-slabs). ## How do tendons fail? ### Cutting during alterations Tendons can be cut by other trades or during renovations [6]. Plumbing and other openings are normally placed between tendons at their 3-to-4-foot spacing without changing them [5], and saw cuts are supposed to be placed so they do not damage tendons [5]. When a strand is cut, its force is lost along that line. ### Corrosion Unbonded tendons can corrode, especially in aggressive environments [6]. Water that gets inside the sheathing collects at low points, where corrosion is often worst [6]. If an anchor exposed to water or chlorides is not properly protected, its wedges may corrode to the point that they can no longer grip the strand [6]. During construction, the stressing pockets at the slab edge are grouted to protect the anchor, cable and wedges [3]. Encapsulated tendons add a plastic boot over the anchor to isolate it from moisture [4]. ## Why is a cut tendon a hazard? The stresses behind a stressed anchor are very high, and the engineering literature warns they can cause sudden, explosive concrete failure [6]. Sudden loss of tension on a tendon can damage ceiling and floor finishes [6]. Engineers treat safety as the first consideration in any tendon repair [6]. ## What can tendon failure look like? The typical sign is a visible slab crack (https://terrabrain.vercel.app/signs/visible-slab-cracks), often near where work was done or along the line of a tendon. Damage at an anchor may show as cracking or spalling at the slab edge. Because ordinary shrinkage and soil movement also crack slabs, the history of cuts, cores and remodels is a key part of the diagnosis. See visible slab cracks (https://terrabrain.vercel.app/signs/visible-slab-cracks) and heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). ## How is tendon damage repaired? Repairs are essentially the same whether the strand was cut or corroded: the damaged length is spliced so it can be stressed again [6]. | Repair step | What it involves | |---|---| | Splice | Splice chucks or in-line couplers join new strand to the existing strand [6] | | Anchor replacement | An access hole is opened at least 3 feet from the anchor, the strand is cut and new strand is spliced in [6] | | Strand replacement | Typically runs from quarter-point to quarter-point along the tendon [6] | | Safety measures | A temporary lock-off anchor can keep tension on the tendon during anchor work [6] | These repairs are engineered work. In severe cases, slab or foundation replacement (https://terrabrain.vercel.app/repairs/slab-or-foundation-replacement) may be considered, and a monitoring program (https://terrabrain.vercel.app/repairs/monitoring-program) can track whether cracks are changing. See working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). ## Related - Post-tensioned slabs (https://terrabrain.vercel.app/foundations/post-tensioned-slabs) - Visible slab cracks (https://terrabrain.vercel.app/signs/visible-slab-cracks) - Slab or foundation replacement (https://terrabrain.vercel.app/repairs/slab-or-foundation-replacement) - Monitoring program (https://terrabrain.vercel.app/repairs/monitoring-program) - Codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits) - Working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers) Sources: [1] Slab-on-Ground, Post-Tensioning Institute https://www.post-tensioning.org/education/ptapplications/slab-on-ground.aspx [2] Exclusion of Post-Tensioned Residential Slabs-on-Ground from ACI 318 (Technical Note 21), Post-Tensioning Institute https://www.post-tensioning.org/Portals/13/Files/Pdfs/Education/Technical Note_21.pdf [3] Post-Tensioned Slabs, Journal of Light Construction https://www.jlconline.com/how-to/foundations/post-tensioned-slabs_o/ [4] General Considerations for Post-Tensioned Slabs on Ground, STRUCTURE magazine (NCSEA) https://www.structuremag.org/wp-content/uploads/2014/08/C-BuildingBlocks-Allred-Jan101.pdf [5] Post-Tensioned Slabs on Ground, Part 2: Specific Design Considerations, STRUCTURE magazine (NCSEA) https://www.structuremag.org/wp-content/uploads/2014/08/c-structuraldesign-allred-April101.pdf [6] Repair of Unbonded Single-Strand Tendons, STRUCTURE magazine (NCSEA) https://structuremag.org/wp-content/uploads/2014/09/c-build-blocks-Repair-of-PT-Tendons-by-Gail-Kelley-web-ver1.pdf [7] Residential House Foundations on Expansive Soils in Changing Climates, HUD USER, Cityscape (Oklahoma State University authors) https://www.huduser.gov/PORTAL/node/10259 [8] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html --- # What is a post-tensioned slab and does it move on Oklahoma clay? URL: https://terrabrain.vercel.app/foundations/post-tensioned-slabs Answer: A PT slab is reinforced with steel tendons pulled tight after pouring; used on expansive clay, it still moves when clay swells or shrinks unevenly. In short: A post-tensioned (PT) slab is a concrete slab foundation reinforced with steel cables, called tendons, that are pulled tight after the concrete is placed. PT slabs are one of the foundation types used on expansive soil. In Oklahoma, newer PT homes are identified by a label on the electrical panel door, and PT slabs still move when clay under them swells or shrinks unevenly. ## What makes a slab post-tensioned? Trade terms used on this page: - **Tendon:** a high-strength steel strand inside a plastic sheath, laid in the slab before the pour. - **Stressing:** pulling the tendons tight with a hydraulic jack after the concrete has gained strength, then locking them at the slab edge. - **Anchor pocket:** the recess at the slab edge where a tendon is locked off, later filled with grout or patching. A conventionally reinforced slab uses rebar or wire mesh instead of stressed tendons. ## Why are PT slabs used on clay? Clay-rich soils can swell 10% or more by volume when wetted, and volume increases of 3% or more are generally considered damaging enough that engineers call for specially designed foundations [6]. The residential code sends foundations on expansive soil to the building code's expansive-soil design section (IBC 1808.6) [3]. A soil counts as expansive under that framework if, among other tests, its plasticity index is 15 or more or its expansion index exceeds 20 [3]. Engineering guidance for swelling soils lists post-tensioned slabs and structural floors as options under certain conditions, while ordinary slabs on grade were not recommended on swelling soils in that guidance [2]. ## How do you identify a PT slab in Oklahoma? - **Panel label:** Oklahoma's adoption of the 2024 International Residential Code, effective September 14, 2026, requires post-tensioned slabs on grade to carry a label on the electrical panel door [1]. - **Anchor pockets:** patched circles or squares spaced along the slab edge or garage stem. - **Paperwork:** builder plans, engineering letters or permit records. Homes built before the 2024 code took effect may not have a panel label [1], so older PT slabs are often identified by their anchor pockets or plans. ## How do PT slabs still move? The tendons do not stop the soil from moving. On a uniformly loaded rectangular slab on swelling soil, the corners press down with about one-fourth the pressure of the center, so corners tend to lift relative to the middle, and moisture differences at the slab edge make this worse [4]. Seasonal moisture change in clay can reach from 3 to 40 ft deep [4]. Research modeling a leaking water line under a slab-on-ground foundation on expansive soil compared three conditions: edge swelling after a wet climate, center lift after a long dry period, and edge shrinkage after a dry climate, and examined how a leak changed the slab's differential movement and bending [5]. These patterns correspond to the following movement types: | Pattern | What drives it | Typical sign | |---|---|---| | Perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) | Clay at the edge dries and shrinks [5] | One side or corner low, often the whole edge tilted | | Perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) | Edge soil wets and swells [4][5] | Edges and corners high | | Center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) | Edges dry and shrink while the middle stays wetter, leaving the center high [5] | Interior hump, interior door problems | | Leak-induced heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave) | Water line leak under the slab [5] | Local hump near plumbing | An elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) maps which of these shapes a slab has taken. ## What should be considered when repairing a PT slab? PT slabs use the same repair families as other slabs: perimeter piers, drainage, moisture control and leak repair. Work that cuts or cores through the slab, such as interior piers (https://terrabrain.vercel.app/repairs/interior-piers-tunnel-or-core), passes through the zone where tendons run. A broken or corroded tendon is its own mechanism, covered under post-tension tendon failure (https://terrabrain.vercel.app/causes/post-tension-tendon-failure). ## Related - Slab on Grade (https://terrabrain.vercel.app/foundations/slab-on-grade) - Post-Tension Tendon Failure (https://terrabrain.vercel.app/causes/post-tension-tendon-failure) - Interior Piers (Tunnel or Core) (https://terrabrain.vercel.app/repairs/interior-piers-tunnel-or-core) - Construction Era by Decade (https://terrabrain.vercel.app/guides/construction-era-by-decade) - Working with Engineers (https://terrabrain.vercel.app/guides/working-with-engineers) Sources: [1] Adoption of International Residential Code 2024 (IRC 2024), Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2024%20IRC%20Code%20Changes%20Summary%20-%20for%20website.pdf [2] Home Construction on Shrinking and Swelling Soils (Special Publication 11), Colorado Geological Survey (Holtz and Hart, 1978) https://coloradogeologicalsurvey.org/wp-content/uploads/woocommerce_uploads/SP-11.pdf [3] Foundations on Expansive Soils – Residential (IHB TB 10-01), Texas Department of Licensing and Regulation https://tdlr.texas.gov/ihb/pdf/TB1001.pdf [4] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [5] Investigation of a leaking water line beneath residential foundation on expansive soils, American Society of Civil Engineers, Geotechnical Special Publication 147 (Michigan Technological University Digital Commons) https://digitalcommons.mtu.edu/michigantech-p/8670 [6] Expansive Soil, Colorado Geological Survey https://coloradogeologicalsurvey.org/hazards/expansive-soil/ --- # What is Abilene soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/abilene Answer: Abilene is a deep, well-drained terrace soil of southwest Oklahoma with a 35 to 50 percent clay subsoil that shrinks and swells with the seasons. In short: Abilene is a deep, well-drained soil with a clay to clay loam subsoil, formed in calcareous old river deposits on terraces in the Red Plains of Texas and southwestern Oklahoma. Its subsoil holds 35 to 50 percent clay, enough to shrink and swell with the seasons. It is less extreme than the cracking clays nearby, but moisture swings at the foundation edge still matter. ## What does the official description say? | Property | Value | |---|---| | Taxonomic class | Fine, mixed, superactive, thermic Pachic Argiustolls [1] | | Parent material | Calcareous alluvium or outwash, presumably Quaternary [1] | | Landform | Treads of terraces on dissected plains [1] | | Slopes | 0–3%, mainly under 1% [1] | | Drainage | Well drained [1] | | Permeability | Moderately slow [1] | | Runoff | Negligible to very low [1] | | Subsoil clay | 35–50% in the Bt and Btk horizons [1] | | Carbonates | Secondary carbonates from about 10–28 in; calcic horizon from about 28–60 in [1] | | Mean annual precipitation | About 26 in (21–30 in) [1] | | Mean annual temperature | About 63°F [1] | | Setting | MLRA 78, Central Rolling Red Plains and Rolling Limestone Prairies of Texas and Oklahoma [1] | The type location is in Haskell County, Texas, and the series was established in Taylor County, Texas, in 1915 [1]. It is described as extensive [1]. ### Reading the class name - **Fine** means the subsoil is clayey. - **Mixed** mineralogy means no single clay mineral, such as smectite, dominates the clay. - **Argiustoll** means a dark, fertile prairie topsoil over a subsoil where clay has built up, in a climate that is dry for part of the year. - **Pachic** means the dark topsoil is unusually thick. ## How much might it swell? Soil scientists rate shrink-swell by **linear extensibility**, the percent a soil's length changes from moist to oven-dry. Under 3 percent is low, 3 to 6 moderate, 6 to 9 high and 9 or more very high [3]. The Abilene description gives no linear extensibility value and does not describe cracks or slickensides [1]. With 35 to 50 percent clay in the subsoil [1], a moderate to high rating is plausible, but the map-unit value in the USDA Web Soil Survey, or lab tests on site, are the way to confirm it. See soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values). For contrast, Hollister, a series associated with Abilene in the same region, is a smectitic Vertisol whose cracks reach more than 30 inches deep and stay open 150 or more days in most years [1][2]. ## What does it mean for foundations? - **Edge movement with moisture.** Clayey soil shrinks as it dries and swells as it wets, and uneven moisture around a house causes more damage than uniform change [4]. See perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) and perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift). - **Dry climate.** With about 26 inches of rain a year [1], the soil is often dry, so a leak, a sprinkler line or a downspout can create a sharp local wet spot. See leak-induced localized heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave). - **Flat lots, slow drainage.** Slopes are mostly under 1 percent and permeability is moderately slow [1], so water can sit near the foundation. The ASCE guide recommends sloping soil at least 3 inches in the first 5 feet and discharging downspouts at least 3 feet from the foundation [4]. See surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). - **Carbonate layers.** Calcium carbonate accumulations begin within about 10 to 28 inches [1] and can make the subsoil harder to dig. ## Where does Abilene soil form? Abilene forms on Quaternary terrace deposits in southwestern Oklahoma's Red Plains. See Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) and the Southwest (Lawton and Red Plains) (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains) region page. ## Related - Southwest (Lawton and Red Plains) (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains) - Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) - Hollister soil (https://terrabrain.vercel.app/soils/hollister) - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Soil Series Description: ABILENE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/A/ABILENE.html [2] Official Soil Series Description: HOLLISTER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/H/HOLLISTER.html [3] Linear Extensibility (definition and shrink-swell classes, after NRCS National Soil Survey Handbook), UC Davis California Soil Resource Lab https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Apperson soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/apperson Answer: Apperson is a smectite clay Vertisol over hard limestone 40 to 60 inches down that cracks and swells seasonally, so heave and settlement are both concerns. In short: Apperson is a clay soil formed from Pennsylvanian limestone on the prairie uplands of north-central and northeastern Oklahoma. It is a Vertisol, meaning its smectite clay shrinks and swells enough to crack open and close with the seasons. It sits on hard limestone 40 to 60 inches down and stays wet through winter and spring, so both seasonal heave and settlement are common concerns. ## What does the official description say? | Property | Value | |---|---| | Taxonomic class | Fine, smectitic, thermic Aquic Hapluderts [1] | | Parent material | Calcareous residuum weathered from Pennsylvanian limestone [1] | | Landform | Broad, smooth ridges and slightly convex side slopes of prairie uplands [1] | | Slopes | 0–5% [1] | | Drainage | Somewhat poorly drained; slow permeability [1] | | Wetness | Perched saturation December through April [1] | | Subsoil | Silty clay with slickensides (Btss horizons) [1] | | Depth to hard limestone | 40–60 in; about 44 in typical [1] | | Mean annual precipitation | About 40 in (36–44 in) [1] | | Frost-free days | 190–220 [1] | | Extent | North-central and northeastern Oklahoma, possibly south-central and southeastern Kansas; moderately extensive [1] | | MLRAs | Cherokee Prairies (112) and Bluestem Hills (76) [1] | The typical profile is in Osage County, about 1 mile north of Foraker [1]. Most Apperson land is native range, hay meadow or pasture, with some cropland [1]. ### Reading the class name - **Fine, smectitic** means the subsoil is clayey and dominated by smectite, the clay mineral family that swells most when wet; the smectitic class is stated in the USDA description [1]. - **Hapludert** places it among the Vertisols, soils defined by shrink-swell clay, in a humid climate. - **Aquic** means it is saturated for part of the year [1]. ## What signs of shrink-swell are in the profile? The USDA description reports cracks that open and close periodically, slickensides in the Btss and BCss horizons, and shiny pressure faces on the clay [1]. **Slickensides** are polished, grooved surfaces formed when clay masses shear past each other as they swell. Soil scientists rate shrink-swell by **linear extensibility**, the percent change in a soil's length from moist to dry. Under 3 percent is low and 9 percent or more is very high [2]. The Apperson description does not give a number, so the map-unit value in the USDA Web Soil Survey is the place to confirm it for a lot. ## What is the limestone underneath like? Apperson forms on Pennsylvanian limestone [1]. In northeastern Oklahoma, limestone units such as the Oologah are described as blue cherty limestone with bands of black shale, about 80 to 145 feet thick [4]. See Pennsylvanian limestones (https://terrabrain.vercel.app/geology/pennsylvanian-limestones). ## What does Apperson soil mean for foundations? - **Seasonal heave and settlement.** Smectite clay over rock swells when wet and shrinks when dry, and uneven moisture causes more damage than uniform change [1][3]. On this soil, slab edges can drop in late summer and rise in wet spells. See perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop), perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) and center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab). - **Winter and spring wetness.** Perched saturation from December through April and slow permeability [1] can keep crawl spaces damp and add pressure on below-grade walls. See crawl space moisture (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) and lateral earth and hydrostatic pressure (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls). - **Trees.** Tree roots draw water from clay soils and are a recognized cause of local drying under foundations [3]. See tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement). - **Moisture practices.** The ASCE guide recommends grading at least 3 inches of fall in the first 5 feet, discharging downspouts at least 3 feet out, watering evenly and planting trees farther from the house than their mature height [3]. ## Related - Tulsa metro (https://terrabrain.vercel.app/regions/tulsa-metro) - Northeast (Ozark Plateau and Grand Lake) (https://terrabrain.vercel.app/regions/northeast-ozark-plateau-and-grand-lake) - Pennsylvanian limestones (https://terrabrain.vercel.app/geology/pennsylvanian-limestones) - Cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally) - Soil series in the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) Sources: [1] Official Soil Series Description: APPERSON Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/A/APPERSON.html [2] Linear Extensibility (definition and shrink-swell classes, after NRCS National Soil Survey Handbook), UC Davis California Soil Resource Lab https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [3] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [4] Geolex unit references: Oologah, USGS National Geologic Map Database (Geolex) https://ngmdb.usgs.gov/Geolex/UnitRefs/OologahRefs_9678.html --- # What is Bates soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/bates Answer: A well-drained, loamy eastern Oklahoma soil over soft sandstone at 20 to 40 inches. It swells less than nearby clays, so drainage, erosion and fill matter most. In short: Bates is a well-drained, loamy prairie soil formed from Pennsylvanian sandstone in eastern Oklahoma, southeastern Kansas and southwestern Missouri. It reaches soft sandstone or shale at 20 to 40 inches. Its swell potential is lower than the clay soils around it, so drainage, erosion, fill and shallow rock are the main foundation questions. ## What does the official description say? | Property | Value | |---|---| | Taxonomic class | Fine-loamy, siliceous, active, thermic Typic Argiudolls [1] | | Parent material | Residuum from Pennsylvanian sandstone, often with thin silty or sandy shale beds [1] | | Landform | Interfluves and hillslopes on plains [1] | | Slopes | 1–8% [1] | | Drainage | Well drained; moderate permeability [1] | | Saturated hydraulic conductivity | Moderately high to high [1] | | Runoff | Low or medium [1] | | Depth to soft rock (paralithic contact) | 20–40 in; about 33 in typical [1] | | Mean annual precipitation | 35–45 in [1] | | Extent | Extensive; MLRAs 76, 84A, 85, 87B, 112 and 118B [1] | The type location is in Crawford County, Kansas, and the series is mapped across eastern Oklahoma [1]. About half of Bates land is grassland and half is cropland [1]. ### Reading the class name - **Fine-loamy** means the subsoil is loam to clay loam, with less clay than a "fine" (clayey) soil. - **Siliceous** means the soil is dominated by quartz-type minerals rather than swelling clay. - **Argiudoll** means a dark prairie topsoil over a subsoil enriched in clay, in a humid climate. ## What soils are nearby? Bates is associated with several Tulsa-area soils that behave differently [1]: | Series | How it differs from Bates | |---|---| | Dennis | Similar position but a fine-textured (clayey) subsoil [1]; somewhat poorly drained with perched water 12–30 in, Dec–Apr [2] | | Eram | Similar position but a fine-textured subsoil [1] | | Collinsville | Steeper, with hard rock within 20 in [1]; typical depth 9 in [3] | | Coweta | Steeper, with bedrock within 20 in [1] | Because these soils are mapped next to each other [1], the ground within one subdivision can change from shallow Collinsville to Bates to clayey Dennis. ## How much might it swell? Shrink-swell is rated by **linear extensibility**, the percent change in a soil's length from moist to dry, with under 3 percent rated low and 3 to 6 percent moderate [4]. The Bates description gives no number [1]. A fine-loamy, siliceous subsoil points toward the low to moderate range, and the map-unit value in the USDA Web Soil Survey is the way to confirm it. ## What does it mean for foundations? - **Water and erosion.** Moderately high to high hydraulic conductivity [1] lets water move readily through the loamy soil, so a plumbing leak or concentrated roof water can carry soil from beside a footing. See erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) and plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab). - **Fill on sloping lots.** Bates occurs on slopes up to 8 percent next to steeper Collinsville and Coweta ground [1], so many lots are leveled with fill. See fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). - **Shallow soft rock.** Soft sandstone or shale at 20 to 40 inches [1] means footings may rest partly on rock. In 2025 Tulsa installation records, steel push piers reached refusal at a median depth of about 12 feet, well below the rock depths shown in soil surveys [6]. See Tulsa bedrock (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro). - **Drainage basics.** The ASCE guide recommends grading at least 3 inches of fall in the first 5 feet and downspouts discharging at least 3 feet from the foundation [5]. ## Related - Tulsa metro (https://terrabrain.vercel.app/regions/tulsa-metro) - East-Central (Arkoma) (https://terrabrain.vercel.app/regions/east-central-arkoma) - Pennsylvanian sandstones (https://terrabrain.vercel.app/geology/pennsylvanian-sandstones) - Dennis soil (https://terrabrain.vercel.app/soils/dennis) - Collinsville soil (https://terrabrain.vercel.app/soils/collinsville) - Soil series in the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) Sources: [1] Official Soil Series Description: BATES Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/B/BATES.html [2] Official Soil Series Description: DENNIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DENNIS.html [3] Official Soil Series Description: COLLINSVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COLLINSVILLE.html [4] Linear Extensibility (definition and shrink-swell classes, after NRCS National Soil Survey Handbook), UC Davis California Soil Resource Lab https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [5] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [6] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # What is Bernow soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/bernow Answer: Bernow is a deep, well-drained loamy soil from Cretaceous sandstone with about 20 to 32 percent clay, so water, erosion and fill matter most. In short: Bernow is a deep, well-drained soil of eastern and southeastern Oklahoma that formed from weathered Cretaceous sandstone. Its subsoil is loam, sandy clay loam or clay loam with roughly 20 to 32 percent clay, far less than the heavy clays that drive most seasonal foundation movement in the state. For a Bernow lot, water management, erosion and fill quality are usually the first things to look at. ## Where does Bernow soil occur? The USDA Natural Resources Conservation Service (NRCS) maintains an Official Series Description (OSD) for every named soil. The Bernow OSD places the series in eastern Oklahoma, and possibly Arkansas, Louisiana and Texas, with its type location in Bryan County about 4 miles northeast of Bokchito [1]. It lies in Major Land Resource Areas 87B (Texas Claypan Area) and 133B (Western Coastal Plain) and is described as moderately extensive [1]. Bernow forms on hillslopes of dissected plains, on slopes of 0 to 12 percent [1]. This puts it in the Southeast (Ouachitas and Red River) (https://terrabrain.vercel.app/regions/southeast-ouachitas-and-red-river) and South-Central (Arbuckles and Texoma) (https://terrabrain.vercel.app/regions/south-central-arbuckles-and-texoma) parts of the state, on sandy and loamy material weathered from Cretaceous sandstones (https://terrabrain.vercel.app/geology/cretaceous-shales-clays-and-sandstones) [1]. ## What are the key properties of Bernow soil? | Property | Bernow (from the OSD) [1] | |---|---| | Classification | Fine-loamy, siliceous, active, thermic Glossic Paleudalfs | | Parent material | Sandy and loamy residuum from Cretaceous sandstone | | Depth | Deep, at least 80 inches | | Drainage | Well drained | | Permeability | Moderate | | Subsoil (Bt) | Loam, sandy clay loam or clay loam, 20-32% clay | | Slopes | 0-12% | | Mean annual rainfall | About 45 in (range 38-46 in) | | Mean annual temperature | About 63°F | "Residuum" means soil that weathered in place from the rock below it. The "Bt" horizon is the subsoil layer where clay has built up over time. Most Bernow land is used for tame pasture or woodland, and native vegetation is mainly oak with a grass understory [1]. ## What do these properties mean for foundations? ### Lower clay content Clayey soils swell when they take on water and shrink when they dry, which pushes foundations up and lets them drop as seasons change [4]. Bernow's subsoil tops out around 32 percent clay and is loam, sandy clay loam or clay loam rather than clay [1]. NRCS rates shrink-swell by linear extensibility percent (LEP), the change in length of a soil sample between moist and oven-dry: under 3 percent is low, 3 to 6 percent moderate, 6 to 9 percent high and 9 percent or more very high [3]. The rated LEP for each map unit is listed in Web Soil Survey [2]. ### Water, leaks and erosion Even on less expansive soils, uneven moisture under a foundation is more damaging than uniform moisture, and leaks in sewer or water lines can cause localized movement [4]. Bernow is well drained with moderate permeability [1], and its sandy surface layers lie on hillslopes where runoff ranges from very low to medium [1]. Concentrated water from downspouts or leaks is worth tracing on these lots; see erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) and surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). ### Fill and site grading Fill placed during lot grading is not part of the native Bernow profile that the OSD describes [1]; its behavior depends on how it was placed. See fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) and fill soils and lot history (https://terrabrain.vercel.app/guides/fill-soils-and-lot-history). ## How do you check a specific lot? - Look up the address in Web Soil Survey, which publishes soil data produced by the National Cooperative Soil Survey [2]. - Check the map unit's LEP value against the NRCS shrink-swell classes [3]. - Keep soil moisture next to the foundation as uniform as practical: slope soil away from the house and discharge downspouts away from the foundation [4]. - Watch for warning signs such as stair-step cracks in brick, sticking doors and sloping floors [4]. ## Related - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Cretaceous Shales, Clays and Sandstones (https://terrabrain.vercel.app/geology/cretaceous-shales-clays-and-sandstones) - Southeast Oklahoma (Ouachitas and Red River) (https://terrabrain.vercel.app/regions/southeast-ouachitas-and-red-river) - Durant soil (https://terrabrain.vercel.app/soils/durant) Sources: [1] Official Series Description - BERNOW Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/B/BERNOW.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Bethany soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/bethany Answer: Bethany is a very deep central Oklahoma soil with a silty clay subsoil of 35 to 45 percent clay, with a subsoil rated moderate in shrink-swell, so homes can move seasonally. In short: Bethany is a very deep, well-drained soil of central Oklahoma whose subsoil is silty clay with about 35 to 45 percent clay. Oklahoma State University testing rated Bethany's subsoil moderate in shrink-swell, with a largely montmorillonitic fine clay, and noted moderate limitations for building sites. Homes on Bethany soils can move seasonally as the clay wets and dries. ## Where does Bethany soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) places Bethany in central Oklahoma and Kansas, in Major Land Resource Area 80A, the Central Rolling Red Prairies [1]. The series covers about 525,000 acres, and its type location is in Oklahoma County about 1 mile east of Wheatland [1]. That puts it squarely in the OKC metro (https://terrabrain.vercel.app/regions/okc-metro); see also soil series of the OKC metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro). Bethany forms on summits and backslopes of old terraces ("paleoterraces") at 1,000 to 1,500 feet elevation, on slopes of 0 to 5 percent [1]. Its parent material is Pleistocene loess (wind-blown silt) or alluvium lying over Permian shale [1], the setting covered on the Hennessey Shale (https://terrabrain.vercel.app/geology/hennessey-shale-group) and Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) pages. ## What are Bethany soil's key properties? | Property | Bethany (from the OSD) [1] | |---|---| | Classification | Fine, mixed, superactive, thermic Pachic Paleustolls | | Parent material | Pleistocene loess or alluvium over Permian shale | | Depth | Very deep; solum more than 60 in | | Drainage | Well drained | | Permeability | Moderately low | | Subsoil (Bt) | Silty clay in the typical pedon; 35-45% clay | | Slopes | 0-5% | | Mean annual rainfall | About 34 in (range 31-37 in) | | Mean annual temperature | About 59°F | The "solum" is the upper, weathered part of the soil profile (topsoil plus subsoil). Bethany land is used for small grains, grain sorghum, cotton and alfalfa, with some pasture and rangeland [1]. ## How much does Bethany soil shrink and swell? ### What Oklahoma State University measured A 1978 Oklahoma Agricultural Experiment Station bulletin studied Bethany silt loam as one of five benchmark soils of western Oklahoma [4]. The researchers found: - Clay rising to about 38.5 percent below the surface [4]. - A coefficient of linear extensibility (COLE) reaching 0.095 in the most expansive horizon [4]. - Fine clay that is largely montmorillonite, a smectite clay mineral that swells when wet; coarse clay was a mix of illite and montmorillonite [4]. - Shrink-swell rated low in the surface layer and moderate in the subsoil, with moderate limitations for building sites and severe limitations for septic filter fields [4]. For comparison, NRCS shrink-swell classes put linear extensibility under 3 percent (COLE under 0.03) as low, 3 to 6 percent as moderate, 6 to 9 percent as high and 9 percent or more as very high [3]. The rated value for each map unit appears in Web Soil Survey [2]. ### How it shows up in houses Clay soils swell (heave) when they gain moisture and shrink when they dry, moving shallow foundations up and down [5]. Uneven moisture, such as a dry edge next to a wet one, does more damage than uniform changes [5]. Typical signs include stair-step cracks in brick, sticking doors or windows and sloping floors [5]. These patterns are covered in perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) and perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift). ### Drought and wet cycles The Oklahoma Mesonet measures soil moisture at depths of 2, 4, 10 and 24 inches at most of its sites, which shows how deeply rain soaks in and how fast soils dry [6]. These readings help explain why movement on clay soils such as Bethany often follows drought and wet spells; see drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles). ## What should you know about a Bethany lot? - Look up the map unit and its linear extensibility in Web Soil Survey [2]. - Keep soil moisture next to and under the foundation as even as practical; the ASCE guide calls this the single most useful step a homeowner can take [5]. - Grade soil away from the house and repair water or sewer leaks promptly, since leaks can cause localized movement [5]. - Plant trees farther from the foundation than their mature height [5]. ## Related - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Clay Mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Soil Series - OKC Metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - BETHANY Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/B/BETHANY.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma Agricultural Experiment Station, Oklahoma State University https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [5] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [6] Tracking Drought Using Soil Moisture Information (BAE-1541), Oklahoma State University Extension https://extension.okstate.edu/fact-sheets/tracking-drought-using-soil-moisture-information.html --- # What is Chickasha soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/chickasha Answer: Chickasha is a well-drained loamy soil over weakly cemented Permian sandstone at 40 to 60 inches; drainage, erosion and fill matter more than swelling. In short: Chickasha is a well-drained, fine-loamy soil that formed from weathered Permian sandstone and sits on weakly cemented sandstone 40 to 60 inches down. Its subsoil is mainly sandy clay loam with moderate permeability. Compared with Oklahoma's heavy clays, Chickasha has less clay, so drainage, erosion and fill tend to matter more than seasonal swelling. ## Where does Chickasha soil occur? According to the USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD), Chickasha occurs in Oklahoma and Texas within Major Land Resource Area 80A, the Central Rolling Red Prairies [1]. The type location is in Carter County, the series was established in Washita County, and it is of moderate extent [1]. Chickasha forms on nearly level to sloping broad ridgetops and side slopes of convex hills, on slopes of 0 to 8 percent [1]. Its parent rock is Permian sandstone [1], part of the Western Permian red beds (https://terrabrain.vercel.app/geology/western-permian-red-beds) and related units such as the Garber Sandstone (https://terrabrain.vercel.app/geology/garber-sandstone). The series spans the South-Central (Arbuckles and Texoma) (https://terrabrain.vercel.app/regions/south-central-arbuckles-and-texoma) and Southwest (Lawton and Red Plains) (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains) regions. ## What are its key properties? | Property | Chickasha (from the OSD) [1] | |---|---| | Classification | Fine-loamy, mixed, active, thermic Udic Argiustolls | | Parent material | Material weathered from Permian sandstone | | Depth to rock | 40-60 in to weakly cemented sandstone | | Drainage | Well drained | | Permeability | Moderate | | Subsoil (Bt) | Sandy clay loam (range loam to clay loam) | | Clay in control section | 18-30% | | Slopes | 0-8% | | Mean annual rainfall | 35-41 in (typical pedon 34 in) | | Mean annual temperature | 59-63°F | "Fine-loamy" is a soil-taxonomy family name for soils with a loamy texture and moderate clay. Most Chickasha land is cultivated to small grains, grain sorghum, cotton and improved pasture, and native vegetation is tallgrass prairie [1]. ## What do its properties mean for foundations? ### Moderate clay, lower shrink-swell Clayey soils swell when they gain water and shrink when they dry, which moves shallow foundations up and down [4]. Chickasha's weighted clay content of 18 to 30 percent is modest [1]. NRCS measures shrink-swell as linear extensibility percent (LEP): under 3 percent is low, 3 to 6 percent moderate, 6 to 9 percent high and 9 percent or more very high [3]. The rated LEP for each Chickasha map unit is listed in Web Soil Survey [2]. ### Sandstone within reach Weakly cemented sandstone lies 40 to 60 inches below the surface in Chickasha [1]. "Weakly cemented" means the rock grains are only loosely bound, so the rock is softer than hard sandstone. Where foundation repair involves driving piers (steel or concrete supports pushed down to firm bearing), the depth and hardness of this layer is part of what an engineer evaluates; see shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata) and depth to rock from borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings). ### Water and erosion Uneven soil moisture causes more damage than uniform moisture, and water or sewer leaks can cause localized foundation movement [4]. Sandy and loamy soils on sloping ground are the setting described in erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). Downspouts that discharge well away from the house and soil graded away from the foundation keep water from concentrating at the slab edge [4]. ## How can a specific lot be checked? - Find the map unit and its LEP in Web Soil Survey [2]. - Compare the LEP with the NRCS shrink-swell classes [3]. - Watch for stair-step brick cracks, sticking doors and sloping floors, and track existing cracks over time [4]. ## Related - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) - Garber Sandstone (https://terrabrain.vercel.app/geology/garber-sandstone) - Fill Consolidation Settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) - Surface Drainage and Grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Darnell soil (https://terrabrain.vercel.app/soils/darnell) Sources: [1] Official Series Description - CHICKASHA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/CHICKASHA.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Choteau soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/choteau Answer: Choteau is a very deep, somewhat poorly drained clayey soil with a perched water table 2.5 to 3 feet down from December through April. In short: Choteau is a very deep, clayey soil of eastern Oklahoma that is somewhat poorly drained, with a perched water table 2.5 to 3 feet down from December through April. Its subsoil holds about 35 to 45 percent clay. Seasonal wetness and clay that swells and shrinks with moisture are the two soil traits most relevant to foundations on Choteau. ## Where does Choteau soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) describes Choteau as an extensive series in southeastern Kansas and eastern Oklahoma, mapped in Major Land Resource Areas 112, 116, 117 and 118 [1]. The type location is in Mayes County, and the series was established in Wagoner County [1]. Choteau forms on nearly level to gently sloping high terraces and upland footslopes in the Cherokee Prairies, on slopes of 0 to 5 percent [1]. Its parent material is loamy and clayey alluvium or colluvium over Pennsylvanian shale [1]. This is the landscape of the Tulsa metro (https://terrabrain.vercel.app/regions/tulsa-metro) and the Northeast (Ozark Plateau and Grand Lake) (https://terrabrain.vercel.app/regions/northeast-ozark-plateau-and-grand-lake) region, underlain by Pennsylvanian shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales). ## What are its key properties? | Property | Choteau (from the OSD) [1] | |---|---| | Classification | Fine, mixed, active, thermic Aquic Paleudolls | | Parent material | Loamy and clayey alluvium or colluvium over Pennsylvanian shale | | Depth | Very deep; solum more than 60 in | | Drainage | Somewhat poorly drained | | Saturated hydraulic conductivity | Moderately low | | Water table | Perched; top at 2.5-3 ft, December to April | | Subsoil (Bt) | Silty clay loam to clay; 35-45% clay | | Slopes | 0-5% (generally 0-3%) | | Mean annual rainfall | About 42 in (range 37-46 in) | "Colluvium" is soil material that has crept or washed down a slope. "Aquic" in the classification signals a soil that is wet for part of the year. Most Choteau land is cropland for small grains, sorghum or soybeans, with some tame pasture and native tallgrass prairie [1]. ## What do the properties mean for foundations? ### A perched water table A perched water table is a local zone of saturated soil held above the main groundwater by a slowly permeable layer, usually clay [5]. In Choteau the top of this zone sits 2.5 to 3 feet below the surface and its bottom 5 to 8 feet down, from December to April [1]. Related topics: groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water), crawl space moisture and wood decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay), and lateral earth, swell and hydrostatic pressure on walls (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls). ### Clay that responds to moisture Clayey soils swell when they take on water and shrink when they dry, and uneven moisture causes more foundation damage than uniform changes [4]. Choteau's subsoil holds 35 to 45 percent clay [1]. NRCS rates shrink-swell by linear extensibility percent (LEP): under 3 percent low, 3 to 6 percent moderate, 6 to 9 percent high and 9 percent or more very high [3]. Web Soil Survey lists the LEP for each Choteau map unit [2]. Wet winters followed by dry summers are the setting for perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) and perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). ## What should you know about a Choteau lot? - Look up the map unit, LEP and water table data in Web Soil Survey [2]. - Grade soil away from the foundation and route downspouts away from the house so roof water does not add to seasonal saturation [4]. - Keep sprinkler heads and planter beds from ponding water near the foundation [4]. - Monitor existing cracks and check drainage around the house each year [4]. ## Related - Soil Series - Tulsa Metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) - Groundwater and Perched Water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Dennis soil (https://terrabrain.vercel.app/soils/dennis) - Crawl Space Encapsulation (https://terrabrain.vercel.app/repairs/crawl-space-encapsulation) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - CHOTEAU Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/CHOTEAU.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] perched water table (NAL Agricultural Thesaurus), USDA National Agricultural Library https://lod.nal.usda.gov/nalt/en/page/57413 --- # What is Clarksville soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/clarksville Answer: A deep, cherty Ozark soil on steep slopes with fast-draining gravelly upper layers and clay 3 to 4.5 feet down; slope and runoff are the main concerns. In short: Clarksville is a deep, gravelly soil of the Ozarks that forms on steep side slopes and narrow ridgetops, including in northeastern Oklahoma. Its upper layers are loaded with chert gravel and drain quickly, while clayey layers with more than 40 percent clay begin 3 to 4.5 feet down. Slope, runoff and the rocky, variable profile are the main foundation-related traits. ## Where does Clarksville soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) maps Clarksville across the Ozark region (Major Land Resource Areas 116A and 116B) of Kansas, Missouri, Oklahoma and Arkansas, as well as in dissected cherty areas of other southeastern states [1]. It is a series of large extent; its type location is in Shannon County, Missouri [1]. In Oklahoma, this places Clarksville in the Northeast (Ozark Plateau and Grand Lake) (https://terrabrain.vercel.app/regions/northeast-ozark-plateau-and-grand-lake) region, where the bedrock includes Mississippian cherty limestone (https://terrabrain.vercel.app/geology/mississippian-cherty-limestone). The soil forms in hillslope sediments over clayey residuum weathered from cherty dolomite or cherty limestone [1]. "Residuum" is material that weathered in place from the rock beneath. ## What are its key properties? | Property | Clarksville (from the OSD) [1] | |---|---| | Classification | Loamy-skeletal, siliceous, semiactive, mesic Typic Paleudults | | Parent material | Hillslope sediments over clayey residuum from cherty dolomite or limestone | | Depth to bedrock | More than 80 in | | Drainage | Somewhat excessively drained | | Permeability | Moderate | | Runoff | Medium to very high | | Slopes | 1-70% | | Clay layers (>40% clay) | Begin at 36-54 in | | Mean annual rainfall | About 43 in (range 40-46 in) | | Mean annual temperature | About 55°F | "Loamy-skeletal" means the soil has a large share of rock fragments mixed into a loamy matrix. Clarksville land is mostly second-growth timber of oak, hickory and shortleaf pine, with some pasture and hayland [1]. ## What is the Clarksville profile, layer by layer? The OSD's typical profile shows how much chert the soil holds [1]: - Surface (A): gravelly silt loam with about 30 percent chert gravel. - Upper subsoil (Bt1 to Bt2): gravelly silt loam to very gravelly loam, 20 to 45 percent chert gravel. - Middle subsoil (2Bt3 to 2Bt4): extremely to very gravelly clay loam, 40 to 55 percent chert gravel plus cobbles. - Lower subsoil (3Bt5): cobbly clay. ## What do the properties mean for foundations? ### Steep ground and fast runoff Clarksville occupies slopes up to 70 percent and sheds water with medium to very high runoff [1]. On sloped sites, concentrated runoff and erosion are the main soil-related concerns; see erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes), slope creep and lateral movement (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement) and surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). The ASCE homeowner guide describes grading soil away from a foundation and sending downspout water away from the house to keep moisture even [4]. ### Rocky upper layers, clay below The gravelly upper layers drain readily, but the clayey residuum with over 40 percent clay begins 36 to 54 inches down [1]. Clay soils swell when wet and shrink when dry [4]. NRCS rates shrink-swell by linear extensibility percent (LEP): under 3 percent low, 3 to 6 percent moderate, 6 to 9 percent high and 9 percent or more very high [3]. The rated LEP for each Clarksville map unit is published in Web Soil Survey [2]. ### Cut-and-fill pads Where a building pad was cut into the hillside or built up with fill, that fill is not part of the native profile the OSD describes [1], and its behavior depends on how it was placed; see fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). ## How is a specific lot checked? - Look up the map unit, slope class and LEP in Web Soil Survey [2]. - Check drainage within several feet of the foundation each year and monitor existing cracks [4]. ## Related - Mississippian Cherty Limestone (https://terrabrain.vercel.app/geology/mississippian-cherty-limestone) - Northeast Oklahoma (Ozark Plateau and Grand Lake) (https://terrabrain.vercel.app/regions/northeast-ozark-plateau-and-grand-lake) - Slope and Erosion Stabilization (https://terrabrain.vercel.app/repairs/slope-and-erosion-stabilization) - Hector soil (https://terrabrain.vercel.app/soils/hector) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - CLARKSVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/CLARKSVILLE.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Collinsville soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/collinsville Answer: Collinsville is a shallow sandy loam over hard sandstone 4 to 20 inches down, with 5 to 20 percent clay, so rock depth and runoff matter more than swelling. In short: Collinsville is a shallow, sandy loam soil that sits on hard Pennsylvanian sandstone only 4 to 20 inches below the surface. It holds just 5 to 20 percent clay, drains quickly and sheds a lot of runoff. The series was first described in Tulsa County, and on these sites the closeness of rock and the handling of surface water matter more than clay swelling. ## Where does Collinsville soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) maps Collinsville in Oklahoma, Kansas and Missouri, in Major Land Resource Areas 84A, 112, 118A and 118B [1]. It is an extensive series, established in Tulsa County in 1935, with its type location in Rogers County about 2 miles north and 1.5 miles east of Inola [1]. Collinsville forms on interfluves (the ridges between drainages) and hillslopes, on slopes of 1 to 35 percent [1]. It weathered in place from Pennsylvanian sandstone (https://terrabrain.vercel.app/geology/pennsylvanian-sandstones) [1], one of the rock types that shape the Tulsa metro (https://terrabrain.vercel.app/regions/tulsa-metro) and the Northeast (Ozark Plateau and Grand Lake) (https://terrabrain.vercel.app/regions/northeast-ozark-plateau-and-grand-lake) region. ## What are the key properties of Collinsville soil? | Property | Collinsville (from the OSD) [1] | |---|---| | Classification | Loamy, siliceous, superactive, thermic Lithic Hapludolls | | Parent material | Residuum from Pennsylvanian sandstone | | Depth to hard rock | 4-20 in (typical 9 in) | | Drainage | Well to somewhat excessively drained | | Saturated hydraulic conductivity | High | | Runoff | Medium to very high | | Texture | Loam or fine sandy loam, often gravelly, cobbly or stony | | Clay | 5-20% in all layers | | Slopes | 1-35% | | Mean annual rainfall | About 40 in (range 31-47 in) | The word "Lithic" in the classification refers to this shallow contact with hard rock, which the OSD places at 10 to 50 cm (4 to 20 inches) [1]. Collinsville land is mainly native tallgrass range, with small areas of tame pasture [1]. ## What do these properties mean for foundations? ### Little swelling clay Shrink-swell movement comes from clay soils that swell when wet and shrink when dry [4]. With 5 to 20 percent clay and 30 to 75 percent sand [1], Collinsville has far less clay than Oklahoma's expansive clays. NRCS rates shrink-swell by linear extensibility percent (LEP), with under 3 percent classed as low [3]; the rated LEP for each map unit is in Web Soil Survey [2]. ### Rock close to the surface Hard sandstone lies only 4 to 20 inches below the surface of a Collinsville profile [1]. In Oklahoma steel push pier records, piers (steel pipes driven down to firm bearing) typically reached 8 to 16 feet, with a median of about 12 feet in Tulsa [5]. On Collinsville sites the sandstone is much shallower than that, so a pier depth well under the regional median is consistent with the soil description. Whether shallow refusal is on continuous rock or on a loose ledge or boulder is a question for depth to rock from borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings) and bedrock in the Tulsa metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro). ### Runoff, erosion and fill High runoff and a thin sandy soil over rock make concentrated water a concern [1]. Uneven moisture and leaks are common triggers for localized movement [4]. Where fill was placed to level a lot, it is not part of the native profile the OSD describes [1]; see erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) and fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). ## How do you check a specific lot? - Look up the map unit and depth-to-bedrock rating in Web Soil Survey [2]. - Route downspouts away from the foundation and grade soil to drain away from the house [4]. - Track cracks over time and check drainage around the house yearly [4]. ## Related - Soil Series - Tulsa Metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) - Bedrock - Tulsa Metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Coweta soil (https://terrabrain.vercel.app/soils/coweta) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - COLLINSVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COLLINSVILLE.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # What is Coweta soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/coweta Answer: Coweta is a shallow, well-drained loamy soil on eastern Oklahoma ridges over soft sandstone 10 to 20 inches down. Shallow rock and runoff are its main traits. In short: Coweta is a shallow, loamy soil on eastern Oklahoma ridges and hillslopes that rests on soft Pennsylvanian sandstone, interbedded with shale, just 10 to 20 inches down. It holds about 10 to 30 percent clay and drains well. Shallow, soft rock and runoff on sloping ground are its main foundation-related traits. ## Where does Coweta soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) places Coweta in Major Land Resource Areas 84A, 112, 117 and 118 in eastern Oklahoma, and possibly southeastern Kansas and southwestern Missouri [1]. The type location is in Wagoner County about 11 miles northeast of the town of Coweta, and the series is of moderate extent [1]. Coweta forms on broad, smooth upland ridges, interfluves and hillslopes, on slopes of 1 to 30 percent [1]. It weathered from sandstone interbedded with shale of Pennsylvanian age [1]; see Pennsylvanian sandstones (https://terrabrain.vercel.app/geology/pennsylvanian-sandstones) and Pennsylvanian shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales). This is common ground in the Tulsa metro (https://terrabrain.vercel.app/regions/tulsa-metro) and East-Central (Arkoma) (https://terrabrain.vercel.app/regions/east-central-arkoma) region. ## What are Coweta soil's key properties? | Property | Coweta (from the OSD) [1] | |---|---| | Classification | Loamy, siliceous, superactive, thermic, shallow Typic Hapludolls | | Parent material | Residuum from soft sandstone interbedded with shale | | Depth to soft sandstone | 10-20 in (typical 15 in) | | Drainage | Well to somewhat excessively drained | | Saturated hydraulic conductivity | Moderately high to high | | Runoff | Medium to very high | | Subsoil (Bw) | Loam, fine sandy loam or clay loam, often gravelly; 10-30% clay | | Slopes | 1-30% | | Mean annual rainfall | About 41 in (range 35-45 in) | A "Bw" horizon is a subsoil layer that has changed color or structure but has not gained much clay. Coweta land is mainly rangeland of tallgrass prairie, with tame pasture on slopes under 15 percent and small cultivated areas on slopes under 5 percent [1]. ## What does Coweta soil mean for foundations? ### Low clay content Clay soils swell when wet and shrink when dry, which is the main driver of seasonal foundation movement [4]. Coweta's subsoil has 10 to 30 percent clay [1]. NRCS classes linear extensibility (LEP) under 3 percent as low, 3 to 6 percent as moderate, 6 to 9 percent as high and 9 percent or more as very high [3]. The LEP for each Coweta map unit is listed in Web Soil Survey [2]. ### Soft rock, not hard rock The rock under Coweta is described as soft sandstone, reached at 10 to 20 inches [1]. That contrasts with the neighboring Collinsville series, which sits on hard sandstone at 4 to 20 inches [5]. How soft, interbedded rock behaves as a bearing layer is covered in shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata). In Oklahoma steel push pier records, piers typically reached 8 to 16 feet, with a median near 12 feet in Tulsa [6]; the depth to rock from borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings) page summarizes measured rock depths. ### Runoff and erosion Coweta sheds medium to very high runoff on slopes up to 30 percent [1]. Uneven moisture and water line or sewer leaks can cause localized movement [4]. Related mechanisms are described under erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) and fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). ## How do you check a specific lot? - Look up the map unit, slope and depth to bedrock in Web Soil Survey [2]. - Grade soil away from the foundation and discharge downspouts away from the house [4]. - Repair leaks quickly and confirm repairs with pressure tests [4]. ## Related - Collinsville soil (https://terrabrain.vercel.app/soils/collinsville) - Soil Series - Tulsa Metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) - Bedrock - Tulsa Metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - COWETA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COWETA.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Official Series Description - COLLINSVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COLLINSVILLE.html [6] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # What is crawl space encapsulation and what does code require? URL: https://terrabrain.vercel.app/repairs/crawl-space-encapsulation Answer: Encapsulation covers the ground with a sealed vapor retarder, seals vents, insulates walls and dries the air. Code allows it as an unvented crawl space. In short: Crawl space encapsulation closes a vented crawl space and treats it as part of the house: the ground is covered with a sealed vapor retarder, vents are sealed, walls are insulated and the air is dried. The residential code allows this as an unvented crawl space if specific conditions are met. It controls humidity and ground moisture, not flowing or standing water, so drainage problems are corrected first. ## How do vented and unvented crawl spaces differ? The residential code (IRC Section R408) allows two approaches [1]: | | Vented crawl space | Unvented (encapsulated) crawl space | |---|---|---| | Outside air | Openings of at least 1 sq ft per 150 sq ft of crawl area, one within 3 ft of each corner [1] | No vents to outside [1] | | Ground cover | Optional; with a Class I vapor retarder, vent area can drop to 1 sq ft per 1,500 sq ft [1] | Continuous Class I vapor retarder over all exposed earth [1] | | Seams | n/a | Lapped at least 6 in and sealed or taped [1] | | Wall edge | n/a | Retarder carried at least 6 in up the stem wall and attached [1] | | Air control | Natural cross-ventilation [1] | Continuous exhaust at 1 cfm per 50 sq ft, conditioned supply air at 1 cfm per 50 sq ft, a plenum in existing buildings, or dehumidification sized to the manufacturer's specifications [1] | A **Class I vapor retarder** is a sheet material, such as heavy polyethylene, that lets almost no water vapor pass through. **Dehumidification** means a dehumidifier that removes moisture from the crawl space air. In the warm-humid parts of Climate Zones 1A, 2A and 3A, insulated floors over vented crawl spaces need a Class I or II vapor retarder on the exposed face of the insulation [1]. ## What does encapsulation typically include? - Removing debris, vegetation and organic material from the crawl floor, which the code requires in any crawl space [1]. - A sealed ground liner, lapped and taped at seams and attached and sealed to the stem wall [1]. - Sealing vents and the rim area to outside air. - Insulating the perimeter walls instead of the floor above. - A dehumidifier or a small conditioned-air supply, one of the code's options [1]. - A sealed access door. Polyethylene sheeting under a slab acts as a capillary break, and properly installed vapor retarders in crawl spaces and basements can reduce moisture movement through concrete [6]. ## Why must water problems be fixed first? Encapsulation does not fix bulk water. The code's crawl space section calls for raising the under-floor grade or adding a drainage system where groundwater may rise to within 6 in of the finished floor at the perimeter or where surface water does not drain readily [1]. Outside, the grade must fall at least 6 in within the first 10 ft of the foundation, with swales or drains where that is not possible, and gutters and downspouts discharging away from the foundation [4]. Where below-grade space is enclosed by earth-retaining walls, footing drains discharge by gravity or pump [5]. Home inspectors are required to report signs of active water penetration and wood in contact with or near soil [3], two of the conditions that point to water work before a liner goes in. Seasonal perched water under Oklahoma crawl spaces is explained in groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water), and surface fixes are covered in drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). ## How does encapsulation apply to manufactured homes? For manufactured homes, HUD's installation standard requires a vapor retarder of at least 6-mil polyethylene covering the ground whenever the space under the home is skirted or enclosed, with joints overlapped at least 12 in and tears repaired, unless the home is in an arid region with dry soil [2]. See manufactured homes on piers (https://terrabrain.vercel.app/foundations/manufactured-homes-on-piers). ## How does encapsulation relate to structural repair? Encapsulation protects new or repaired framing from moisture but does not re-support a sagging floor. Rot, failed shims and settled piers are addressed under crawl space repair (https://terrabrain.vercel.app/repairs/crawl-space-repair), and the moisture mechanism is described in crawl space moisture and wood decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay). ## Related - Crawl Space Repair (https://terrabrain.vercel.app/repairs/crawl-space-repair) - Water, Condensation or Mold in Crawl (https://terrabrain.vercel.app/signs/water-condensation-or-mold-in-crawl) - Crawl Space Moisture and Wood Decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) - Pier and Beam Crawl Space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) Sources: [1] Inspecting Under-Floor Crawl Spaces: A Guide for Home Inspectors (2024 IRC Section R408), InterNACHI https://www.nachi.org/under-floor-crawl-space.htm [2] 24 CFR Part 3285 – Model Manufactured Home Installation Standards (Code of Federal Regulations, 2020), U.S. Government Publishing Office https://www.govinfo.gov/content/pkg/CFR-2020-title24-vol5/pdf/CFR-2020-title24-vol5-part3285.pdf [3] InterNACHI Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [4] Foundation Fundamentals: Inspecting Load Paths and Water Paths (IRC R401.2 & R401.3), InterNACHI https://nachi.org/foundation-load-water.htm [5] Inspecting Foundation Drainage: Essential Guidelines for Below-Grade Spaces (IRC R405), InterNACHI https://www.nachi.org/foundation-drainage-below-grade.htm [6] Understanding Efflorescence and Spalling: Critical Assessment Points for Home Inspectors, InterNACHI https://www.nachi.org/efflorescence-capillary-osmosis-spalling --- # What is Dale soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/dale Answer: Dale is a very deep, well-drained silt loam to clay loam on central Oklahoma flood plains, so flood exposure and variable layering are the key questions. In short: Dale is a very deep, well-drained soil formed in loamy stream sediment on the flood plains of central Oklahoma. Its layers are silt loam to clay loam rather than heavy clay. Because Dale lies on flood plains, flood exposure and the variable layering of stream deposits are the key questions for a house built on it. ## Where does Dale soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) places Dale in central Oklahoma and south-central Kansas, in Major Land Resource Area 80A, the Central Rolling Red Prairies [1]. It is moderately extensive [1]. The type location is in Lincoln County about 1 mile east of Harrah, at 1,070 feet elevation, and the series was established in Okfuskee County in 1940 [1]. Dale forms on level to sloping flood plains, on slopes of 0 to 8 percent [1]. Its parent material is loamy alluvium [1], the young stream deposits described on the Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) page. Within Oklahoma that ties Dale to river and creek valleys of the OKC metro (https://terrabrain.vercel.app/regions/okc-metro) and the Southwest (Lawton and Red Plains) (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains). ## What are its key properties? | Property | Dale (from the OSD) [1] | |---|---| | Classification | Fine-silty, mixed, superactive, thermic Pachic Haplustolls | | Parent material | Loamy alluvium | | Landform | Flood plains on alluvial plains | | Depth | Very deep | | Drainage | Well drained | | Permeability | Moderate | | Layers (A, Bw, BCk) | Silt loam, loam, silty clay loam or clay loam | | Calcium carbonate | Begins at 20-60 in | | Slopes | 0-8% | | Mean annual rainfall | About 33 in (range 25-41 in) | | Mean annual temperature | About 61°F | "Alluvium" is sediment deposited by flowing water. "Pachic" means the dark, organic-rich topsoil is unusually thick. Dale is mostly cultivated for alfalfa, small grains, grain sorghum and cotton, and native vegetation included tall and mid grasses with pecan, black walnut, bur oak and cottonwood [1]. ## What do its properties mean for foundations? ### Flood plain setting The OSD describes Dale as a flood plain soil [1]. Official flood hazard maps for the National Flood Insurance Program are published through FEMA's Flood Map Service Center, which can be searched by address [5]. Flood history for Oklahoma creeks and rivers is summarized in creeks and flood history (https://terrabrain.vercel.app/data/creeks-and-flood-history). ### Layered stream deposits Some Dale profiles contain thin strata of loamy fine sand, fine sandy loam or very fine sandy loam below 50 inches [1]. Settlement in soft or variable alluvial layers is covered under soft soil consolidation in alluvium and wet clays (https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays). ### Shrink-swell Clayey soils swell when wet and shrink when dry [4]. Dale's layers are loamy, and the OSD lists geographically associated series such as Brewer, Lela and McLain as having more than 35 percent clay in the control section [1]. NRCS classes linear extensibility (LEP) under 3 percent as low and 3 to 6 percent as moderate [3]; the LEP for each Dale map unit is in Web Soil Survey [2]. ### Water near the foundation Uneven soil moisture is more damaging than uniform moisture, and leaks or poor drainage near a house can cause localized movement [4]. Related topics: erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) and surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). ## How can a specific lot be checked? - Look up the map unit and its LEP in Web Soil Survey [2]. - Search the address in FEMA's Flood Map Service Center [5]. - Keep downspout water and sprinklers from ponding next to the foundation [4]. ## Related - Quaternary Alluvium and Terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) - Erosion, Creeks and Slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Groundwater and Perched Water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Soil Series - OKC Metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - DALE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DALE.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] FEMA Flood Map Service Center | Welcome!, Federal Emergency Management Agency https://msc.fema.gov/ --- # What is Dalhart soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/dalhart Answer: Dalhart is a deep, well-drained Panhandle soil formed in wind-laid loamy sediment; wetting response and water management are the main foundation questions. In short: Dalhart is a deep, well-drained soil of the Oklahoma Panhandle that formed in loamy sediment laid down by wind. Its subsoil is sandy clay loam over limy loam, and the area averages only about 18 inches of rain a year. For foundations, the main soil questions are how the wind-laid material responds to wetting and how water is managed around the house. ## Where does Dalhart soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) places Dalhart in the Southern High Plains, Northern Part (Major Land Resource Area 77A) of Kansas, Oklahoma and Texas, and describes the series as extensive [1]. The type location is in Cimarron County, about 8 miles west and 1 mile south of the Boise City courthouse, at roughly 4,295 feet elevation [1]. Dalhart forms on interdunes and sand sheets on tablelands, on slopes of 0 to 8 percent [1]. Its parent material is loamy eolian (wind-deposited) sediment of Holocene age [1]. This is the Panhandle (High Plains) (https://terrabrain.vercel.app/regions/panhandle-high-plains) landscape, where wind-laid deposits cover the Ogallala Formation (https://terrabrain.vercel.app/geology/ogallala-formation-and-loess). ## What are its key properties? | Property | Dalhart (from the OSD) [1] | |---|---| | Classification | Fine-loamy, mixed, superactive, mesic Aridic Haplustalfs | | Parent material | Loamy Holocene eolian sediment | | Depth | Solum more than 80 in | | Drainage | Well drained | | Permeability | Moderate | | Subsoil | Bt sandy clay loam; Btk loam | | Clay in control section | 18-30% | | Calcium carbonate | Depth to secondary carbonates 10-66 in | | Slopes | 0-8% | | Mean annual rainfall | About 18 in (range 15-23 in) | | Mean annual temperature | About 55°F | "Btk" marks a subsoil layer that has gained both clay and calcium carbonate (lime). "Aridic" signals a dry moisture regime. Dalhart is used mainly for wheat and grain sorghum, with some grazing on native mixed grasses [1]. ## What do the properties mean for foundations? ### Wind-laid soil and wetting Collapsible soils are unsaturated soils that lose volume when wetted, loaded, or both, and wind-deposited soils such as loess and dune sands are among the deposits where they occur, especially in dry climates [4]. Collapse depends on a loose, open grain structure held together by weak bonds such as clay or calcium carbonate, which water can weaken [4]. Common wetting sources include irrigation, leaking pipes, septic fields and redirected rainwater [4]. The OSD does not rate Dalhart's collapse potential, so this is a site question; see hydrocollapse (collapsible soil) (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil) and collapsible and loess soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils). ### Shrink-swell Clayey soils swell when wet and shrink when dry [5]. Dalhart's control section has 18 to 30 percent clay [1]. NRCS classes linear extensibility (LEP) under 3 percent as low, 3 to 6 percent moderate, 6 to 9 percent high and 9 percent or more very high [3]; the LEP for each Dalhart map unit is published in Web Soil Survey [2]. ### Water management The ASCE homeowner guide stresses keeping soil moisture uniform around a foundation, grading soil away from the house and having leaks found and repaired [5]. On wind-laid soils, the same steps limit the wetting that can trigger collapse [4]. See surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) and plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab). ## How do you check a specific lot? - Look up the map unit and LEP in Web Soil Survey [2]. - Route downspouts and irrigation water away from the foundation [5]. ## Related - Collapsible and Loess Soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils) - Ogallala Formation and Loess (https://terrabrain.vercel.app/geology/ogallala-formation-and-loess) - Panhandle (High Plains) (https://terrabrain.vercel.app/regions/panhandle-high-plains) - Freeze-Thaw and Frost Depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - DALHART Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DALHART.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Collapsible Soil (Geotechnical Manual module, January 2026), California Department of Transportation https://dot.ca.gov/-/media/dot-media/programs/engineering/documents/geotechnical-services/202601-gm-collapsiblesoil-a11y.pdf [5] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Darnell soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/darnell Answer: A shallow, sandy, rapidly drained soil over Permian sandstone 10 to 20 inches down; shallow rock, slopes and runoff matter more than clay swelling. In short: Darnell is a shallow, sandy soil on the hills of Oklahoma's Cross Timbers, resting on Permian sandstone only 10 to 20 inches down. It drains rapidly and is not a clay soil. For houses on Darnell, the shallow rock, slopes and handling of runoff and leaks matter more than seasonal clay swelling. ## Where does Darnell soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) lists Darnell in Oklahoma, Kansas and Texas within Major Land Resource Area 84A, the Cross Timbers [1]. It is an extensive series found at 740 to 1,315 feet elevation [1]. The type location is about 8 miles west of Tryon in Lincoln County, and the series was established in Okfuskee County in 1942 [1]. Darnell forms on very gently sloping to steep ridge crests and upper side slopes of hills, on slopes of 1 to 45 percent [1]. It weathered from Permian sandstone [1]; Oklahoma's Permian sandstones are covered on the Garber Sandstone (https://terrabrain.vercel.app/geology/garber-sandstone) page, and the type location in Lincoln County lies east of the OKC metro (https://terrabrain.vercel.app/regions/okc-metro). ## What are its key properties? | Property | Darnell (from the OSD) [1] | |---|---| | Classification | Loamy, siliceous, active, thermic, shallow Udic Haplustepts | | Parent material | Permian sandstone | | Depth to sandstone | 10-20 in (typical 15 in) | | Drainage | Well to somewhat excessively drained | | Permeability | Very high | | Surface (A) | Sandy loam, fine sandy loam or loam | | Subsoil (Bw) | Sandy loam or fine sandy loam | | Bedrock (Cr) | Sandstone, high to very high excavation difficulty | | Slopes | 1-45% | | Mean annual rainfall | About 32 in (range 28-40 in) | A "paralithic contact" is the boundary with rock that is weathered or only weakly cemented, as opposed to hard rock. The OSD notes that the Cr sandstone has high or very high excavation difficulty, meaning it is hard to dig [1]. Darnell is used mainly as rangeland under post oak, blackjack oak and eastern red cedar [1]. ## What do the properties mean for foundations? ### Sandy texture, little clay Clay soils swell when they take on water and shrink when they dry, moving foundations up and down [4]. Darnell's surface and subsoil are sandy loam or fine sandy loam [1]. NRCS classes linear extensibility (LEP) under 3 percent as low and 3 to 6 percent as moderate [3]; the rated LEP for each Darnell map unit is in Web Soil Survey [2]. ### Rock within 20 inches Sandstone lies 10 to 20 inches below the surface [1]. Questions about whether a foundation bears on soil, weathered rock or sound rock are covered in shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata) and depth to rock from borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings). ### Runoff, leaks and erosion Darnell's very high permeability and steep slopes mean water moves quickly through and across it [1]. Uneven moisture causes more damage than uniform moisture, and water or sewer leaks can produce localized movement [4]. See erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) and plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab). ### Trees Native vegetation on Darnell is post oak, blackjack oak and eastern red cedar [1]. Tree roots can dry soil unevenly near a foundation, and the ASCE guide describes planting trees farther from the house than their mature height [4]; see trees and roots (https://terrabrain.vercel.app/guides/trees-and-roots). ## How is a specific lot checked? - Look up the map unit, slope and depth to bedrock in Web Soil Survey [2]. - Grade soil to drain away from the foundation and discharge downspouts away from the house [4]. - Monitor existing cracks and inspect drainage around the house each year [4]. ## Related - Garber Sandstone (https://terrabrain.vercel.app/geology/garber-sandstone) - Chickasha soil (https://terrabrain.vercel.app/soils/chickasha) - Dougherty soil (https://terrabrain.vercel.app/soils/dougherty) - Fill Consolidation Settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - DARNELL Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DARNELL.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Dennis soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/dennis Answer: Dennis is a deep, somewhat poorly drained clay soil with 28 to 50 percent clay and a perched water table 12 to 30 inches down in winter and spring. In short: Dennis is a very deep clayey soil of northeastern Oklahoma, first described in Wagoner County and typified near Claremore. It is somewhat poorly drained, with a perched water table 12 to 30 inches down in winter and spring, and its subsoil holds 28 to 50 percent clay. Seasonal saturation followed by summer drying is the main soil condition behind foundation movement on Dennis. ## Where does Dennis soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) maps Dennis in southeastern Kansas, southwestern Missouri and eastern Oklahoma, mostly in Major Land Resource Area 112 (the Cherokee Prairies), with smaller areas in MLRA 76 and LRUs 84A, 116A and 118B [1]. It is an extensive series [1]. The type location is about half a mile north of Claremore in Rogers County, and the series was established in Wagoner County in 1941 [1]. Dennis forms on interfluves and hillslopes on plains, on slopes of 0 to 8 percent, commonly 1 to 5 percent [1]. It weathered from Pennsylvanian shale (https://terrabrain.vercel.app/geology/pennsylvanian-shales) [1]. Its type location near Claremore and its founding in Wagoner County place it in the Tulsa metro (https://terrabrain.vercel.app/regions/tulsa-metro) area; see also the neighboring East-Central (Arkoma) (https://terrabrain.vercel.app/regions/east-central-arkoma) region. See soil series of the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) for neighboring soils. ## What are the key properties of Dennis soil? | Property | Dennis (from the OSD) [1] | |---|---| | Classification | Fine, mixed, active, thermic Aquic Argiudolls | | Parent material | Residuum from Pennsylvanian shale | | Depth | Very deep; solum more than 60 in | | Drainage | Somewhat poorly drained | | Saturated hydraulic conductivity | Moderately low | | Water table | Perched, 12-30 in, typically December-April | | Surface (A) | Loam, silt loam or silty clay loam | | Subsoil (Bt) | Silty clay loam, silty clay or clay; 28-50% clay | | Control section clay | 37-60% | | Slopes | 0-8% (commonly 1-5%) | | Mean annual rainfall | About 39 in (range 37-46 in) | "Argiudolls" are prairie soils with a dark topsoil and a clay-enriched subsoil in a humid climate; "Aquic" marks periodic wetness. Dennis is mainly cropland for small grains, sorghum, soybeans and some cotton, with tame pasture and native tallgrass range [1]. ## What do these properties mean for foundations? ### Perched water A perched water table is a local saturated zone held above the main groundwater by a slowly permeable layer, usually clay [5]. In Dennis it ranges from 12 to 30 inches below the surface from December through April in normal years [1]. Wet conditions at that depth relate to crawl space moisture and wood decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) and groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water). ### Clay that swells and shrinks Clay soils swell (heave) when they gain moisture and shrink when they dry, and uneven changes do more damage than uniform ones [4]. Dennis's subsoil holds 28 to 50 percent clay [1]. NRCS rates shrink-swell by linear extensibility percent (LEP): under 3 percent low, 3 to 6 percent moderate, 6 to 9 percent high and 9 percent or more very high [3]. Web Soil Survey lists the LEP for each Dennis map unit [2]. A wet winter edge and a dry summer edge are the patterns described in perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) and perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). ### Repair depth context In Oklahoma steel push pier records, piers (steel pipes driven to firm bearing below the moving clay) typically reached 8 to 16 feet, with a median near 12 feet in Tulsa [6]. Dennis itself is very deep, with a solum thicker than 60 inches [1]. ## What should you know about a Dennis lot? - Look up the map unit, water table and LEP in Web Soil Survey [2]. - Grade soil away from the house and send downspout water well away from the foundation [4]. - Water evenly on all sides during dry spells, with extra attention to the sunnier south and west sides [4]. - Track cracks and check drainage each year [4]. ## Related - Choteau soil (https://terrabrain.vercel.app/soils/choteau) - Eram soil (https://terrabrain.vercel.app/soils/eram) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - DENNIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DENNIS.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] perched water table (NAL Agricultural Thesaurus), USDA National Agricultural Library https://lod.nal.usda.gov/nalt/en/page/57413 [6] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # What is Dougherty soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/dougherty Answer: Dougherty is a very deep central Oklahoma soil with 20 to 40 inches of loose fine sand over sandy clay loam, so erosion and water management are main concerns. In short: Dougherty is a very deep, well-drained soil of central Oklahoma with 20 to 40 inches of loose fine sand on top of a sandy clay loam subsoil. It formed on old stream terraces where wind reworked the sand into dunes that are now covered with vegetation. The thick sand layer makes erosion and water management the main soil concerns for houses built on it. ## Where does Dougherty soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) places Dougherty in central Oklahoma and Texas, in Major Land Resource Areas 80A and 84A, at 750 to 1,220 feet elevation [1]. It is a series of large extent [1]. The type location is in Payne County, about 9 miles south and 8 miles west of Stillwater on State Highway 33, and the series was established in Murray County [1]. Dougherty forms on stabilized dunes on reworked stream terraces, on slopes that are dominantly 0 to 8 percent and range to 20 percent [1]. Its parent material is sandy and loamy Pleistocene terrace sediment [1], covered on the Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) page. The Payne County type location sits in the North-Central (Red Prairies and Wheat Belt) (https://terrabrain.vercel.app/regions/north-central-red-prairies-and-wheat-belt) region, north of the OKC metro (https://terrabrain.vercel.app/regions/okc-metro). ## What are Dougherty soil's key properties? | Property | Dougherty (from the OSD) [1] | |---|---| | Classification | Loamy, mixed, active, thermic Arenic Haplustalfs | | Parent material | Sandy and loamy Pleistocene terrace sediment | | Depth | Very deep, more than 60 in | | Drainage | Well drained | | Saturated hydraulic conductivity | Moderately high | | Surface (A and E) | Fine sand or loamy fine sand, 20-40 in thick | | Subsoil (Bt) | Fine sandy loam or sandy clay loam; 18-35% clay | | Slopes | 0-8% (to 20%) | | Mean annual rainfall | About 34 in (range 31-43 in) | | Mean annual temperature | About 59°F | "Arenic" in the classification refers to the thick sandy layer above the clay-enriched subsoil. The "E" horizon is a pale layer from which clay has been washed downward. Dougherty is used for sorghum, small grains, peanuts and improved pasture, and native vegetation is post oak, blackjack and hickory savannah [1]. ## What does Dougherty soil mean for foundations? ### Thick sand at the surface The upper 20 to 40 inches of Dougherty are fine sand or loamy fine sand, and the typical pedon has 27 inches of sandy material [1]. Washout of sandy soil by concentrated water is covered in erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). The ASCE homeowner guide describes using clay rather than sandy soil as fill next to a foundation, compacted so it sheds water away from the house [4]. ### Clay subsoil below Under the sand, the Bt subsoil holds 18 to 35 percent clay [1]. Clay soils swell when wet and shrink when dry, and uneven moisture causes more damage than uniform changes [4]. NRCS classes linear extensibility (LEP) under 3 percent as low and 3 to 6 percent as moderate [3]; the LEP for each Dougherty map unit is in Web Soil Survey [2]. ### Leaks and drainage Water or sewer leaks can cause localized foundation movement, and the ASCE guide advises monitoring water bills and having leaks located and repaired [4]. The guide also describes downspouts discharging away from the foundation onto splash blocks that prevent erosion [4]. See plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) and surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). ## How do you check a specific lot? - Look up the map unit, slope and LEP in Web Soil Survey [2]. - Check that soil next to the foundation slopes away from the house and has not washed out [4]. - Look for gaps or soil pulled away from the foundation (https://terrabrain.vercel.app/signs/soil-pulled-away-from-foundation) and exposed footings. ## Related - Quaternary Alluvium and Terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) - Exposed Slab Edge or Void Under Footing (https://terrabrain.vercel.app/signs/exposed-slab-edge-or-void-under-footing) - Void and Compaction Grouting (https://terrabrain.vercel.app/repairs/void-and-compaction-grouting) - Darnell soil (https://terrabrain.vercel.app/soils/darnell) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - DOUGHERTY Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DOUGHERTY.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Durant soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/durant Answer: Durant is a very deep south-central Oklahoma clay, 40 to 60 percent smectitic, that cracks over 1 cm wide and 30 inches deep when dry, so it shrinks and swells. In short: Durant is a very deep clay soil of south-central Oklahoma formed from Cretaceous shale and claystone. Its subsoil holds 40 to 60 percent smectitic clay, and in dry periods it cracks more than 1 cm wide and 30 inches deep. Those traits mark Durant as a shrink-swell soil, so seasonal foundation movement is the central concern for houses built on it. ## Where does Durant soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) places Durant in south-central Oklahoma, in Major Land Resource Area 85, the Grand Prairie of Oklahoma [1]. It is of moderate extent, and its type location is in Bryan County about 4 miles west and 1 mile north of Albany [1]. Durant forms on flat to slightly convex summits, shoulders and backslopes of broad ridges, on slopes of 0 to 6 percent [1]. It weathered from clayey Cretaceous shale and claystone (https://terrabrain.vercel.app/geology/cretaceous-shales-clays-and-sandstones) [1]. That places it in the South-Central (Arbuckles and Texoma) (https://terrabrain.vercel.app/regions/south-central-arbuckles-and-texoma) region, near the Southeast (Ouachitas and Red River) (https://terrabrain.vercel.app/regions/southeast-ouachitas-and-red-river). ## What are its key properties? | Property | Durant (from the OSD) [1] | |---|---| | Classification | Fine, smectitic, thermic Udertic Argiustolls | | Parent material | Clayey residuum from Cretaceous shale and/or claystone | | Depth | Very deep; shale or claystone below 64 in in some pedons | | Drainage | Moderately well drained | | Permeability | Very slow | | Upper subsoil (Bt) | Clay; 40-60% clay | | Control section clay | 35-60% | | Dry-period cracks | More than 1 cm wide and 30 in deep | | Slopes | 0-6% | | Mean annual rainfall | 45 in (range 37-45 in) | | Mean annual temperature | About 62°F | "Udertic" means the soil is an intergrade toward the Vertisols, the soil order defined by shrink-swell clay. "Smectitic" means smectite is the dominant clay mineral. Durant is used for cotton, small grains, grain sorghum, tame pasture and range [1]. ## Why does Durant soil move? ### Vertic behavior Vertisols are clay-rich soils that shrink as they dry and swell as they rewet, forming deep, wide cracks that open and close, and this shrink-swell action causes serious engineering problems including damage to structures [5]. Durant does not fully meet the Vertisol criteria, but its OSD records cracks more than 1 cm wide and 30 inches deep in dry periods, with the moisture control section dry in some part for about 90 to 135 days a year [1]. ### What that does to a house Clay soils swell (heave) when they gain moisture and shrink (settle) when they dry, moving shallow foundations up and down [4]. Uneven changes, such as a dry edge beside a wet interior, cause more damage than uniform ones [4]. Common patterns include: - Perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) in drought. - Perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) after wet spells. - Center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) as moisture builds under a slab. - Tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) near large trees. Warning signs include stair-step cracks in brick, sticking doors and windows, sloping floors and slab cracks 1/16 inch or wider [4]; see cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally). ### Measuring shrink-swell NRCS rates shrink-swell by linear extensibility percent (LEP), the change in length of soil between moist and oven-dry: under 3 percent low, 3 to 6 percent moderate, 6 to 9 percent high and 9 percent or more very high [3]. The LEP for each Durant map unit is published in Web Soil Survey [2]. ## What are the practical points for a Durant lot? - Look up the map unit and LEP in Web Soil Survey [2]. - Keep soil moisture next to and under the foundation as uniform as practical [4]. - Plant trees farther from the house than their mature height; deep root barriers can help where trees are already close [4]. - Repair leaks promptly and keep sprinklers at least 5 feet from the foundation [4]. ## Related - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Clay Mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Root Barriers and Moisture Control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control) - Bernow soil (https://terrabrain.vercel.app/soils/bernow) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - DURANT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DURANT.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Vertisols, University of Idaho, College of Agricultural and Life Sciences https://www.uidaho.edu/cals/soil-orders/vertisols --- # What is Eram soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/eram Answer: Eram is a clayey soil over weathered shale 20 to 40 inches down with a 1 to 2 foot seasonal water table; wet saturation and dry shrinkage affect foundations. In short: Eram is a clayey soil of eastern Oklahoma that sits on weathered Pennsylvanian shale 20 to 40 inches down. Its subsoil holds 35 to 55 percent clay, is extremely hard when dry, and lies under a seasonal water table 1 to 2 feet deep in winter and spring. Wet-season saturation, dry-season shrinkage and shallow weathered shale are the main traits that affect foundations. ## Where does Eram soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) maps Eram in Oklahoma, Kansas and Missouri, in Major Land Resource Areas 76, 84A, 112, 118B and 119 [1]. It is moderately extensive [1]. The type location is about 5 miles northeast of Beggs in Okmulgee County at 775 feet elevation, and the series was established in Okfuskee County in 1942 [1]. Eram forms on interfluves and hillslopes, including ridges and side slopes of hills, on slopes of 1 to 20 percent [1]. Its parent material is Pennsylvanian shale (https://terrabrain.vercel.app/geology/pennsylvanian-shales) with thin sandstone layers [1]. Okmulgee and Okfuskee counties lie in the East-Central (Arkoma) (https://terrabrain.vercel.app/regions/east-central-arkoma) region, south of the Tulsa metro (https://terrabrain.vercel.app/regions/tulsa-metro). ## What are its key properties? | Property | Eram (from the OSD) [1] | |---|---| | Classification | Fine, mixed, active, thermic Aquic Argiudolls | | Parent material | Pennsylvanian shale with thin sandstone | | Depth to bedrock | 20-40 in | | Drainage | Moderately well drained | | Saturated hydraulic conductivity | Moderately low to high above 31 in; very low to moderately high below | | Water table | Apparent seasonal high at 1-2 ft, winter and spring | | Subsoil (Bt, BC) | Clay loam to clay; 35-55% clay | | Consistence (Bt) | Extremely hard dry, very firm moist | | Slopes | 1-20% | | Mean annual rainfall | About 41 in (range 35-47 in) | "Consistence" describes how hard or firm a soil feels; "extremely hard when dry" is a sign of a dense clay. Eram is mainly rangeland of tall grass prairie, with some cropland and tame pasture [1]. ## What do the properties mean for foundations? ### Clay that wets and dries Clay soils swell when they gain water and shrink when they dry, and uneven moisture causes more damage than uniform moisture [4]. Eram combines 35 to 55 percent clay with a water table that rises to 1 to 2 feet in winter and spring [1]. NRCS classes linear extensibility (LEP) under 3 percent as low, 3 to 6 percent moderate, 6 to 9 percent high and 9 percent or more very high [3]; the LEP for each Eram map unit appears in Web Soil Survey [2]. See perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) and perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). ### Shallow weathered shale The bedrock layer (Cr) is weathered shale or compacted clay beds, reached at 20 to 40 inches [1]. Weathered shale is not the same as hard rock, a distinction covered in shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata). In Oklahoma steel push pier records, piers typically reached 8 to 16 feet, with a median near 12 feet in Tulsa [5]. Below 31 inches, Eram's saturated hydraulic conductivity drops as low as 0.01 micrometers per second [1], meaning water moves through the lower layers very slowly. ### Water management The ASCE homeowner guide describes grading soil away from the foundation, discharging downspouts away from the house and having leaks isolated and repaired [4]. Eram's seasonal water table already sits 1 to 2 feet down in winter and spring [1]. See surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) and groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water). ## How do you check a specific lot? - Look up the map unit, depth to bedrock, water table and LEP in Web Soil Survey [2]. - Watch for stair-step brick cracks, sticking doors and sloping floors, and track cracks over time [4]. ## Related - Dennis soil (https://terrabrain.vercel.app/soils/dennis) - Pennsylvanian Shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales) - Bedrock - Tulsa Metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - ERAM Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/E/ERAM.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # What is Foard soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/foard Answer: A sodium-affected smectitic clay of southwest Oklahoma with very slow drainage; seasonal shrink-swell and slow drainage drive foundation problems. In short: Foard is a clay soil of southwest Oklahoma that formed in old alluvium from the Wichita Mountains over Permian red beds. Its subsoil holds 35 to 45 percent smectitic clay, shows slickensides from shrink-swell, and is affected by sodium, which is linked to very slow water movement. Seasonal clay movement and very slow drainage are the main soil traits behind foundation problems on Foard. ## Where does Foard soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) places Foard in Oklahoma and Texas, in Major Land Resource Areas 78B and 78C, the Central Rolling Red Plains [1]. It is an extensive series [1]. The type location is in Cotton County, Oklahoma, at 1,092 feet elevation, and the series was established in Foard County, Texas [1]. Foard forms on nearly level to gently sloping broad summits and shoulders of terrace pediments, on slopes of 0 to 5 percent [1]. Its parent material is clayey old alluvium from granitic outwash of the Wichita Mountains (https://terrabrain.vercel.app/geology/wichita-granite-and-granite-wash), over clayey Permian red beds (https://terrabrain.vercel.app/geology/western-permian-red-beds) [1]. That places it in the Southwest (Lawton and Red Plains) (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains) region. ## What are its key properties? | Property | Foard (from the OSD) [1] | |---|---| | Classification | Fine, smectitic, thermic Vertic Natrustolls | | Parent material | Old granitic alluvium over Permian clayey sediments | | Solum | 40 to more than 60 in | | Drainage | Well drained | | Permeability | Very slow | | Subsoil (Btss) | Silty clay loam to clay; 35-45% clay | | Slickensides | Few to common in the subsoil | | Exchangeable sodium (ESP) | Under 15 upper subsoil; 15-25 deeper | | Slopes | 0-5% | | Mean annual rainfall | About 26 in (range 22-32 in) | "Natrustolls" are prairie soils with a natric horizon, a clay subsoil high in sodium. "Slickensides" are polished, grooved surfaces found in shrink-swell clays [5]. Foard is used mainly for small grains and cotton, with some native range [1]. ## What do the properties mean for foundations? ### Vertic shrink-swell The "Vertic" part of Foard's name means it meets shrink-swell criteria close to those of the Vertisols: cracks at least 5 mm wide through 30 cm or more within 125 cm of the surface plus a slickenside layer, or a linear extensibility of 6.0 or more to 100 cm [1]. Vertisols shrink as they dry, swell as they rewet and cause serious engineering problems, including damage to structures [5]. NRCS classes linear extensibility (LEP) of 6 to 9 percent as high and 9 percent or more as very high [3]; the LEP for each Foard map unit is published in Web Soil Survey [2]. ### Sodium Exchangeable sodium percentage (ESP) in Foard rises from under 15 in the upper subsoil to 15 to 25 in deeper layers [1]. Soil structure starts to break down once about 15 percent of the exchange sites hold sodium [6]. Sodium makes clay particles repel each other and stay dispersed; dispersed clay plugs pores, forms crusts and restricts movement of air and water [6]. That is consistent with Foard's very slow permeability [1]. ### Typical movement patterns Clay soils heave when they gain moisture and settle when they dry, and uneven moisture causes more damage than uniform moisture [4]. Related movement patterns: - Perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) in dry spells. - Perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) after rain. - Center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) under slabs. - Tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) near trees. ## What practical points apply to a Foard lot? - Look up the map unit and LEP in Web Soil Survey [2]. - Keep soil moisture around the foundation as even as practical, watering more on the drier south and west sides in drought [4]. - Grade soil away from the house and repair leaks quickly [4]. ## Related - Hollister soil (https://terrabrain.vercel.app/soils/hollister) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Soil Testing and Lab Values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values) - Wichita Granite and Granite Wash (https://terrabrain.vercel.app/geology/wichita-granite-and-granite-wash) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - FOARD Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/F/FOARD.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Vertisols, University of Idaho, College of Agricultural and Life Sciences https://www.uidaho.edu/cals/soil-orders/vertisols [6] Dirt Diggers Digest - Issue 13, August 2022 (Soil Sodicity), Utah State University Extension https://extension.usu.edu/dirtdiggersdigest/soil-sodicity.php --- # What is frost heave and can it lift Oklahoma porches and steps? URL: https://terrabrain.vercel.app/causes/frost-heave Answer: Frost heave happens when moist, fine-grained soil freezes and grows ice lenses that push up shallow footings, steps, porches and slabs. In short: Frost heave is the upward push on shallow footings, steps, porches and slabs that happens when moist, fine-grained soil freezes and grows layers of ice called ice lenses. It needs three things at once: freezing temperatures, water and frost-susceptible soil. Shallow elements such as stoops, steps and flatwork are the most exposed. ## How does frost heave work? When the ground surface freezes, a freezing front moves downward through the soil. Water in the unfrozen soil below is drawn up toward that front by capillary action, the same wicking action that pulls water up a paper towel, and freezes into a distinct layer of ice called an ice lens [1]. Stacked ice lenses lift the soil and anything resting on it [1]. The expansion of water as it turns to ice (about 9%) is not the main cause. Work by researcher Stephen Taber showed that the growth of ice lenses, fed by water drawn up from warmer soil below, drives the heave [2]. Ice lenses grow parallel to the ground surface and range from hair-thin to much thicker [2]. ### Three conditions 1. **Freezing temperatures** with a freezing front moving down into the soil [1]. 2. **Available water** from unfrozen soil or groundwater below [1]. 3. **Frost-susceptible soil**, mainly fine-grained soil with small pores [1]. Remove any one of the three and ice lenses do not form, which is why drainage, non-frost-susceptible fill and insulation are used to reduce heave [1]. ## Which soils heave? | Soil | Frost susceptibility | |---|---| | Silt, loam, very fine sand | Most pronounced heave; allow capillary flow [2] | | Clay | Conducts water poorly, which the North Dakota survey says limits lens growth and reduces heave [2], though InterNACHI groups it with silt as fine-grained and susceptible [1] | | Coarse sand and gravel | Rarely heave; pores too large for lenses [2] | Differences in soil, moisture and exposure from one spot to the next cause differential heave, which is what does most of the damage to roads and structures [2]. ## What happens when the ground thaws? When thawing works down from the surface, meltwater can be trapped in the upper soil and weaken it [2]. Ground lifted by heave tends to subside back toward its original level after thaw, but frost jacking of isolated structures, such as posts and small footings, is usually permanent and can accumulate over several winters [2]. ## How common is frost heave in Oklahoma? Oklahoma's climate ranges from humid subtropical in the east to semi-arid in the west [5]. During a January 2005 winter storm, Oklahoma Mesonet sensors at about 2 inches deep in northwestern Oklahoma read in the mid-30s to low-40s °F, showing that the soil just below the surface had not yet frozen even as the storm moved through [3]. The Mesonet's network of about 120 automated stations records soil and air conditions across the state [4], which makes it a source for checking freeze periods at a given location. See Mesonet for foundation pros (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros) and freeze-thaw and frost depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth). Shallow elements are the most exposed. InterNACHI notes that shallow footings are especially vulnerable to frost heave [1]. Local frost depth rules for footings are covered on the permits, licensing and frost depth page (https://terrabrain.vercel.app/rules/permits-licensing-and-frost-depth-oklahoma-cities). ## What are the signs of frost heave? - heaved or settled flatwork (https://terrabrain.vercel.app/signs/heaved-or-settled-flatwork), such as sidewalks, porches and stoops that rise in winter - a horizontal crack at the brick ledge or slab edge (https://terrabrain.vercel.app/signs/horizontal-crack-at-brick-ledge-or-slab-edge) where a shallow element meets the house A similar-looking lift at the edge of a slab can come from clay swelling after heavy rain rather than freezing; see perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift). ## How is frost heave typically addressed? - **Reduce water.** Drainage reduces the water available to form ice lenses [1]; see drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). - **Use non-frost-susceptible material.** Non-frost-susceptible fill helps prevent ice lens formation [1]. - **Support below the frozen zone.** Because shallow footings are the vulnerable ones [1], supports that bear below the depth of freezing are used for elements that keep heaving; see helical piers (https://terrabrain.vercel.app/repairs/helical-piers). ## Related - Freeze-Thaw and Frost Depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) - Flatwork and Exterior Slabs (https://terrabrain.vercel.app/foundations/flatwork-and-exterior-slabs) - Panhandle (High Plains) (https://terrabrain.vercel.app/regions/panhandle-high-plains) - Slabjacking and Polyurethane (https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane) - Perimeter Wetting Heave (Edge Lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) Sources: [1] Frost Heave Caused by Ice Lens, InterNACHI https://www.nachi.org/frost-heave-ice-lens.htm [2] Frost Heave (GEO NEWS, July 2011), North Dakota Geological Survey https://www.dmr.nd.gov/ndgs/documents/newsletter/2011Summer/FrostHeave.pdf [3] The Winter Weather Events of January 3-5, 2005: Answer #8, OK-FIRST, Oklahoma Climatological Survey https://okfirst.mesonet.org/train/casestudies/WinterWxLab/answers/ans8.html [4] Drought monitoring: a system for tracking plant available soil moisture based on the Oklahoma Mesonet, Oklahoma State University https://apps.dasnr.okstate.edu/SSL/soilphysics.okstate.edu/research/droughtmonitoring.htm [5] Soil Matric Suction and Active Zone Depth in Oklahoma, Oklahoma State University (Er Yue, Ph.D. dissertation, 2017) https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf --- # What is Grant soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/grant Answer: Grant is a deep, well-drained silty soil from Permian siltstone with about 22 to 28 percent clay in the subsoil and weathered rock 40 to 60 inches down. In short: Grant is a deep, well-drained soil of north-central Oklahoma that formed from Permian siltstone or silty shale, sometimes under a thin cap of wind-blown silt. Its subsoil is silty clay loam with about 22 to 28 percent clay, and weathered rock starts 40 to 60 inches down. Moderate clay, water management and the depth of the siltstone are the main soil factors for foundations. ## Where does Grant soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) places Grant in Oklahoma and south-central Kansas, in Major Land Resource Area 80A, the Central Rolling Red Prairies, at 700 to 1,500 feet elevation [1]. It is a series of large extent [1]. The type location is in Garfield County about 2 miles north and 6.5 miles west of Hillsdale, and the series was established in Grant County [1]. Grant forms on paleoterraces, on summits and backslopes, with slopes of 0 to 20 percent [1]. Its parent material is weathered siltstone or silty shale, and some areas have a thin loess mantle [1]. That is the landscape of the North-Central (Red Prairies and Wheat Belt) (https://terrabrain.vercel.app/regions/north-central-red-prairies-and-wheat-belt) region; the OSD dates the siltstone and silty shale to the Permian [1]. Permian shales of central Oklahoma are covered on the Hennessey Shale (https://terrabrain.vercel.app/geology/hennessey-shale-group) page. ## What are the key properties of Grant soil? | Property | Grant (from the OSD) [1] | |---|---| | Classification | Fine-silty, mixed, superactive, thermic Udic Argiustolls | | Parent material | Siltstone or silty shale; thin loess mantle in places | | Depth to weathered rock | 40-60 in (typical 59 in) | | Drainage | Well drained | | Permeability | Moderate; saturated hydraulic conductivity moderately low | | Subsoil (Bt) | Silty clay loam or clay loam; 22-28% clay (range 18-35%) | | Slopes | 0-20% | | Mean annual rainfall | About 32 in (range 26-38 in) | | Mean annual temperature | About 61°F | "Fine-silty" means the soil is dominated by silt with a moderate amount of clay. "Paleoterraces" are old, high stream terraces left behind as rivers cut down. Grant is mostly cropland for wheat and other small grains, with some native tall and mid grasses [1]. ## What do these properties mean for foundations? ### Moderate clay Clay soils swell when wet and shrink when dry, and uneven moisture causes more damage than uniform changes [4]. Grant's subsoil holds about 22 to 28 percent clay [1]. NRCS classes linear extensibility (LEP) under 3 percent as low, 3 to 6 percent as moderate, 6 to 9 percent as high and 9 percent or more as very high [3]. The LEP for each Grant map unit is in Web Soil Survey [2]. For lab tests that measure swell directly, see soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values). ### Thin loess mantle Some Grant areas carry a thin cap of loess [1]. Wind-deposited soils such as loess are among the deposits that can be collapsible, meaning they lose volume when wetted under load [5]. Collapse depends on a loose, open structure held by weak bonds that water can weaken [5]. The OSD does not rate collapse potential for Grant; see hydrocollapse (collapsible soil) (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil) and collapsible and loess soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils). ### Water and leaks Water from leaking pipes, irrigation and redirected rainwater are common wetting sources [5], and sewer or water line leaks can cause localized foundation movement [4]. The ASCE guide describes sloping soil away from the foundation and discharging downspouts away from the house [4]. Related: erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) and surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). ## How do you check a specific lot? - Look up the map unit and LEP in Web Soil Survey [2]. - Keep soil moisture around the foundation even and have plumbing leaks located and repaired [4]. - Track existing cracks and check drainage around the house each year [4]. ## Related - Kingfisher soil (https://terrabrain.vercel.app/soils/kingfisher) - Hennessey Shale (Group) (https://terrabrain.vercel.app/geology/hennessey-shale-group) - Collapsible and Loess Soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils) - Fill Consolidation Settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - GRANT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/G/GRANT.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Collapsible Soil (Geotechnical Manual module, January 2026), California Department of Transportation https://dot.ca.gov/-/media/dot-media/programs/engineering/documents/geotechnical-services/202601-gm-collapsiblesoil-a11y.pdf --- # What is Hector soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/hector Answer: Hector is a shallow, stony sandy loam over hard sandstone 14 to 20 inches down. Shallow bedrock, steep slopes and runoff are the main factors for houses. In short: Hector is a shallow, stony soil that forms on sandstone ridgetops and steep mountainsides, with hard sandstone bedrock only 14 to 20 inches down. It is a sandy loam to loam, not a clay, and drains readily. For houses on Hector, the closeness of bedrock, steep slopes and control of runoff are the main soil factors. ## Where does Hector soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) maps Hector in Arkansas, Alabama, Georgia, Kansas, Missouri, Oklahoma and Tennessee, probably on more than 800,000 acres [1]. Its Major Land Resource Areas include 117 and 118 (Boston Mountains and Arkansas Valley), 116B (Ozark Border) and several Appalachian areas [1]. The type location is in Washington County, Arkansas, and the series was established in Pope County, Arkansas [1]. Hector forms on nearly level to moderately steep ridgetops and steep to very steep mountainsides, on slopes of 2 to 60 percent [1]. It weathered from sandstone bedrock, locally with some colluvium (material moved downslope) [1]. For Oklahoma context, see the East-Central (Arkoma) (https://terrabrain.vercel.app/regions/east-central-arkoma) and Southeast (Ouachitas and Red River) (https://terrabrain.vercel.app/regions/southeast-ouachitas-and-red-river) region pages and the rock units Pennsylvanian sandstones (https://terrabrain.vercel.app/geology/pennsylvanian-sandstones) and Ouachita folded rocks (https://terrabrain.vercel.app/geology/ouachita-folded-rocks). ## What are Hector soil's key properties? | Property | Hector (from the OSD) [1] | |---|---| | Classification | Loamy, siliceous, subactive, thermic Lithic Dystrudepts | | Parent material | Sandstone residuum, locally colluvium | | Depth to bedrock | 14-20 in (typical 15 in) | | Drainage | Well drained | | Permeability | Moderately rapid | | Surface (A) | Sandy loam, fine sandy loam or loam; 0-50% rock fragments | | Subsoil (Bw) | Sandy loam, fine sandy loam or loam; 0-35% rock fragments | | Slopes | 2-60% | | Mean annual rainfall | 45 in at the type location | | Mean annual temperature | 59.5°F at the type location | "Lithic" in the name refers to hard bedrock close to the surface, which the OSD puts at 14 to 20 inches [1]. Hector is mostly low-grade cedar-hardwood forest, and cleared pasture is limited by droughtiness [1]. ## What does Hector soil mean for foundations? ### Little clay Shrink-swell movement comes from clay soils that swell when wet and shrink when dry [4]. Hector's layers are sandy loam to loam with rock fragments [1]. NRCS classes linear extensibility (LEP) under 3 percent as low [3]; the LEP for each Hector map unit appears in Web Soil Survey [2]. ### Bedrock within 20 inches Hard sandstone lies 14 to 20 inches below the surface [1]. How shallow rock, ledges and weathered layers are evaluated as bearing material is covered in depth to rock from borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings). ### Steep slopes and runoff The OSD describes runoff ranging from slow to rapid depending on slope, on ground as steep as 60 percent [1]. Uneven moisture causes more foundation damage than uniform moisture, and the ASCE guide describes grading soil away from a foundation and discharging downspouts onto splash blocks away from the house to prevent erosion [4]. Related topics: erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) and slope creep and lateral movement (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement). ### Fill on hillside lots Where a building pad was cut into a slope or built up with fill, that fill is not part of the native profile described in the OSD [1]; see fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). ## How do you check a specific lot? - Look up the map unit, slope and depth to bedrock in Web Soil Survey [2]. - Inspect drainage near the foundation every year and monitor existing cracks [4]. ## Related - Clarksville soil (https://terrabrain.vercel.app/soils/clarksville) - Collinsville soil (https://terrabrain.vercel.app/soils/collinsville) - Ouachita Folded Rocks (https://terrabrain.vercel.app/geology/ouachita-folded-rocks) - Slope and Erosion Stabilization (https://terrabrain.vercel.app/repairs/slope-and-erosion-stabilization) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - HECTOR Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/H/HECTOR.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Hennessey shale and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/geology/hennessey-shale-group Answer: Red Permian shale west of OKC that weathers into swelling red clay soils, which shrink in drought and swell when wet, driving seasonal foundation movement. In short: The Hennessey Group is red-brown Permian shale and siltstone that forms the surface across western Oklahoma County and much of north-central Oklahoma. It weathers into red clay soils rich in swelling clay minerals. These soils shrink in drought and swell when wet, which is the classic cause of seasonal foundation movement in the western OKC metro. ## What is Hennessey Group rock? The Hennessey is a **group**, meaning several related rock formations mapped together. It is early Permian in age and named for exposures at Hennessey in Kingfisher County [1]. Its subunits include the Fairmont Shale, Kingman Siltstone, Salt Plain Formation and Bison Formation, among others [1]. A USGS study of a site northwest of Oklahoma City described the Hennessey as mainly red-brown shale interbedded with red-brown and orange-brown siltstone, with greenish-gray beds, some sandstone and gypsum lenses, about 90 meters (roughly 300 feet) thick there [2]. A regional groundwater model notes thin gypsum beds of 1/2 to 2 inches higher in the section and more sand to the south [3]. ### Where is it at the surface? Rock layers in central Oklahoma dip west, so the surface of Oklahoma County is mostly Hennessey shale, with the Garber Sandstone appearing on the east side [3]. The Hennessey is about 400 feet thick on the west side of the model's project area [3]. See the Garber Sandstone (https://terrabrain.vercel.app/geology/garber-sandstone) page for the sandier ground to the east. ## How does the shale behave near the surface? The unweathered shale is very tight and nearly impermeable [3]. Near the surface it is different: - Weathered zones reach about 10 to 15 feet deep and are fractured by expansion, contraction and leaching [3]. - USGS cores found slickensides at depths from about 6 to 37 meters and thin gypsum lenses at about 19 to 24 meters, and hydraulic conductivity was highest at shallow depth [2]. - At one test boring, about 6.4 meters of soil and surface clay overlay the rock [2]. **Slickensides** are polished, grooved surfaces left when clay or shale shears against itself, a common mark of repeated swelling and shrinking. ## What red clay soils form on the Hennessey? | Series | Parent material | Notable traits | |---|---|---| | Renfrow | Weathered Permian clayey shale [4] | Vertic cracks at least 5 mm wide, slickensides, low permeability [4] | | Kirkland | Clayey sediments over Permian shale [5] | Slow permeability, intersecting slickensides in the subsoil [5] | | Bethany | Weathered shale and clay beds, capped with loess [6] | High shrink-swell in OSU lab tests [6] | An Oklahoma State University study measured the **coefficient of linear extensibility (COLE)**, a lab measure of how much a soil shrinks as it dries. It found values up to about 0.090 in a Kirkland-like soil and 0.095 in Bethany, tied to large amounts of smectite clay [6]. The authors described the Kirkland soil as inherently unstable and said these values indicate severe limitations for many engineering projects [6]. ## What does this mean for foundations? Because the clay changes volume with moisture, foundations on Hennessey soils commonly show: - **Edge drop in drought.** Clay loses volume as it dries, so the ground settles [7]. See perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). - **Edge lift or center heave in wet periods.** Clay gains volume as it takes up water [7]. See perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) and center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab). - **Tree-related drying.** Roots pull water from clay and can cause local settlement [7]. See tree-root desiccation (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement). The ASCE homeowner guide lists sun-driven drying on south and west sides, tree roots, leaks and poor drainage among the main causes of uneven moisture under shallow foundations on clay [7]. It recommends sloping soil at least 3 inches in the first 5 feet and placing trees farther away than their mature height [7]. ## Related - OKC metro (https://terrabrain.vercel.app/regions/okc-metro) - North-Central (Red Prairies and Wheat Belt) (https://terrabrain.vercel.app/regions/north-central-red-prairies-and-wheat-belt) - Renfrow soil (https://terrabrain.vercel.app/soils/renfrow) - Kirkland soil (https://terrabrain.vercel.app/soils/kirkland) - Shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata) - Drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) Sources: [1] Geologic Unit: Hennessey, USGS National Geologic Map Database (Geolex) https://ngmdb.usgs.gov/Geolex/Units/Hennessey_8611.html [2] Geologic and Hydraulic Characteristics of Selected Shaly Geologic Units in Oklahoma (WRI 96-4303), U.S. Geological Survey https://pubs.usgs.gov/wri/1996/4303/report.pdf [3] OK County Groundwater Model (Project 174601), Association of Central Oklahoma Governments https://www.oklahomacounty.org/Portals/0/OK%20County%20Groundwater%20Model.pdf [4] Official Soil Series Description: RENFROW Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/R/RENFROW.html [5] Official Soil Series Description: KIRKLAND Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KIRKLAND.html [6] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [7] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Hollister soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/hollister Answer: Hollister is a southwest Oklahoma clay Vertisol, 35 to 55 percent smectitic clay, with cracks deeper than 30 inches, so seasonal movement is the key concern. In short: Hollister is a clay Vertisol of the Red Plains of southwest Oklahoma and north Texas, formed in calcareous Pleistocene clays over Permian sediments. Its layers hold 35 to 55 percent smectitic clay, and cracks extend deeper than 30 inches and stay open 150 or more days in most years. It belongs to the soil order defined by shrink-swell behavior, so seasonal foundation movement is the key issue. ## Where does Hollister soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) places Hollister in Texas and Oklahoma, in Major Land Resource Areas 78B and 78C, the Central Rolling Red Plains [1]. It is described as extensive [1]. The type location is in Hardeman County, Texas, near Chillicothe [1]. Hollister forms on paleoterraces (old, high terraces) on broad plains, on slopes of 0 to 3 percent [1]. Its parent material is Pleistocene calcareous alluvial clay deposited over Permian sediments [1]. In Oklahoma this is the Southwest (Lawton and Red Plains) (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains) region; see Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) and Western Permian red beds (https://terrabrain.vercel.app/geology/western-permian-red-beds). ## What are its key properties? | Property | Hollister (from the OSD) [1] | |---|---| | Classification | Fine, smectitic, thermic Typic Haplusterts | | Parent material | Pleistocene calcareous alluvial clays over Permian sediments | | Solum | 60 to more than 80 in, over dense clay, clay loam or claystone | | Drainage | Well drained | | Permeability | Very slow | | Clay | Surface 32-40%; subsoil 35-55% | | Slickensides | Begin at 8-20 in | | Cracks | Deeper than 30 in; open 150+ cumulative days in most years | | Secondary lime | Begins at 6-30 in | | Slopes | 0-3% | | Mean annual rainfall | About 25 in (range 23-28 in) | "Calcareous" means the material contains calcium carbonate (lime). Hollister is mainly cropland for wheat, cotton and grain sorghum [1]. ## Why does Hollister soil move? ### A true shrink-swell soil Vertisols are clay-rich soils with at least 30 percent clay to 50 cm; they shrink as they dry and swell as they rewet, opening deep, wide cracks and forming slickensides, the polished, grooved surfaces found in these clays [5]. That shrink-swell action causes serious engineering problems, including damage to structures [5]. In Hollister, slickensides begin 8 to 20 inches down and cracks reach below 30 inches [1]. NRCS rates shrink-swell by linear extensibility percent (LEP): 6 to 9 percent is high and 9 percent or more very high [3]. The LEP for each Hollister map unit is listed in Web Soil Survey [2]. ### What it does to a house Clay soils heave when they gain moisture and settle when they dry, and uneven moisture does more damage than uniform moisture [4]. Movement patterns described elsewhere on this site: - Perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) - Center heave under slabs (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) - Tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) Signs include stair-step brick cracks, sticking doors and windows, sloping floors and slab cracks 1/16 inch or wider [4]; see cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally). ### A dry climate Hollister's area averages about 25 inches of rain a year [1], and its cracks stay open for 150 or more days in most years [1]. The ASCE guide describes watering evenly around a foundation and adding more water on the drier south and west sides during drought, to keep soil moisture uniform [4]. ## What are the practical points for a Hollister lot? - Look up the map unit and LEP in Web Soil Survey [2]. - Keep soil moisture uniform around and under the foundation [4]. - Plant trees farther from the house than their mature height [4]. - Repair leaks quickly; leaks cause localized movement [4]. ## Related - Foard soil (https://terrabrain.vercel.app/soils/foard) - Durant soil (https://terrabrain.vercel.app/soils/durant) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Drought and Wet Cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - HOLLISTER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/H/HOLLISTER.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Vertisols, University of Idaho, College of Agricultural and Life Sciences https://www.uidaho.edu/cals/soil-orders/vertisols --- # What is Kingfisher soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/kingfisher Answer: Kingfisher is a well-drained silty clay loam with 27 to 42 percent clay over weathered red-bed rock 20 to 40 inches down. In short: Kingfisher is a well-drained soil of north-central Oklahoma that formed from Permian red-bed silty shale. Its subsoil is silty clay loam or clay loam with 27 to 42 percent clay, and weathered siltstone, shale and sandstone begin 20 to 40 inches down. Moderate clay over fairly shallow weathered rock is the main soil setting for foundations on Kingfisher. ## Where does Kingfisher soil occur? The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) places Kingfisher in Oklahoma and probably south-central Kansas, in Major Land Resource Area 80A, the Central Rolling Red Prairies [1]. It is of moderate extent [1]. The type location is in Kingfisher County about 1 mile west and 5 miles south of the town of Kingfisher [1]. Kingfisher forms on uplands with slopes of 0 to 8 percent [1]. Its parent material is loamy material weathered from Permian silty shale red beds [1], the red rocks described on the Hennessey Shale (https://terrabrain.vercel.app/geology/hennessey-shale-group) page. Kingfisher County sits in the North-Central (Red Prairies and Wheat Belt) (https://terrabrain.vercel.app/regions/north-central-red-prairies-and-wheat-belt) region, northwest of the OKC metro (https://terrabrain.vercel.app/regions/okc-metro). ## What are its key properties? | Property | Kingfisher (from the OSD) [1] | |---|---| | Classification | Fine-silty, mixed, active, thermic Udic Argiustolls | | Parent material | Loamy material from Permian silty shale red beds | | Depth to weathered rock | 20-40 in (typical 38 in) | | Drainage | Well drained | | Permeability | Moderately slow | | Surface (A) | Silt loam or loam | | Subsoil (Bt) | Silty clay loam or clay loam; 27-35% clay upper, up to 42% lower | | Weathered rock (Cr) | Interbedded siltstone, shale and sandstone | | Slopes | 0-8% | | Mean annual rainfall | About 33 in | | Mean annual temperature | About 59°F | "Argiustolls" are prairie soils with a dark topsoil over a clay-enriched subsoil. Kingfisher is mainly cropland, especially winter wheat, and native vegetation was tallgrass prairie [1]. ## What do the properties mean for foundations? ### Clay in the subsoil Clay soils swell (heave) when they gain water and shrink (settle) when they dry, and uneven moisture causes more damage than uniform moisture [4]. Kingfisher's clay rises from 27 to 35 percent in the upper subsoil to as much as 42 percent lower down [1]. NRCS classes linear extensibility (LEP) under 3 percent as low, 3 to 6 percent moderate, 6 to 9 percent high and 9 percent or more very high [3]. Web Soil Survey lists the LEP for each Kingfisher map unit [2]. Related patterns: perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) and perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift). ### Weathered rock at 20 to 40 inches The Cr layer is paralithic bedrock, meaning weathered rock that is softer than hard bedrock, made of interbedded siltstone, shale and sandstone [1]. How these layers behave as bearing material is covered in shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata) and depth to rock from borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings). ### Drought and soil moisture The Oklahoma Mesonet measures soil moisture at 2, 4, 10 and 24 inches at most sites, and changes at different depths show how deeply rain penetrates [5]. Wetting and drying of clay is what moves shallow foundations up and down [4]; see Mesonet for foundation pros (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros). ## What should you know about a Kingfisher lot? - Look up the map unit, depth to bedrock and LEP in Web Soil Survey [2]. - Keep soil moisture next to the foundation as even as practical, and grade soil away from the house [4]. - Repair leaks quickly and track existing cracks over time [4]. ## Related - Grant soil (https://terrabrain.vercel.app/soils/grant) - Bethany soil (https://terrabrain.vercel.app/soils/bethany) - Hennessey Shale (Group) (https://terrabrain.vercel.app/geology/hennessey-shale-group) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - KINGFISHER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KINGFISHER.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab (from the NRCS National Soil Survey Handbook) https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Tracking Drought Using Soil Moisture Information (BAE-1541), Oklahoma State University Extension https://extension.okstate.edu/fact-sheets/tracking-drought-using-soil-moisture-information.html --- # What is Kiomatia soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/kiomatia Answer: A deep, sandy Red River floodplain soil that floods often and has a seasonal water table at 42 to 60 inches; water, not clay swell, drives concerns. In short: Kiomatia is a deep, sandy soil that forms in Red River alluvium (river-laid sediment) on floodplains and natural levees. It is well drained but floods frequently where unprotected and has a water table about 42 to 60 inches down for part of the year. Its low clay content means flooding and water, not clay swelling, drive most foundation concerns. ## What is Kiomatia soil? Kiomatia is a soil series described by the USDA Natural Resources Conservation Service (NRCS). Its taxonomic class is "Sandy, mixed, thermic Typic Udifluvents" [1]. "Sandy" describes the texture of its control section [1]. The "fluv" in its name marks it as a Fluvent; the USDA soil glossary lists flood plains among the landscapes where soils grading toward Fluvents occur [4]. The series forms in sandy alluvial sediments with thin finer layers, washed down from Permian red beds [1]. It occurs in the Red River alluvium of Texas, Oklahoma, Arkansas and Louisiana and is rated as extensive [1]. The series was established in Haskell County, Oklahoma, in 1972, although its type location (the reference profile) is in Red River County, Texas [1]. In Oklahoma, Red River floodplain soils fall within the Southeast (Ouachitas and Red River) (https://terrabrain.vercel.app/regions/southeast-ouachitas-and-red-river) and South-Central (Arbuckles and Texoma) (https://terrabrain.vercel.app/regions/south-central-arbuckles-and-texoma) regions, on the Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) geologic unit. ## What is the typical soil profile? The official description gives this typical profile [1]: | Depth | Layer | Texture | |---|---|---| | 0-4 in | A | Loamy fine sand | | 4-9 in | C1 | Fine sand with finer strata | | 9-15 in | C2 | Very fine sandy loam | | 15-80 in | C3 | Stratified fine sand, very fine sandy loam, fine sandy loam and loamy fine sand | Key properties from the same description [1]: - **Clay content:** 5 to 18 percent clay and 60 to 92 percent sand in the control section [1]. - **Drainage:** well drained, with rapid permeability (water moves through quickly) [1]. - **Slopes:** 0 to 5 percent, usually under 2 percent [1]. - **Water table:** fluctuates between 42 and 60 inches below the surface, typically January through July [1]. - **Flooding:** frequently flooded for brief periods in most years where unprotected [1]. - **Climate:** mean annual precipitation about 44 inches (range 40 to 48) [1]. - **Use:** mostly bermudagrass pasture; native trees are cottonwood and willow [1]. ## What does it mean for foundations? ### Shrink-swell is not the main driver Shrink-swell soils are clays that grow and shrink as their moisture changes. Soil scientists measure this as linear extensibility, the linear expression of the change in volume between moist and oven-dry soil, with less than 3 percent rated "low" [5]. Kiomatia's sandy, low-clay profile [1] does not fit the clay-rich pattern behind most seasonal foundation movement. The exact rating for a mapped unit is listed in Web Soil Survey [2]. ### Flooding and a seasonal water table The bigger factors on Kiomatia are water-related. The soil floods frequently where it is not protected, and its water table fluctuates between 42 and 60 inches below the surface, typically January through July [1]. For any lot on a floodplain soil, the official flood zone comes from FEMA's flood maps, which can be searched by address [3]. Layered sandy and loamy floodplain sediments can behave differently from layer to layer. For how loose or wet alluvium can compress under a house, see soft soil consolidation (https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays). For how flowing water can carry sandy soil from beneath footings, see erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). Filled or built-up lots on floodplains are covered under fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). ## How is the soil at a property confirmed? - Web Soil Survey shows the mapped soil units for an area and lets users judge soil suitability for a particular use [2]. - Check the FEMA Flood Map Service Center for the Flood Insurance Rate Map panel covering the address [3]. - A site-specific soil boring is the way to confirm actual layers and water levels; see soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values). ## Related - Groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Soft soil consolidation (alluvium and wet clays) (https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays) - Creeks and flood history data (https://terrabrain.vercel.app/data/creeks-and-flood-history) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - KIOMATIA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KIOMATIA.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] FEMA Flood Map Service Center: Search By Address, Federal Emergency Management Agency https://msc.fema.gov/portal/search [4] A Glossary of Terms Used in Soil Survey and Soil Classification, USDA Natural Resources Conservation Service https://nrcs.usda.gov/sites/default/files/2022-08/A_Glossary_of_Terms_Used_in_Soil_Survey_and_Classification.pdf [5] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html --- # What is Kirkland soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/kirkland Answer: Kirkland is a deep central Oklahoma terrace soil with a dense clay subsoil of 35 to 60 percent clay, so homes on it are exposed to seasonal shrink-swell movement. In short: Kirkland is a very deep, well-drained soil on old stream terraces in central Oklahoma, with a dense clay subsoil that holds 35 to 60 percent clay. Its subsoil shows slickensides, which form when clay swells and shrinks over and over. Homes on Kirkland soil are exposed to seasonal shrink-swell movement. ## What is Kirkland soil? Kirkland is an official USDA soil series classified as "Fine, mixed, superactive, thermic Udertic Paleustolls" [1]. The word "Udertic" marks a vertic intergrade, a soil that trends toward the Vertisols, the order of clay soils defined by shrink-swell behavior [3]. Vertisols crack deeply when dry and swell when wet, and that movement creates serious engineering problems [4]. The soil formed in clayey sediments over Permian shale on paleoterraces (old, high stream terraces) in the Central Rolling Red Prairies [1]. Slopes are 0 to 3 percent [1]. The series occurs in central Oklahoma and south-central Kansas and is rated as extensive; its type location is in Logan County, about 4 miles south and 8 miles west of Guthrie [1]. Mean annual precipitation is about 32 inches [1]. In Oklahoma this places Kirkland in the OKC Metro (https://terrabrain.vercel.app/regions/okc-metro) and North-Central (Red Prairies and Wheat Belt) (https://terrabrain.vercel.app/regions/north-central-red-prairies-and-wheat-belt) regions, over red-bed shale units such as the Hennessey Shale (https://terrabrain.vercel.app/geology/hennessey-shale-group) and Wellington Formation (https://terrabrain.vercel.app/geology/wellington-formation). ## What does a Kirkland soil profile look like? | Depth (typical) | Layer | Texture | Clay | |---|---|---|---| | 0-8 in | Ap | Silt loam | 10-20% | | 8-19 in | Bt | Silty clay | 35-40% | | 19-28 in | Btss | Silty clay | 35-60% | | 28-51 in | Btkss | Silty clay | 35-60% | | 51-82 in | Btk | Silty clay | 35-60% | | 82-98 in | 2Cr | Weakly cemented siltstone | - | Source for the table: [1]. Other properties from the official description [1]: - **Slickensides:** the Btss and Btkss layers have prominent intersecting slickensides [1]. - **Permeability:** slow; saturated hydraulic conductivity is low [1]. - **Bedrock:** a paralithic contact (weakly cemented siltstone) at about 82 inches in the typical pedon [1]. Paralithic material is partially weathered or weakly consolidated bedrock [3]. - **Drainage:** well drained, medium runoff [1]. ## What does Kirkland soil mean for foundations? ### Seasonal shrink-swell Clay soils swell (heave) as they gain water and shrink (settle) as they dry [5]. Uniform changes in soil moisture are less damaging than localized changes [5]. Slickensides are polished, grooved surfaces formed by this repeated shrinking and swelling [4], so their presence in Kirkland's subsoil [1] is a field sign of a soil that moves. The standard soil-survey measure of this behavior is linear extensibility. On a percent basis, 6 to 9 percent is "high" and 9 percent or more is "very high" [6]. For vertic subgroups like Kirkland, soil taxonomy uses a total linear extensibility of 6 cm or more in the upper 100 cm as a key criterion [3]. The value for the mapped unit at a specific address is listed in Web Soil Survey [2]. Common patterns on soils like this include: - Perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) during droughts. - Perimeter wetting heave (edge lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) after wet periods. - Center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) as moisture builds under a slab. - Tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) near large trees. ### Moisture management factors The ASCE Geo-Institute homeowner guide lists moisture sources to manage on shrink-swell soils, including rainfall and downspouts, poor drainage, sprinklers and overwatering, drought, trees, plumbing leaks and shallow seepage [5]. It suggests discharging downspouts at least 3 feet from the foundation and grading at least 3 inches of fall in 5 feet [5]. Statewide soil moisture is tracked by the Oklahoma Mesonet, which measures it at 5, 25, 60 and 75 cm depths with a network of more than 110 stations covering all 77 counties [7]. ## Related - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Renfrow soil (https://terrabrain.vercel.app/soils/renfrow) - Norge soil (https://terrabrain.vercel.app/soils/norge) - Soil series in the OKC metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) - Heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) Sources: [1] Official Series Description - KIRKLAND Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KIRKLAND.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] A Glossary of Terms Used in Soil Survey and Soil Classification, USDA Natural Resources Conservation Service https://nrcs.usda.gov/sites/default/files/2022-08/A_Glossary_of_Terms_Used_in_Soil_Survey_and_Classification.pdf [4] Vertisols, University of Idaho College of Agricultural and Life Sciences https://www.uidaho.edu/agricultural-life-sciences/soil-orders/vertisols [5] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, Geo-Institute of the American Society of Civil Engineers https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [6] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [7] The Oklahoma Mesonet (Fact Sheet), Oklahoma Climatological Survey https://www.mesonet.org/common/pubs/factsheets/Mesonet%20Fact%20Sheet.pdf --- # What is Konawa soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/konawa Answer: Konawa is a deep sandy terrace soil of the Cross Timbers with an 18-30% clay subsoil. Its foundation issues more often trace to water, drainage and fill. In short: Konawa is a deep, well-drained soil formed in old sandy and loamy stream deposits on low terraces in Oklahoma's Cross Timbers. It has a sandy surface over a sandy clay loam subsoil with 18 to 30 percent clay, and bedrock lies deeper than 80 inches. Its loamy texture means foundation issues on Konawa more often trace to water, drainage and fill than to clay swelling. ## What is Konawa soil? Konawa is an official USDA soil series classified as "Fine-loamy, mixed, active, thermic Ultic Haplustalfs" [1]. "Fine-loamy" refers to the texture of its subsoil, which is fine sandy loam or sandy clay loam [1]. The soil formed in loamy and sandy alluvium of Pleistocene (Ice Age) age on the treads and risers of low stream terraces [1]. Slopes range from 0 to 20 percent [1]. It occurs in the North Cross Timbers (MLRA 84A) of Oklahoma, Kansas and Texas and is rated as extensive [1]. The type location is in Payne County, about 8 miles west of Perkins, and the series was first established in Pottawatomie County in 1965 [1]. Konawa soils were formerly included in the Dougherty series [1]. In Oklahoma, Konawa areas fall in parts of the OKC Metro (https://terrabrain.vercel.app/regions/okc-metro) and East-Central (Arkoma) (https://terrabrain.vercel.app/regions/east-central-arkoma) regions, on Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces). ## What does a Konawa soil profile look like? | Depth (typical) | Layer | Texture | Clay | |---|---|---|---| | 0-9 in | A | Fine sand, loamy fine sand or fine sandy loam | not stated | | 9-17 in | E | Fine sand, loamy fine sand or fine sandy loam | not stated | | 17-53 in | Bt | Fine sandy loam or sandy clay loam | 18-30% | | 53-72 in | BC | Loamy fine sand, fine sandy loam or sandy clay loam | not stated | Source for the table: [1]. Other properties from the official description [1]: - **Drainage:** well drained [1]. - **Permeability:** moderate; saturated hydraulic conductivity moderately high [1]. - **Runoff:** negligible on 0-1 percent slopes, low on 1-5 percent, medium on 5-20 percent [1]. - **Depth to bedrock:** more than 80 inches [1]. - **Climate:** mean annual precipitation about 36 inches (range 31-43) [1]. - **Native vegetation:** post oak, blackjack oak and hickory with a grass understory [1]. ## What does Konawa soil mean for foundations? ### Shrink-swell Shrink-swell soils change volume as moisture changes, and the USDA measures this as linear extensibility: under 3 percent is low and 3 to 6 percent is moderate [3]. Konawa's subsoil clay content is 18 to 30 percent [1]; compare higher-clay central Oklahoma claypan soils such as Kirkland (https://terrabrain.vercel.app/soils/kirkland). The rated linear extensibility for each mapped unit is available in Web Soil Survey [2]. ### Water, leaks and fill On loamy and sandy soils, the more common questions involve how water moves and whether the soil under a footing has been disturbed: - Moderate permeability [1] means water from roofs, irrigation and plumbing leaks soaks in and moves through the soil. The ASCE Geo-Institute guide lists roof runoff, poor grading, irrigation and plumbing leaks as the key moisture sources to control around shallow foundations [4]. - That guide suggests discharging downspouts at least 3 feet from the foundation and keeping sprinkler heads at least 5 feet away [4]. - Where a sloping terrace lot was leveled with fill, see fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) and fill soils and lot history (https://terrabrain.vercel.app/guides/fill-soils-and-lot-history). - For how running water can carry sandy soil out from under slabs and footings, see erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). ## How do you confirm the soil at a property? Web Soil Survey shows the mapped soil units for an area, covering more than 95 percent of U.S. counties, and can generate custom soil reports [2]. Because soil maps are general, a boring or test pit is the way to confirm the layers under a specific house; see soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values). ## Related - Dougherty soil (https://terrabrain.vercel.app/soils/dougherty) - Pulaski soil (https://terrabrain.vercel.app/soils/pulaski) - Surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - KONAWA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KONAWA.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, Geo-Institute of the American Society of Civil Engineers https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Lucien soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/lucien Answer: Lucien is a shallow loamy soil on central Oklahoma hilltops with weathered Permian sandstone 10 to 20 inches down; shallow rock and water flow matter most. In short: Lucien is a shallow, well-drained loamy soil on the tops and shoulders of low hills in central Oklahoma. Weathered Permian sandstone, sometimes mixed with clay, siltstone or sandy shale, starts just 10 to 20 inches below the surface. The main foundation questions on Lucien are about shallow, soft rock and how water runs off and through it, rather than clay swelling. ## What is Lucien soil? Lucien is an official USDA soil series classified as "Loamy, mixed, superactive, thermic, shallow Udic Haplustolls" [1]. "Shallow" in the name refers to its limited depth to rock [1]. The soil formed in material weathered from Permian sandstone interbedded with clay, siltstone or sandy shale [1]. It sits on summits and shoulders of low hills in the Central Rolling Red Prairies (MLRA 80A), with slopes of 1 to 30 percent [1]. The series occurs in Oklahoma, Kansas and Texas and is rated as moderately extensive [1]. It was established in Noble County, Oklahoma, in 1947, and the type location is about 8 miles north and 6 miles east of Perry [1]. Mean annual precipitation is about 33 inches (range 26-41) [1]. In Oklahoma, Lucien areas fall in the OKC Metro (https://terrabrain.vercel.app/regions/okc-metro) and North-Central (Red Prairies and Wheat Belt) (https://terrabrain.vercel.app/regions/north-central-red-prairies-and-wheat-belt) regions, over red-bed sandstone units such as the Garber Sandstone (https://terrabrain.vercel.app/geology/garber-sandstone) and Wellington Formation (https://terrabrain.vercel.app/geology/wellington-formation). ## What is its typical soil profile? | Depth | Layer | Texture | |---|---|---| | 0-4 in | A | Very fine sandy loam | | 4-8 in | BA | Very fine sandy loam | | 8-14 in | Bw | Very fine sandy loam, about 10% sandstone pebbles | | 14-20 in | Cr | Weathered bedrock | Source for the table: [1]. Other properties from the official description [1]: - **Depth to rock:** 10 to 20 inches; paralithic contact at 14 inches in the typical profile [1]. - **Texture range:** loam, fine sandy loam or very fine sandy loam, including gravelly or stony phases [1]. - **Drainage:** well drained, with very high runoff and high permeability [1]. - **Use:** mainly rangeland; gentler areas mixed with deeper soils are farmed [1]. ## What does it mean for foundations? ### Shallow, soft rock A paralithic contact is the boundary between soil and soft bedrock that is very weakly to moderately coherent [3]. Paralithic material can be dug with hand tools, with some difficulty [3]. On Lucien, this layer starts within 20 inches of the surface [1], so the soil layer between a footing and rock is thin. The parent material includes interbedded clay, siltstone and sandy shale [1]. For background on how weathered red-bed rock behaves as a bearing layer, see shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata) and depth to rock from borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings). When steel push piers are used in Oklahoma, installation records show typical pier depths of about 8 to 16 feet, with a median near 12 feet in Tulsa [4]. On a shallow-rock soil like Lucien, a pier may stop sooner. Whether that early stop is on competent rock or on a soft or broken layer is a question for the installer's pressure records and, where needed, an engineer; see steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) and working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). ### Slopes and runoff Lucien has slopes up to 30 percent, very high runoff and high permeability [1]. Related pages cover surface drainage, erosion under footings and settlement of placed fill (see Related below). ## How can the soil at a property be confirmed? Web Soil Survey shows mapped soil units and soil data for more than 95 percent of U.S. counties [2]. Actual rock depth at a house is confirmed by a boring or by pier installation records. ## Related - Quinlan soil (https://terrabrain.vercel.app/soils/quinlan) - Bedrock in the OKC metro (https://terrabrain.vercel.app/guides/bedrock-okc-metro) - Surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) - Fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - LUCIEN Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/L/LUCIEN.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] A Glossary of Terms Used in Soil Survey and Soil Classification, USDA Natural Resources Conservation Service https://nrcs.usda.gov/sites/default/files/2022-08/A_Glossary_of_Terms_Used_in_Soil_Survey_and_Classification.pdf [4] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # What is Muskogee soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/muskogee Answer: Muskogee is a deep terrace soil with silt loam over silty clay and firm clay; its slow permeability makes water management the central foundation issue. In short: Muskogee is a deep, moderately well drained soil on stream terraces in eastern Oklahoma and the lower Mississippi valley states. It has silt loam at the surface over a subsoil that becomes silty clay and then very firm clay below about 26 inches. Its slow permeability and clay lower subsoil make water management the central foundation issue. ## What is Muskogee soil? Muskogee is an official USDA soil series classified as "Fine-silty, mixed, active, thermic Aquic Paleudalfs" [1]. "Aquic" in a soil name signals periodic saturation and the reduced (oxygen-poor) conditions that come with it [3]. The soil formed in silty material over clayey sediments on stream terraces [1]. The series is mapped in Arkansas, Louisiana, Mississippi, eastern Oklahoma and western Tennessee, and possibly eastern Texas [1]. It was established in Muskogee County, Oklahoma, in 1913, but its type location is now in Franklin County, Arkansas [1]. Mean annual precipitation is about 45 inches [1]. In Oklahoma, Muskogee soils fall within the East-Central (Arkoma) (https://terrabrain.vercel.app/regions/east-central-arkoma) and Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro) regions, on Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces). ## What is the typical soil profile? | Depth | Layer | Texture | |---|---|---| | 0-5 in | Ap | Silt loam | | 5-9 in | E | Silt loam | | 9-14 in | BE | Silt loam | | 14-26 in | Bt1 | Silty clay loam | | 26-46 in | Bt2 | Silty clay | | 46-72 in | Bt3 | Clay | Source for the table: [1]. Other properties from the official description [1]: - **Drainage:** moderately well drained, slow to medium runoff [1]. - **Permeability:** slow [1]. - **Lower subsoil:** described as very firm and sticky [1]. - **Solum thickness:** more than 60 inches; depth to bedrock is not stated [1]. - **Slopes:** 1 to 15 percent (the setting section gives 1 to 12 percent); the typical profile is on a 2 percent slope [1]. ## What does Muskogee soil mean for foundations? ### Clay below a silty cap The upper 14 inches of Muskogee are silt loam, while the subsoil becomes silty clay at about 26 inches and clay at about 46 inches [1]. Clayey soils swell as they gain water and shrink as they dry [4], so the clay lower subsoil is the part most likely to change volume. The official description does not list a shrink-swell value. Soil surveys rate this as linear extensibility, from "low" (under 3 percent) to "very high" (9 percent or more) [5]. The rated value for a mapped unit is listed in Web Soil Survey [2]. ### Slow drainage Slow permeability [1] means water that soaks in near a house stays in the soil longer. The ASCE Geo-Institute guide identifies roof runoff, poor grading, irrigation and plumbing leaks as the moisture sources to control around shallow foundations [4]. It suggests sloping soil away from the house at least 3 inches in 5 feet and discharging downspouts at least 3 feet out [4]. Related topics: - Groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) - Fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) ### Signs to watch The ASCE guide lists stair-step cracks in brick, sticking doors and windows, sloping floors and concrete floor cracks about 1/16 inch or wider as indicators of foundation movement [4]. See stair-step brick cracks (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top) and sloping floors. ## How do you confirm the soil at a property? Web Soil Survey shows mapped soil units and lets users generate custom soil reports [2]. ## Related - Soil series in the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) - Okemah soil (https://terrabrain.vercel.app/soils/okemah) - Parsons soil (https://terrabrain.vercel.app/soils/parsons) - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - MUSKOGEE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/M/MUSKOGEE.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] A Glossary of Terms Used in Soil Survey and Soil Classification, USDA Natural Resources Conservation Service https://nrcs.usda.gov/sites/default/files/2022-08/A_Glossary_of_Terms_Used_in_Soil_Survey_and_Classification.pdf [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, Geo-Institute of the American Society of Civil Engineers https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html --- # What is Niotaze soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/niotaze Answer: A somewhat poorly drained hillside soil with a smectitic clay subsoil over shale at 20 to 40 inches, so homes can face clay movement and wet soil. In short: Niotaze is a soil of wooded hillsides in north-central and northeastern Oklahoma, with a stony sandy surface over a dense clay subsoil and shale 20 to 40 inches down. It is somewhat poorly drained, and its smectitic clay subsoil is the type associated with shrink-swell. Homes on Niotaze can face both clay movement and wet-soil problems, with soft rock fairly close to the surface. ## What is Niotaze soil? Niotaze is an official USDA soil series classified as "Fine, smectitic, thermic Albaquic Hapludalfs" [1]. It formed in residuum (rock weathered in place) from interbedded Pennsylvanian shale and sandstone, with a surface layer of sandstone colluvium (material that slid or washed downslope) [1]. It sits on backslopes of hills and cuestas, with slopes of 3 to 45 percent [1]. The series covers about 350,000 acres, about 300,000 of them in Oklahoma and the rest in southeast Kansas [1]. It occurs in the Northern Cross Timbers (MLRA 84A) of north-central and northeastern Oklahoma [1]. The type location is in Chautauqua County, Kansas [1]. Mean annual precipitation is 39 to 45 inches [1]. Native vegetation is oak-hickory savannah with tall grasses [1]. In Oklahoma, Niotaze is mapped in the Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro) and Northeast (Ozark Plateau and Grand Lake) (https://terrabrain.vercel.app/regions/northeast-ozark-plateau-and-grand-lake) regions, over Pennsylvanian shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales). ## What is the typical soil profile? | Depth | Layer | Texture | |---|---|---| | 0-3 in | A | Very cobbly fine sandy loam (about 40% sandstone fragments) | | 3-10 in | E | Cobbly fine sandy loam (about 30% sandstone fragments) | | 10-18 in | 2Bt | Silty clay (series range 35-55% clay) | | 18-28 in | 2BCt | Silty clay loam | | 28-61 in | 2Cd | Shale bedrock, noncemented to weakly cemented, slakes in water | | 61-80 in | 2Cr | Shale bedrock | Source for the table: [1]. Other properties from the official description [1]: - **Drainage:** somewhat poorly drained; permeability slow [1]. - **Depth to shale:** 20 to 40 inches [1]. - **Clay jump:** clay rises by more than 20 percentage points within about 3 inches going from the E layer into the Bt [1]. - **Mineralogy:** smectitic, though both smectitic and mixed pedons have been sampled [1]. ## What does it mean for foundations? ### Shrink-swell clay Clay soils swell as they gain water and shrink as they dry, and uneven moisture change under a shallow foundation causes uneven movement [5]. A federal survey of expansive materials identified montmorillonite, a smectite clay, as a main contributor to expansive soils, notably in the Great Plains [4]. Niotaze's subsoil is 35 to 55 percent clay and is classed as smectitic [1]. The USDA rates shrink-swell as linear extensibility, with 6 to 9 percent "high" and 9 percent or more "very high" [6]; the value for a mapped unit is in Web Soil Survey [2]. Patterns to read about: - Perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Perimeter wetting heave (edge lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) - Tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) ### Wet soil and slow drainage An abrupt textural change, where clay increases sharply over a short distance, significantly restricts water movement [3]. Niotaze has this abrupt change at the top of its clay subsoil and is somewhat poorly drained [1]. See groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water), crawl space moisture and wood decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) and lateral earth and hydrostatic pressure on walls. ### Shale close to the surface Shale at 20 to 40 inches [1] is shallower than typical pier depths. Oklahoma steel push pier records show typical depths of about 8 to 16 feet, with a median near 12 feet in Tulsa [7]. The upper shale in Niotaze is described as weakly cemented and slaking in water [1], meaning it breaks down when soaked. ## Related - Soil series in the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) - Bedrock in the Tulsa metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro) - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - NIOTAZE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/N/NIOTAZE.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] A Glossary of Terms Used in Soil Survey and Soil Classification, USDA Natural Resources Conservation Service https://nrcs.usda.gov/sites/default/files/2022-08/A_Glossary_of_Terms_Used_in_Soil_Survey_and_Classification.pdf [4] An Occurrence and Distribution Survey of Expansive Materials in the United States by Physiographic Areas, U.S. Federal Highway Administration (via ROSA P) https://rosap.ntl.bts.gov/view/dot/58199 [5] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, Geo-Institute of the American Society of Civil Engineers https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [6] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [7] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # What is Nixa soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/nixa Answer: Nixa is a very gravelly, cherty Ozark soil with a dense fragipan 14 to 27 inches down that perches water and speeds runoff on slopes. In short: Nixa is a very gravelly soil of the Ozark Highlands that reaches into northeast Oklahoma. It is packed with chert (flint-like rock) fragments and has a dense, brittle fragipan starting 14 to 27 inches down that slows water to a crawl. For foundations, the main issues are water perching on that dense layer, fast runoff on slopes, and a mix of rock and clay at depth. ## What is Nixa soil? Nixa is an official USDA soil series classified as "Loamy-skeletal, siliceous, active, mesic Glossic Fragiudults" [1]. "Loamy-skeletal" reflects its high rock-fragment content, and "Fragi" refers to its fragipan [1]. It formed in colluvium (material moved downslope) and loamy residuum weathered from cherty limestone, on upland ridgetops and side slopes of the Ozark Highlands (MLRA 116A) [1]. Slopes range from 1 to 35 percent [1]. The series is mapped in Arkansas, Kansas, Kentucky, Missouri, Oklahoma, Tennessee and Virginia and is described as of large extent [1]. It was established in Christian County, Missouri, in 1942; the type location is in Marion County, Arkansas [1]. Native forests were mainly oaks and hickory [1]. In Oklahoma, this places Nixa in the Northeast (Ozark Plateau and Grand Lake) (https://terrabrain.vercel.app/regions/northeast-ozark-plateau-and-grand-lake) region on Mississippian cherty limestone (https://terrabrain.vercel.app/geology/mississippian-cherty-limestone). ## What does a Nixa soil profile look like? | Depth | Layer | Texture | Chert by volume | |---|---|---|---| | 0-2 in | A | Very gravelly silt loam | about 40% | | 2-11 in | E | Very gravelly silt loam | about 40% | | 11-22 in | Bw | Extremely gravelly silt loam | about 60% | | 22-44 in | 2Btx (fragipan) | Extremely gravelly silt loam | about 70% | | 44-72 in | 3Bt | Extremely gravelly silty clay loam | about 80% | Source for the table: [1]. Other properties from the official description [1]: - **Fragipan:** begins at 14 to 27 inches across the series [1]. - **Deep subsoil:** the fine earth in the 3Bt is clay, silty clay or silty clay loam [1]. - **Drainage:** moderately well drained; permeability very slow; saturated hydraulic conductivity low [1]. - **Runoff:** high to very high [1]. - **Depth to bedrock:** 60 to more than 80 inches [1]. ## What does Nixa soil mean for foundations? ### A dense layer that holds water up Fragic soil material is firm and brittle when moist, is not cemented (dry pieces break apart in water) and restricts roots [3]. Nixa's fragipan is part of why its permeability is very slow [1]. When a saturated layer sits above unsaturated layers, soil scientists call it episaturation, the condition behind a perched water table [3]. For how perched water affects basements and crawl spaces, see groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) and crawl space moisture and wood decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay). ### Runoff on slopes Nixa has high to very high surface runoff and slopes up to 35 percent [1]. The ASCE Geo-Institute homeowner guide identifies roof runoff, poor grading and shallow seepage as moisture sources to control around shallow foundations, and describes an upslope trench drain with a water barrier as one response to shallow seepage [4]. See surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) and erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes). ### Rock fragments and clay at depth With 35 to 85 percent chert in the subsoil [1], digging in Nixa means working through chert gravel and cobbles. The deepest layer has clayey fine earth between the chert [1]. The official description gives no shrink-swell value; Web Soil Survey lists properties for each mapped unit [2]. Where a sloping lot was leveled with fill, see fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). For how water can carry soil from beneath footings, see erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). ## How do you confirm the soil at a property? Web Soil Survey covers more than 95 percent of U.S. counties and can produce custom soil reports [2]. ## Related - Pier and beam crawl space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) - Water at cove joint or efflorescence (https://terrabrain.vercel.app/signs/water-at-cove-joint-or-efflorescence) - Basements (https://terrabrain.vercel.app/foundations/basements) - Oklahoma geologic provinces (https://terrabrain.vercel.app/guides/oklahoma-geologic-provinces) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - NIXA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/N/NIXA.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] A Glossary of Terms Used in Soil Survey and Soil Classification, USDA Natural Resources Conservation Service https://nrcs.usda.gov/sites/default/files/2022-08/A_Glossary_of_Terms_Used_in_Soil_Survey_and_Classification.pdf [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, Geo-Institute of the American Society of Civil Engineers https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Norge soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/norge Answer: Norge is a deep, well-drained silt loam over reddish silty clay loam in central Oklahoma. It is less clayey than nearby soils, so drainage and fill matter. In short: Norge is a deep, well-drained soil on broad flats and upper slopes of old upland terraces in central Oklahoma. It has brown silt loam at the surface over a reddish silty clay loam subsoil. It is less clayey than neighboring soils like Kirkland and Renfrow, so drainage, leaks and fill deserve attention alongside any clay movement. ## What is Norge soil? Norge is an official USDA soil series classified as "Fine-silty, mixed, active, thermic Udic Paleustolls" [1]. "Fine-silty" is its particle-size family; in Norge the subsoil is silty clay loam throughout [1]. The soil formed in loamy alluvium of Pleistocene (Ice Age) age on paleoterraces, meaning old, high terraces left by ancient streams [1]. Norge lies in the Central Rolling Red Prairies (MLRA 80A) and is rated as extensive [1]. The type location is in Pawnee County, about 8 miles northeast of Pawnee, and the series was established in Grady County in 1942 [1]. Mean annual precipitation is about 34 inches (range 30-42) [1]. Most areas have been farmed for small grains, sorghum, cotton and alfalfa [1]. In Oklahoma, Norge areas fall in the OKC Metro (https://terrabrain.vercel.app/regions/okc-metro) and North-Central (Red Prairies and Wheat Belt) (https://terrabrain.vercel.app/regions/north-central-red-prairies-and-wheat-belt) regions on Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces). ## What does a Norge soil profile look like? | Depth | Layer | Texture | Color | |---|---|---|---| | 0-12 in | A | Silt loam | Brown | | 12-18 in | BA | Silty clay loam | Reddish brown | | 18-36 in | Bt1 | Silty clay loam | Reddish brown | | 36-48 in | Bt2 | Silty clay loam | Red | | 48-66 in | Bt3 | Silty clay loam | Red | Source for the table: [1]. Other properties from the official description [1]: - **Drainage:** well drained; permeability moderately slow [1]. - **Slopes:** 0 to 8 percent; runoff low to high depending on slope [1]. - **Solum thickness:** more than 60 inches. Depth to bedrock is not stated [1]. - **Subsoil:** very hard and firm, with clay films on ped faces [1]. - **Carbonates:** secondary carbonates deeper than 40 inches [1]. ## What does Norge soil mean for foundations? ### Shrink-swell The USDA rates shrink-swell as linear extensibility, a linear expression of the volume change between moist soil and oven dryness: under 3 percent is low, 3 to 6 percent moderate, 6 to 9 percent high and 9 percent or more very high [3]. The official description notes that Bethany, Kirkland and Renfrow have a finer, more clayey control section than Norge [1]. The rated value for a specific mapped unit is in Web Soil Survey [2]. Clayey soils swell as they gain water and shrink as they dry, and uneven moisture change around a foundation is what drives damaging movement [4]. See shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). ### Water around the house Moderately slow permeability [1] means water that soaks in near a foundation drains away gradually. The ASCE Geo-Institute guide lists roof runoff, grading, irrigation, trees and plumbing leaks as the moisture sources to control [4]. It suggests: - Discharging downspouts at least 3 feet from the foundation [4]. - Sloping soil away at least 3 inches in 5 feet [4]. - Keeping irrigation lines and heads at least 5 feet from the house [4]. - Watching water bills and repairing plumbing leaks [4]. See plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) and surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). ### Fill and erosion Where a lot was built up or leveled with fill, see fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). For how running water can remove soil from beneath footings, see erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). ## How do you confirm the soil at a property? Web Soil Survey shows the mapped soil unit for an address and lets users create custom reports [2]. ## Related - Kirkland soil (https://terrabrain.vercel.app/soils/kirkland) - Renfrow soil (https://terrabrain.vercel.app/soils/renfrow) - Pond Creek soil (https://terrabrain.vercel.app/soils/pond-creek) - Bethany soil (https://terrabrain.vercel.app/soils/bethany) - Soil series in the OKC metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) Sources: [1] Official Series Description - NORGE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/N/NORGE.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, Geo-Institute of the American Society of Civil Engineers https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Okemah soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/okemah Answer: Okemah is a deep eastern Oklahoma prairie soil with a shrink-swell silty clay subsoil and a perched water table 2 to 3 feet down in winter and spring. In short: Okemah is a deep, somewhat poorly drained soil of eastern Oklahoma's prairies, with silt loam over a silty clay subsoil. Water perches 2 to 3 feet below the surface each winter and spring, and the clay subsoil shows slickensides, a sign of shrink-swell. Homes on Okemah deal with both seasonal wetness and clay movement. ## What is Okemah soil? Okemah is an official USDA soil series classified as "Fine, mixed, active, thermic Aquic Paleudolls" [1]. "Aquic" in a soil name indicates periodic saturation and the oxygen-poor conditions that come with it [3]. The soil formed in material weathered from loamy and clayey alluvium or colluvium derived from Pennsylvanian shale [1]. It lies on broad, smooth high terraces and lower upland slopes in the Cherokee Prairies, with slopes of 0 to 5 percent [1]. The series occurs in eastern Oklahoma and southeastern Kansas and is rated as extensive [1]. Its type location is in Okmulgee County, about 5.5 miles west of Beggs, and it was established in Okfuskee County in 1948 [1]. Mean annual precipitation is about 41 inches (range 37-46) [1]. Native vegetation is tall grass prairie [1]. In Oklahoma, Okemah areas fall in the Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro) and East-Central (Arkoma) (https://terrabrain.vercel.app/regions/east-central-arkoma) regions, on Pennsylvanian shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales) and Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces). ## What is its typical soil profile? | Depth | Layer | Texture | |---|---|---| | 0-4 in | A1 | Silt loam | | 4-12 in | A2 | Silt loam | | 12-21 in | A3 | Silt loam | | 21-29 in | Bt1 | Silty clay (few slickensides) | | 29-43 in | Bt2 | Silty clay | | 43-62 in | Bt3 | Silty clay | | 62-79 in | BC | Clay | Source for the table: [1]. Other properties from the official description [1]: - **Water table:** perched seasonal high water table at 2 to 3 feet, December to April in normal years [1]. - **Drainage:** somewhat poorly drained; permeability slow; saturated hydraulic conductivity moderately low [1]. - **Solum thickness:** more than 60 inches. Depth to bedrock is not stated [1]. - **Subsoil texture range:** clay loam to clay [1]. ## What does it mean for foundations? ### Clay movement Slickensides are polished, grooved surfaces formed by repeated shrinking and swelling of clay [4]. Okemah's upper subsoil has a few slickensides, and its subsoil is silty clay to clay [1]. Clayey soils swell as they gain water and shrink as they dry, and uneven moisture change around a shallow foundation causes uneven movement [5]. The USDA rates shrink-swell as linear extensibility: 3 to 6 percent is moderate, 6 to 9 percent high and 9 percent or more very high [6]. The rated value for a mapped unit is in Web Soil Survey [2]. Patterns to read about: - Perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Perimeter wetting heave (edge lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) ### Seasonal perched water A perched water table forms where one or more saturated layers sit above unsaturated layers, a condition called episaturation [3]. On Okemah, this happens 2 to 3 feet below the surface from December to April [1]. Related topics: - Groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Crawl space moisture and wood decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) ### Moisture control The ASCE Geo-Institute guide lists roof runoff, grading, irrigation, trees, plumbing leaks and shallow seepage as the moisture sources to manage around shallow foundations [5]. For shallow seepage it describes an upslope trench drain with a water barrier membrane [5]. ## How can the soil at a property be confirmed? Web Soil Survey shows mapped soil units and soil data for an area and can generate custom reports [2]. The water table described for Okemah is seasonal, present from December to April in normal years [1], so the time of year matters when water levels are checked on site. ## Related - Parsons soil (https://terrabrain.vercel.app/soils/parsons) - Muskogee soil (https://terrabrain.vercel.app/soils/muskogee) - Soil series in the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) - Seasonal movement calendar (https://terrabrain.vercel.app/guides/seasonal-movement-calendar) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - OKEMAH Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OKEMAH.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] A Glossary of Terms Used in Soil Survey and Soil Classification, USDA Natural Resources Conservation Service https://nrcs.usda.gov/sites/default/files/2022-08/A_Glossary_of_Terms_Used_in_Soil_Survey_and_Classification.pdf [4] Vertisols, University of Idaho College of Agricultural and Life Sciences https://www.uidaho.edu/agricultural-life-sciences/soil-orders/vertisols [5] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, Geo-Institute of the American Society of Civil Engineers https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [6] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html --- # What is Osage soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/osage Answer: Osage is a poorly drained floodplain Vertisol with 40-65% clay and a water table 6-18 inches down in winter and spring, so clay movement and wetness combine. In short: Osage is a thick, poorly drained clay soil on the flood plains of major streams in eastern Oklahoma. It is a Vertisol, the soil order defined by strong shrink-swell, with 40 to 65 percent smectitic clay and a water table that rises to 6 to 18 inches in winter and spring. Homes on Osage face clay movement, wet soil and floodplain exposure at the same time. ## What is Osage soil? Osage is an official USDA soil series classified as "Fine, smectitic, thermic Typic Epiaquerts" [1]. The "-ert" ending places it in the Vertisols, clay-rich soils that shrink and form deep, wide cracks when dry and expand when wet [3]. That movement creates serious engineering problems [3]. The soil formed in thick clayey alluvium on flood plains along major streams, with slopes of 0 to 2 percent [1]. It occurs in southwestern Missouri, southeastern Kansas and eastern Oklahoma and is rated as extensive [1]. The type location is in Vernon County, Missouri, and the series was established in Bates County, Missouri, in 1908 [1]. Mean annual precipitation is about 39 inches (range 38-44) [1]. In Oklahoma, Osage soils are mapped along streams in the Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro), Northeast (Ozark Plateau and Grand Lake) (https://terrabrain.vercel.app/regions/northeast-ozark-plateau-and-grand-lake) and East-Central (Arkoma) (https://terrabrain.vercel.app/regions/east-central-arkoma) regions, on Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces). ## What is the typical soil profile? | Depth | Layer | Texture | Slickensides | |---|---|---|---| | 0-8 in | Ap1, Ap2 | Clay, silty clay | - | | 8-13 in | A | Clay | - | | 13-23 in | Bss | Clay | Few | | 23-36 in | Bssg1 | Clay | Many, prominent | | 36-45 in | Bssg2 | Clay | Common, prominent | | 45-60 in | Bssg3 | Clay | Few | | 60-79 in | Bg | Silty clay | - | Source for the table: [1]. Other properties from the official description [1]: - **Clay:** 40 to 65 percent in the subsoil; the control section averages 35 to 60 percent [1]. - **Mineralogy:** smectitic [1]. - **Water table:** apparent seasonal high water table at 6 to 18 inches, November through May in normal years [1]. - **Drainage:** poorly drained; permeability very slow; saturated hydraulic conductivity low [1]. - **Redox features:** present in all layers, reflecting wet conditions [1]. ## What does Osage soil mean for foundations? ### Strong shrink-swell Slickensides, polished and grooved surfaces formed by repeated shrinking and swelling, are one of the diagnostic features of Vertisols [3]. Osage has continuous, intersecting slickensides from about 13 to 60 inches [1]. A federal survey of expansive materials found that montmorillonite, a smectite clay, contributes to widespread expansive materials, notably in the Great Plains [4], and Osage is classed as smectitic [1]. The USDA rates shrink-swell as linear extensibility, with 6 to 9 percent "high" and 9 percent or more "very high" [7]. The rated value for each mapped unit is in Web Soil Survey [2]. Clayey soils heave as they gain water and settle as they dry, and uneven moisture change under a shallow foundation causes the damaging differential movement [6]. Patterns to read about: - Perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) - Tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) ### Wet soil With the water table as high as 6 inches below the surface from November through May [1], Osage soils are wet during the cool season. See groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water), crawl space moisture and wood decay and lateral earth and hydrostatic pressure on walls. ### Floodplain setting Osage forms on flood plains [1]. The official flood hazard for an address is shown on FEMA's Flood Insurance Rate Maps, searchable by address in the Flood Map Service Center [5]. ## Related - Clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Soil series in the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) - Verdigris soil (https://terrabrain.vercel.app/soils/verdigris) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - OSAGE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OSAGE.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Vertisols, University of Idaho College of Agricultural and Life Sciences https://www.uidaho.edu/agricultural-life-sciences/soil-orders/vertisols [4] An Occurrence and Distribution Survey of Expansive Materials in the United States by Physiographic Areas, U.S. Federal Highway Administration (via ROSA P) https://rosap.ntl.bts.gov/view/dot/58199 [5] FEMA Flood Map Service Center: Search By Address, Federal Emergency Management Agency https://msc.fema.gov/portal/search [6] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, Geo-Institute of the American Society of Civil Engineers https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [7] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html --- # What is Parsons soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/parsons Answer: A claypan soil with about a foot of silt loam on dense clay; water perches 6 to 18 inches down in winter and spring, and the clay can change volume. In short: Parsons is a claypan soil of the prairies in northeast Oklahoma, with about a foot of silt loam sitting abruptly on dense clay. Water perches on that clay 6 to 18 inches below the surface from December through April. Homes on Parsons deal with seasonal wetness near the surface and a clay subsoil that can change volume with moisture. ## What is Parsons soil? Parsons is an official USDA soil series classified as "Fine, mixed, active, thermic Mollic Albaqualfs" [1]. The "aqu" in its name points to aquic conditions, which in soil science means periodic saturation and reduction [3]. The soil formed in clayey old alluvium or in residuum from fissile (thin-splitting) Pennsylvanian shales, possibly with a thin loess cap [1]. It occurs on interfluves, divides and paleoterraces on plains, with slopes of 0 to 3 percent [1]. The series is mapped in northwestern Arkansas, southeastern Kansas, southwestern Missouri and eastern Oklahoma and is rated as extensive [1]. Its type location is about 1.75 miles north of Wagoner, Oklahoma; the series was established in Labette County, Kansas, in 1926 [1]. Mean annual precipitation is about 41 inches (range 38-45) [1]. Native vegetation is tall grass prairie [1]. In Oklahoma, Parsons falls in the Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro) and Northeast (Ozark Plateau and Grand Lake) (https://terrabrain.vercel.app/regions/northeast-ozark-plateau-and-grand-lake) regions, on Pennsylvanian shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales). ## What is the typical soil profile? | Depth | Layer | Texture | |---|---|---| | 0-9 in | A | Silt loam | | 9-12 in | E | Silt loam | | 12-22 in | Btg1 | Clay | | 22-36 in | Btg2 | Clay | | 36-45 in | Btg3 | Clay | | 45-58 in | BC | Clay, with siltstone fragments | | 58-79 in | C | Clay | Source for the table: [1]. Other properties from the official description [1]: - **Clay:** 10 to 27 percent in the E layer; 35 to 60 percent in the Btg, BC and C layers [1]. - **Abrupt textural change:** at about 12 inches, from the E layer into the clay subsoil [1]. - **Water table:** perched, top at 6 to 18 inches, December through April in normal years [1]. - **Drainage:** somewhat poorly drained; saturated hydraulic conductivity low; runoff high to very high [1]. - **Solum thickness:** 40 to more than 60 inches. Depth to bedrock is not stated [1]. ## What does it mean for foundations? ### A claypan that holds water near the surface An abrupt textural change is a sharp increase in clay over a very short distance, and it significantly restricts water movement [3]. Parsons has this change at the top of its clay subsoil [1]. A perched water table is a saturated layer resting on drier layers below, which soil scientists call episaturation [3]. On Parsons, it sits 6 to 18 inches down for much of the winter and spring [1]. Related pages: - Groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Crawl space moisture and wood decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) - Lateral earth, swell and hydrostatic pressure on walls (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls) ### Clay movement Clayey soils swell as they gain water and shrink as they dry, and uneven moisture change around a shallow foundation causes uneven movement [4]. Parsons' subsoil is 35 to 60 percent clay [1]. The USDA rates shrink-swell as linear extensibility, from low (under 3 percent) to very high (9 percent or more) [5]; the value for a mapped unit is in Web Soil Survey [2]. See perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) and perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift). ### Moisture control The ASCE Geo-Institute guide lists roof runoff, grading, irrigation, plumbing leaks and shallow seepage as moisture sources to manage [4]. It suggests sloping soil away from the house at least 3 inches in 5 feet, discharging downspouts at least 3 feet out, and, for shallow seepage, an upslope trench drain with a water barrier [4]. ## Related - Taloka soil (https://terrabrain.vercel.app/soils/taloka) - Okemah soil (https://terrabrain.vercel.app/soils/okemah) - Soil series in the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) - Seasonal movement calendar (https://terrabrain.vercel.app/guides/seasonal-movement-calendar) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - PARSONS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/PARSONS.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] A Glossary of Terms Used in Soil Survey and Soil Classification, USDA Natural Resources Conservation Service https://nrcs.usda.gov/sites/default/files/2022-08/A_Glossary_of_Terms_Used_in_Soil_Survey_and_Classification.pdf [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, Geo-Institute of the American Society of Civil Engineers https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html --- # What is perched water and how does it affect Oklahoma homes? URL: https://terrabrain.vercel.app/guides/groundwater-and-perched-water Answer: Perched water is rain backed up above a dense clay layer; in eastern Oklahoma it can wet crawl spaces, seep into basements and saturate footing clay. In short: Many soils in eastern Oklahoma hold a temporary "perched" water table in late fall, winter and spring, when rain soaks down to a dense clay layer and backs up above it. That water can wet crawl spaces, seep into basements and keep clay under footings saturated. Near rivers, flood-plain soils add a seasonal high water table and occasional flooding. ## How is perched water different from the true water table? - **Perched water table**: a temporary saturated zone sitting on a layer that water passes through slowly, such as dense clay or shale. It can drain away in dry months. - **Apparent or regional water table**: the top of the groundwater that fills the soil or rock below; along rivers it can be close to the surface. USDA Official Series Descriptions record both kinds for each soil, with depth and months, which makes them a useful guide to where and when shallow water is expected. ## Which Oklahoma soils have seasonal shallow water? | Series | Setting | Shallow water | Months | Source | |---|---|---|---|---| | Parsons | Uplands, old alluvium or shale | Perched, 6–18 in. | Dec–Apr | [1] | | Okemah | Shale-derived alluvium or colluvium | Perched, 2–3 ft | Dec–Apr | [2] | | Dennis | Pennsylvanian shale | Perched, 12–30 in. | Dec–Apr | [3] | | Summit | Clayey shale colluvium or residuum | Perched, 12–36 in. | Nov–May | [4] | | Osage | Flood plains, thick clay | Apparent water table, 6–18 in. | Nov–May | [5] | Dennis, Okemah, Parsons and Summit are common in the Tulsa area; see soil series - Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro). ### Why water perches in these soils Parsons has an abrupt change at about 12 inches from a loamy surface to a clay subsoil of 35–60% clay [1]. Dennis and Okemah have very firm clay subsoils [2][3], and Okemah has slow permeability [2]. Water moves down easily through the upper layer, then slows sharply at the clay, so it spreads and builds up above it. ### Flood plains Osage soils lie on flood plains along major streams and are poorly drained [5]. Port soils, found on narrow flood plains in central Oklahoma, flood occasionally or frequently for very brief periods from March through October [6]. Houses on these soils deal with both high water and the soft, wet clay that comes with it; see soft soil consolidation (https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays). ## How does shallow water affect houses? - **Crawl spaces**: standing water, damp framing and condensation (water, condensation or mold in crawl (https://terrabrain.vercel.app/signs/water-condensation-or-mold-in-crawl)). - **Basements**: seepage at the joint where the wall meets the floor (water at cove joint (https://terrabrain.vercel.app/signs/water-at-cove-joint-or-efflorescence)), and saturated soil pressing on walls. - **Foundation movement**: groundwater is one of the moisture sources engineers list as causing differential movement on expansive clay [7]. - **Mold**: the EPA notes mold grows where moisture persists and advises fixing water problems promptly and drying wet materials within 24–48 hours [8]. Saturated soil pushing on a wall is called **hydrostatic pressure**; together with swelling clay it is one of the loads behind horizontal cracks or inward bowing in basement walls (https://terrabrain.vercel.app/signs/horizontal-crack-or-inward-bow-in-basement-wall). ## What approaches address shallow water? Engineering guidance lists dealing with the sources of moisture, including groundwater and drainage, as a first step [7]. Common approaches include intercepting water upslope with French or curtain drains, interior drain tile with a sump, and crawl space vapor barriers and dehumidification; these are described on drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions), crawl space encapsulation (https://terrabrain.vercel.app/repairs/crawl-space-encapsulation) and basement wall repair (https://terrabrain.vercel.app/repairs/basement-wall-repair). ## Related - Bedrock - Tulsa Metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro) - Surface Drainage and Grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Lateral Earth, Swell and Hydrostatic Pressure on Walls (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls) - Basements (https://terrabrain.vercel.app/foundations/basements) - Crawl Space Repair (https://terrabrain.vercel.app/repairs/crawl-space-repair) Sources: [1] Official Series Description - PARSONS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/PARSONS.html [2] Official Series Description - OKEMAH Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OKEMAH.html [3] Official Series Description - DENNIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DENNIS.html [4] Official Series Description - SUMMIT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/S/SUMMIT.html [5] Official Series Description - OSAGE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OSAGE.html [6] Official Series Description - PORT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/PORT.html [7] Expansive Soils (The Mystery), STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [8] A Brief Guide to Mold, Moisture and Your Home, U.S. Environmental Protection Agency https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home --- # What is Pond Creek soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/pond-creek Answer: Pond Creek is a deep, well-drained silty soil partly formed in loess, with moderate clay, so water management and possible collapse are the main concerns. In short: Pond Creek is a deep, well-drained silty soil on the broad wheat-growing uplands of north-central Oklahoma. It formed partly in loess (windblown silt) and has a thick dark topsoil over silty clay loam. Its moderate clay content and well-drained setting mean water management around the house, and checking for collapse where loess is involved, are the main foundation topics. ## What is Pond Creek soil? Pond Creek is an official USDA soil series classified as "Fine-silty, mixed, superactive, thermic Pachic Argiustolls" [1]. It formed in calcareous loamy material high in silt and very fine sand, derived from loess, alluvium and residuum from red beds [1]. It sits on the treads of paleoterraces (old, high terraces) on broad uplands, with slopes of 0 to 8 percent [1]. The series occurs in the Central Rolling Red Prairies (MLRA 80A) of north-central Oklahoma and south-central Kansas and is rated as extensive [1]. The type location is in Garfield County, about half a mile north of Carrier, and the series was established in Grant County in 1931 [1]. Mean annual precipitation is about 32 inches (range 27-36) [1]. Most areas are cropped to wheat and other small grains [1]. In Oklahoma, Pond Creek falls in the North-Central (Red Prairies and Wheat Belt) (https://terrabrain.vercel.app/regions/north-central-red-prairies-and-wheat-belt) region, on Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) and red beds such as the Hennessey Shale (https://terrabrain.vercel.app/geology/hennessey-shale-group). ## What does a Pond Creek soil profile look like? | Depth | Layer | Texture | Clay (series range) | |---|---|---|---| | 0-12 in | Ap, A | Silt loam | Not stated | | 12-22 in | BA | Silty clay loam | 20-32% | | 22-46 in | Bt1, Bt2 | Silty clay loam | 28-35% in upper 20 in of control section, up to 45% lower | | 46-60 in | BC | Silty clay loam | 20-45% | | 60-68 in | BCk | Silty clay loam, few carbonate concretions | 20-45% | Source for the table: [1]. Other properties from the official description [1]: - **Drainage:** well drained; permeability moderate; saturated hydraulic conductivity moderately high [1]. - **Topsoil:** the dark mollic layer is 40 to 49 inches thick [1]. - **Depth to bedrock:** more than 60 inches [1]. - **Carbonates:** secondary calcium carbonate at 40 to 80 inches [1]. ## What does Pond Creek soil mean for foundations? ### Shrink-swell The USDA rates shrink-swell as linear extensibility, the linear expression of volume change from moist to oven-dry: under 3 percent low, 3 to 6 percent moderate, 6 to 9 percent high [4]. Pond Creek's subsoil is silty clay loam with clay rising to as much as 45 percent in its lower part [1]. The rated value for each mapped unit is in Web Soil Survey [2]. Clayey soils swell as they gain water and shrink as they dry, and uneven wetting or drying around a house is what drives damaging movement [5]. ### Loess and collapse Collapsible soils are unsaturated soils whose particles rearrange and lose volume when wetted, often while carrying load [3]. Engineering guidance lists windblown deposits, including loess, among the main collapsible deposit types, especially in arid and semi-arid climates [3]. Pond Creek is derived partly from loess [1], but its official description does not report collapse. Collapse is confirmed by testing rather than by soil name. Caltrans guidance describes index tests (dry density, moisture, Atterberg limits) and direct oedometer testing under ASTM D4546, and recommends considering both [3]. See collapsible and loess soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils) and hydrocollapse (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil). ### Water around the house Moderate permeability [1] lets water from roofs, sprinklers and leaks soak in. The ASCE Geo-Institute guide recommends discharging downspouts at least 3 feet from the foundation, keeping irrigation at least 5 feet away and finding and repairing plumbing leaks [5]. Related pages: erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) and fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). ## Related - Norge soil (https://terrabrain.vercel.app/soils/norge) - Grant soil (https://terrabrain.vercel.app/soils/grant) - Kirkland soil (https://terrabrain.vercel.app/soils/kirkland) - Soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - POND CREEK Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/POND_CREEK.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Collapsible Soil, California Department of Transportation (Caltrans), Geotechnical Services https://dot.ca.gov/-/media/dot-media/programs/engineering/documents/geotechnical-services/202601-gm-collapsiblesoil-a11y.pdf [4] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [5] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, Geo-Institute of the American Society of Civil Engineers https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Port silt loam, Oklahoma's state soil, and does it flood? URL: https://terrabrain.vercel.app/soils/port Answer: Port silt loam is Oklahoma's state soil, a deep floodplain soil on about one million acres in 33 counties that floods briefly between March and October. In short: Port silt loam is Oklahoma's official state soil, a deep, well-drained floodplain soil covering about one million acres in 33 counties. It floods occasionally or frequently for very brief periods between March and October. For homes, its floodplain location matters more than anything else, and soil scientists also note low strength and some shrink-swell. ## What is Port soil? Port is an official USDA soil series classified as "Fine-silty, mixed, superactive, thermic Cumulic Haplustolls" [1]. Flood plains are among the landscape positions that periodically receive fresh sediment [6]. The soil formed in calcareous loamy alluvium of Recent age on narrow flood plains, with slopes of 0 to 3 percent [1]. It occurs in the Central Rolling Red Plains and Central Rolling Red Prairies of Oklahoma, Kansas and Texas and is rated as extensive [1]. Its type location is in Grady County, about 7 miles east of Chickasha, and the series was established in Jackson County in 1942 [1]. ### Oklahoma's state soil The Governor and Oklahoma Legislature named Port silt loam the state soil in 1987 [2]. It covers about one million acres in 33 of the state's 77 counties, occurring in more counties than any other soil, mainly in western and central Oklahoma [2]. In Oklahoma, Port is common along streams in the OKC Metro (https://terrabrain.vercel.app/regions/okc-metro), North-Central (Red Prairies and Wheat Belt) (https://terrabrain.vercel.app/regions/north-central-red-prairies-and-wheat-belt) and Southwest (Lawton and Red Plains) (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains) regions, on Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces). ## What does a Port soil profile look like? | Depth | Layer | Texture | |---|---|---| | 0-9 in | Ap | Silt loam | | 9-27 in | A | Silt loam | | 27-42 in | Bk | Silty clay loam with calcium carbonate | | 42-72 in | C | Silt loam with thin silty clay loam strata | Source for the table: [1]. Other properties from the official description [1]: - **Flooding:** occasional or frequent, very brief, March to October [1]. - **Drainage:** well drained; permeability moderate [1]. - **Climate:** mean annual precipitation about 32 inches (range 26-40) [1]. - **Native vegetation:** tall grasses with pecan, black walnut, bur oak and eastern cottonwood [1]. - **Depth to bedrock and water table:** not stated [1]. ## What does Port soil mean for foundations? ### Flooding comes first Port forms on flood plains and floods occasionally or frequently [1]. The Soil Science Society of America summary identifies occasional flooding as Port's main limitation [2]. The official flood zone for any address is shown on FEMA's Flood Insurance Rate Maps, searchable in the Flood Map Service Center [4]. See creeks and flood history (https://terrabrain.vercel.app/data/creeks-and-flood-history) and severe weather effects (https://terrabrain.vercel.app/guides/severe-weather-effects). ### Strength and shrink-swell The same summary notes that low strength and shrink-swell limit Port's use for local roads and streets [2]. The USDA rates shrink-swell as linear extensibility, from low (under 3 percent) through moderate (3 to 6 percent) to high and very high [5]. The rated value for each mapped unit is in Web Soil Survey [3]. For how soft or wet alluvium can compress under a building, see soft soil consolidation (https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays). For how water can strip soil from under footings and slabs, see erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). ## How do you confirm the soil at a property? - Web Soil Survey shows the mapped soil unit and soil data for an area, and can generate custom reports [3]. - FEMA's map service center provides the FIRM panel and a printable flood map (FIRMette) for an address, and notes that later map changes (LOMCs) should be checked [4]. ## Related - Pulaski soil (https://terrabrain.vercel.app/soils/pulaski) - Kiomatia soil (https://terrabrain.vercel.app/soils/kiomatia) - Erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Soil series in the OKC metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - PORT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/PORT.html [2] Port Silt Loam, Oklahoma State Soil, Soil Science Society of America https://www.soils4teachers.org/files/s4t/k12outreach/ok-state-soil-booklet.pdf [3] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [4] FEMA Flood Map Service Center: Search By Address, Federal Emergency Management Agency https://msc.fema.gov/portal/search [5] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [6] A Glossary of Terms Used in Soil Survey and Soil Classification, USDA Natural Resources Conservation Service https://nrcs.usda.gov/sites/default/files/2022-08/A_Glossary_of_Terms_Used_in_Soil_Survey_and_Classification.pdf --- # What is Pratt soil and is it found in Oklahoma? URL: https://terrabrain.vercel.app/soils/pratt Answer: Pratt is a deep, sandy dune soil with thin clay bands, mapped mainly in south-central Kansas; its Oklahoma extent should be confirmed site by site. In short: Pratt is a deep, well-drained sandy soil formed in wind-blown sand on dunes, with thin clay-enriched bands called lamellae. It is mapped mainly in south-central Kansas, and its official description is unclear about Oklahoma, so the mapped soil at any Oklahoma site should be confirmed. Its very low clay content means foundation concerns center on loose sand, water and collapse testing rather than clay swelling. ## What is Pratt soil? Pratt is an official USDA soil series classified as "Sandy, mixed, mesic Lamellic Haplustalfs" [1]. "Lamellic" refers to its lamellae, and "sandy" describes its texture [1]. It formed in sandy eolian (wind-deposited) material on dunes on paleo-terraces, and also occurs on terraces and in some places on floodplains [1]. Slopes are 0 to 15 percent [1]. ### Where it occurs The official description places Pratt in south-central Kansas, in the Great Bend Sand Plains (MLRA 79), and calls it of large extent [1]. The series was established in Pratt County, Kansas, in 1910, and the type location is in Reno County, Kansas [1]. Oklahoma's status is unclear in the record. The description's header lists "KS+OK" and a remark records a 1995 update of the series for Oklahoma, but the distribution section names only Kansas [1]. Web Soil Survey shows which soil is actually mapped at a given location [2]. Other sandy soils on this site include Tivoli (https://terrabrain.vercel.app/soils/tivoli) and Dougherty (https://terrabrain.vercel.app/soils/dougherty). ## What is its typical soil profile? | Depth | Layer | Texture | Clay | |---|---|---|---| | 0-8 in | Ap | Fine sand | 5% | | 8-24 in | Bt | Loamy fine sand with 11 lamellae of fine sandy loam | 9% | | 24-64 in | E&Bt | Fine sand with 3 lamellae of loamy fine sand | 3% (E) | | 64-80 in | C | Fine sand | 5% | Source for the table: [1]. Other properties from the official description [1]: - **Clay in control section:** 4 to 11 percent; sand 80 to 90 percent [1]. - **Drainage:** well drained; saturated hydraulic conductivity rapid; runoff low [1]. - **Climate:** mean annual precipitation 19 to 32 inches [1]. - **Use:** gentler slopes farmed to grain sorghum, wheat and alfalfa; steeper slopes in native range [1]. ## What does it mean for foundations? ### Little clay, little shrink-swell The USDA measures shrink-swell as linear extensibility, with under 3 percent rated low [5]. With 4 to 11 percent clay and 80 to 90 percent sand in its control section [1], Pratt lacks the clay content behind seasonal shrink-swell. The rated value for a mapped unit is in Web Soil Survey [2]. ### Lamellae and water Lamellae are thin layers, each under about 3 inches (7.5 cm) thick, where clay has accumulated in otherwise sandy soil, and they slow water movement [3]. In Pratt, these bands sit within rapidly permeable sand [1]. Rapid conductivity means water from roofs and leaks soaks in quickly [1]. For how flowing water can carry sand out from beneath slabs and footings, see erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). ### Windblown sand and collapse Collapsible soils are unsaturated soils that lose volume when wetted, and engineering guidance lists windblown sand dunes and loess among the main collapsible deposit types [4]. Pratt formed in eolian sand on dunes [1], though its official description does not report collapse. Collapse is evaluated by index tests and by oedometer testing under ASTM D4546 [4]. See collapsible and loess soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils) and hydrocollapse (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil). ### Fill Pratt slopes reach 15 percent [1]. Where a lot was leveled with fill, see fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). ## Related - Tivoli soil (https://terrabrain.vercel.app/soils/tivoli) - Northwest (Gypsum Hills) region (https://terrabrain.vercel.app/regions/northwest-gypsum-hills) - Ogallala Formation and loess (https://terrabrain.vercel.app/geology/ogallala-formation-and-loess) - Soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - PRATT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/PRATT.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] A Glossary of Terms Used in Soil Survey and Soil Classification, USDA Natural Resources Conservation Service https://nrcs.usda.gov/sites/default/files/2022-08/A_Glossary_of_Terms_Used_in_Soil_Survey_and_Classification.pdf [4] Collapsible Soil, California Department of Transportation (Caltrans), Geotechnical Services https://dot.ca.gov/-/media/dot-media/programs/engineering/documents/geotechnical-services/202601-gm-collapsiblesoil-a11y.pdf [5] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html --- # What is Pulaski soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/pulaski Answer: Pulaski is a very deep, well-drained creek floodplain sandy loam; flooding, water movement and erosion, not clay swelling, are its foundation issues. In short: Pulaski is a very deep, well-drained fine sandy loam that forms on the flood plains of small creeks in central Oklahoma's Cross Timbers. It floods occasionally to frequently for very brief periods between March and October. Its sandy loam texture means flooding, water movement and erosion, not clay swelling, are the foundation issues. ## What is Pulaski soil? Pulaski is an official USDA soil series classified as "Coarse-loamy, mixed, superactive, nonacid, thermic Udic Ustifluvents" [1]. The "fluv" in its name refers to stream deposits; USDA soil terminology uses flood plains, which periodically receive fresh sediment, as the example setting for such soils [4]. It formed in loamy alluvial sediments of Holocene (recent) age [1]. The soil occurs on flood plains of small tributaries in the Northern Cross Timbers (MLRA 84A) of Oklahoma, Kansas and Texas and is rated as extensive [1]. Its type location is in Lincoln County, Oklahoma, about 6 miles north and 1 mile east of Chandler; the series was established in Lonoke County, Arkansas, in 1921 [1]. Mean annual precipitation is about 34 inches (range 30-40) [1]. In Oklahoma, Pulaski areas include creek bottoms in and around the OKC Metro (https://terrabrain.vercel.app/regions/okc-metro), on Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces). ## What is the typical soil profile? | Depth | Layer | Texture | |---|---|---| | 0-7 in | Ap | Fine sandy loam | | 7-19 in | A | Fine sandy loam | | 19-40 in | C1 | Fine sandy loam | | 40-64 in | C2 | Fine sandy loam with thin strata of loamy fine sand | Source for the table: [1]. Other properties from the official description [1]: - **Flooding:** occasional to frequent, very brief, March to October [1]. - **Drainage:** well drained; permeability moderately rapid; runoff negligible [1]. - **Slopes:** 0 to 3 percent [1]. - **Subsoil:** no B horizon; the soil goes from topsoil directly into layered C material [1]. - **Vegetation:** tall and midgrasses with pecan, black walnut, American elm, eastern cottonwood and tamarisk [1]. - **Depth to bedrock and water table:** not stated [1]. ## What does Pulaski soil mean for foundations? ### Flooding Pulaski forms on creek flood plains and floods occasionally to frequently [1]. FEMA's Flood Map Service Center provides the official Flood Insurance Rate Map panel and a printable flood map (FIRMette) for any address, and lists any later map revisions [3]. See creeks and flood history (https://terrabrain.vercel.app/data/creeks-and-flood-history) and erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes). ### Low clay The USDA rates shrink-swell as linear extensibility, with under 3 percent rated low [5]. Pulaski is coarse-loamy, fine sandy loam from top to bottom, with no clay-enriched subsoil [1]. The rated value for a specific mapped unit is in Web Soil Survey [2]. ### Water moving through sandy soil Moderately rapid permeability [1] means water from floods, roof runoff or plumbing leaks moves into and through the soil readily. For how moving water can wash soil from beneath slabs and footings, see erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) and plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab). ### Soft or placed layers Layered creek sediments and any fill placed to raise a lot are covered on these pages: - Soft soil consolidation (alluvium and wet clays) (https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays) - Fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) ## How do you confirm the soil at a property? Web Soil Survey shows mapped soil units and soil data for more than 95 percent of U.S. counties [2]. ## Related - Port soil (https://terrabrain.vercel.app/soils/port) - Konawa soil (https://terrabrain.vercel.app/soils/konawa) - Kiomatia soil (https://terrabrain.vercel.app/soils/kiomatia) - Soil series in the OKC metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - PULASKI Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/PULASKI.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] FEMA Flood Map Service Center: Search By Address, Federal Emergency Management Agency https://msc.fema.gov/portal/search [4] A Glossary of Terms Used in Soil Survey and Soil Classification, USDA Natural Resources Conservation Service https://nrcs.usda.gov/sites/default/files/2022-08/A_Glossary_of_Terms_Used_in_Soil_Survey_and_Classification.pdf [5] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html --- # What is Quinlan soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/quinlan Answer: A shallow loam over soft Permian sandstone at 10 to 20 inches in western Oklahoma; shallow rock, steep slopes and fast runoff matter more than clay swell. In short: Quinlan is a shallow, well-drained loam on hills, ridges and escarpments of western Oklahoma's red plains. Soft, noncemented Permian sandstone begins only 10 to 20 inches below the surface. For foundations, the main issues are shallow soft rock, steep slopes and fast runoff rather than clay swelling. ## What is Quinlan soil? Quinlan is an official USDA soil series classified as "Loamy, mixed, superactive, thermic, shallow Typic Haplustepts" [1]. It formed in loamy residuum (rock weathered in place) from noncemented, calcareous Permian sandstone or siltstone [1]. The soil occurs on interfluves and side slopes of hills, ridges and escarpments on dissected plains, with slopes of 1 to 50 percent [1]. It is found in the Central Rolling Red Plains (MLRAs 78B and 78C) of western Oklahoma, a few counties in southern Kansas and northwestern Texas, and is of large extent [1]. The series was established in 1932 in Woodward County, where its type location lies about 1.5 miles west of Quinlan [1]. Mean annual precipitation is about 25 inches (range 20-30) [1]. Most areas are used for grazing; native vegetation is mainly little bluestem and grama grasses [1]. In Oklahoma, Quinlan is part of the Northwest (Gypsum Hills) (https://terrabrain.vercel.app/regions/northwest-gypsum-hills) landscape, on the Western Permian red beds (https://terrabrain.vercel.app/geology/western-permian-red-beds). ## What is the typical soil profile? | Depth | Layer | Texture | Clay | |---|---|---|---| | 0-8 in | A | Loam | - | | 8-13 in | Bw | Loam | mostly 10-20% (range 5-27%) | | 13-64 in | Cd | Noncemented, calcareous sandstone bedrock | - | Source for the table: [1]. Other properties from the official description [1]: - **Depth to bedrock:** densic bedrock at 10 to 20 inches; densic contact at about 13 inches in the typical profile [1]. - **Drainage:** well drained; moderate permeability in the soil and moderately slow in the bedrock [1]. - **Runoff:** medium on 1-5 percent slopes, high on 5-20 percent and very high above 20 percent [1]. - **Clay in control section:** 10 to 30 percent [1]. ## What does it mean for foundations? ### Shallow, dense but soft rock Densic materials are compact, noncemented layers that restrict roots, with compaction from geologic or human causes rather than soil formation [3]. Quinlan's sandstone fits this description: noncemented and dense enough to restrict roots, and it breaks down to very fine sandy loam, loam or silt loam [1]. It begins within 20 inches of the surface [1]. Steel push piers in Oklahoma typically reach about 8 to 16 feet, with a median near 12 feet in Tulsa, based on installation records [4]. On a shallow-rock soil like Quinlan, a pier may stop shallower. Whether that layer is adequate bearing is a matter for installation pressure records and, where needed, an engineer. See steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers), shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata) and working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). ### Slopes and runoff With slopes up to 50 percent and high to very high runoff on steeper ground [1], Quinlan sites can be steep and shed water fast. Related pages: - Erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) - Slope creep and lateral movement (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement) - Surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) ### Shrink-swell The USDA rates shrink-swell as linear extensibility, with under 3 percent low and 3 to 6 percent moderate [5]. Quinlan's subsoil is loam with mostly 10 to 20 percent clay [1]. The rated value for each mapped unit is in Web Soil Survey [2]. ## Related - Lucien soil (https://terrabrain.vercel.app/soils/lucien) - Woodward soil (https://terrabrain.vercel.app/soils/woodward) - St. Paul soil (https://terrabrain.vercel.app/soils/st-paul) - Depth to rock from borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - QUINLAN Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/Q/QUINLAN.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] A Glossary of Terms Used in Soil Survey and Soil Classification, USDA Natural Resources Conservation Service https://nrcs.usda.gov/sites/default/files/2022-08/A_Glossary_of_Terms_Used_in_Soil_Survey_and_Classification.pdf [4] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data [5] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html --- # What is Renfrow soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/renfrow Answer: Renfrow is a deep clay soil from Permian shale with seasonal cracks, slickensides and high linear extensibility, all signs of strong shrink-swell. In short: Renfrow is a deep, well-drained soil formed from clayey Permian shale on low hills of north-central Oklahoma. Below about 13 inches it is clay, and its official description records seasonal cracks, slickensides and a high linear extensibility, all signs of strong shrink-swell. Houses on Renfrow are exposed to seasonal foundation movement as the clay wets and dries. ## What is Renfrow soil? Renfrow is an official USDA soil series classified as "Fine, mixed, superactive, thermic Udertic Paleustolls" [1]. "Udertic" marks a vertic intergrade, a soil trending toward the Vertisols [3]. Vertisols are clay soils that crack when dry and swell when wet, a movement that creates serious engineering problems [4]. The soil formed in material weathered from clayey Permian shale on summits and backslopes of low hills, with slopes of 0 to 5 percent [1]. It occurs in the Central Rolling Red Prairies (MLRA 80A) of Oklahoma, Kansas and Texas and is rated as extensive [1]. The type location is in Kay County, about 4 miles south and 3 miles west of Tonkawa; the series was established in 1931 [1]. Mean annual precipitation is about 32 inches (range 26-40) [1]. Most areas are farmed to wheat [1]. In Oklahoma, Renfrow is mapped in the North-Central (Red Prairies and Wheat Belt) (https://terrabrain.vercel.app/regions/north-central-red-prairies-and-wheat-belt) and OKC Metro (https://terrabrain.vercel.app/regions/okc-metro) regions, on red-bed shales such as the Hennessey Shale (https://terrabrain.vercel.app/geology/hennessey-shale-group) and Wellington Formation (https://terrabrain.vercel.app/geology/wellington-formation). ## What does a Renfrow soil profile look like? | Depth | Layer | Texture | Slickensides | |---|---|---|---| | 0-9 in | A | Silt loam | - | | 9-13 in | BA | Clay loam | - | | 13-25 in | Btss1 | Clay | Few | | 25-40 in | Btss2 | Clay | Common | | 40-65 in | Btss3 | Clay | Few | | 65-75 in | C | Clay | - | Source for the table: [1]. Other properties from the official description [1]: - **Clay:** 35 to 55 percent in the control section [1]. - **Cracks:** at least 5 mm wide through 30 cm or more, within 125 cm of the surface, for some time in most years [1]. - **Linear extensibility:** 6.0 cm or more between the surface and 100 cm [1]. - **Saturated hydraulic conductivity:** low. Runoff high to very high [1]. - **Shale:** noncemented densic shale deeper than 60 inches [1]. ## What does Renfrow soil mean for foundations? ### Strong shrink-swell Slickensides are polished, grooved faces formed by repeated shrinking and swelling [4], and Renfrow has them through most of its subsoil [1]. Its linear extensibility of 6 cm or more in the upper meter [1] meets the key criterion soil taxonomy uses for vertic subgroups [3]. On a percent basis, the USDA rates 6 to 9 percent as "high" and 9 percent or more as "very high" [6]; the value for each mapped unit is in Web Soil Survey [2]. Clayey soils heave as they gain water and settle as they dry, and uneven moisture change around a shallow foundation causes the most damage [5]. Patterns to read about: - Perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Perimeter wetting heave (edge lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) - Center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) - Tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) ### Moisture control The ASCE Geo-Institute guide lists the main moisture sources to manage on shrink-swell soils [5]: | Source | Guide's suggestion | |---|---| | Roof runoff | Discharge water at least 3 ft from the foundation | | Grading | At least 3 in of fall in 5 ft away from the house | | Irrigation | Keep lines and heads at least 5 ft away; water evenly | | Trees | Plant farther away than mature height | | Plumbing | Watch water bills; find and repair leaks | Soil moisture at 5, 25, 60 and 75 cm is measured by the Oklahoma Mesonet, whose more than 110 stations cover all 77 counties [7]. ## Related - Kirkland soil (https://terrabrain.vercel.app/soils/kirkland) - Norge soil (https://terrabrain.vercel.app/soils/norge) - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Soil series in the OKC metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) Sources: [1] Official Series Description - RENFROW Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/R/RENFROW.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] A Glossary of Terms Used in Soil Survey and Soil Classification, USDA Natural Resources Conservation Service https://nrcs.usda.gov/sites/default/files/2022-08/A_Glossary_of_Terms_Used_in_Soil_Survey_and_Classification.pdf [4] Vertisols, University of Idaho College of Agricultural and Life Sciences https://www.uidaho.edu/agricultural-life-sciences/soil-orders/vertisols [5] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, Geo-Institute of the American Society of Civil Engineers https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [6] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [7] The Oklahoma Mesonet (Fact Sheet), Oklahoma Climatological Survey https://www.mesonet.org/common/pubs/factsheets/Mesonet%20Fact%20Sheet.pdf --- # What is Richfield soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/richfield Answer: Richfield is a deep Panhandle loess soil with a smectitic subsoil of 35 to 42 percent clay, so clay movement and collapse on wetting both matter. In short: Richfield is a deep, well-drained soil formed in thick windblown silt (loess) on the flat tablelands of the Oklahoma Panhandle and nearby high plains. Its subsoil is a smectitic silty clay loam with 35 to 42 percent clay, the type of clay associated with shrink-swell. Because it formed in loess in a dry climate, both clay movement and collapse on wetting are topics for foundations. ## What is Richfield soil? Richfield is an official USDA soil series classified as "Fine, smectitic, mesic Aridic Argiustolls" [1]. "Smectitic" refers to its clay mineralogy [1]. It formed in calcareous loess 1 meter (about 3 feet) to more than 3 meters (about 10 feet) thick [1]. The soil occurs on tablelands, mostly plane, with slopes of 0 to 6 percent at elevations of 2,600 to 4,600 feet [1]. It is mapped in western Kansas and Nebraska, eastern Colorado, southwestern South Dakota and the Oklahoma Panhandle, and is of large extent [1]. The type location is in Grant County, Kansas [1]. Mean annual precipitation is about 18 inches (range 13-22) [1]. Most areas are cultivated to winter wheat and sorghum [1]. In Oklahoma, this places Richfield in the Panhandle (High Plains) (https://terrabrain.vercel.app/regions/panhandle-high-plains), on the Ogallala Formation and loess (https://terrabrain.vercel.app/geology/ogallala-formation-and-loess). ## What does a Richfield soil profile look like? | Depth | Layer | Texture | Clay (series range) | |---|---|---|---| | 0-6 in | Ap | Silt loam | - | | 6-16 in | Bt | Silty clay loam | 35-42% | | 16-20 in | BCk1 | Silty clay loam, soft carbonate | 20-32% | | 20-30 in | BCk2 | Silty clay loam, soft carbonate | 20-32% | | 30-60 in | C | Silt loam, 10-15% calcium carbonate equivalent | 10-32% | Source for the table: [1]. Other properties from the official description [1]: - **Drainage:** well drained; saturated hydraulic conductivity moderately high [1]. - **Carbonates:** secondary calcium carbonate at 10 to 24 inches [1]. - **Classification note:** lab data place it near the boundary of fine and fine-silty families [1]. - **Water table and cracks:** not described [1]. ## What does Richfield soil mean for foundations? ### Smectitic clay in the subsoil A federal survey of expansive materials noted that montmorillonite, a smectite clay, contributes to the widespread occurrence of expansive materials, notably in the Great Plains [3]. Richfield's subsoil is smectitic with 35 to 42 percent clay [1]. Clayey soils heave as they gain water and settle as they dry, and uneven moisture change around a shallow foundation is what causes damaging movement [5]. The USDA rates shrink-swell as linear extensibility: 3 to 6 percent moderate, 6 to 9 percent high, 9 percent or more very high [6]. The rated value for each mapped unit is in Web Soil Survey [2]. Patterns to read about: - Perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Perimeter wetting heave (edge lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) - Tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) ### Loess and collapse Collapsible soils are unsaturated soils that rearrange and lose volume when wetted [4]. Engineering guidance lists windblown deposits such as loess among the natural sources of collapsible soil, and notes these deposits are common in arid and semi-arid climates [4]. Collapse does not require full saturation [4]. Richfield formed in loess in a climate with about 18 inches of annual precipitation [1], though its official description does not report collapse. Collapse potential is evaluated with index tests and oedometer testing under ASTM D4546, and the guidance recommends weighing both [4]. See collapsible and loess soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils) and hydrocollapse (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil). ### Water around the house Shrink-swell movement and collapse are both driven by changes in soil moisture [4][5]. The ASCE Geo-Institute guide recommends discharging downspouts at least 3 feet from the foundation, keeping irrigation at least 5 feet away and repairing plumbing leaks [5]. See surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) and plumbing leaks under slab. ## Related - Ulysses soil (https://terrabrain.vercel.app/soils/ulysses) - Dalhart soil (https://terrabrain.vercel.app/soils/dalhart) - Freeze-thaw and frost depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) - Clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - RICHFIELD Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/R/RICHFIELD.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] An Occurrence and Distribution Survey of Expansive Materials in the United States by Physiographic Areas, U.S. Federal Highway Administration (via ROSA P) https://rosap.ntl.bts.gov/view/dot/58199 [4] Collapsible Soil, California Department of Transportation (Caltrans), Geotechnical Services https://dot.ca.gov/-/media/dot-media/programs/engineering/documents/geotechnical-services/202601-gm-collapsiblesoil-a11y.pdf [5] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, Geo-Institute of the American Society of Civil Engineers https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [6] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html --- # What is shrink-swell clay and the active zone under a foundation? URL: https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone Answer: Expansive clay swells when wet and shrinks when dry; the active zone is the layer, often several to over 10 feet thick, whose moisture changes enough to move. In short: Expansive clay swells when it gets wet and shrinks when it dries. The active zone is the layer of soil, often several feet to more than 10 feet thick, whose moisture changes enough to make it move. When moisture under a house changes unevenly, the foundation bends into an edge-drop, edge-lift or center-heave shape. ## What are the key terms? - **Shrink-swell**: the change in volume of clay soil as its moisture changes. Expansive soils swell when water enters and shrink when they dry [1]. - **Active zone**: the depth of soil whose moisture changes with seasons and other influences, and therefore moves. Engineers describe it as the soil that contributes to heave [4]. - **Edge moisture variation distance**: how far in from the edge of a slab the soil moisture changes with the weather. It is used in slab design [1][2]. - **Heave**: upward movement of soil or a foundation, usually from swelling clay. ## Why do some clays swell more? Clay particles are extremely small, under 2 microns [1]. Smectite clays, including montmorillonite, take water into the spaces between their mineral layers, and that is the main way they swell [7]. Engineers often use the plasticity index, a lab measure of how much water a clay can hold while staying moldable, as a quick indicator: clays below about 20 are only marginally expansive and clays above about 40 are considered highly expansive [6]. In Oklahoma, a State University study found peak swell measurements (coefficient of linear extensibility) of 0.095 for Bethany and 0.090 for Kirkland subsoils, both clay soils common in central Oklahoma [7]. ## How deep does the active zone go? There is no single number. Engineers note that active depth is hard to calculate and that local or regional experience is the most effective way to establish it [4]. | Setting | Reported depth | Source | |---|---|---| | Texas, statewide range | about 5 ft (Gulf Coast) to more than 30 ft inland | [4] | | Texas clay sites before the 2011 drought | about 8–10 ft | [3] | | Same sites after the 2011 drought | about 10–12 ft | [3] | | Houston site with large trees | about 28 ft (vs. 6 ± 2 ft commonly assumed) | [5] | | Colorado test site under a slab | moisture increases to 18 ft | [2] | What makes it deeper: - **Drought**: the 2011 drought deepened the active zone by about 2 feet at the sites studied [3]. - **Trees**: tree water demand can extend drying far deeper than seasonal weather alone, and paving limits how fast the soil recharges [5]. See trees and roots (https://terrabrain.vercel.app/guides/trees-and-roots). - **Water sources**: irrigation, impermeable surfaces and drainage all affect the active zone [4]. What can limit it: water-bearing permeable layers below the clay can keep the lower soil moist [3], and shallow rock leaves less soil to move. ## What movement patterns does clay cause? | Pattern | Typical cause | Common signs | |---|---|---| | Edge drop | Perimeter dries while the center stays moist | Exterior brick cracks, perimeter settlement | | Edge lift | Perimeter gets wetter and swells while the center is drier | Interior cracks, gaps at the base of exterior walls | | Center lift (center heave) | Long-term moisture build-up under the slab | Interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump), cracks radiating from the middle | Uneven moisture twists a slab into a center-lift or edge-lift shape [1]. Center lift is linked to long-term moisture gain under older foundations, while edge lift and edge drop follow seasonal or short-term moisture changes [6]. Telling them apart is covered in heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). ## Why don't piers alone address the cause? Piers transfer a foundation's weight to deeper soil or rock, which stops a perimeter from going down. Engineering sources note that the first step is dealing with what causes the moisture difference, such as drainage, leaking pipes, trees or irrigation [6]. Remedial leveling with piers or injection can produce only temporary leveling if those causes remain [6]. Moisture-related options are described under root barriers and moisture control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control) and chemical soil stabilization (https://terrabrain.vercel.app/repairs/chemical-soil-stabilization). ## Related - Clay Mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Drought and Wet Cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) - Seasonal Movement Calendar (https://terrabrain.vercel.app/guides/seasonal-movement-calendar) - Elevation Surveys (https://terrabrain.vercel.app/guides/elevation-surveys) - OK Data - Active Zone and Drought Depth (https://terrabrain.vercel.app/data/active-zone-and-drought-depth) Sources: [1] Residential House Foundations on Expansive Soils in Changing Climates, HUD Office of Policy Development and Research (Cityscape, Vol. 25 No. 1) https://www.huduser.gov/PORTAL/periodicals/cityscape/vol25num1/ch10.pdf [2] Active zone depth and edge moisture variation distance in expansive soils, Colorado State University (Ph.D. dissertation) https://mountainscholar.org/items/7d3d0e52-a824-4d77-a17c-17dab4f9098c/full [3] Ground Conditions in the 2011 Drought, CIGMAT Conference, University of Houston https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2012/3.pdf [4] TRB Webinar: Foundations in Shrink Swell Soil: Innovation and State of Practice, Transportation Research Board, National Academies https://www.nationalacademies.org/cdn/materials/a067d915-1c17-4a16-840d-06452b68646c [5] Case Study of Settlement of a Foundation on Expansive Clay Due to Moisture Demand of Trees, ASCE (Geo-Frontiers 2011) https://ascelibrary.com/doi/10.1061/41165%28397%29249 [6] Expansive Soils (The Mystery), STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [7] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma Agricultural Experiment Station, Oklahoma State University https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf --- # What is St. Paul soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/st-paul Answer: St. Paul is a deep, well-drained western Oklahoma terrace soil with a silty clay loam subsoil of 27-40% clay; moisture control is the main foundation issue. In short: St. Paul is a deep, well-drained soil on broad old terraces in western Oklahoma, with dark silt loam over a silty clay loam subsoil. Its clay content is moderate, about 27 to 40 percent in the subsoil, and water moves through it moderately slowly. Foundation questions on St. Paul center on moisture control, with the mapped shrink-swell rating checked for each site. ## What is St. Paul soil? St. Paul is an official USDA soil series classified as "Fine-silty, mixed, superactive, thermic Pachic Argiustolls" [1]. It formed in a thin layer of Pleistocene (Ice Age) silty alluvium over residuum (rock weathered in place) from Permian siltstone and sandstone [1]. It lies on broad, nearly level to moderately sloping paleoterraces, old terrace remnants of an alluvial plain [1]. Slopes are mainly under 3 percent, ranging up to 8 percent [1]. The series occurs in the Central Rolling Red Plains (MLRAs 78B and 78C) of Oklahoma, Texas and Kansas and is rated as extensive [1]. The type location is in Roger Mills County, about 2 miles south and 4 miles west of Leedey; the series was established in Kiowa County in 1931 [1]. Laboratory-sampled profiles come from Dewey, Woodward, Woods and Harper counties [1]. Mean annual precipitation is about 26 inches (range 21-28) [1]. Most areas are cropped to wheat and other small grains [1]. In Oklahoma, St. Paul falls in the Southwest (Lawton and Red Plains) (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains) and Northwest (Gypsum Hills) (https://terrabrain.vercel.app/regions/northwest-gypsum-hills) regions, on Western Permian red beds (https://terrabrain.vercel.app/geology/western-permian-red-beds) and Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces). ## What is the typical soil profile? | Depth | Layer | Texture | |---|---|---| | 0-7 in | Ap | Silt loam | | 7-12 in | A | Silt loam | | 12-18 in | BA | Silty clay loam | | 18-34 in | Bt1 | Silty clay loam | | 34-45 in | Bt2 | Silty clay loam | | 45-56 in | BCk | Silty clay loam | | 56-70 in | C | Silt loam | Source for the table: [1]. Other properties from the official description [1]: - **Clay:** 23 to 38 percent in the control section; upper Bt 27 to 35 percent, up to 40 percent in the lower part; BC or BCk 20 to 40 percent [1]. - **Dark topsoil:** the mollic layer extends to about 45 inches in the typical profile [1]. - **Drainage:** well drained; permeability moderately slow [1]. - **Runoff:** low on 0-1 percent slopes, medium on 1-5 percent, high on 5-8 percent [1]. - **Depth to bedrock and water table:** not stated [1]. ## What does St. Paul soil mean for foundations? ### Shrink-swell The USDA rates shrink-swell as linear extensibility, a linear expression of the change in soil volume between moist and oven-dry states: under 3 percent low, 3 to 6 percent moderate, 6 to 9 percent high, 9 percent or more very high [3]. St. Paul's subsoil is silty clay loam with clay up to about 40 percent [1]. The rated value for each mapped unit is in Web Soil Survey [2]. Clayey soils swell as they gain water and shrink as they dry, and uneven moisture change around a shallow foundation is what drives damaging movement [4]. See shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) and heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). ### Moisture control Moderately slow permeability [1] means water that soaks in near a house drains away gradually. The ASCE Geo-Institute guide lists these moisture sources and responses [4]: - **Roof runoff:** discharge downspouts at least 3 feet from the foundation [4]. - **Grading:** slope soil away at least 3 inches in 5 feet [4]. - **Irrigation:** keep lines and heads at least 5 feet away and water evenly [4]. - **Trees:** plant farther from the house than the tree's mature height [4]. - **Plumbing leaks:** watch water bills and repair leaks [4]. See surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) and trees and roots (https://terrabrain.vercel.app/guides/trees-and-roots). ### Runoff Runoff on St. Paul ranges from low on nearly level ground to high on 5 to 8 percent slopes [1]. ## Related - Quinlan soil (https://terrabrain.vercel.app/soils/quinlan) - Pond Creek soil (https://terrabrain.vercel.app/soils/pond-creek) - Woodward soil (https://terrabrain.vercel.app/soils/woodward) - Soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values) - Soil series index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - ST. PAUL Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/S/ST._PAUL.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Linear Extensibility Percent, UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, Geo-Institute of the American Society of Civil Engineers https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Stephenville soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/stephenville Answer: A moderately deep, well-drained sandy soil over soft sandstone at 20 to 40 inches; sandy texture, shallow rock and water handling matter more than swelling. In short: Stephenville is a moderately deep, well-drained soil of central Oklahoma that formed from weathered Permian sandstone. Its subsoil is sandy clay loam or fine sandy loam, and soft sandstone typically sits 20 to 40 inches down. For houses on Stephenville, the sandy texture, the shallow rock and how water is handled around the foundation matter more than clay swelling. ## Where does Stephenville soil occur? Every named soil in the U.S. has an Official Series Description (OSD) kept by the USDA Natural Resources Conservation Service (NRCS). The Stephenville OSD places the series in central Oklahoma, in Major Land Resource Area 84A, the Northern Cross Timbers, and calls it extensive [1]. Its type location is in Oklahoma County, about 2.5 miles east and 1 mile north of Spencer [1]. Stephenville forms on the side slopes of hills on uplands, on slopes of 1 to 25 percent [1]. That places it in parts of the OKC Metro (https://terrabrain.vercel.app/regions/okc-metro) [1]; for the local Permian sandstone, see the Garber Sandstone (https://terrabrain.vercel.app/geology/garber-sandstone) page. Native vegetation is post oak, blackjack oak, hickory and eastern red cedar with tall and mid grasses, the typical Cross Timbers mix [1]. ## What are its key properties? | Property | Stephenville (from the OSD) [1] | |---|---| | Classification | Fine-loamy, siliceous, active, thermic Ultic Haplustalfs | | Parent material | Weathered Permian sandstone | | Depth to soft rock | 20-40 in (about 33 in in the typical profile) | | Drainage | Well drained | | Water movement (Ksat) | Moderately high | | Subsoil (Bt) | Sandy clay loam or fine sandy loam | | Slopes | 1-25% | | Mean annual rainfall | 30-40 in (about 32 in) | A "paralithic contact" is the top of soft, weakly cemented rock that can be dug with effort. In Stephenville it is weakly cemented sandstone [1]. The "Bt" horizon is the subsoil layer where clay has collected over time. Closely related soils include Darnell and Darsil, which are shallower to rock and sit on hill crests, and Harrah and Konawa, which are deeper [1]. ## What do the properties mean for foundations? ### Shrink-swell Clay soils swell when wet and shrink when dry, and uneven moisture change is what moves foundations [4]. NRCS rates this with linear extensibility: under 3 percent is low, 3 to 6 percent moderate, 6 to 9 percent high, and above 9 percent very high [3]. Stephenville's subsoil is sandy clay loam rather than clay, and the OSD does not record the cracking or slickensides (polished shear surfaces) that mark strongly expansive soils [1]. The rated value for any map unit can be checked in Web Soil Survey [2]. Statewide, the Oklahoma Geological Survey notes that more than 75 percent of Oklahoma has bedrock that can produce expansive soils, so nearby shale-derived soils can behave very differently from Stephenville [5]. ### Shallow, soft sandstone Because soft sandstone is only 20 to 40 inches down, footings and piers on Stephenville lots meet rock quickly [1]. Weakly cemented sandstone is not the same as hard rock, which is why the actual bearing layer is usually confirmed during repair work. See shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata) and bedrock in the OKC metro (https://terrabrain.vercel.app/guides/bedrock-okc-metro). ### Water, slopes and erosion Runoff on Stephenville ranges from low on gentle slopes to high on slopes steeper than 20 percent [1]. Sandy and loamy soils on slopes are more open to erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) when roof water or leaks are concentrated next to a foundation. The ASCE homeowner guide recommends that ground slope at least 3 inches down over the first 5 feet away from the house and that downspouts discharge at least 3 feet out [4]. Hillside lots are also often leveled with cut and fill, which brings in fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) as a separate issue from the native soil. ## Related - Soil series in the OKC metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) - Darnell soil (https://terrabrain.vercel.app/soils/darnell) - Konawa soil (https://terrabrain.vercel.app/soils/konawa) - Garber Sandstone (https://terrabrain.vercel.app/geology/garber-sandstone) - Surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - STEPHENVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/S/STEPHENVILLE.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html --- # What is Summit soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/summit Answer: Summit is a deep shale-derived soil with a 40 to 70 percent smectitic clay subsoil, high to very high shrink-swell and a perched water table in winter and spring. In short: Summit is a very deep clay soil of northeastern Oklahoma, including the Tulsa area, that formed from Pennsylvanian shale. Its subsoil is 40 to 70 percent clay of the smectite family, its official description lists a coefficient of linear extensibility (COLE) of 0.09 or more, and it holds a perched water table through winter and spring. These traits make seasonal foundation movement a central concern on Summit lots. ## Where does Summit soil occur? The USDA Natural Resources Conservation Service (NRCS) keeps an Official Series Description (OSD) for every named soil. The Summit OSD lists the series in Major Land Resource Areas 112 and 116 across eastern Oklahoma, southeastern Kansas, southwestern Missouri and northwestern Arkansas, and calls it extensive [1]. Its type location is in Rogers County, Oklahoma [1]. Summit forms on interfluves (the broad ground between drainages), divides and hillslopes on plains, on slopes of 0 to 12 percent [1]. It developed in clayey colluvium or residuum weathered from Pennsylvanian shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales) [1], which places it in the Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro) and the Northeast (https://terrabrain.vercel.app/regions/northeast-ozark-plateau-and-grand-lake). Native vegetation is tallgrass prairie [1]. ## What are the key properties of Summit soil? | Property | Summit (from the OSD) [1] | |---|---| | Classification | Fine, smectitic, thermic Oxyaquic Vertic Argiudolls | | Parent material | Clayey colluvium or residuum from Pennsylvanian shale | | Depth to bedrock | More than 60 in | | Drainage | Moderately well to somewhat poorly drained | | Permeability | Slow (Ksat moderately low) | | Subsoil (Bt) | Silty clay or clay, 40-70% clay | | Shrink-swell feature | COLE 0.09 or more; deep, wide summer cracks | | Seasonal water table | Perched at 12-36 in, November-May | | Mean annual rainfall | About 41 in (35-47 in) | "Smectitic" means the clay is dominated by smectite, the clay mineral group that swells most when wet [6]. "Vertic" in the name signals soil that cracks deeply and shows slickensides, the polished shear faces left by repeated swelling, and the OSD records slickensides in the B horizons [1]. ## What do these properties mean for foundations? ### Very high shrink-swell The coefficient of linear extensibility (COLE) is the change in length of a soil clod from moist to dry, and as a percent it is called linear extensibility (LEP) [3]. NRCS rates 6 to 9 percent as high and more than 9 percent as very high, and notes that soils above 3 percent can damage buildings and roads and commonly need special design [4]. Summit's COLE of 0.09 or more (9 percent or more) puts it at the high to very high end of that scale [1][4]. The rated value for each mapped Summit unit is listed in Web Soil Survey [2]. Clay soils swell when they gain water and shrink when they lose it, and localized moisture changes around a house are more damaging than uniform ones [5]. Expansive clays are easy to spot in dry seasons by their deep cracks, and seasonal moisture change can reach from 3 to 40 feet deep depending on climate [6]. Typical movement patterns on soils like this include perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop), center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) and tree-root drying (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement). The Oklahoma Geological Survey notes that clay-rich shales and soils weathered from shale can contain montmorillonite, a smectite clay, and that saturation from rain, lawn watering or sewer leaks can damage foundations [7]. ### Perched water A perched water table is a temporary saturated zone that sits on top of a slow-draining layer. On Summit it sits 12 to 36 inches down from November to May in normal years [1]. Wet crawl spaces and water pressure on basement walls are related concerns; see groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) and lateral earth and hydrostatic pressure (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls). ### Keeping moisture even The ASCE homeowner guide stresses even soil moisture around the whole foundation, grading at least 3 inches of fall over 5 feet, downspouts discharging at least 3 feet out, and planting trees farther from the house than their mature height [5]. ## Related - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Soil series in the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) - Clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Dennis soil (https://terrabrain.vercel.app/soils/dennis) - Okemah soil (https://terrabrain.vercel.app/soils/okemah) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - SUMMIT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/S/SUMMIT.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [5] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [6] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [7] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html --- # What is Tabler soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/tabler Answer: Tabler is a very deep clay soil of north-central Oklahoma with a 35 to 50 percent clay subsoil that drains very slowly and moves with the seasons. In short: Tabler is a very deep clay soil found on old, nearly level terraces in north-central Oklahoma. Its subsoil is 35 to 50 percent clay, drains very slowly and is full of slickensides, the polished surfaces left by repeated swelling and shrinking. Those features point to clay that moves with the seasons, so even soil moisture around a foundation is a key factor on Tabler lots. ## Where does Tabler soil occur? The USDA Natural Resources Conservation Service (NRCS) maintains an Official Series Description (OSD) for each named soil. The Tabler OSD places it in the Central Rolling Red Prairies (Major Land Resource Area 80A) of north-central Oklahoma and south-central Kansas, with moderate extent [1]. Its type location is in Grant County, about 4 miles east and 1.5 miles south of Medford [1]. Tabler forms on broad, nearly level summits of paleoterraces, which are old river terraces left high above today's streams, on slopes of 0 to 1 percent [1]. It developed in calcareous loamy or clayey alluvium [1], tying it to the Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) of the North-Central region (https://terrabrain.vercel.app/regions/north-central-red-prairies-and-wheat-belt). Most Tabler land grows small grains and sorghum [1]. ## What are Tabler soil's key properties? | Property | Tabler (from the OSD) [1] | |---|---| | Classification | Fine, mixed, active, thermic Udertic Paleustolls | | Parent material | Calcareous loamy or clayey alluvium | | Depth | Very deep | | Drainage | Moderately well drained | | Permeability | Very slow | | Surface (A) | Silt loam, 14-27% clay | | Subsoil (Btss, Btk) | Silty clay loam or silty clay, 35-50% clay | | Slickensides | 20-80% in Btss layers, from about 10 to 42 in | | Slopes | 0-1% | | Mean annual rainfall | 33-35 in | The jump from a silt loam surface to a clay subsoil is typical of a claypan profile. "Udertic" in the classification [1] marks some vertic traits without a full Vertisol; Tabler has slickensides [1], the polished surfaces that Vertisols form through shrinking and swelling [4]. Similar soils listed in the OSD include Bethany (https://terrabrain.vercel.app/soils/bethany), Kirkland (https://terrabrain.vercel.app/soils/kirkland) and Renfrow; Pond Creek and Norge are associated soils with less clay [1]. ## What does Tabler soil mean for foundations? ### Clay that moves Vertisols and vertic soils shrink and crack in dry periods and swell when rewetted, and that behavior creates serious engineering problems [4]. Tabler's slickensides, which cover up to 80 percent of some subsoil layers, are a physical record of that movement [1]. NRCS rates shrink-swell by linear extensibility: 6 to 9 percent is high and 9 or more very high, and anything above 3 percent can damage buildings and commonly needs special design [3]. The rated value for each map unit is in Web Soil Survey [2]. Uneven drying and wetting is what moves foundations. Common patterns on soils like Tabler include perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop), perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) and center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) [5][6]. ### Slow drainage on flat ground Tabler's very slow permeability and nearly level setting mean water from roofs, sprinklers or leaks does not move away quickly [1]. Lawn and garden watering creates a moist zone along the outside of a foundation, and leaking pipes add water unevenly [6]. The ASCE homeowner guide recommends at least 3 inches of fall over the first 5 feet from the house and sprinkler heads at least 5 feet from the foundation [5]. ### Trees Tree roots can dry clay soil and cause uneven settlement, and the ASCE guide suggests planting trees farther from the house than their mature height [5]. See trees and roots (https://terrabrain.vercel.app/guides/trees-and-roots). ## Related - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Renfrow soil (https://terrabrain.vercel.app/soils/renfrow) - Kirkland soil (https://terrabrain.vercel.app/soils/kirkland) - Tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - TABLER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TABLER.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [4] Vertisols, University of Idaho, College of Agricultural and Life Sciences https://www.uidaho.edu/cals/soil-orders/vertisols [5] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [6] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf --- # What is Talihina soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/talihina Answer: Talihina is a shallow, poorly drained eastern Oklahoma clay over soft shale 10 to 20 inches down, so shallow shale, wet-season water and clay matter most. In short: Talihina is a shallow clay soil of eastern Oklahoma that sits on soft Pennsylvanian shale only 10 to 20 inches below the surface. It is poorly drained, water moves through it slowly, and it can hold a perched water table in winter and spring. On Talihina lots, the shallow shale, wet-season water and the clay content are the main foundation factors. ## Where does Talihina soil occur? The USDA Natural Resources Conservation Service (NRCS) keeps an Official Series Description (OSD) for each named soil. The Talihina OSD lists the series in eastern Oklahoma, southeastern Kansas and southwestern Missouri, and calls it extensive [1]. Its type location is in Hughes County, about 2 miles east of Holdenville [1]. Talihina forms on smooth ridge crests and side slopes of sloping to steep dissected uplands in the Cherokee Prairies (Major Land Resource Area 112), on slopes of 5 to 30 percent [1]. It developed in clayey material weathered from soft Pennsylvanian shale (https://terrabrain.vercel.app/geology/pennsylvanian-shales) with thin sandstone and siltstone layers [1], part of the East-Central (Arkoma) (https://terrabrain.vercel.app/regions/east-central-arkoma) landscape. Most of it is native tallgrass range [1]. ## What are its key properties? | Property | Talihina (from the OSD) [1] | |---|---| | Classification | Clayey, mixed, active, thermic, shallow Aquic Hapludolls | | Parent material | Soft Pennsylvanian shale with thin sandstone/siltstone | | Depth to soft bedrock | 10-20 in (about 15 in typical) | | Drainage | Poorly drained | | Permeability | Slow | | Surface (A) | Silty clay loam to clay, 35-55% clay | | Subsoil (Bw) | Silty clay loam, silty clay or clay, 35-40% clay | | Water table | Perched 0.5-2.0 ft, short periods November-April | | Slopes | 5-30% | | Mean annual rainfall | 38-44 in | "Bw" means a weakly developed subsoil layer; Talihina has no clay-enriched "Bt" layer. The soft rock at its base is a "paralithic contact," rock that is weakly cemented rather than hard [1]. Soils on lower slopes nearby include Dennis (https://terrabrain.vercel.app/soils/dennis) and Eram (https://terrabrain.vercel.app/soils/eram), and smooth ridges carry Bates (https://terrabrain.vercel.app/soils/bates), Collinsville and Coweta [1]. ## What do its properties mean for foundations? ### Clay content Talihina's surface layer has 35 to 55 percent clay and its subsoil 35 to 40 percent [1]. The OSD does not record deep cracks or slickensides for Talihina; it notes only a few pressure faces [1]. NRCS rates shrink-swell by linear extensibility, from low (under 3 percent) to very high (more than 9 percent), and anything above 3 percent can damage buildings [3]. The rated value for any map unit is in Web Soil Survey [2]. The Oklahoma Geological Survey notes that soils weathered from shale can contain montmorillonite, a clay that swells when wet [4]. ### Shallow, soft shale With soft shale 10 to 20 inches down [1], footings on Talihina can bear on or near weathered rock. Clay-rich shale can itself contain swelling montmorillonite [4], so its condition at depth matters for both footings and piers; see shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata). ### Wet seasons and slopes Poor drainage, slow permeability and a perched water table mean water collects in and above the soil from late fall into spring [1]. That pattern relates to crawl space moisture and wood decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) and to water pressure on below-grade walls. Runoff on Talihina is moderate to very high [1]. The ASCE homeowner guide recommends at least 3 inches of fall over the first 5 feet from the house and downspouts that discharge at least 3 feet out [5]. Uneven wetting along one side of a house can cause perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) [5]. ## Related - Groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Crawl space encapsulation (https://terrabrain.vercel.app/repairs/crawl-space-encapsulation) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - TALIHINA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TALIHINA.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [4] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [5] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Taloka soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/taloka Answer: Taloka is a very deep soil with a silty surface that changes abruptly to dense clay, and a perched water table 12 to 24 inches down from late fall through spring. In short: Taloka is a very deep soil of northeastern Oklahoma with a silty surface that changes abruptly to a dense clay subsoil. It is somewhat poorly drained and holds a perched water table 12 to 24 inches down from late fall through spring. For foundations, the clay subsoil and the seasonal wetness are the main factors. ## Where does Taloka soil occur? The USDA Natural Resources Conservation Service (NRCS) keeps an Official Series Description (OSD) for every named soil. The Taloka OSD lists the series in Major Land Resource Areas 112, 116 and 118 of northeastern Oklahoma, northwestern Arkansas and southeastern Kansas, with moderate extent [1]. Its type location is in Wagoner County, about 4 miles southeast of Wagoner [1]. Taloka forms on interfluves and paleoterraces (old, high stream terraces) on plains with 0 to 3 percent slopes [1]. It developed in loamy and clayey colluvium or alluvium weathered from interbedded Pennsylvanian shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales) and sandstone, sometimes with a thin loess cap [1]. That puts it in the Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro) and the Northeast (https://terrabrain.vercel.app/regions/northeast-ozark-plateau-and-grand-lake). Most Taloka land is farmed for small grains, sorghum and soybeans [1]. ## What are its key properties? | Property | Taloka (from the OSD) [1] | |---|---| | Classification | Fine, mixed, active, thermic Mollic Albaqualfs | | Parent material | Colluvium/alluvium from Pennsylvanian shale and sandstone | | Depth | Very deep | | Drainage | Somewhat poorly drained | | Permeability | Very slow (Ksat low) | | Surface (A, E) | Silt loam, 8-25% clay | | Subsoil (Bt) | Silty clay loam to clay, 35-60% clay | | Seasonal water table | Perched at 12-24 in, November-May | | Slopes | 0-3% | | Mean annual rainfall | About 41 in (37-45 in) | The "E" horizon is a pale, leached layer above the subsoil; in Taloka it runs from about 8 to 28 inches and ends at an abrupt boundary where texture jumps to silty clay or clay loam [1]. Redox features (gray and rust mottles that form under repeated saturation) appear in all layers below 8 inches [1]. Parsons is a competing series on similar landforms, and Choteau, Dennis and Bates occur nearby [1]. ## What do the properties mean for foundations? ### A clay layer under a silty cap With 35 to 60 percent clay, Taloka's subsoil can shrink when it dries and swell when it wets [1][4]. The OSD does not record deep cracks or slickensides for this series [1]. NRCS rates shrink-swell by linear extensibility, and values above 3 percent can damage buildings and commonly call for special design [3]. The rated value for a specific map unit is in Web Soil Survey [2]. Lab tests such as plasticity index are described on soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values). ### Perched water and slow drainage A perched water table is water held up temporarily above a slow-draining layer. On Taloka it sits 12 to 24 inches down from November through May in normal years [1]. HUD's soil guide identifies water table depth, natural drainage and seepage as key controls on soil moisture, and notes that lawn watering and covering the soil also change it [5]. Seasonal saturation is linked to crawl space moisture (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay), perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) and water pressure on basement walls (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls). ### Dry summers The same clay can shrink in hot, dry weather. HUD notes that vegetation can worsen shrinkage during warm, dry periods [5], and the ASCE guide links non-uniform drying near trees to uneven settlement [4]. See perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). ## Related - Groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Soil series in the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) - Parsons soil (https://terrabrain.vercel.app/soils/parsons) - Drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - TALOKA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TALOKA.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Guide to Use of the FHA Soil PVC Meter (HUD Handbook 4075.15), U.S. Department of Housing and Urban Development https://www.hud.gov/sites/documents/407515hsgh.pdf --- # What is Teller soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/teller Answer: A very deep, well-drained terrace loam with about 18 to 30 percent clay in its subsoil; drainage, leaks, erosion and fill quality are checked first. In short: Teller is a very deep, well-drained loamy soil that formed in old stream-terrace sediments in central Oklahoma. Its subsoil is sandy clay loam or clay loam with roughly 18 to 30 percent clay in the upper part, well below the clay levels of Oklahoma's strongly expansive soils. On Teller lots, drainage, leaks, erosion and fill quality are usually the first foundation factors to check. ## Where does Teller soil occur? The USDA Natural Resources Conservation Service (NRCS) keeps an Official Series Description (OSD) for each named soil. The Teller OSD places the series in the Central Rolling Red Prairies (Major Land Resource Area 80A) of Oklahoma and Texas, with moderate extent [1]. Its type location is in Payne County, about 1 mile west and 1 mile north of Perkins, and the series was first established in Johnston County in 1906 [1]. Teller forms on the treads and risers of stream terraces on alluvial plains, on slopes of 0 to 8 percent [1]. A terrace tread is the flat top of an old floodplain level; the riser is the slope between levels. Teller developed in loamy Pleistocene sediments [1], which ties it to the Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) of the OKC Metro (https://terrabrain.vercel.app/regions/okc-metro) and the North-Central region (https://terrabrain.vercel.app/regions/north-central-red-prairies-and-wheat-belt). Most Teller land is cropland for small grains, sorghum, peanuts and cotton [1]. ## What are its key properties? | Property | Teller (from the OSD) [1] | |---|---| | Classification | Fine-loamy, mixed, active, thermic Udic Argiustolls | | Parent material | Loamy Pleistocene sediments | | Depth to bedrock | More than 80 in | | Drainage | Well drained | | Permeability | Moderate | | Surface (A) | Fine sandy loam, very fine sandy loam, silt loam or loam | | Subsoil (Bt) | Sandy clay loam or clay loam; upper 20 in averages 18-30% clay | | Slopes | 0-8% | | Mean annual rainfall | 33-43 in (about 37 in) | The "Bt" horizon is the subsoil layer where clay has built up over time; in Teller it runs from about 20 to 60 inches [1]. Competing series in the OSD include Chickasha (https://terrabrain.vercel.app/soils/chickasha), and nearby soils include Dougherty (https://terrabrain.vercel.app/soils/dougherty), Konawa (https://terrabrain.vercel.app/soils/konawa), Norge and Pond Creek [1]. ## What do the properties mean for foundations? ### Shrink-swell NRCS rates shrink-swell by linear extensibility: under 3 percent is low, 3 to 6 percent moderate, 6 to 9 percent high and above 9 percent very high [3]. Teller's subsoil is a loam-family texture rather than a clay, and its OSD records no cracking or slickensides [1]. The rated value for a specific map unit is in Web Soil Survey [2]. Even soils with modest clay respond to uneven moisture, so keeping moisture consistent around a foundation still matters [4]. ### Water and erosion Loamy and sandy soils can wash out when water is concentrated beside a foundation, a process covered on erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). The ASCE homeowner guide recommends at least 3 inches of fall over the first 5 feet from the house, downspouts that discharge at least 3 feet out, and clay rather than sandy soil for backfill against the foundation [4]. Leaking water or sewer lines create localized wet spots, and the guide suggests watching water bills for unexplained increases [4]. ### Fill and terrace edges Terrace risers and lots near streams are often graded with fill, which can compress over time; see fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). Because terraces sit beside streams, flood maps for a lot can be checked at FEMA's Flood Map Service Center [5]. ## Related - Soil series in the OKC metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) - Fill soils and lot history (https://terrabrain.vercel.app/guides/fill-soils-and-lot-history) - Plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) - Norge soil (https://terrabrain.vercel.app/soils/norge) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - TELLER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TELLER.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] FEMA Flood Map Service Center: Search By Address, Federal Emergency Management Agency https://msc.fema.gov/portal/search --- # What is Tillman soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/tillman Answer: Tillman is a deep red-bed clay in southwest Oklahoma with cracks over 48 inches deep and high shrink-swell, so seasonal wetting and drying drive movement. In short: Tillman is a very deep clayey soil of southwestern Oklahoma that formed in alluvium washed from Permian red-bed clays. Its official description records cracks more than 48 inches deep and a linear extensibility above 6 percent, which is in the high shrink-swell class. In a dry climate with about 26 inches of rain a year, seasonal drying and wetting of this clay drives foundation movement. ## Where does Tillman soil occur? The USDA Natural Resources Conservation Service (NRCS) keeps an Official Series Description (OSD) for each named soil. Tillman was established in Tillman County, Oklahoma, in 1932, and its current type location is in Wilbarger County, Texas, near Lockett [1]. The OSD places it in the Rolling Limestone Prairie (MLRA 78D) and the eastern Central Rolling Red Plains (MLRA 78C) of northwest Texas and western Oklahoma, and its extent is large [1]. Tillman forms on paleoterraces, which are old alluvial terraces left above today's streams, on nearly level to gently sloping plains [1]. It developed in loamy and clayey alluvium from Permian red-bed clays and claystone, mainly of the Clear Fork Group [1]. That ties it to the Western Permian Red Beds (https://terrabrain.vercel.app/geology/western-permian-red-beds) and Quaternary terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) of the Southwest (Lawton and Red Plains) (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains). Most Tillman land grows small grains, cotton and sorghum [1]. ## What are the key properties of Tillman soil? | Property | Tillman (from the OSD) [1] | |---|---| | Classification | Fine, mixed, superactive, thermic Vertic Paleustolls | | Parent material | Alluvium from Permian red-bed clays and claystone | | Depth | Very deep; solum 60-80+ in over dense clay or claystone | | Drainage | Well drained | | Permeability | Slow | | Subsoil (Bt, Btk) | Clay loam, silty clay loam, silty clay or clay | | Control-section clay | 35-50% | | Shrink-swell feature | COLE above 0.06 in upper 40 in; cracks over 48 in deep | | Slopes | 0-5% | | Mean annual rainfall | About 26 in (23-28 in) | "Vertic" in the classification means the soil shows strong shrink-swell features such as deep cracks; Tillman was reclassified from Typic to Vertic Paleustolls in 2000 [1]. Some profiles also show a few slickensides, polished faces formed when swelling clay shears against itself [1]. The "k" in Btk marks a layer with lime (calcium carbonate) accumulation [1]. Associated soils include Hollister, on slightly lower landscape positions, and Vernon [1]. ## What do these properties mean for foundations? ### High shrink-swell The coefficient of linear extensibility (COLE) is the change in length of a soil clod from moist to oven-dry; times 100 it is linear extensibility percent [3]. NRCS classes 6 to 9 percent as high and notes that values above 3 percent can damage buildings and commonly need special design [4]. Tillman's COLE above 0.06 meets the high class [1]. The rated value for a specific map unit is in Web Soil Survey [2]. Expansive clays are easiest to recognize in the dry season by their deep cracks, and seasonal moisture change can reach depths of 3 to 40 feet [5]. Areas with pronounced wet and dry seasons carry the greatest hazard [5]. Typical movement patterns include perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) in drought and perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) or center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) after wet spells. ### Trees and watering in a dry climate Tree roots can dry clay unevenly and cause settlement, and the ASCE guide suggests keeping trees farther from the house than their mature height [6]. It also warns that overwatering can cause heave, and recommends even moisture on all sides of the foundation [6]. Lawn and garden watering creates a moist zone along the outside of a foundation [5]. See trees and roots (https://terrabrain.vercel.app/guides/trees-and-roots) and drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles). ## Related - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Hollister soil (https://terrabrain.vercel.app/soils/hollister) - Foard soil (https://terrabrain.vercel.app/soils/foard) - Tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - TILLMAN Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TILLMAN.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [4] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [5] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [6] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Tivoli soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/tivoli Answer: Tivoli is very deep, excessively drained dune sand in northwestern Oklahoma with no clay subsoil, so loose sand, not shrink-swell, is the main concern. In short: Tivoli is a very deep sandy soil that formed in wind-blown dune sand along river valleys in northwestern Oklahoma. It is sandy throughout, drains excessively and has no clay subsoil, so clay shrink-swell is not its main foundation issue. Instead, foundation concerns on Tivoli land center on how loose sand behaves around water, slopes and footings. ## Where does Tivoli soil occur? The USDA Natural Resources Conservation Service (NRCS) keeps an Official Series Description (OSD) for each named soil. Tivoli was established in Major County, Oklahoma, in 1936, and its type location is about 2.5 miles northeast of Woodward in Woodward County [1]. The OSD places it in Major Land Resource Areas 78B and 78C in Oklahoma, Kansas and Texas, and calls it extensive [1]. Tivoli forms on sand dunes on sand sheets and stream terraces in river valleys and dissected plains, with hummocky relief and complex slopes of 1 to 45 percent [1]. "Eolian" means wind-deposited; Tivoli's parent material is sandy eolian sediment [1]. That places it in the Northwest (Gypsum Hills) (https://terrabrain.vercel.app/regions/northwest-gypsum-hills) on sandy deposits along major rivers, part of the Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) group. The land is mostly used for grazing, with sand bluestem, sand dropseed and sand reedgrass as native cover [1]. ## What are Tivoli soil's key properties? | Property | Tivoli (from the OSD) [1] | |---|---| | Classification | Mixed, thermic Typic Ustipsamments | | Parent material | Sandy eolian (wind-blown) sediments | | Depth | Very deep | | Drainage | Excessively drained | | Permeability | Rapid | | Surface (A) | Fine sand, loamy sand or loamy fine sand; under 1% organic matter | | Below (C) | Sand, fine sand, loamy sand or loamy fine sand | | Structure | Single grain (loose, not clumped) | | Slopes | 1-45% | | Mean annual rainfall | About 26 in (20-32 in) | "Psamments" are sandy soils with little horizon development. Tivoli has no B horizon; a sandy surface layer sits on sandy C layers, in places with a transitional AC layer between [1]. "Single grain" means the sand grains do not stick together into clods [1]. ## What does Tivoli soil mean for foundations? ### Little shrink-swell NRCS rates shrink-swell by linear extensibility, with under 3 percent classed as low [3]. Tivoli has no clay-rich layer at all, so it lacks the material that drives seasonal swelling [1]. The rated value for a map unit is in Web Soil Survey [2]. ### Loose sand, water and slopes Because the sand is single grain and drains rapidly, water from roofs, leaks or broken lines soaks in and moves through quickly [1]. How concentrated water moves soil from beside and beneath footings is covered on erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). The ASCE homeowner guide recommends at least 3 inches of fall over the first 5 feet from the house, downspouts that discharge at least 3 feet out, and compacted clay rather than sandy soil for backfill against the foundation so it sheds water [4]. Tivoli slopes range up to 45 percent [1]; where a building pad was leveled with placed soil, fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) is a separate question from the native sand. Wind-deposited soils are also screened for collapse behavior; see collapsible and loess soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils) and hydrocollapse (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil). ### Climate Northwestern Oklahoma's rainfall on Tivoli land averages about 26 inches a year [1]. The Oklahoma Mesonet runs 120 automated weather stations, with at least one in every county, for tracking local rainfall [5]. ## Related - Pratt soil (https://terrabrain.vercel.app/soils/pratt) - Woodward soil (https://terrabrain.vercel.app/soils/woodward) - Collapsible and loess soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils) - Slope and erosion stabilization (https://terrabrain.vercel.app/repairs/slope-and-erosion-stabilization) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - TIVOLI Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TIVOLI.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] About the Mesonet, Oklahoma Mesonet (University of Oklahoma and Oklahoma State University) https://www.mesonet.org/about --- # What is Ulysses soil and is it still mapped in Oklahoma? URL: https://terrabrain.vercel.app/soils/ulysses Answer: Ulysses is a deep, well-drained loess soil of the High Plains; Oklahoma was removed from its mapped extent in 2016, though older reports may name it. In short: Ulysses is a deep, well-drained silty soil formed in loess (wind-blown silt) on the High Plains tablelands. Its official description says Oklahoma was removed from the series' mapped extent in 2016, so it is now mapped mainly in Kansas, Nebraska, Colorado, Wyoming and South Dakota. It is included here because Panhandle homeowners may see the name in older reports, and because it shows how loess soils on the High Plains are described. ## Is Ulysses soil mapped in Oklahoma? Every named U.S. soil has an Official Series Description (OSD) maintained by the USDA Natural Resources Conservation Service (NRCS). The Ulysses OSD's revision history records that Oklahoma was removed from the extent because the major Ulysses components had been removed from the state, in an April 2016 change [1]. The series now covers western Kansas, western Nebraska, southeastern Wyoming, southwestern South Dakota and eastern Colorado, and it is of large extent [1]. For a lot in the Panhandle (High Plains) (https://terrabrain.vercel.app/regions/panhandle-high-plains), the soil series currently mapped is shown in Web Soil Survey, NRCS's free online soil map [2]. Other Panhandle soil pages on this site include Richfield (https://terrabrain.vercel.app/soils/richfield) and Dalhart (https://terrabrain.vercel.app/soils/dalhart). ## What are its key properties? | Property | Ulysses (from the OSD) [1] | |---|---| | Classification | Fine-silty, mixed, superactive, mesic Torriorthentic Haplustolls | | Parent material | Loess | | Depth to bedrock | More than 200 cm (about 80 in) | | Drainage | Well drained | | Water movement (Ksat) | Moderately high | | Subsoil (Bw, Bk) | Silt loam, silty clay loam, loam or clay loam | | Control-section clay | 19-34% | | Lime | Strong effervescence starts at 7-15 in | | Slopes | 0-20% (commonly 1-8%) | | Mean annual rainfall | About 19 in (14-24 in) | "Torriorthentic" is the subgroup in the name; the OSD notes it replaced the earlier Aridic Haplustolls classification in 2016 [1]. The "Bk" horizon is a subsoil layer with accumulated lime (calcium carbonate) [1]. Most rain falls in intense convective thunderstorms from late spring through early autumn, and winter precipitation is mostly snow [1]. Ulysses forms on plains, rises and hillslopes on tablelands in the Central High Tableland (MLRA 72) [1]. That setting is tied to the Ogallala Formation and loess (https://terrabrain.vercel.app/geology/ogallala-formation-and-loess) cap of the High Plains. ## What do loess soils like Ulysses mean for foundations? ### Shrink-swell NRCS rates shrink-swell by linear extensibility: under 3 percent is low and 3 to 6 percent moderate, with damage to buildings possible above 3 percent [3]. Ulysses is a silty soil with 19 to 34 percent clay in its control section, a silty rather than clayey texture [1]. For any Panhandle lot, the map unit's rated value in Web Soil Survey is the number that applies [2]. ### Dry climate and sudden wetting With about 19 inches of rain a year and most of it in summer storms [1], most wetting of these soils comes in short, heavy summer storms. Wind-deposited silts are routinely screened for collapse when wetted; see collapsible and loess soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils) and hydrocollapse (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil). ### Water management The ASCE homeowner guide stresses even soil moisture around a foundation, at least 3 inches of fall over the first 5 feet, downspouts discharging at least 3 feet out and sprinkler heads at least 5 feet from the foundation [4]. Leaking water or sewer lines create localized wet spots that can cause localized movement [4]. Related topics include erosion and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) and fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). ## Related - Richfield soil (https://terrabrain.vercel.app/soils/richfield) - Dalhart soil (https://terrabrain.vercel.app/soils/dalhart) - Panhandle (High Plains) region (https://terrabrain.vercel.app/regions/panhandle-high-plains) - Soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - ULYSSES Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/U/ULYSSES.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Verdigris soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/verdigris Answer: Verdigris is a very deep, well-drained silty floodplain soil with 15-33% clay; flood exposure and soft water-laid layers are the main foundation concerns. In short: Verdigris is a very deep, well-drained silty soil that forms on stream flood plains in northeastern Oklahoma, including the Tulsa area. It has a thick, dark silty topsoil and averages 15 to 33 percent clay, but its official description states that it is subject to flooding. For buildings on Verdigris, flood exposure and soft, water-laid layers are the main foundation considerations. ## Where does Verdigris soil occur? The USDA Natural Resources Conservation Service (NRCS) maintains an Official Series Description (OSD) for each named soil. The Verdigris OSD lists the series in Major Land Resource Areas 76, 112, 116 and 118 and LRU 84A, across southeastern Kansas, northeastern Oklahoma and southwestern Missouri, and calls it extensive [1]. Its type location is on the flood plain west of the Verdigris River near Elk City, Kansas [1]. Verdigris forms on flood plains with 0 to 3 percent slopes, in silty alluvium (sediment laid down by streams) [1]. That ties it to the Quaternary alluvium (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) along streams in the Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro) and the Northeast (https://terrabrain.vercel.app/regions/northeast-ozark-plateau-and-grand-lake). Most Verdigris land is cultivated for corn, sorghum, alfalfa and wheat [1]. ## What are its key properties? | Property | Verdigris (from the OSD) [1] | |---|---| | Classification | Fine-silty, mixed, superactive, thermic Cumulic Hapludolls | | Parent material | Silty alluvium | | Depth | Very deep | | Drainage | Well drained | | Water movement (Ksat) | Moderately high to high | | Topsoil (A) | Silt loam or silty clay loam, 28-86 cm (11-34 in) thick | | Control-section clay | 15-33% | | Below 40 in | May range to sandy loam, loam, clay loam or silty clay | | Flooding | Subject to flooding | | Slopes | 0-3% | | Mean annual rainfall | About 41 in (35-47 in) | "Cumulic" is a soil-taxonomy term for an unusually thick dark topsoil, which on flood plains typically builds up as floods add sediment. Below 40 inches, textures range from sandy loam to silty clay [1]. Wynona (https://terrabrain.vercel.app/soils/wynona) is a closely related flood-plain soil that is somewhat poorly drained, and Osage (https://terrabrain.vercel.app/soils/osage) is an associated clayey bottomland soil with high shrink-swell [1][2]. ## What do the properties mean for foundations? ### Flood exposure The OSD states plainly that Verdigris soils are subject to flooding, though it does not give a frequency [1]. Official flood hazard maps for a specific address are published through FEMA's Flood Map Service Center [5]. The Oklahoma Geological Survey notes that Oklahoma floods tend to occur in spring and fall, and that flood-prone areas are mapped to show land with about a 1-in-100 chance of flooding in a given year [6]. See creeks and flood history (https://terrabrain.vercel.app/data/creeks-and-flood-history). ### Soft, layered sediment Verdigris formed in stream-laid silty alluvium, and its textures below 40 inches range from sandy loam to silty clay [1]. Layered alluvium is the setting for soft soil consolidation (https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays), where wet, compressible layers settle under load. Where a lot was raised with placed soil, fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) is a separate factor. ### Shrink-swell and water NRCS rates shrink-swell by linear extensibility: under 3 percent is low and 3 to 6 percent moderate [4]. Verdigris has a fine-silty control section with 15 to 33 percent clay, while neighboring Osage has a clayey (fine) control section and high shrink-swell [1][2]. The rated value is in Web Soil Survey [3]. The ASCE homeowner guide recommends at least 3 inches of fall over the first 5 feet and downspouts that discharge at least 3 feet from the foundation [7]. ## Related - Wynona soil (https://terrabrain.vercel.app/soils/wynona) - Osage soil (https://terrabrain.vercel.app/soils/osage) - Erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Soil series in the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - VERDIGRIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/V/VERDIGRIS.html [2] Official Series Description - WYNONA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/W/WYNONA.html [3] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [4] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [5] FEMA Flood Map Service Center, Federal Emergency Management Agency https://msc.fema.gov/portal/search [6] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [7] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Vernon soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/vernon Answer: A red clay soil with 40 to 60 percent clay over dense claystone at 20 to 40 inches; clay movement with moisture and the shallow claystone drive behavior. In short: Vernon is a red clay soil that formed in place from Permian red-bed claystone and sits on dense claystone 20 to 40 inches down. Its subsoil holds 40 to 60 percent clay, water barely soaks in, and it covers large areas of western Oklahoma and parts of the Oklahoma City area. Clay movement with moisture and the nature of the shallow claystone are the main foundation factors. ## Where does Vernon soil occur? The USDA Natural Resources Conservation Service (NRCS) keeps an Official Series Description (OSD) for each named soil. Vernon was established in Wilbarger County, Texas, in 1902, and its type location is about 12.5 miles south-southeast of Vernon, Texas [1]. The OSD places it in the Central Rolling Red Plains (MLRA 78B, 78C) and Rolling Limestone Prairie (MLRA 78A) of Texas, Kansas and Oklahoma, and calls it extensive [1]. Vernon forms on hillslopes, pediments (gently sloping erosion surfaces at the foot of higher ground) and escarpments on dissected plains, with slopes of 1 to 45 percent, mostly 1 to 12 percent [1]. It is clayey residuum, meaning soil weathered in place, from noncemented Permian red-bed claystone [1]. In Oklahoma that ties it to the Western Permian Red Beds (https://terrabrain.vercel.app/geology/western-permian-red-beds) and the Hennessey Shale (https://terrabrain.vercel.app/geology/hennessey-shale-group), across the Southwest (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains), Northwest (https://terrabrain.vercel.app/regions/northwest-gypsum-hills) and OKC Metro (https://terrabrain.vercel.app/regions/okc-metro). Most Vernon land is native rangeland [1]. ## What are its key properties? | Property | Vernon (from the OSD) [1] | |---|---| | Classification | Fine, mixed, active, thermic Typic Haplustepts | | Parent material | Residuum from noncemented Permian red-bed claystone | | Depth to densic bedrock | 20-40 in | | Drainage | Well drained | | Permeability | Very slow | | Runoff | Very high | | Surface (A) | Clay loam to clay, 35-60% clay | | Subsoil (Bk or Bw) | Silty clay or clay, 40-60% clay | | Lime and gypsum | 5-20% CaCO3 equivalent; 0-2% gypsum in subsoil | | Slopes | 1-45% | | Mean annual rainfall | About 25 in (20-30 in) | "Densic" bedrock is very dense but noncemented material; in Vernon it is red-bed claystone or dense clay, fractured at less than 4-inch spacing in its upper part [1]. Vernon has no clay-enriched "Bt" layer; its subsoil is a weakly developed "Bw" or lime-bearing "Bk" layer [1]. Nearby soils include Tillman on flatter ground and Hollister on lower, flatter positions with smectitic clay [1]. ## What do the properties mean for foundations? ### Clay content With 40 to 60 percent clay in the soil and in the claystone below it, Vernon is a clay soil top to bottom [1]. The OSD does not list a shrink-swell value or slickensides for Vernon [1]. NRCS rates shrink-swell by linear extensibility and notes that values above 3 percent can damage buildings and commonly need special design [3]. The rated value for any map unit is in Web Soil Survey [2]. The Oklahoma Geological Survey notes that clay-rich shales and soils weathered from them can contain montmorillonite, which swells when wet [4]. Lab tests such as plasticity index are explained on soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values). ### Shallow claystone Footings and piers on Vernon lots meet dense claystone within 20 to 40 inches [1]. Because the claystone is noncemented and itself 40 to 60 percent clay, it is not equivalent to hard rock [1]. See shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata). ### Runoff and uneven moisture Very slow permeability and very high runoff mean rain mostly runs off, while water that does enter moves through the clay very slowly [1]. Localized moisture changes are more damaging than uniform ones, so the ASCE guide recommends even moisture on all sides, at least 3 inches of fall over the first 5 feet, and trees planted farther away than their mature height [5]. Seasonal moisture change in expansive clays can reach 3 to 40 feet deep [6]. Common patterns include perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) and perimeter wetting heave. ## Related - Tillman soil (https://terrabrain.vercel.app/soils/tillman) - Hollister soil (https://terrabrain.vercel.app/soils/hollister) - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Soil series in the OKC metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - VERNON Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/V/VERNON.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [4] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [5] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [6] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf --- # What is Woodward soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/woodward Answer: Woodward is a well-drained silty soil with 8 to 18 percent clay over soft sandstone 20 to 40 inches down, so rock depth and runoff matter more than swell. In short: Woodward is a moderately deep, well-drained silty soil of western Oklahoma that formed from soft, limy Permian sandstone and siltstone. It holds only 8 to 18 percent clay, and the soft rock usually sits 20 to 40 inches down. On Woodward land, foundation concerns tend to involve shallow soft rock, runoff on slopes and water management rather than clay swelling. ## Where does Woodward soil occur? The USDA Natural Resources Conservation Service (NRCS) keeps an Official Series Description (OSD) for each named soil. Woodward was established in Woodward County, Oklahoma, in 1944, and its type location is about a quarter mile south of Fort Supply [1]. It occurs across western Oklahoma, a few counties of southern Kansas and northwestern Texas, in the Central Rolling Red Plains (MLRA 78B and 78C), and its extent is large [1]. Woodward forms on summits, shoulders and backslopes of interfluves and on side slopes of hills, ridges and escarpments, with slopes of 1 to 40 percent [1]. It is residuum from noncemented, calcareous, fine-grained Permian sandstone and siltstone, mainly the Marlow and Rush Springs formations of the Whitehorse Group, plus the Cloud Chief and Quartermaster formations [1]. For these rock units, see Western Permian Red Beds (https://terrabrain.vercel.app/geology/western-permian-red-beds); Woodward occurs in the Northwest (Gypsum Hills) (https://terrabrain.vercel.app/regions/northwest-gypsum-hills) and Southwest (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains) regions of western Oklahoma [1]. Most Woodward land is grazed, with crops on gentler slopes [1]. ## What are the key properties of Woodward soil? | Property | Woodward (from the OSD) [1] | |---|---| | Classification | Coarse-silty, mixed, superactive, thermic Typic Haplustepts | | Parent material | Residuum from calcareous Permian sandstone/siltstone | | Depth to densic bedrock | 20-40 in (about 28 in typical) | | Drainage | Well drained | | Permeability | Moderate | | Texture throughout | Very fine sandy loam, loam or silt loam | | Control-section clay | 8-18% | | Lime and gypsum | 2-15% CaCO3 equivalent below the surface; 0-3% gypsum | | Slopes | 1-40% | | Mean annual rainfall | About 25 in (20-30 in) | The "Cd" layer at the base is soft sandstone or siltstone that breaks down to loamy material and has a root-restricting density [1]. Associated soils include Quinlan, which is less than 20 inches to sandstone, along with Aspermont, Obaro and others [1]. ## What do these properties mean for foundations? ### Low clay content NRCS rates shrink-swell by linear extensibility, with under 3 percent classed as low and over 3 percent able to damage buildings [3]. Woodward's control section has only 8 to 18 percent clay [1]. The rated value for a map unit is in Web Soil Survey [2]. Western Oklahoma also has gypsum-bearing rock units, which the Oklahoma Geological Survey notes can dissolve and create sinkhole and collapse risks [5]; see gypsum karst and sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes) and the Permian gypsum units (https://terrabrain.vercel.app/geology/permian-gypsum-units-e-g-blaine). ### Shallow soft rock On Woodward soils, soft sandstone or siltstone lies within 20 to 40 inches of the surface [1]. Because that rock is noncemented and breaks down to loam, it is not equivalent to hard bedrock [1]. See shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata). ### Slopes, runoff and water Runoff is low on 1 to 5 percent slopes and high on slopes steeper than 20 percent [1]. Loamy soils near foundations are where erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) are evaluated. The ASCE homeowner guide recommends at least 3 inches of fall over the first 5 feet from the house, downspouts that discharge at least 3 feet out, and compacted clay rather than sandy soil for backfill against the foundation [4]. Graded hillside pads may also involve fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). ## Related - Quinlan soil (https://terrabrain.vercel.app/soils/quinlan) - Tivoli soil (https://terrabrain.vercel.app/soils/tivoli) - Northwest (Gypsum Hills) (https://terrabrain.vercel.app/regions/northwest-gypsum-hills) - Surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - WOODWARD Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/W/WOODWARD.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html --- # What is Wynona soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/wynona Answer: Wynona is a very deep, somewhat poorly drained silty floodplain soil of eastern Oklahoma that floods occasionally and holds a perched water table near 2 feet. In short: Wynona is a very deep silty soil on flood plains of eastern Oklahoma, including streams around Tulsa. It is somewhat poorly drained, floods occasionally in winter through midsummer, and holds a perched water table about 2 feet down from November to April. Flood exposure, wet ground and soft stream-laid layers are the main foundation factors on Wynona. ## Where does Wynona soil occur? The USDA Natural Resources Conservation Service (NRCS) keeps an Official Series Description (OSD) for each named soil. Wynona was established in 1975 in Osage County, Oklahoma, and its type location is about 4 miles south and 1 mile west of Skiatook [1]. It was previously included with the Verdigris series [1]. The OSD lists it in MLRAs 84A, 85, 112, 117 and 118 of eastern Oklahoma, southeastern Kansas and southwestern Missouri, and calls it moderately extensive [1]. Wynona forms on nearly level to slightly concave flood plains, in silty alluvium (stream-laid sediment) [1]. That places it on the Quaternary alluvium (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) along creeks and rivers in the Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro) and East-Central (Arkoma) (https://terrabrain.vercel.app/regions/east-central-arkoma) regions. Most Wynona land is tame pasture, with some areas cultivated or kept as native range and hay meadows [1]. ## What are Wynona soil's key properties? | Property | Wynona (from the OSD) [1] | |---|---| | Classification | Fine-silty, mixed, active, thermic Cumulic Epiaquolls | | Parent material | Silty alluvium | | Depth to bedrock | More than 72 in | | Drainage | Somewhat poorly drained | | Water movement (Ksat) | Moderately low | | Topsoil (A) | Silt loam or silty clay loam | | Subsoil (Bg) | Silty clay loam or silty clay | | Control-section clay | 27-35% | | Water table | Perched near 2 ft, November-April | | Flooding | Occasional, very brief, January-July | | Slopes | 0-3% | | Mean annual rainfall | About 39 in (36-42 in) | "Epiaquolls" are dark-surfaced soils with a wet (aquic) moisture regime; in Wynona the wetness comes from a perched water table [1]. The "g" in Bg stands for gleyed, the gray colors that form when soil stays saturated, and Wynona shows redox mottling in both its topsoil and subsoil [1]. The OSD names Verdigris as a competing series that is well drained, and Osage as an associated soil with a clayey control section and high shrink-swell [1]. ## What does Wynona soil mean for foundations? ### Flooding Wynona floods occasionally for very brief periods from January through July in normal years [1]. FEMA's Flood Map Service Center can be searched by address for the flood map covering a lot [4]. See creeks and flood history (https://terrabrain.vercel.app/data/creeks-and-flood-history). ### Perched water and wet crawl spaces A perched water table is a temporary saturated zone held up above slower-draining soil. On Wynona it sits about 2 feet down for half the year [1]. HUD's soil guide identifies water table depth, natural drainage and seepage as key controls on soil moisture [5]. Shallow seasonal water is the setting for crawl space moisture and wood decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay), perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) and water pressure on below-grade walls (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls). ### Soft, wet sediment Saturated, stream-laid silts and clays are the soils covered on soft soil consolidation (https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays). Some Wynona profiles also contain buried former surface layers below 40 inches, a sign of repeated deposition [1]. ### Shrink-swell and drainage NRCS rates shrink-swell by linear extensibility, from low (under 3 percent) to very high (more than 9 percent) [3]. Wynona's control section is fine-silty, with 27 to 35 percent clay, while associated Osage has a clayey control section [1]. The rated value is in Web Soil Survey [2]. The ASCE homeowner guide recommends at least 3 inches of fall over the first 5 feet and downspouts that discharge at least 3 feet from the foundation [6]. ## Related - Verdigris soil (https://terrabrain.vercel.app/soils/verdigris) - Osage soil (https://terrabrain.vercel.app/soils/osage) - Groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Crawl space encapsulation (https://terrabrain.vercel.app/repairs/crawl-space-encapsulation) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - WYNONA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/W/WYNONA.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [4] FEMA Flood Map Service Center, Federal Emergency Management Agency https://msc.fema.gov/portal/search [5] Guide to Use of the FHA Soil PVC Meter (HUD Handbook 4075.15), U.S. Department of Housing and Urban Development https://www.hud.gov/sites/documents/407515hsgh.pdf [6] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # What is Zaneis soil and how does it affect Oklahoma foundations? URL: https://terrabrain.vercel.app/soils/zaneis Answer: Zaneis is a deep, well-drained loamy soil on central Oklahoma hills over Permian sandstone and shale at 40 to 60 inches; runoff and drainage matter most. In short: Zaneis is a deep, well-drained loamy soil on low hills in central Oklahoma, including the Edmond and Oklahoma City area. Its subsoil is clay loam or sandy clay loam over interbedded Permian sandstone and shale at 40 to 60 inches. On Zaneis lots, runoff on slopes, water around the foundation and the mixed sandstone-shale bedrock are the main foundation factors. ## Where does Zaneis soil occur? The USDA Natural Resources Conservation Service (NRCS) keeps an Official Series Description (OSD) for each named soil. Zaneis was established in Carter County, Oklahoma, in 1932, and its type location is about 1 mile east and 5 miles north of Edmond in Oklahoma County [1]. It lies in the Central Rolling Red Prairies (MLRA 80A) and is extensive [1]. Zaneis forms on summits, backslopes and side slopes of low hills, on slopes of 0 to 8 percent [1]. It is residuum (soil weathered in place) from interbedded Permian sandstone and shale [1]; for the local Permian rock units, see the Garber Sandstone (https://terrabrain.vercel.app/geology/garber-sandstone) and Wellington Formation (https://terrabrain.vercel.app/geology/wellington-formation) pages. It occurs in the OKC Metro (https://terrabrain.vercel.app/regions/okc-metro) and parts of South-Central Oklahoma (https://terrabrain.vercel.app/regions/south-central-arbuckles-and-texoma). Zaneis land is used for crops and grazing, and native vegetation is mid and tall grass prairie [1]. ## What are its key properties? | Property | Zaneis (from the OSD) [1] | |---|---| | Classification | Fine-loamy, siliceous, active, thermic Udic Argiustolls | | Parent material | Residuum from interbedded Permian sandstone and shale | | Depth to bedrock | 40-60 in (about 59 in typical) | | Drainage | Well drained | | Permeability | Moderate (Ksat moderately high) | | Surface (A) | Fine sandy loam or loam | | Subsoil (Bt) | Loam, clay loam or sandy clay loam, 18-38% clay | | Bedrock (Cr) | Weakly consolidated fine sandstone and sandy shale | | Slopes | 0-8% | | Mean annual rainfall | 33-39 in (about 34 in) | The "Bt" horizon is a subsoil layer where clay has built up over time; in Zaneis it runs from about 19 to 55 inches [1]. "Cr" marks weakly consolidated bedrock; in Zaneis it is rated as having high or very high excavation difficulty [1]. Associated soils include Bethany and Renfrow, which have clayey control sections, and Lucien, which is shallow to bedrock, along with Chickasha [1]. ## What do its properties mean for foundations? ### Shrink-swell NRCS rates shrink-swell by linear extensibility: under 3 percent is low, 3 to 6 percent moderate, and values above 3 percent can damage buildings [3]. Zaneis has a loamy rather than clayey subsoil, and its OSD records no cracking or slickensides [1]. The rated value for any map unit is in Web Soil Survey [2]. Zaneis often sits next to clayey soils such as Renfrow and Bethany [1], so conditions can change across a single neighborhood. The Oklahoma Geological Survey notes that more than 75 percent of the state has bedrock that can produce expansive soils, and that shale-derived soils can contain swelling montmorillonite [5]. ### Mixed sandstone and shale bedrock The bedrock below Zaneis alternates between weakly consolidated sandstone and sandy shale [1]. Layered soft rock like this is described on shale weathering and bearing strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata) and bedrock in the OKC metro (https://terrabrain.vercel.app/guides/bedrock-okc-metro). ### Runoff and water The OSD rates runoff as high on 1 to 5 percent slopes and very high on 5 to 8 percent slopes [1]. Concentrated runoff and leaks next to a house are the setting for erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). The ASCE homeowner guide recommends at least 3 inches of fall over the first 5 feet from the foundation, downspouts that discharge at least 3 feet out, and sprinkler heads at least 5 feet from the wall [4]. Graded lots on hillsides may also involve fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). ## Related - Soil series in the OKC metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) - Renfrow soil (https://terrabrain.vercel.app/soils/renfrow) - Bethany soil (https://terrabrain.vercel.app/soils/bethany) - Surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - ZANEIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/Z/ZANEIS.html [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [4] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, American Society of Civil Engineers, Geo-Institute https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [5] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html --- # What must Oklahoma home inspectors report about foundations? URL: https://terrabrain.vercel.app/data/legal-and-real-estate Answer: Oklahoma inspectors must inspect the foundation, describe signs of movement and recommend correction, evaluation or monitoring, but need not find the cause. In short: In Oklahoma, licensed home inspectors must inspect the foundation and describe any signs of foundation or structural movement, then recommend correction, further evaluation or monitoring. They are not required to find the cause, choose a repair method, judge geotechnical conditions or estimate repair costs. That leaves diagnosis to engineers and other specialists. ## Who regulates home inspectors in Oklahoma? Home inspection in Oklahoma is regulated under Title 158, Chapter 70 of the Oklahoma Administrative Code. The Construction Industries Board issues home inspection licenses, and no one may perform or offer home inspection work, including by advertising, without a valid license from the Board unless legally exempt [2]. Licensees must report a change of business address to the Board in writing within 30 days [2]. For building permits, contractor rules and related topics, see codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits) and real estate disclosure and inspections (https://terrabrain.vercel.app/rules/real-estate-disclosure-and-inspections-foundation-issues-in-oklahoma). ## What must inspectors check? Under OAC 158:70-1-3, the structural part of a home inspection covers [1]: - The **foundation**, including slabs, piers, columns, posts and stem walls [1]. - Floor, wall, roof and ceiling structures [1]. - Moisture conditions in the crawl space, basement and attic, and signs of harmful water getting into structural parts [1]. A stem wall is the short concrete or block wall that rises from a footing to carry the house frame. See foundation types (https://terrabrain.vercel.app/foundations/stem-wall-and-grade-beam) for more. ### What must go in the report | Requirement | What the standard says | |---|---| | Describe structure | Describe the foundation, floor, roof, ceiling and wall structures [1] | | Movement | Describe "indicators of foundation or structural movement" [1] | | Crawl space and attic | Enter them to judge general condition, or state in the report how they were observed [1] | | Probing | Probe structural parts where deterioration is suspected or clearly indicated [1] | | Problems | Report structural components that are not in normal working order, with the reason if not self-evident [1] | | Next steps | Recommend correction, further evaluation or monitoring of reported conditions [1] | Typical "indicators of movement" a homeowner might see in a report include sloping floors (https://terrabrain.vercel.app/signs/sloping-floors), diagonal drywall cracks at openings (https://terrabrain.vercel.app/signs/diagonal-drywall-cracks-at-openings) and stair-step brick cracks (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top). ## What are inspectors not required to do? The same standard lists limits on the inspection [1]: - **Cause and repair:** inspectors need not determine the causes of any condition or defect, or the methods or materials for repair [1]. - **Structural adequacy:** they need not determine the strength, adequacy or effectiveness of any component, its remaining life, or whether it will fail in the future [1]. - **Costs:** inspectors must not estimate repair costs [1]. - **Geotechnical conditions:** soil and subsurface conditions are excluded from the exterior inspection requirements [1]. - **Invasive work:** inspectors need not perform invasive or destructive inspection [1]. - **Hidden defects:** the standards do not require finding concealed conditions or latent defects [1]. ### Crawl space and attic entry limits | Space | Entry not required if | |---|---| | Crawl space or foundation area | Headroom under 18 inches, access opening under 18 by 24 inches, excessively wet, or hazardous to the inspector [1] | | Attic | Headroom under 30 inches, access opening under 18 by 24 inches, or hazardous to the inspector [1] | For homes on pier and beam crawl spaces (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space), this means a report may state that the crawl space was observed only from the access opening [1]. ## What must Oklahoma sellers disclose about foundations? The Residential Property Condition Disclosure Act applies to homes with one or two dwelling units [5]. Sellers must give the buyer either a disclaimer statement (only for sellers who never occupied the home and know of no defects) or a disclosure statement of conditions they actually know about, delivered before an offer to purchase is accepted [5]. If the seller later learns of a defect, an amended disclosure is required [5]. The state disclosure form asks directly about foundations [6]: | Question | Wording | |---|---| | 12 | Whether the seller is aware of any previous foundation repairs [6] | | 14 | Any defect or condition affecting walls, slab/foundation, basement, floors, windows, doors and similar parts [6] | | 21 | Major fire, tornado, hail, earthquake or wind damage [6] | A buyer may sue for failure to deliver the statement or to disclose a known defect; the remedy is actual damages, including repair costs, and the action must be filed within two years after the date of transfer [5]. See real estate disclosure and inspections (https://terrabrain.vercel.app/rules/real-estate-disclosure-and-inspections-foundation-issues-in-oklahoma) for more. ## What time limits apply to foundation and construction claims? | Claim type | Time limit | |---|---| | Tort claims over deficient design or construction of an improvement to real property | Barred after 10 years from substantial completion (statute of repose) [3] | | Written contract | 5 years [4] | | Oral or implied contract | 3 years [4] | | Trespass upon real property | 2 years [4] | | Fraud | 2 years, counted from discovery of the fraud [4] | A statute of repose is an outer deadline that runs from completion of the work, regardless of when damage is discovered [3]. ## What consumer protections apply to in-home sales? - **Cancellation:** The federal Cooling-Off Rule gives buyers until midnight of the third business day to cancel many sales made at their home, and the seller must explain this right and provide cancellation forms at the time of sale [9]. - **Deceptive practices:** Oklahoma's Consumer Protection Act lists unlawful practices, including falsely claiming that services or repairs are needed [7]. For contract terms, warranties and lien rules, see contracts, warranties and liens (https://terrabrain.vercel.app/rules/contracts-warranties-liens). ## Who licenses contractors, and are permits needed? The Construction Industries Board regulates plumbers, electricians, mechanical tradespeople, home inspectors, building inspectors and roofing [8]. General contracting and foundation repair are not on that list [8]. Permit rules are set by each city: - **Tulsa:** For repairs that do not add space, construction plans are required when damage is extensive or structural [10]. All residential properties must accept and convey drainage without damaging adjoining properties [10]. - **Oklahoma City:** Permits are required to construct, alter, repair, enlarge, move or demolish a structure, and certain trades must also register with the city to work within city limits [11]. See codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits) for building code topics and surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) for drainage. ## What happens after the inspection? Home inspectors identify signs of movement but are not required to determine causes or perform engineering services [1]. A report recommending "further evaluation" usually leads to a structural engineer or another specialist who examines cause, often using an elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) and soil information. The working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers) guide explains what that evaluation typically includes. ## Related - Real estate disclosure and inspections (https://terrabrain.vercel.app/rules/real-estate-disclosure-and-inspections-foundation-issues-in-oklahoma) - Contracts, warranties and liens (https://terrabrain.vercel.app/rules/contracts-warranties-liens) - Codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits) - Inspection protocol (https://terrabrain.vercel.app/guides/inspection-protocol) - Working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers) Sources: [1] Okla. Admin. Code 158:70-1-3, Standards of workmanship and practice, Justia Regulations (Oklahoma Administrative Code) https://regulations.justia.com/states/oklahoma/title-158/chapter-70/subchapter-1/section-158-70-1-3/ [2] Okla. Admin. Code 158:70-5-1, Home inspection license requirements, Justia Regulations (Oklahoma Administrative Code) https://regulations.justia.com/states/oklahoma/title-158/chapter-70/subchapter-5/section-158-70-5-1/ [3] Oklahoma Statutes §12-109, Limitation of action to recover damages arising from design, planning or construction of improvement to real property, Justia (Oklahoma Statutes) https://law.justia.com/codes/oklahoma/title-12/section-12-109/ [4] Oklahoma Statutes §12-95, Limitation of other actions, Justia (Oklahoma Statutes) https://law.justia.com/codes/oklahoma/title-12/section-12-95 [5] Residential Property Condition Disclosure Act, Oklahoma Real Estate Commission https://oklahoma.gov/content/dam/ok/en/orec/documents/contracts-and-forms-page/RPCD%20Act%20Updated%202025%20.pdf [6] Appendix A. Residential Property Condition Disclosure Statement, Oklahoma Real Estate Commission https://www.oklahoma.gov/content/dam/ok/en/orec/documents/contracts-and-forms-page/2024-form-changes/2024%20Appendix%20A%20Residential%20Property%20Condition.pdf [7] Oklahoma Statutes §15-753, Unlawful practices, Justia (Oklahoma Statutes) https://law.justia.com/codes/oklahoma/title-15/section-15-753/ [8] About the Construction Industries Board, Oklahoma Construction Industries Board https://oklahoma.gov/cib/about.html [9] Buyer's Remorse: The FTC's Cooling-Off Rule May Help, Federal Trade Commission https://consumer.ftc.gov/articles/buyers-remorse-ftcs-cooling-rule-may-help [10] Residential Building Permit Process, City of Tulsa Development Services https://www.cityoftulsa.org/media/10918/residential2019.pdf [11] Building & Trade Permits, City of Oklahoma City https://www.okc.gov/Services/Permits/Building-Trade-Permits --- # What permits, licensing and frost depth apply in Oklahoma? URL: https://terrabrain.vercel.app/rules/permits-licensing-and-frost-depth-oklahoma-cities Answer: Oklahoma leaves frost depth to each city or county, with published values about 18 inches, and does not license foundation repair as a trade. In short: Oklahoma sets one statewide residential code but leaves frost depth to each city or county, and the published values found are about 18 inches [1][2][3]. The state does not license foundation repair as a trade [5]. Tulsa and Oklahoma City publish general permit and contractor rules, but neither publishes a foundation-repair-specific permit page [6][7]. ## What is the statewide code framework? The 2024 International Residential Code (IRC) with Oklahoma amendments is the statewide minimum residential code as of September 14, 2026 [4]. It replaced the 2018 IRC, which had been in effect since September 14, 2022 [8]. Local governments enforce it, run permit offices and fill in certain local values. **Oklahoma footing amendments.** Oklahoma's amendments to IRC Section R403.1 add two No. 4 reinforcing bars (rebar) to all footings, and require cold joints between footings and stem walls to be tied with No. 4 rebar at every corner and no more than 6 feet apart, embedded 12 inches into each [4]. The same rebar rule was part of Oklahoma's 2018 IRC amendments [9]. The 2024 amendments also limit fill under slabs: fill goes in 8- to 12-inch lifts, clean sand or gravel fill may be up to 48 inches deep, and earth fill stays limited to 8 inches [4]. **When the model code requires a permit.** The IRC requires an owner or authorized agent who intends to construct, enlarge, alter, repair, move or demolish a building to apply for and obtain a permit first [10]. The model list of work exempt from a permit covers items such as small one-story accessory buildings, fences up to 7 feet, retaining walls up to 4 feet, sidewalks and driveways, and finish work like painting, tiling, carpeting, cabinets and countertops [10]. Foundation repair is not on that list [10]. Cities can amend these provisions locally. **Frost depth is local.** In the climate table of Oklahoma's adopted code, the frost line column is left for the jurisdiction to fill in with the minimum footing depth below finished grade [1]. **Frost depth** is how deep the ground can freeze in winter; footings above it can be lifted by freezing soil (see frost heave (https://terrabrain.vercel.app/causes/frost-heave)). ## What frost depth values are used? | Jurisdiction | Frost depth | Source | |---|---|---| | Statewide code | Left blank for each jurisdiction | [1] | | Stillwater | 18 inches (air freezing index 500) | [2] | | Oklahoma City | About 18 inches below finished grade (as cited by the state engineering board, from Federal Housing Administration guidance) | [3] | | Tulsa, Edmond, Norman, Broken Arrow and others | Not found in published city materials reviewed | — | For any specific address, the local building department's adopted climate table is the controlling value. ## What did the engineering board warn about? At a 2007 public meeting, Oklahoma's engineering board described common shallow "pier and grade beam" foundations: piers 8 to 10 inches across, no more than about 36 inches deep and 6 to 8 feet apart, with grade beam bottoms often only 1 to 8 inches below finished grade [3]. The board noted that codes require grade beam bottoms below frost depth unless perimeter insulation is used, and that these systems typically lacked that insulation [3]. More: stem wall and grade beam foundations (https://terrabrain.vercel.app/foundations/stem-wall-and-grade-beam). ## Is foundation repair a licensed trade? - **State.** The Construction Industries Board licenses plumbers, electricians, mechanical contractors, home inspectors and building inspectors, and registers roofing contractors [5]. Foundation piering is not on that list, though plumbing, electrical or drainage work connected to a repair can be. - **Oklahoma City.** Under Municipal Code Chapter 12-1, anyone contracting for a change, addition or improvement that needs a building permit must register as a building contractor: a $100 annual registration fee, general liability insurance of at least $50,000 per occurrence, workers' compensation of at least $100,000 per occurrence or an exemption form, and an immigration affidavit where applicable [6]. - **Broken Arrow.** General contractor registration requires a certificate of general liability insurance with at least $50,000 coverage, workers' compensation proof or an affidavit of exemption, and a copy of the contractor's driver's license, with the City of Broken Arrow listed as certificate holder [12]. - **Tulsa.** The owner, contractor, architect or owner's authorized agent can apply for a building permit; only electrical, mechanical and plumbing permits require licensed contractors [7]. ## Do you need a permit for foundation repair? | City | What the city publishes | |---|---| | Tulsa | Repair (no-expansion) permits are applied for in person; construction plans are required if damage is extensive or structural, as decided by the plans examiner at submittal [7] | | Oklahoma City | Contractor registration applies to any work requiring a building permit [6]; no foundation-specific permit page was found | | Norman | Monthly permit reports list "Foundation" permit categories for multi-family and commercial work; no single-family residential foundation category appears [11] | | Broken Arrow, Edmond, Moore, Owasso, Jenks, Bixby, Sand Springs | No foundation-repair permit guidance found in published materials reviewed | Because published guidance is thin, the local permit desk is the authority on whether underpinning needs a permit, an engineer's letter or inspections. ## When are engineer letters used? Oklahoma's engineering board published compliance guidelines for foundation repair companies and warned that anyone violating them may be in violation of the state engineering licensure law (Title 59, Section 475.1 et seq.) and board rules (OAC 245:15) [3]. Under the guidelines [3]: - A repair company that is not authorized by the board must bring in a professional engineer (PE) or an authorized engineering firm; a PE in responsible charge takes over the engineering. - A PE visits the site, or directs a technician working under the PE's responsible charge to gather information. - Any repair plan must be signed, sealed and dated and include contact information. If no pier repair is needed, the PE issues a signed, sealed and dated statement saying so. - The foundation company carries out the PE's repair plan. - A PE may issue an engineering completion letter only after being on site during the work or receiving enough information from a qualified technician under the PE's responsible charge. A repair company may not present its own letter as an engineering completion letter. - The PE keeps a design file with repair criteria, calculations, changes, why repairs were needed and what caused the damage, and must report to the board if a company overrules the PE's judgment and public welfare is endangered. See working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). ## Related - Codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits) - Freeze-thaw and frost depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) - Legal and real estate data (https://terrabrain.vercel.app/data/legal-and-real-estate) - Contracts, warranties and liens (https://terrabrain.vercel.app/rules/contracts-warranties-liens) - Tulsa metro region (https://terrabrain.vercel.app/regions/tulsa-metro) - OKC metro region (https://terrabrain.vercel.app/regions/okc-metro) Sources: [1] Oklahoma Administrative Code 748:20-6-8, IRC 2018 Chapter 3 Building Planning, Justia (Oklahoma Administrative Code) https://regulations.justia.com/states/oklahoma/title-748/chapter-20/subchapter-6/section-748-20-6-8/ [2] Adopted Construction Standards, City of Stillwater Building Safety Division https://stillwaterok.gov/DocumentCenter/View/532/Adopted-Construction-Standards-PDF [3] The Board's Bulletin, Vol. 21, Issue 4 (2007): Compliance Guidelines for Foundation Repair Companies and Residential Foundation Public Meeting, Oklahoma State Board of Licensure for Professional Engineers and Land Surveyors https://oklahoma.gov/content/dam/ok/en/pes/documents/bulletin/Newsletter_Volume21_Issue62.pdf [4] Oklahoma Uniform Building Code Commission, Adoption of International Residential Code 2024: Code Changes Summary, Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2024%20IRC%20Code%20Changes%20Summary%20-%20for%20website.pdf [5] About, Oklahoma Construction Industries Board https://oklahoma.gov/cib/about.html [6] Residential Building Contractor, City of Oklahoma City Development Services https://okc.gov/departments/development-services/business-licensing/contractor-registration/building-contractor [7] Residential Building Permit Process, City of Tulsa Development Services https://www.cityoftulsa.org/media/10918/residential2019.pdf [8] International Residential Code Adoptions, Oklahoma Uniform Building Code Commission https://www.oklahoma.gov/oubcc/codes-and-rules/international-residential-code-adoptions.html [9] OAC 748:20-6, IRC 2018 Permanent Rule (effective September 14, 2022), Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2022%2009%2014%20IRC%202018%20Permanent%20Rule.pdf [10] 2021 International Residential Code, Sections R105.1 and R105.2 (Work Exempt from Permit), Grant County, Washington (reproducing ICC model code text) https://www.grantcountywa.gov/DocumentCenter/View/5840/Exempt-R1052 [11] City of Norman Development Services Division Permit Activity April 2023 Report, City of Norman https://www.normanok.gov/sites/default/files/documents/2023-05/230511_April%20Monthly%20Report%20Binder1.pdf [12] General Contractor Registration, City of Broken Arrow https://brokenarrowok.gov/home/showpublisheddocument/500/638593980150100000 --- # What safety rules apply to foundation repair work in Oklahoma? URL: https://terrabrain.vercel.app/rules/safety-and-osha Answer: Federal OSHA rules cover trench protection, excavation inspections and silica dust from concrete cutting; heat and crawl spaces add other hazards. In short: Foundation repair involves digging next to a house, cutting concrete and working in hot crawl spaces and yards. Federal OSHA rules set requirements for trench protection, excavation inspections and silica dust [1][2][3]. Knowing the basics helps homeowners understand why work areas are fenced, sloped or shored, and why crews keep people out of the holes. ## What rules apply to excavations and trenches? Exterior piers are installed from holes dug beside the foundation. Under OSHA's excavation rules: - Every worker in an excavation must be protected from cave-ins by an adequate **protective system**, meaning sloping or benching the sides, shoring, or a shield such as a trench box [1]. - The exceptions are an excavation made entirely in stable rock, or one less than 5 feet deep where a **competent person** (someone trained to recognize hazards and authorized to fix them) examines the ground and sees no sign of a possible cave-in [1]. - Some sloping, benching and support designs must be approved by a registered professional engineer [1]. - Trenches 4 feet or deeper need a ladder, stairway, ramp or other exit within 25 feet of lateral travel [2]. - Dug soil and equipment must be kept at least 2 feet back from the edge, or held back by retaining devices [2]. - A competent person must inspect excavations daily, before work starts, as needed during the shift, and after every rainstorm or other event that increases hazards [2]. Oklahoma clay can be wet near the surface even when deeper layers are dry. One Oklahoma City geotechnical report found high saturation in some soils as shallow as 3 feet and noted that perched water may exist in the soil and at the contact with bedrock, with water levels that can change through the year with rainfall [6]. See groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water). ## What rules apply to concrete cutting and silica dust? Interior piers and slab repairs often require cutting or coring concrete, which releases **respirable crystalline silica**, a fine dust that can damage lungs. OSHA's construction silica standard [3]: | Item | Requirement | |---|---| | Permissible exposure limit | 50 micrograms per cubic meter, 8-hour average | | Action level (triggers exposure assessment) | 25 micrograms per cubic meter | | Handheld power saws | Water delivered to the blade; respirator for indoor or enclosed use | | Rig-mounted core saws or drills | Water delivered to the cutting surface | | Jackhammers and chipping tools | Continuous water spray or a dust-collecting shroud | For homeowners, this explains why crews use water, vacuums and plastic sheeting when cutting slabs indoors. See interior piers (https://terrabrain.vercel.app/repairs/interior-piers-tunnel-or-core). ## What are the hazards in crawl spaces? Crawl spaces can be tight, wet and hazardous. Oklahoma's home inspection standards do not require inspectors to enter a crawl space with less than 18 inches of headroom, an access opening smaller than 18 by 24 inches, excessive wetness or hazardous conditions [5]. Repair crews face the same conditions. See crawl space repair (https://terrabrain.vercel.app/repairs/crawl-space-repair). ## How is summer heat handled? Oklahoma summers are when much repair work happens. The U.S. Department of Labor's heat illness campaign centers on "Water. Rest. Shade." and on **acclimatization**, letting workers build tolerance to heat gradually [4]. Lack of acclimatization was the cause in 74 percent of heat-related citations reviewed over three years, and new and temporary workers are especially at risk [4]. ## Why are post-tensioned slabs a safety concern? Some slabs are reinforced with tensioned steel cables (tendons) rather than ordinary rebar. How to tell and what that means for cutting or coring is covered on the post-tensioned slabs (https://terrabrain.vercel.app/foundations/post-tensioned-slabs) page. ## Related - Interior piers (tunnel or core) (https://terrabrain.vercel.app/repairs/interior-piers-tunnel-or-core) - Steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Crawl space repair (https://terrabrain.vercel.app/repairs/crawl-space-repair) - Post-tensioned slabs (https://terrabrain.vercel.app/foundations/post-tensioned-slabs) - Codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits) Sources: [1] 29 CFR § 1926.652 - Requirements for protective systems, Legal Information Institute, Cornell Law School https://www.law.cornell.edu/cfr/text/29/1926.652 [2] 29 CFR § 1926.651 - Specific excavation requirements, Legal Information Institute, Cornell Law School https://www.law.cornell.edu/cfr/text/29/1926.651 [3] 1926.1153 - Respirable crystalline silica, Occupational Safety and Health Administration https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.1153 [4] Annual summer campaign to prevent heat-related illnesses launched by US Labor Department, U.S. Department of Labor https://www.dol.gov/newsroom/releases/osha/osha20140522-0 [5] OAC 158:70 Home Inspector rules, 158:70-1-3 Standards of workmanship and practice, Oklahoma Construction Industries Board https://oklahoma.gov/content/dam/ok/en/cib/documents/your-industry/home-inspector/title_158_chapter_70.pdf [6] Report of Geotechnical Engineering Services, Proposed Retaining Wall C2, Crossroads Interchange Reconstruction, I-35/I-240, Oklahoma Department of Transportation https://oklahoma.gov/content/dam/ok/en/odot/business-center/upcoming-major-projects/2026/september/0903206/geotech-reports/0903206%20Geotech%20Retaining%20Wall%20C2,%20Crossroads%20Interchange%20Reconstruction%20I-35%20-%20I-240.pdf --- # What should an Oklahoma foundation repair contract cover? URL: https://terrabrain.vercel.app/rules/contracts-warranties-liens Answer: Scope of work, what lift means, exclusions and drainage duties afterward. Many in-home sales allow 3-day cancellation, and Oklahoma liens have strict deadlines. In short: A foundation repair contract sets out the scope of work, what "lift" means, what is excluded and who is responsible for drainage afterward. Federal rules give a 3-day cancellation right for many in-home sales, with exceptions [1]. Oklahoma lien law sets strict deadlines for contractors and suppliers who go unpaid [2]. ## What can a repair contract spell out? Topics that a written foundation repair contract can address include: - **Scope**: number and location of piers (see loads, pier spacing and capacity (https://terrabrain.vercel.app/guides/loads-pier-spacing-and-capacity)), repair method, and how depth beyond an estimate is handled. Pier depth varies widely; Oklahoma installation records show Tulsa steel piers stopping at a median of 12 feet but ranging from 2 to 40 feet on one site [6]. - **Lift expectation**: foundations are not built perfectly level [4], so a contract can state the lift goal rather than promise "level." - **Disclosed risks**: possible new cracks, changes in how doors and windows fit, disturbed landscaping, and plumbing damage. Forensic engineering guidance recommends plumbing tests after any lifting or lowering [4]. - **Exclusions**: conditions outside the repair, such as plumbing leaks, heave, or drainage problems the owner does not correct. - **Owner responsibilities**: gutters, grading and watering. See surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). - **Engineering**: if a licensed engineer is involved, an engineering completion letter comes from the engineer; a company may send a completion letter signed by its own representative but may not represent it as an engineering completion letter [5]. ## How does the FTC 3-day Cooling-Off Rule apply? For covered sales made at a buyer's home, workplace or a seller's temporary location, the buyer can cancel for a full refund until midnight of the third business day after the sale [1]. Key points [1]: - Home sales under $25 are not covered. - Saturdays count as business days; Sundays and federal holidays do not. - The seller must give notice of the cancellation right, two cancellation forms and a dated contract or receipt. - **Exceptions** include sales needed to meet an emergency and sales made because the buyer asked the seller to visit to repair or maintain the buyer's personal property, although extra items bought beyond that request are covered. - After a cancellation, the seller has 10 days to refund money and cancel any signed check. ## Do foundation warranties carry over when a house is sold? Oklahoma's seller disclosure form asks, "Are you aware of any previous foundation repairs?" and also asks about warranties covering the property, naming foundation warranties as an example [3]. Whether a warranty transfers, and any transfer steps, fees or maintenance conditions, are set by the written warranty. Keeping pier logs, surveys and photos supports both warranty claims and buyer questions. See real estate disclosure and inspections (https://terrabrain.vercel.app/rules/real-estate-disclosure-and-inspections-foundation-issues-in-oklahoma). ## How do Oklahoma mechanic's liens work? A **mechanic's lien** is a legal claim against the property filed by someone who supplied labor or materials and was not paid. Oklahoma's rules under Title 42 [2]: | Claimant | Deadline to file lien statement | |---|---| | Original contractor (contracted with the owner) | 4 months after last labor or materials (42 O.S. §142) | | Subcontractor | 90 days after last labor or materials (42 O.S. §143) | | Foreclosure suit on a filed lien | Within 1 year of filing (42 O.S. §172) | **Pre-lien notice (42 O.S. §142.6)** [2]: - Sent to the original contractor and the owner no later than 75 days after last supplying materials, services, labor or equipment, and before the lien is filed. - Not required for claims under $10,000, except on owner-occupied dwellings, where it applies regardless of amount. - Not required on residential projects of four or fewer units where no unit is owner-occupied. Other points [2]: - Lien statements are verified by affidavit and filed with the county clerk, who mails notice to the owner. - An owner can discharge a lien by posting a bond or cash for 125% of the claim. - The prevailing party may recover a reasonable attorney fee. The bar journal summary is general information; the statutes themselves control any specific lien [2]. ## Related - Lifting procedure and restoration (https://terrabrain.vercel.app/guides/lifting-procedure-and-restoration) - Codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits) - Working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers) - Monitoring program (https://terrabrain.vercel.app/repairs/monitoring-program) - Method selection matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix) - How to choose a foundation repair contractor in Oklahoma (https://terrabrain.vercel.app/rules/how-to-choose-a-foundation-repair-contractor-in-oklahoma) Sources: [1] Buyer's Remorse: The FTC's Cooling-Off Rule May Help, Federal Trade Commission https://consumer.ftc.gov/articles/buyers-remorse-ftcs-cooling-rule-may-help [2] To Lien or Not To Lien (and How To Lien): A Summary of Oklahoma's Mechanic's and Materialmen's Lien Laws, Oklahoma Bar Journal (Oklahoma Bar Association) https://www.okbar.org/barjournal/june-2024/to-lien-or-not-to-lien/ [3] 2026 Appendix A: Residential Property Condition Disclosure Statement, Oklahoma Real Estate Commission https://oklahoma.gov/content/dam/ok/en/orec/documents/contracts-and-forms-page/2026-contract-forms/2026%20Appendix%20A%20Residential%20Property%20Condition.pdf [4] Beyond the Building Code: Expansive Soils, Journal of the National Academy of Forensic Engineers https://journal.nafe.org/ojs/index.php/nafe/article/download/975/924/4846 [5] The Board's Bulletin, Vol. 21, Issue 4 (2007): Compliance Guidelines for Foundation Repair Companies, Oklahoma State Board of Licensure for Professional Engineers and Land Surveyors https://oklahoma.gov/content/dam/ok/en/pes/documents/bulletin/Newsletter_Volume21_Issue62.pdf [6] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # What soil types are in the Oklahoma City metro? URL: https://terrabrain.vercel.app/guides/soil-series-okc-metro Answer: Mostly soils from Permian red shale, claystone and sandstone. Clay-rich Renfrow and Kirkland shrink and swell strongly; sandy Dougherty and Lucien move less. In short: Soils around Oklahoma City mostly formed from Permian-age red shale, claystone and sandstone. Clay-rich series such as Renfrow and Kirkland shrink and swell strongly with moisture changes, while sandy series such as Dougherty and Lucien move much less. Knowing the mapped soil series is a starting point, but lots are often regraded, so the actual soil under a house has to be checked on site. ## How is a soil series description read? A soil series is a named soil type that the USDA describes in an Official Series Description (OSD): its layers, clay content, drainage and parent material (the rock or sediment it formed from). OSDs don't give a single "shrink-swell rating," but several details point to it: - **Clay content**: higher clay usually means more volume change. - **Slickensides**: polished, grooved surfaces inside clay layers that form when clay repeatedly swells and shrinks. - **Vertic properties and cracks**: deep seasonal cracking, a hallmark of strongly expansive clay. - **Depth to rock**: a "paralithic contact" is soft, weathered rock that a shovel can still dig; "densic" material is very dense soil-like material. ## What are the major OKC metro soil series? | Series | Clay (control section) | Drainage | Depth to rock or dense layer | Parent material | |---|---|---|---|---| | Renfrow | 35–55% | Well drained, slow water movement | More than 60 in. to noncemented shale | Permian clayey shale [1] | | Kirkland | 40–60% | Well drained, slow permeability | Weak siltstone at about 82 in. in the typical profile | Clayey sediments over Permian shale [2] | | Bethany | 35–50% | Well drained | Solum (soil layers) more than 60 in. thick | Loess or alluvium over Permian shale [3] | | Vernon | 40–60% | Well drained, very slow permeability | Dense bedrock at 20–40 in. | Permian redbed claystone [4] | | Zaneis | about 18–38% by layer | Well drained | Soft rock at 40–60 in. | Permian sandstone and shale [5] | | Lucien | loamy | Well drained | Rippable sandstone at 10–20 in. | Permian sandstone with shale [6] | | Dougherty | 18–35% in subsoil | Well drained | More than 60 in., no rock noted | Sandy terrace sediments [7] | | Kingfisher | 27–35% (up to 42% in lower subsoil) | Well drained | Soft rock at 20–40 in. | Permian silty shale red beds [15] | | Chickasha | 18–30% | Well drained | Weakly cemented sandstone at 40–60 in. | Permian sandstone [17] | | Stephenville | sandy loam to sandy clay loam | Well drained | Sandstone at 20–40 in. | Permian sandstone [9] | | Darnell | loamy | Well to somewhat excessively drained | Sandstone at 10–20 in. | Permian sandstone [10] | | Norge | silty clay loam to silty clay subsoil | Well drained | Solum more than 60 in. | Pleistocene loamy alluvium on old terraces [13] | | Teller | 18–30% in upper subsoil | Well drained | More than 80 in. | Pleistocene loamy sediments on stream terraces [14] | | Konawa | 18–30% in subsoil | Well drained | More than 80 in. | Pleistocene loamy and sandy alluvium on low terraces [16] | | Port | silt loam to clay loam | Well drained; occasional or frequent brief flooding | Very deep | Calcareous loamy alluvium on flood plains [11] | | Pulaski | sandy and loamy | Well drained; occasional or frequent brief flooding | Very deep | Loamy Holocene alluvium on flood plains [12] | | Dale | silt loam to clay loam | Well drained | Very deep | Loamy alluvium on flood plains of minor streams [18] | ### Clay-rich series Renfrow has vertic properties, with cracks at least 5 mm wide within about 4 feet of the surface for part of most years, and slickensides in the subsoil [1]. Kirkland has intersecting slickensides in its subsoil [2]. Renfrow's type location is in Kay County and Kirkland's is in Logan County, both in Oklahoma [1][2]. An Oklahoma State University study of benchmark soils found Kirkland's subsoil liquid limit exceeded 50% with high plasticity indices and described it as highly expansive, with a severe rating for low buildings [8]. Bethany, whose type location is in Oklahoma County near Wheatland, had moderate shrink-swell in its subsoil [3][8]. ### Shallow-rock and sandy series Vernon is a red clay over dense claystone at 20–40 inches and is described as very sticky and plastic [4]. Zaneis, with a type location north of Edmond, is loamier and reaches soft rock at 40–60 inches [5]. Lucien is shallow, with rippable sandstone at 10–20 inches [6]. Dougherty formed in sandy, dune-like terrace deposits and is well drained [7]. The same OSU study found that sandy soils with little plasticity had low shrink-swell and good ratings as building sites [8]. Other sandstone soils in the metro follow the same pattern of loamy soil over Permian sandstone. Darnell, with a type location west of Tryon in Lincoln County, reaches sandstone at 10–20 inches on summits and shoulders of low hills [10]. Stephenville, with a type location near Spencer in Oklahoma County, reaches sandstone at 20–40 inches [9]. Chickasha averages 18–30% clay and sits over weakly cemented sandstone at 40–60 inches [17]. Kingfisher formed in Permian silty shale red beds, averages 27–35% clay and reaches soft rock at 20–40 inches [15]. ### Terrace and flood-plain series Along streams, some soils formed in water-laid sediment rather than in rock [11][12][13][14][16][18]: - **Old terraces.** Norge (Pleistocene loamy alluvium, silty clay loam to silty clay subsoil), Teller and Konawa (each 18–30% clay in the subsoil, more than 80 inches deep) are well drained terrace soils [13][14][16]. - **Flood plains.** Port, a calcareous loamy soil with a type location east of Chickasha, and Pulaski, a sandier loamy soil, are both occasionally or frequently flooded for very brief periods from March to October [11][12]. Dale, with a type location east of Harrah, lies on flood plains of minor streams [18]. ## What does this mean for foundations? - Clay-rich series are the ones most associated with perimeter settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) in drought and heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) when they rewet. - Where soft rock is shallow, as in Lucien and Vernon, the depth of soil that can change volume is limited by the rock below. - The underlying rock units are described on the Hennessey Shale (https://terrabrain.vercel.app/geology/hennessey-shale-group) and Garber Sandstone (https://terrabrain.vercel.app/geology/garber-sandstone) pages. Soil maps show the dominant soil in an area, but map units include patches of other soils and urban lots are often cut or filled. Hand-auger samples or borings confirm what is actually under a slab; see soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values). ## Related - R - OKC Metro (https://terrabrain.vercel.app/regions/okc-metro) - Bedrock - OKC Metro (https://terrabrain.vercel.app/guides/bedrock-okc-metro) - Soil - Renfrow (https://terrabrain.vercel.app/soils/renfrow) - Soil - Kirkland (https://terrabrain.vercel.app/soils/kirkland) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) Sources: [1] Official Series Description - RENFROW Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/R/RENFROW.html [2] Official Series Description - KIRKLAND Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KIRKLAND.html [3] Official Series Description - BETHANY Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/B/BETHANY.html [4] Official Series Description - VERNON Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/V/VERNON.html [5] Official Series Description - ZANEIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/Z/ZANEIS.html [6] Official Series Description - LUCIEN Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/L/LUCIEN.html [7] Official Series Description - DOUGHERTY Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DOUGHERTY.html [8] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma Agricultural Experiment Station, Oklahoma State University https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [9] Official Series Description - STEPHENVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/S/STEPHENVILLE.html [10] Official Series Description - DARNELL Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DARNELL.html [11] Official Series Description - PORT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/PORT.html [12] Official Series Description - PULASKI Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/PULASKI.html [13] Official Series Description - NORGE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/N/NORGE.html [14] Official Series Description - TELLER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TELLER.html [15] Official Series Description - KINGFISHER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KINGFISHER.html [16] Official Series Description - KONAWA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KONAWA.html [17] Official Series Description - CHICKASHA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/CHICKASHA.html [18] Official Series Description - DALE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DALE.html --- # What soil types are in the Tulsa metro and how do they behave? URL: https://terrabrain.vercel.app/guides/soil-series-tulsa-metro Answer: Tulsa soils formed mostly from shale and sandstone. Shale soils are clayey and can shrink and swell; sandstone soils on hills are loamy and shallow to rock. In short: Tulsa-area soils mostly formed from Pennsylvanian-age shale and sandstone. Shale-derived soils are clayey, often hold perched water in winter and spring, and can shrink and swell, while sandstone-derived soils on the hills are loamy and shallow to rock. The mapped soil series is a starting point, and the actual soil under a house has to be confirmed on site. ## How are the official soil descriptions read? Each soil series has a USDA Official Series Description (OSD) listing its layers, clay content, drainage and parent material (what it weathered from). Terms used below: - **Perched water table**: a temporary saturated layer that sits on top of a dense clay layer or rock, above the true water table. - **Smectitic**: dominated by smectite, the clay mineral family most prone to swelling. - **Slickensides**: polished surfaces in clay formed by repeated swelling and shrinking. - **Paralithic or lithic contact**: the top of soft (paralithic) or hard (lithic) rock. ## What are the major Tulsa metro soil series? | Series | Clay | Drainage and water | Depth to rock | Parent material | |---|---|---|---|---| | Dennis | 28–50% in subsoil | Somewhat poorly drained; perched water 12–30 in., Dec–Apr | Solum more than 60 in. | Pennsylvanian shale [1] | | Okemah | Clay loam to clay subsoil | Somewhat poorly drained; perched water 2–3 ft, Dec–Apr | Not stated | Alluvium or colluvium from Pennsylvanian shale [2] | | Parsons | 35–60% below about 12 in. | Somewhat poorly drained; perched water 6–18 in., Dec–Apr | Not stated | Old alluvium or Pennsylvanian shale [3] | | Summit | 40–70% in subsoil | Moderately well to somewhat poorly drained; perched water 12–36 in., Nov–May | More than 60 in. | Pennsylvanian shale [4] | | Osage | 40–65% in subsoil | Poorly drained; water table 6–18 in., Nov–May; flood plains | Not stated | Thick clayey alluvium [5] | | Eram | 35–55% | Moderately well drained; water table 1–2 ft in winter and spring | Soft rock at 20–40 in. | Shale with thin sandstone [6] | | Bates | 5–35% | Well drained | Soft rock at 20–40 in. | Pennsylvanian sandstone [7] | | Collinsville | 5–20% | Well to somewhat excessively drained | Hard sandstone at about 4–20 in. | Pennsylvanian sandstone [8] | | Coweta | 10–30% | Well to somewhat excessively drained | Soft sandstone at about 15 in. (solum 10–20 in.) | Sandstone interbedded with Pennsylvanian shale [9] | | Wynona | 27–35% | Somewhat poorly drained; perched water about 2 ft, Nov–Apr; occasional flooding | More than 72 in. | Silty alluvium on flood plains [10] | | Verdigris | about 15–33% | Well drained; subject to flooding | Not stated | Silty alluvium on flood plains [11] | | Niotaze | more than 40% average; 35–55% in clay subsoil | Somewhat poorly drained, slow permeability | Shale at 20–40 in. | Interbedded Pennsylvanian shale and sandstone, sandstone colluvium on top [12] | | Taloka | 35–60% in subsoil | Somewhat poorly drained; perched water 12–24 in., Nov–May | Not stated | Colluvium or alluvium from Pennsylvanian shale and sandstone [13] | | Choteau | 35–45% in subsoil | Somewhat poorly drained; perched water from 2.5–3 ft, Dec–Apr | Solum more than 60 in. | Alluvium or colluvium over Pennsylvanian shale [14] | | Muskogee | silty over clayey | Moderately well drained, slow permeability | Solum more than 60 in. | Silty material over clayey sediments on stream terraces [15] | | Apperson | 35–60% | Somewhat poorly drained; perched water from 1.5–2 ft, Dec–Apr | Hard limestone at 40–60 in. | Pennsylvanian limestone [16] | ## How do clay soils formed from shale behave? Dennis has its type location just north of Claremore in Rogers County [1]. Okemah's subsoil is very firm when moist and has a few slickensides [2]. Parsons has an abrupt change at about 12 inches, where a loamy surface layer sits on a clayey subsoil [3]. That sharp contrast is one reason water perches above it. Summit, with a type location about 6 miles east of Tulsa, is smectitic and develops deep, wide cracks, usually in summer [4]. Osage, a flood-plain clay, is also smectitic and has intersecting slickensides from about 13 to 60 inches deep [5]. These are the series most associated with cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally). Eram reaches soft shale at 20–40 inches, so the clay layer is thinner, but it is still 35–55% clay [6]. Three more upland clays are common in the area: - **Apperson** is smectitic and is classified as an Aquic Hapludert, a Vertisol. Its subsoil has slickensides and cracks that open and close periodically, over hard limestone at 40–60 inches; the type location is near Foraker in Osage County [16]. - **Niotaze** is also smectitic, averages more than 40% clay and reaches shale at 20–40 inches on hillsides with slopes of 3 to 45 percent [12]. - **Taloka** and **Choteau** formed on old terraces and footslopes. Taloka's silt loam surface changes abruptly to silty clay at about 28 inches, with a type location southeast of Wagoner [13]. Choteau's type location is near Pryor in Mayes County [14]. ## How do sandstone soils on the hills behave? Bates, Collinsville and Coweta formed from Pennsylvanian sandstone [7][8][9]. Coweta, with a type location in Wagoner County, has only 10 to 20 inches of soil over soft sandstone [9]. Collinsville's typical profile near Inola hits hard sandstone at about 9 inches, and the series range is about 4 to 20 inches [8]. Where rock is this shallow, there is less soil available to shrink or swell, but cut-and-fill grading on these slopes can place houses partly on rock and partly on fill; see fill soils and lot history (https://terrabrain.vercel.app/guides/fill-soils-and-lot-history). ## Which soils are on Tulsa-area flood plains? Wynona, Verdigris and Osage formed in alluvium (sediment laid down by streams) on flood plains [5][10][11]. Wynona, with a type location south of Skiatook in Osage County, is somewhat poorly drained, has perched water about 2 feet down from November through April and is occasionally flooded for very brief periods from January through July [10]. Verdigris is a well-drained silty soil that is subject to flooding [11]. Muskogee sits higher, on stream terraces, with silty layers over clayey sediments [15]. ## How does perched water affect foundations? Dennis, Okemah, Parsons, Summit, Taloka, Choteau, Wynona and Apperson all list a seasonal perched water table in late fall through spring [1][2][3][4][10][13][14][16]. That timing lines up with wet crawl spaces and water at basement cove joints described on the groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) page. Soil maps show the dominant soil in an area; map units include patches of other soils and city lots are often regraded. On-site samples or borings confirm what is under a specific house. ## Related - R - Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro) - Bedrock - Tulsa Metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro) - Pennsylvanian Shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales) - Soil - Summit (https://terrabrain.vercel.app/soils/summit) - Soil - Parsons (https://terrabrain.vercel.app/soils/parsons) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description - DENNIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DENNIS.html [2] Official Series Description - OKEMAH Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OKEMAH.html [3] Official Series Description - PARSONS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/PARSONS.html [4] Official Series Description - SUMMIT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/S/SUMMIT.html [5] Official Series Description - OSAGE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OSAGE.html [6] Official Series Description - ERAM Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/E/ERAM.html [7] Official Series Description - BATES Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/B/BATES.html [8] Official Series Description - COLLINSVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COLLINSVILLE.html [9] Official Series Description - COWETA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COWETA.html [10] Official Series Description - WYNONA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/W/WYNONA.html [11] Official Series Description - VERDIGRIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/V/VERDIGRIS.html [12] Official Series Description - NIOTAZE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/N/NIOTAZE.html [13] Official Series Description - TALOKA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TALOKA.html [14] Official Series Description - CHOTEAU Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/CHOTEAU.html [15] Official Series Description - MUSKOGEE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/M/MUSKOGEE.html [16] Official Series Description - APPERSON Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/A/APPERSON.html --- # What soils affect foundations in east-central Oklahoma? URL: https://terrabrain.vercel.app/regions/east-central-arkoma Answer: A wet region of shale, sandstone ridges and floodplains; many soils hold a seasonal high water table, and floodplain clays such as Osage are smectitic Vertisols. In short: East-central Oklahoma is wetter than the rest of central Oklahoma and is built largely on Pennsylvanian-age shale with sandstone ridges and broad river floodplains [1][2][4]. Many shale-derived soils hold a seasonal high water table within a few feet of the surface in winter and spring [1][2][3], and floodplain clays such as Osage are Vertisols with smectitic clay [5]. Wetting heave, crawl-space moisture and slope movement are common concerns. **Cities covered:** Muskogee, McAlester, Okmulgee, Henryetta, Wagoner and eastern Shawnee. ## What is the climate like? USDA descriptions for the region's soils list mean annual precipitation of roughly 35 to 47 inches, with typical values near 39 to 41 inches, and mean annual temperatures of about 55 to 64 °F [1][2][3]. Statewide, rainfall climbs from about 17 inches in the far western Panhandle to about 56 inches in the far southeast [7], and this region sits on the wetter side of that gradient. Major Oklahoma floods frequently occur in spring and fall [6]. See creeks and flood history (https://terrabrain.vercel.app/data/creeks-and-flood-history). ## What is the ground made of? ### Shale clays Much of the region is underlain by Pennsylvanian shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales) with thin sandstone and siltstone layers. - **Eram (https://terrabrain.vercel.app/soils/eram):** moderately deep soils from Pennsylvanian shale with thin sandstone, with bedrock at 20 to 40 inches and a seasonal high water table at 1 to 2 feet in winter and spring [1]. - **Talihina (https://terrabrain.vercel.app/soils/talihina):** shallow, poorly drained clayey soils from soft Pennsylvanian shale, with soft bedrock at 10 to 20 inches, slow permeability and a perched water table within 0.5 to 2 feet from November to April. They occur on sloping to steep uplands of 5 to 30 percent [2]. - **Okemah (https://terrabrain.vercel.app/soils/okemah):** very deep, somewhat poorly drained soils on high terraces and lower slopes, with a perched water table at 2 to 3 feet from December through April; type location in Okmulgee County [3]. A **perched water table** is a layer of saturated soil sitting above a tighter layer below. ### Sandstone ridges **Hector (https://terrabrain.vercel.app/soils/hector)** soils are shallow, well drained soils formed from sandstone, with hard rock at 14 to 20 inches, on ridgetops and mountainsides with slopes of 2 to 60 percent [4]. These are tied to Pennsylvanian sandstones (https://terrabrain.vercel.app/geology/pennsylvanian-sandstones). ### Floodplain clays **Osage (https://terrabrain.vercel.app/soils/osage)** soils are very deep, poorly drained clays in thick alluvium on floodplains of major streams. USDA classifies them as Vertisols (Typic Epiaquerts) with smectitic clay and continuous slickensides from about 13 to 60 inches. They have very slow permeability and a seasonal high water table at 6 to 18 inches from November to May [5]. ## What are the main soils? | Series | Depth to rock | Drainage / water table | Notes | |---|---|---|---| | Eram | 20–40 in | Moderately well; 1–2 ft in wet season | Shale with sandstone [1] | | Talihina | 10–20 in | Poorly; perched 0.5–2 ft Nov–Apr | Steep uplands [2] | | Okemah | Very deep | Somewhat poorly; perched 2–3 ft Dec–Apr | Some slickensides [3] | | Hector | 14–20 in | Well drained | Sandstone ridges [4] | | Osage | Very deep | Poorly; 6–18 in Nov–May | Vertisol, smectitic [5] | ## What foundation problems are common? - **Perimeter wetting heave** where shale clays stay wet through winter and spring. - **Crawl space moisture and wood decay** under homes on soils with shallow seasonal water. - **Slope creep** on steeper shale hillsides. The Oklahoma Geological Survey reports that most Oklahoma landslides occur in the eastern third of the state [6]. - Settlement on soft floodplain clays. The Oklahoma Geological Survey also lists the Arkoma Basin among the state's principal seismic areas, with typical small magnitudes of about 1.8 to 2.5 [6]. Statewide research put the depth of seasonal soil-moisture change at about 0.5 to 4 meters [7]. ## Related - Groundwater and Perched Water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Pennsylvanian Shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales) - Crawl Space Repair (https://terrabrain.vercel.app/repairs/crawl-space-repair) - Erosion, Creeks and Slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro) Sources: [1] Official Series Description – ERAM Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/E/ERAM.html [2] Official Series Description – TALIHINA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TALIHINA.html [3] Official Series Description – OKEMAH Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OKEMAH.html [4] Official Series Description – HECTOR Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/H/HECTOR.html [5] Official Series Description – OSAGE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OSAGE.html [6] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [7] Soil Matric Suction and Active Zone Depth in Oklahoma (PhD dissertation), Oklahoma State University https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf --- # What soils affect foundations in the Oklahoma Panhandle? URL: https://terrabrain.vercel.app/regions/panhandle-high-plains Answer: The driest region, about 17 to 18 inches of rain in the west; soils formed in wind-deposited loess, and some, like Richfield, have clay subsoils that swell. In short: The Oklahoma Panhandle is the state's driest region, with about 17 to 18 inches of rain a year in the west [1][3]. Its soils formed mostly in wind-deposited material — thick loess and loamy wind-blown sediments on flat tablelands — rather than from local bedrock [1][2]. Some, such as Richfield, have smectite-rich clay subsoils that can swell when wetted, and long dry periods mean soils can react sharply when water is added [1][5]. **Cities covered:** Guymon, Boise City, Goodwell and Beaver. ## What is the climate like? Oklahoma's climate grades from humid subtropical in the east to semi-arid in the west, and annual precipitation drops to about 17 inches in the far western Panhandle [3]. USDA descriptions for Panhandle soils list typical mean annual precipitation near 18 inches and mean annual temperatures of about 54 to 55 °F [1][2]. Richfield soils have a frost-free period of about 140 to 201 days [1]. For footing depth in cold weather, see freeze-thaw and frost depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) and frost heave (https://terrabrain.vercel.app/causes/frost-heave). ## What is the ground made of? ### Loess tablelands **Loess** is silt deposited by wind. **Richfield (https://terrabrain.vercel.app/soils/richfield)** soils are very deep, well drained soils formed in calcareous loess about 3 to more than 10 feet thick, on nearly level tablelands with slopes of 0 to 6 percent [1]. Their subsoil contains 35 to 42 percent clay and is classified as smectitic [1]. **Smectite** clays, including montmorillonite, can adsorb very large amounts of water and have a large shrink-swell potential [5]. The series extends from western Kansas and Nebraska into the Oklahoma Panhandle [1]. ### Wind-blown loamy soils **Dalhart (https://terrabrain.vercel.app/soils/dalhart)** soils are very deep, well drained soils formed in loamy wind-deposited (eolian) sediments of recent geologic age, on interdunes and sand sheets with slopes of 0 to 8 percent [2]. They belong to the Southern High Plains land resource area, with a type location in Cimarron County [2]. Lime (calcium carbonate) accumulates in the lower subsoil [2]. ### Bedrock Older deposits beneath the wind-blown cover are described on the Ogallala Formation and loess (https://terrabrain.vercel.app/geology/ogallala-formation-and-loess) page. The Oklahoma Geological Survey also notes that gypsum and shallow salt deposits occur in many areas of western Oklahoma; these soluble rocks can dissolve and form sinkholes [4]. See gypsum karst and sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes). ## What are the main soils? | Series | Parent material | Drainage | Notes | |---|---|---|---| | Richfield | Loess, 3–10+ ft | Well drained | 35–42% smectitic clay subsoil [1] | | Dalhart | Loamy eolian sediments | Well drained | Carbonates in lower subsoil [2] | ## What foundation problems are common? - **Hydrocollapse (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil)** — some dry, loose wind-deposited soils can compact suddenly when first soaked; see collapsible and loess soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils). - **Swelling on wetting** in smectitic clay subsoils such as Richfield [1][5], especially near lawn irrigation, leaks or ponding. - **Frost heave** of shallow footings and flatwork in colder winters. Statewide research using Mesonet data estimated active zone depths of about 0.5 to 4 meters, with depth depending on soil properties and climate [3]. ## Related - Collapsible and Loess Soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils) - Ogallala Formation and Loess (https://terrabrain.vercel.app/geology/ogallala-formation-and-loess) - Freeze-Thaw and Frost Depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) - Northwest (Gypsum Hills) (https://terrabrain.vercel.app/regions/northwest-gypsum-hills) - Surface Drainage and Grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) Sources: [1] Official Series Description – RICHFIELD Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/R/RICHFIELD.html [2] Official Series Description – DALHART Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DALHART.html [3] Soil Matric Suction and Active Zone Depth in Oklahoma (PhD dissertation), Oklahoma State University https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf [4] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [5] Chapter C5 – Expansive Soils, Institution of Civil Engineers / British Geological Survey https://nora.nerc.ac.uk/id/eprint/17002/1/C5_expansive_soils_Oct.pdf --- # What soils cause foundation problems in north-central Oklahoma? URL: https://terrabrain.vercel.app/regions/north-central-red-prairies-and-wheat-belt Answer: Red prairie clays over Permian shale, such as Renfrow, Kirkland and Tabler, shrink and swell strongly, while loamy Pond Creek and Grant soils are less reactive. In short: North-central Oklahoma lies in the Central Rolling Red Prairies, a region of red soils formed over Permian shale, siltstone and old terraces [1][3][4]. Its clay soils — Renfrow, Kirkland and Tabler — show cracking and slickensides that mark strong shrink-swell behavior, while loamy soils such as Pond Creek and Grant are less reactive [1][2][3][5]. Drought drying of these clays is the main driver of foundation settlement here. **Cities covered:** Enid, Stillwater, Ponca City, Perry, Kingfisher, Guthrie, Pawnee and Cushing. ## What is the climate like? USDA soil descriptions for the region list mean annual precipitation from roughly 26 to 38 inches and mean annual temperatures of about 57 to 64 °F [2][3][4][5]. Oklahoma's climate shifts from humid in the east to semi-arid in the west [8], and this region sits in the subhumid middle, where long summer droughts dry clay deeply. See drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) and moisture index by city (https://terrabrain.vercel.app/data/moisture-index-by-city). ## What is the ground made of? The region is mapped by USDA as Major Land Resource Area 80A, the **Central Rolling Red Prairies** [1]. Many soils formed in material weathered from Permian-age shale and siltstone — the red beds that include the Hennessey Shale (https://terrabrain.vercel.app/geology/hennessey-shale-group) and Wellington Formation (https://terrabrain.vercel.app/geology/wellington-formation) — or in old alluvium on high terraces (Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces)). ### High shrink-swell clays - **Renfrow (https://terrabrain.vercel.app/soils/renfrow):** very deep, well drained clays from Permian clayey shale. USDA describes vertic properties: cracks at least 5 mm wide in most years and linear extensibility of 6 cm or more in the upper 100 cm. The series was established in Grant County and its type location is in Kay County [1]. - **Kirkland (https://terrabrain.vercel.app/soils/kirkland):** very deep, slowly permeable, 40 to 60 percent clay in the subsoil, with intersecting **slickensides** — polished surfaces formed when swelling clay shears [2]. - **Tabler (https://terrabrain.vercel.app/soils/tabler):** very deep, moderately well drained soils with very slow permeability on nearly level old terraces, with slickensides through much of the subsoil from about 10 to 42 inches. Its type location is near Medford in Grant County [3]. An Oklahoma State University study measured cumulative linear extensibility of about 12 cm in a Kirkland-like profile and about 9 cm in a Norge-like profile, and described the Kirkland-like soil as highly expansive [7]. ### Loamy and shallower soils - **Pond Creek:** very deep, well drained, silty soils from loess, alluvium and red-bed residuum; type location in Garfield County [5]. - **Grant:** well drained soils with siltstone or silty shale at 40 to 60 inches; type location in Garfield County [4]. - **Kingfisher:** moderately deep soils with weathered silty shale at 20 to 40 inches, mainly in north-central Oklahoma [6]. None of these three descriptions lists vertic properties [4][5][6]. ## What are the main soils? | Series | Depth to rock or contact | Drainage | Shrink-swell indicators | |---|---|---|---| | Renfrow | > 60 in to shale | Well drained | Vertic; LE ≥ 6 cm [1] | | Kirkland | ~82 in (typical) | Well drained, slow | Slickensides [2] | | Tabler | Very deep | Moderately well drained, very slow | Slickensides [3] | | Grant | 40–60 in | Well drained | Not listed [4] | | Pond Creek | > 60 in | Well drained | Not listed [5] | | Kingfisher | 20–40 in | Well drained | Not listed [6] | ## What are the common foundation problems? - **Perimeter drying settlement** on Renfrow, Kirkland and Tabler clays during drought. - **Tree-root desiccation settlement** where trees grow close to homes on these clays. - Heave when dried clays rewet after drought or tree removal. Research using Oklahoma Mesonet data estimated statewide active zone depths — where seasonal moisture change occurs — at about 0.5 to 4 meters [8]. The slow permeability of Kirkland and Tabler [2][3] means water enters and leaves these clays slowly. ## Related - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Hennessey Shale (Group) (https://terrabrain.vercel.app/geology/hennessey-shale-group) - Wellington Formation (https://terrabrain.vercel.app/geology/wellington-formation) - OKC Metro (https://terrabrain.vercel.app/regions/okc-metro) - Soil Series Index (https://terrabrain.vercel.app/soils/soil-series-index) Sources: [1] Official Series Description – RENFROW Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/R/RENFROW.html [2] Official Series Description – KIRKLAND Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KIRKLAND.html [3] Official Series Description – TABLER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TABLER.html [4] Official Series Description – GRANT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/G/GRANT.html [5] Official Series Description – POND CREEK Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/POND_CREEK.html [6] Official Series Description – KINGFISHER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KINGFISHER.html [7] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [8] Soil Matric Suction and Active Zone Depth in Oklahoma (PhD dissertation), Oklahoma State University https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf --- # What soils cause foundation problems in northeast Oklahoma? URL: https://terrabrain.vercel.app/regions/northeast-ozark-plateau-and-grand-lake Answer: Cherty Ozark soils and karst around Grand Lake, Grove and Tahlequah, plus shrink-swell shale clays and perched water toward Vinita and Pryor. In short: Northeast Oklahoma combines two landscapes. On the Ozark side around Grand Lake, Grove, Jay and Tahlequah, soils formed from cherty limestone and dolomite on steep, rocky hills, with karst features in the soluble rock below [1][2][6]. Toward Vinita and Pryor, prairie soils on Pennsylvanian shale include high shrink-swell clays and soils with perched water in winter and spring [3][4]. Crawl-space moisture, wet-season heave and slope issues are common concerns. **Cities covered:** Grove, Miami, Vinita, Tahlequah, Jay and Pryor. ## What is the climate like? USDA descriptions for the region's soils give mean annual precipitation of about 35 to 47 inches, with typical values in the low 40s, and mean annual temperatures of about 54 to 65 °F [1][3][4]. ## What is the ground like? ### Ozark cherty soils USDA places these soils in the Ozark Highlands and Ozark land resource areas, whose range includes Oklahoma [1][2]. The bedrock is described on Mississippian cherty limestone (https://terrabrain.vercel.app/geology/mississippian-cherty-limestone). - **Clarksville (https://terrabrain.vercel.app/soils/clarksville):** very deep, somewhat excessively drained soils from hillslope sediment over clayey residuum of cherty dolomite or limestone. Chert fragments make up 35 to 70 percent of the key subsoil zone, and slopes range from 1 to 70 percent [1]. - **Nixa (https://terrabrain.vercel.app/soils/nixa):** very deep, moderately well drained soils from cherty limestone with a **fragipan** — a dense, brittle layer that slows water — at 14 to 27 inches, very slow permeability and up to 85 percent chert in some layers [2]. ### Karst **Karst** is landscape formed where groundwater dissolves soluble rock such as limestone and dolomite, leaving caverns, springs and sinkholes [7]. The Oklahoma Geological Survey reports that limestone and dolomite karst in Oklahoma is found mainly in the Ozark region, the Arbuckle Mountains and the Limestone Hills north of the Wichita Mountains [6]. USGS notes sinkholes can open suddenly where the overlying soil is clay-rich, or develop slowly under sandy cover, and that construction and drainage changes can trigger them [7]. See karst subsidence and sinkholes (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes). ### Prairie shale soils West of the Ozark hills, soils formed on Pennsylvanian shales (https://terrabrain.vercel.app/geology/pennsylvanian-shales): - **Summit (https://terrabrain.vercel.app/soils/summit):** very deep clays from Pennsylvanian shale, smectitic, with slickensides in the subsoil and deep, wide cracks that usually form in summer. USDA gives a COLE (coefficient of linear extensibility, a shrink-swell measure) of 0.09 or more. Type location is in Rogers County [4]. - **Parsons (https://terrabrain.vercel.app/soils/parsons):** very deep, somewhat poorly drained soils with an abrupt change from silty topsoil to clay at about 12 inches and a perched water table 6 to 18 inches deep from December through April. Type location is in Wagoner County [3]. - **Osage (https://terrabrain.vercel.app/soils/osage):** floodplain clays classified as Vertisols, with smectitic clay and intersecting slickensides from about 13 to 60 inches, very slow permeability and a seasonal high water table at 6 to 18 inches [5]. ## Which soils are found here? | Series | Setting | Drainage / water | Shrink-swell indicators | |---|---|---|---| | Clarksville | Ozark hills, cherty | Somewhat excessively drained | High chert; not described as vertic [1] | | Nixa | Ozark ridges | Fragipan at 14–27 in | Very slow permeability [2] | | Summit | Shale prairie | Perched water 12–36 in Nov–May | Smectitic, slickensides, COLE ≥ 0.09 [4] | | Parsons | Shale prairie | Perched water 6–18 in Dec–Apr | Abrupt clay subsoil [3] | | Osage | Floodplains | Water table 6–18 in Nov–May | Vertisol [5] | ## What are the common foundation problems? - **Crawl space moisture and wood decay** where perched water and high rainfall keep soil wet. - **Perimeter wetting heave** and seasonal movement on Summit and Osage clays. - **Slope creep** and erosion on steep Ozark hillsides. Most Oklahoma landslides occur in the eastern third of the state [6]. - Possible karst-related voids. ## Related - Mississippian Cherty Limestone (https://terrabrain.vercel.app/geology/mississippian-cherty-limestone) - Karst Subsidence and Sinkholes (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes) - Crawl Space Encapsulation (https://terrabrain.vercel.app/repairs/crawl-space-encapsulation) - Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro) - Erosion, Creeks and Slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) Sources: [1] Official Series Description – CLARKSVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/CLARKSVILLE.html [2] Official Series Description – NIXA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/N/NIXA.html [3] Official Series Description – PARSONS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/P/PARSONS.html [4] Official Series Description – SUMMIT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/S/SUMMIT.html [5] Official Series Description – OSAGE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OSAGE.html [6] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [7] Sinkholes, U.S. Geological Survey Water Science School https://www.usgs.gov/special-topics/water-science-school/science/sinkholes --- # What soils cause foundation problems in northwest Oklahoma? URL: https://terrabrain.vercel.app/regions/northwest-gypsum-hills Answer: Northwest Oklahoma sits on Permian red beds with gypsum and salt that can form sinkholes, slow-draining clays such as Vernon, and loamy soils on soft rock. In short: Northwest Oklahoma is drier than the rest of the state's center and is built on Permian red beds — claystone, siltstone and soft sandstone — with gypsum and salt layers that can dissolve and form sinkholes [1][3][4]. Clay soils such as Vernon have very slow permeability over dense claystone, loamy soils such as Woodward and Quinlan sit on soft rock within a few feet, and wind-blown Tivoli sands form dunes along river valleys [3][4][5][6]. **Cities covered:** Woodward, Alva, Watonga, Weatherford and Elk City. ## What is the climate like? USDA descriptions for the area's main soils list mean annual precipitation of about 20 to 30 inches, typically near 25 inches, and mean annual temperatures of about 57 to 65 °F [3][4][5]. Oklahoma's climate grades from humid in the east to semi-arid in the west [7], and this region is on the dry side, so soils can dry deeply during long droughts. See drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles). ## What is the ground made of? USDA maps most of this area within the **Central Rolling Red Plains** land resource area [3][4]. ### Gypsum and salt (karst) The Oklahoma Geological Survey reports that gypsum and shallow salt deposits occur in many areas of western Oklahoma, and that water-soluble rocks — including gypsum, anhydrite and salt — can dissolve in circulating groundwater to form sinkholes and caverns that cause settlement or collapse [1]. USGS notes that sinkholes can open suddenly where the overlying soil is clay-rich and that changes in drainage and heavy loads can trigger them [2]. See Permian gypsum units (https://terrabrain.vercel.app/geology/permian-gypsum-units-e-g-blaine), gypsum karst and sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes) and karst subsidence (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes). ### Red-bed clays **Vernon (https://terrabrain.vercel.app/soils/vernon)** soils are moderately deep, well drained clays weathered from Permian red-bed claystone, with dense claystone at 20 to 40 inches and very slow permeability [3]. Lower layers can contain up to 2 percent gypsum, measurable soluble salts and rising sodium with depth [3]. Slopes range up to 45 percent on escarpments [3]. See western Permian red beds (https://terrabrain.vercel.app/geology/western-permian-red-beds). ### Loamy soils on soft sandstone and siltstone - **Woodward (https://terrabrain.vercel.app/soils/woodward):** moderately deep, well drained loamy soils over soft Permian sandstone or siltstone at 20 to 40 inches, mainly in the Marlow, Rush Springs, Cloud Chief and Quartermaster formations; some have thin gypsum seams in the bedrock [4]. - **Quinlan (https://terrabrain.vercel.app/soils/quinlan):** shallow soils with soft sandstone or siltstone at 10 to 20 inches, on hillslopes, ridges and escarpments with slopes up to 50 percent [5]. ### Dune sands **Tivoli** soils are very deep, excessively drained sands deposited by wind, forming hummocky dunes on sand sheets and stream terraces with slopes of 1 to 45 percent. The series was established in Major County and its type location is in Woodward County [6]. ## Which soils are most common? | Series | Depth to rock | Drainage | Notes | |---|---|---|---| | Vernon | 20–40 in claystone | Well drained, very slow permeability | Clay; some gypsum and salts at depth [3] | | Woodward | 20–40 in soft sandstone/siltstone | Well drained | Loamy; thin gypsum seams possible [4] | | Quinlan | 10–20 in soft sandstone/siltstone | Well drained | Shallow, slopes to 50% [5] | | Tivoli | Very deep | Excessively drained | Wind-blown dune sand [6] | ## What are the common foundation problems? - **Karst subsidence and sinkholes** where gypsum or salt lies at shallow depth. - **Perimeter drying settlement** on Vernon clays during long droughts. - Settlement and erosion problems on loose sands and steep escarpments. Where unexplained, progressive settlement occurs in an area with mapped gypsum, a subsurface investigation is the usual first step before repair. ## Related - Gypsum Karst and Sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes) - Permian Gypsum Units (e.g., Blaine) (https://terrabrain.vercel.app/geology/permian-gypsum-units-e-g-blaine) - Western Permian Red Beds (https://terrabrain.vercel.app/geology/western-permian-red-beds) - Panhandle (High Plains) (https://terrabrain.vercel.app/regions/panhandle-high-plains) - Southwest (Lawton & Red Plains) (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains) Sources: [1] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [2] Sinkholes, U.S. Geological Survey Water Science School https://www.usgs.gov/special-topics/water-science-school/science/sinkholes [3] Official Series Description – VERNON Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/V/VERNON.html [4] Official Series Description – WOODWARD Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/W/WOODWARD.html [5] Official Series Description – QUINLAN Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/Q/QUINLAN.html [6] Official Series Description – TIVOLI Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TIVOLI.html [7] Soil Matric Suction and Active Zone Depth in Oklahoma (PhD dissertation), Oklahoma State University https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf --- # What soils cause foundation problems in south-central Oklahoma? URL: https://terrabrain.vercel.app/regions/south-central-arbuckles-and-texoma Answer: Shale clays near Durant crack deeply when dry, the Arbuckles hold limestone karst, and sandy and Red River soils bring drainage and flooding concerns. In short: South-central Oklahoma mixes very different ground. Around Durant, clays formed from Cretaceous shale have smectite-rich subsoils that crack deeply in dry periods [1]. The Arbuckle Mountains contain limestone and dolomite karst [5], while sandy soils on Cretaceous sandstone are well drained and Red River floodplain sands are frequently flooded where unprotected [2][4]. Drought settlement and wetting heave on the clays are the main foundation issues. **Cities covered:** Ardmore, Ada, Durant, Sulphur and Duncan. ## What is the climate like? Rainfall rises from west to east across the region. USDA descriptions give mean annual precipitation of about 33 to 39 inches for Zaneis soils, and about 37 to 45 inches for Durant soils [1][3]. Mean annual temperatures run about 59 to 66 °F [1][2][3]. See drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles). ## What is the ground made of? ### Cretaceous clays (Durant area) **Durant (https://terrabrain.vercel.app/soils/durant)** soils are very deep, moderately well drained clays weathered from Cretaceous clayey shale and claystone on broad, gently sloping ridges [1]. Key facts from the USDA description [1]: - Classified as smectitic with vertic-like (Udertic) properties. - Very slow permeability. - Cracks wider than 1 cm and deeper than 30 inches form during dry periods. - Type location in Bryan County; part of the Grand Prairie land resource area. Smectite clays swell when wet and shrink and crack when dry, and the cracks do not fully close on rewetting [7]. See Cretaceous shales, clays and sandstones (https://terrabrain.vercel.app/geology/cretaceous-shales-clays-and-sandstones). ### Sandy uplands and red-bed soils - **Bernow (https://terrabrain.vercel.app/soils/bernow):** deep, well drained sandy and loamy soils from Cretaceous sandstone, on hillslopes of 0 to 12 percent, with type location in Bryan County [2]. - **Zaneis (https://terrabrain.vercel.app/soils/zaneis):** well drained soils from interbedded Permian sandstone and shale, with soft rock at 40 to 60 inches; the series was established in Carter County [3]. ### Red River floodplain **Kiomatia (https://terrabrain.vercel.app/soils/kiomatia)** soils are well drained, rapidly permeable sandy alluvium on natural levees of the Red River floodplain, and are frequently flooded for brief periods in most years where unprotected [4]. See Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) and creeks and flood history (https://terrabrain.vercel.app/data/creeks-and-flood-history). ### Arbuckle karst The Oklahoma Geological Survey reports limestone and dolomite karst mainly in the Ozark region, the Arbuckle Mountains and the Limestone Hills north of the Wichita Mountains [5]. USGS explains that soluble rock dissolved by groundwater can leave caverns, and that sinkholes may open suddenly beneath clay-rich cover [6]. ## What are the main soils? | Series | Parent material | Drainage | Notes | |---|---|---|---| | Durant | Cretaceous shale/claystone | Moderately well, very slow | Smectitic; deep cracks [1] | | Bernow | Cretaceous sandstone | Well drained | Sandy/loamy [2] | | Zaneis | Permian sandstone and shale | Well drained | Rock at 40–60 in [3] | | Kiomatia | Red River alluvium | Well drained, rapid | Frequently flooded where unprotected [4] | ## What are the common foundation problems? - **Perimeter drying settlement** on Durant and similar clays during drought. - **Center heave** when water collects under slabs on the same clays. - Flood and erosion exposure on Red River and creek floodplains. - Possible karst voids near the Arbuckles. The Oklahoma Geological Survey also lists Love and Carter Counties among the state's principal seismic areas, and gives typical Oklahoma earthquake magnitudes of about 1.8 to 2.5 [5]. ## Related - Cretaceous Shales, Clays and Sandstones (https://terrabrain.vercel.app/geology/cretaceous-shales-clays-and-sandstones) - Arbuckle Carbonates (https://terrabrain.vercel.app/geology/arbuckle-carbonates) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Southeast (Ouachitas & Red River) (https://terrabrain.vercel.app/regions/southeast-ouachitas-and-red-river) - OKC Metro (https://terrabrain.vercel.app/regions/okc-metro) Sources: [1] Official Series Description – DURANT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DURANT.html [2] Official Series Description – BERNOW Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/B/BERNOW.html [3] Official Series Description – ZANEIS Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/Z/ZANEIS.html [4] Official Series Description – KIOMATIA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KIOMATIA.html [5] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [6] Sinkholes, U.S. Geological Survey Water Science School https://www.usgs.gov/special-topics/water-science-school/science/sinkholes [7] Chapter C5 – Expansive Soils, Institution of Civil Engineers / British Geological Survey https://nora.nerc.ac.uk/id/eprint/17002/1/C5_expansive_soils_Oct.pdf --- # What soils cause foundation problems in southeast Oklahoma? URL: https://terrabrain.vercel.app/regions/southeast-ouachitas-and-red-river Answer: Steep, rocky Ouachita slopes, Cretaceous shale clays that shrink and swell, flood-prone Red River sands and the state's heaviest rainfall. In short: Southeast Oklahoma gets the most rain in the state — about 56 inches a year in the far southeast [1]. The Ouachita Mountains bring steep slopes with shallow, rocky soils, where slope movement and runoff are key ground concerns [2][3]. To the south, Cretaceous shale clays can shrink and swell strongly, and Red River bottomland sands are prone to flooding [4][6]. **Cities covered:** Idabel, Broken Bow, Hugo, Poteau and Antlers. ## What is the climate like? Oklahoma's climate grades from humid subtropical in the east to semi-arid in the west, and annual precipitation reaches about 56 inches in the far southeast [1]. USDA soil descriptions for the region list mean annual precipitation of roughly 38 to 48 inches across their mapped ranges, with mean annual temperatures of about 58 to 70 °F [5][6]. The Oklahoma Geological Survey notes that major Oklahoma floods frequently occur in spring and fall [2]. See creeks and flood history (https://terrabrain.vercel.app/data/creeks-and-flood-history) and severe weather effects (https://terrabrain.vercel.app/guides/severe-weather-effects). ## What is the ground like? ### Ouachita Mountains The bedrock of the mountains is described on Ouachita folded rocks (https://terrabrain.vercel.app/geology/ouachita-folded-rocks). **Hector (https://terrabrain.vercel.app/soils/hector)** soils, for example, are shallow, well drained soils formed from sandstone, with hard rock at 14 to 20 inches, on ridgetops and mountainsides with slopes from 2 to 60 percent [3]. The Oklahoma Geological Survey reports that most Oklahoma landslides occur in the eastern third of the state, where wetter climate and steeper, mountainous terrain favor them [2]. ### Cretaceous clays and sands (Gulf Coastal Plain side) Several soils toward the Red River formed from Cretaceous rock [4][5]; see Cretaceous shales, clays and sandstones (https://terrabrain.vercel.app/geology/cretaceous-shales-clays-and-sandstones). - **Durant (https://terrabrain.vercel.app/soils/durant):** very deep, moderately well drained clays from Cretaceous clayey shale and claystone, smectitic, with very slow permeability and cracks wider than 1 cm and deeper than 30 inches in dry periods [4]. - **Bernow (https://terrabrain.vercel.app/soils/bernow):** deep, well drained sandy and loamy soils from Cretaceous sandstone, mapped in eastern Oklahoma in the Texas Claypan and Western Coastal Plain land resource areas [5]. ### Red River bottomlands **Kiomatia (https://terrabrain.vercel.app/soils/kiomatia)** soils are well drained, rapidly permeable sandy alluvium on natural levees of the Red River floodplain, frequently flooded for brief periods in most years where unprotected [6]. ## Which soils are found here? | Series | Setting | Drainage | Notes | |---|---|---|---| | Hector | Ouachita ridges and mountainsides | Well drained | Rock at 14–20 in; slopes to 60% [3] | | Durant | Cretaceous clay uplands | Moderately well, very slow | Smectitic; deep cracks [4] | | Bernow | Cretaceous sandstone hills | Well drained | Sandy/loamy [5] | | Kiomatia | Red River levees | Well drained, rapid | Frequent brief flooding where unprotected [6] | ## What are the common foundation problems? - **Slope creep and lateral movement** on steep Ouachita hillsides. - **Crawl space moisture and wood decay** in a high-rainfall climate. - **Erosion and washout voids** where heavy runoff reaches foundations. - Shrink-swell movement on Durant-type clays toward Durant. On sloped lots, drainage guidance calls for ground next to a foundation to fall at least 6 inches within 10 feet, and notes that bare soil erodes easily and swales that are too steep can erode [7]. ## Related - Ouachita Folded Rocks (https://terrabrain.vercel.app/geology/ouachita-folded-rocks) - Erosion, Creeks and Slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Slope and Erosion Stabilization (https://terrabrain.vercel.app/repairs/slope-and-erosion-stabilization) - South-Central (Arbuckles & Texoma) (https://terrabrain.vercel.app/regions/south-central-arbuckles-and-texoma) - East-Central (Arkoma) (https://terrabrain.vercel.app/regions/east-central-arkoma) Sources: [1] Soil Matric Suction and Active Zone Depth in Oklahoma (PhD dissertation), Oklahoma State University https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf [2] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [3] Official Series Description – HECTOR Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/H/HECTOR.html [4] Official Series Description – DURANT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DURANT.html [5] Official Series Description – BERNOW Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/B/BERNOW.html [6] Official Series Description – KIOMATIA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KIOMATIA.html [7] Drainage Guidelines (FPA-SC-17-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-17-0.pdf --- # What soils cause foundation problems in southwest Oklahoma? URL: https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains Answer: Southwest Oklahoma has deep clays such as Hollister and Tillman that crack more than 30 inches deep when dry, and Foard, a cracking clay with a sodium-rich subsoil. In short: Southwest Oklahoma has some of the state's most strongly shrink-swell soils. Deep clays such as Hollister and Tillman crack more than 30 inches deep in dry periods [1][2], and Foard, another cracking clay, carries a sodium-rich subsoil [3]. With only about 22 to 32 inches of rain a year in much of the region [1][3], long droughts dry these clays deeply, and wetting from rain, irrigation or leaks makes them swell. **Cities covered:** Lawton, Altus, Chickasha, Anadarko and Frederick. ## What is the climate like? USDA descriptions for the region's clay soils list mean annual precipitation of about 22 to 32 inches and mean annual temperatures of about 57 to 65 °F [1][2][3]. Toward Chickasha on the eastern side, soils list about 35 to 41 inches [5]. Statewide, Oklahoma's climate shifts from humid subtropical in the east to semi-arid in the west [7]. See drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles). ## What is the ground made of? Most of the region lies in the **Central Rolling Red Plains** land resource area, where soils formed in clayey alluvium and Permian red beds [1][3][4]. ### Deep-cracking clays - **Hollister (https://terrabrain.vercel.app/soils/hollister):** very deep, well drained clays with very slow permeability, formed in Pleistocene clay alluvium over Permian sediments. USDA classifies Hollister as a smectitic Vertisol (Typic Haplustert): slickensides begin about 8 to 20 inches deep, and cracks deeper than 30 inches stay open 150 or more days in most years [1]. - **Tillman (https://terrabrain.vercel.app/soils/tillman):** very deep clays from Permian red-bed clay and claystone, with slow permeability, cracks more than 48 inches deep and a COLE (coefficient of linear extensibility, a shrink-swell measure) above 0.06 in the upper 40 inches. The series was established in Tillman County [2]. - **Foard (https://terrabrain.vercel.app/soils/foard):** clays from old granitic outwash of the Wichita Mountains over Permian clays, with very slow permeability, vertic cracking and slickensides, and a **natric** (sodium-rich) subsoil within about 22 to 66 inches, with exchangeable sodium of about 15 to 25 percent in its lower layers. Type location is in Cotton County [3]. Expansive clay changes volume as its water content changes. Shrinkage cracks do not close up perfectly on rewetting, and alternating rainfall and drought produce seasonal cycles of swelling and shrinkage [8]. ### Red-bed claystone and sandstone soils - **Vernon (https://terrabrain.vercel.app/soils/vernon):** moderately deep clays over dense red-bed claystone at 20 to 40 inches, with very slow permeability; lower layers can hold some gypsum, soluble salts and sodium [4]. - **Chickasha (https://terrabrain.vercel.app/soils/chickasha):** well drained loamy soils from Permian sandstone with weakly cemented sandstone at 40 to 60 inches; the series was established in Washita County [5]. See western Permian red beds (https://terrabrain.vercel.app/geology/western-permian-red-beds) and Wichita granite and granite wash (https://terrabrain.vercel.app/geology/wichita-granite-and-granite-wash). ### Gypsum and karst The Oklahoma Geological Survey reports gypsum and shallow salt deposits in many areas of western Oklahoma, and limestone and dolomite karst in the Limestone Hills north of the Wichita Mountains [6]. ## Which soils are most common? | Series | Parent material | Permeability | Shrink-swell indicators | |---|---|---|---| | Hollister | Clay alluvium over Permian | Very slow | Vertisol; cracks > 30 in [1] | | Tillman | Permian red-bed clay | Slow | Cracks > 48 in; COLE > 0.06 [2] | | Foard | Granitic outwash over Permian clay | Very slow | Vertic; sodic subsoil [3] | | Vernon | Red-bed claystone, 20–40 in | Very slow | Salts and sodium at depth [4] | | Chickasha | Permian sandstone, 40–60 in | Moderate | Loamy [5] | ## What are the common foundation problems? - **Perimeter drying settlement** and **tree-root desiccation settlement** on deep-cracking clays. - **Center heave** and leak-related heave when water collects under slabs. - Soil pulled away from the foundation and wide surface cracks in summer. Statewide research estimated active zone depths of about 0.5 to 4 meters, depending on soil and climate [7]. Cracks recorded deeper than 30 to 48 inches in Hollister and Tillman [1][2] show that seasonal drying reaches well below the surface in these soils. ## Related - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Clay Mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Western Permian Red Beds (https://terrabrain.vercel.app/geology/western-permian-red-beds) - Northwest (Gypsum Hills) (https://terrabrain.vercel.app/regions/northwest-gypsum-hills) - South-Central (Arbuckles & Texoma) (https://terrabrain.vercel.app/regions/south-central-arbuckles-and-texoma) Sources: [1] Official Series Description – HOLLISTER Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/H/HOLLISTER.html [2] Official Series Description – TILLMAN Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/T/TILLMAN.html [3] Official Series Description – FOARD Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/F/FOARD.html [4] Official Series Description – VERNON Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/V/VERNON.html [5] Official Series Description – CHICKASHA Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/CHICKASHA.html [6] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [7] Soil Matric Suction and Active Zone Depth in Oklahoma (PhD dissertation), Oklahoma State University https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf [8] Chapter C5 – Expansive Soils, Institution of Civil Engineers / British Geological Survey https://nora.nerc.ac.uk/id/eprint/17002/1/C5_expansive_soils_Oct.pdf --- # What soils cause foundation problems in the Oklahoma City metro? URL: https://terrabrain.vercel.app/regions/okc-metro Answer: Much of the OKC metro has deep red shale clays like Renfrow and Kirkland that shrink and swell; other areas have shallower sandy soils over sandstone. In short: The Oklahoma City metro sits on two very different grounds. Much of the area has deep red clays weathered from Permian shale — such as Renfrow and Kirkland — that crack, shrink and swell with the seasons [1][2]. Other parts have shallower sandy soils over Permian sandstone, such as Stephenville and Darnell [4][5]. Drought and wet cycles drive most movement on the clays. **Cities covered:** Oklahoma City, Edmond, Moore, Norman, Midwest City, Del City, Yukon, Mustang and Choctaw. ## What is the Oklahoma City climate like? USDA descriptions of the metro's main soils list mean annual precipitation of roughly 26 to 40 inches and mean annual temperatures around 56 to 64 °F [2][3][4][5]. Statewide, rainfall ranges from about 17 inches in the far western Panhandle to about 56 inches in the far southeast, with Oklahoma's climate shifting from humid subtropical in the east to semi-arid in the west [8]. Central Oklahoma sits in the middle of that range, so long dry spells and wet springs both occur. See drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles). ## What ground lies under the metro? ### Red shale clays (west, south and central metro) Clay soils formed from Permian-age shale — the Hennessey Shale (https://terrabrain.vercel.app/geology/hennessey-shale-group) and related red beds — cover large parts of the metro. - **Renfrow (https://terrabrain.vercel.app/soils/renfrow)** soils are very deep and well drained, formed from Permian clayey shale. USDA describes them as having vertic properties: cracks at least 5 mm wide open in most years, and linear extensibility (a measure of shrink-swell) is 6 cm or more in the upper 100 cm [1]. - **Kirkland (https://terrabrain.vercel.app/soils/kirkland)** soils are very deep with slow permeability, 40 to 60 percent clay in the subsoil, and intersecting slickensides — polished, grooved surfaces formed when clay swells and shears [2]. The type location is in Logan County [2]. - **Bethany (https://terrabrain.vercel.app/soils/bethany)** soils are very deep, formed in loess or alluvium over Permian shale, with type location in Oklahoma County [3]. An Oklahoma State University study measured cumulative linear extensibility of about 11 cm for Bethany and 12 cm for Kirkland profiles and described the Kirkland soil as "inherently unstable" for engineering uses [6]. ### Sandstone soils (east metro) The east side includes soils formed from Permian sandstone, associated with the Garber Sandstone (https://terrabrain.vercel.app/geology/garber-sandstone): - **Stephenville (https://terrabrain.vercel.app/soils/stephenville)** — moderately deep, with weakly cemented sandstone at 20 to 40 inches; type location in Oklahoma County [4]. - **Darnell (https://terrabrain.vercel.app/soils/darnell)** — shallow, with sandstone at 10 to 20 inches; well to somewhat excessively drained [5]. Neither description lists vertic properties [4][5]. On these sites, water, erosion and fill are often bigger factors than swelling clay, though shale and mudstone layers within the sandstone and the Wellington Formation can produce clay pockets that need site-by-site checking. ## Which soils are common in the metro? | Series | Depth to rock or contact | Drainage | Notes | |---|---|---|---| | Renfrow | > 60 in to shale | Well drained | Vertic; LE ≥ 6 cm [1] | | Kirkland | ~82 in in typical pedon | Well drained, slow permeability | Slickensides; 40–60% clay [2] | | Bethany | Solum > 60 in | Well drained | Loess/alluvium over shale [3] | | Stephenville | 20–40 in to sandstone | Well drained | Sandstone-derived [4] | | Darnell | 10–20 in to sandstone | Well to somewhat excessively drained | Shallow [5] | More series are listed in soil series in the OKC metro. ## What foundation problems are common? - **Perimeter drying settlement** and **tree-root desiccation settlement** on the shrink-swell clays during drought. - **Center heave** and leak-related heave when water collects under slabs on the same clays. - Framing and support problems in older crawl-space homes. Oklahoma research using Mesonet data put statewide **active zone** depths — where soil moisture changes seasonally — at about 0.5 to 4 meters [8]. Repairs such as steel push piers aim to bear below that zone. ## Do earthquakes affect OKC foundations? The Oklahoma Geological Survey lists El Reno–Mustang and central Oklahoma among the state's principal seismic areas [7]. Telling earthquake damage from soil movement is covered in seismic damage vs soil movement and induced seismicity in Oklahoma. ## Related - Soil Series - OKC Metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) - Bedrock - OKC Metro (https://terrabrain.vercel.app/guides/bedrock-okc-metro) - Hennessey Shale (Group) (https://terrabrain.vercel.app/geology/hennessey-shale-group) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro) Sources: [1] Official Series Description – RENFROW Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/R/RENFROW.html [2] Official Series Description – KIRKLAND Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/K/KIRKLAND.html [3] Official Series Description – BETHANY Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/B/BETHANY.html [4] Official Series Description – STEPHENVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/S/STEPHENVILLE.html [5] Official Series Description – DARNELL Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DARNELL.html [6] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [7] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [8] Soil Matric Suction and Active Zone Depth in Oklahoma (PhD dissertation), Oklahoma State University https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf --- # What were Oklahoma's worst recent drought and wet years? URL: https://terrabrain.vercel.app/data/drought-and-wet-years Answer: Oklahoma had near-statewide drought in 2011 and 2012, its wettest month on record in May 2015, and a 2022 drought that dried soils at least 32 inches deep. In short: Oklahoma swung from one of its worst droughts, covering nearly the whole state in 2011 and 2012, to its wettest month on record in May 2015. Another severe drought in 2022 dried soils to at least 32 inches deep. These swings drive the shrinking and swelling of clay under foundations. ## Why does weather history matter for foundations? Oklahoma's expansive clays shrink as they dry and swell as they wet. The upper layer that responds to weather, called the active zone, is estimated at about 0.5 to 4 meters (1.6 to 13 feet) deep across the state, and the shallowest soil responds most strongly to climate [5]. Long droughts tend to show up as settlement, especially at the edges of a house, while sudden wet periods after drought can cause heave (upward movement). See drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) and heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). ## What were Oklahoma's historic drought and wet periods? The U.S. Geological Survey identifies four major 20th-century drought periods in Oklahoma by water year: 1929 to 1941, 1952 to 1956, 1961 to 1972 and 1976 to 1981 [8]. | Period | What the records show | |---|---| | 1910 | Driest year on record statewide: 19.04 inches [6] | | 1950 to 1956 | Driest seven-year period of the century, averaging 28.51 inches a year; 1952 to 1956 averaged 25.81 inches [7] | | May 1957 | Heavy rains ended the drought with major flooding on the Cimarron, Arkansas and Canadian rivers; 1957 became the wettest year of the century at the time [7] | | June to July 2007 | 13.14 inches statewide, the wettest June-July on record since 1895 [9] | | October 2010 to September 2014 | 34 of 48 months drier than normal, with a statewide deficit of over 30 inches [10] | | Summer 2011 | Warmest June-August on record statewide, averaging 86.9°F [6] | | 2015 | Wettest year on record: 53.88 inches (preliminary), 17.38 inches above normal [11] | | March 2018 | Exceptional drought (D4) jumped from 0% to 15% of the state, in the far northwest and Panhandle [12] | | May 2019 | 10.48 inches statewide, third-wettest May since 1895; the Arkansas River crested near or above record levels and Tulsa had its worst flooding since 1986 [13] | | Mid-October 2022 | Extreme and exceptional drought (D3 to D4) reached 86% of the state [14] | ## What were the recent weather extremes? | Period | What the records show | |---|---| | August 2011 | 93% of Oklahoma in extreme to exceptional drought (D3 to D4), with 65% exceptional (D4) [1] | | August 2012 | About 97% in D3 to D4, the highest coverage since the U.S. Drought Monitor began in 2000; D4 at 16% [1] | | May 1 to early August 2012 | Statewide rain averaged 5.87 inches, 7.03 inches below normal, second driest such period since 1921 [1] | | Start of May 2015 | 59% of Oklahoma in drought after about five years of drought [2] | | May 2015 | Wettest month ever for Oklahoma: 14.40 inches statewide, 9.58 inches above normal [2] | | End of May 2015 | Drought coverage fell to 3%, the lowest since October 2010 [2] | | September 2022 | Critically dry soils to at least 32 inches; 64% of the state in D3 to D4 and 94% in D2 or worse [3] | Drought levels come from the U.S. Drought Monitor: D2 is severe, D3 extreme, and D4 exceptional. ### The 2011 to 2012 drought By August 2012, the Mesonet reported 63 days without a daily rain of at least 0.10 inch at its Norman site, and the January through July 2012 statewide average temperature of 63.7°F was on pace to challenge the 1954 record [1]. North-central Oklahoma had its driest May-to-early-August period since 1921, with 3.95 inches [1]. ### May 2015 and 2019: drought to flood May 2015 broke the previous statewide monthly record of 10.75 inches set in October 1941 [2]. Local totals were higher still: - Oklahoma City: 19.48 inches, its wettest month on record, beating June 1989's 14.66 inches [2]. - Tulsa Mesonet station: 15.53 inches for the month [2]. The rains nearly ended a drought that had lasted about five years [2], and 2015 went on to become Oklahoma's wettest year on record [11]. In May 2019, statewide rain of 10.48 inches pushed the Arkansas River near or above record levels from the Kansas line to the Arkansas line, and flooding in Tulsa was the worst since 1986 [13]. See creeks and flood history (https://terrabrain.vercel.app/data/creeks-and-flood-history). After years of drying, a sudden soaking like this can rewet clay along the perimeter of a house first; see perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) and over-lift heave after drought lift (https://terrabrain.vercel.app/causes/over-lift-heave-after-drought-lift). ### 2022 From the September 2022 summary: the Mesonet measured critically dry soils down to at least 32 inches, and severe-or-worse drought covered about 94% of the state on September 27 [3]. By mid-October, extreme to exceptional drought covered 86% of the state [14]. Deep drying like this is associated with perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). ## How much water does Oklahoma lose to evaporation? Evaporation pulls water out of exposed soil and water surfaces during the warm season. OSU Extension fact sheet BAE-1529 reports average May to October evaporation from shallow water bodies [4]: | Region (climate division) | May to October evaporation | |---|---| | Panhandle (CD-1) | 44.4 inches [4] | | West central and southwest (CD-4, CD-7) | 40.9 and 40.3 inches [4] | | Northeast (CD-3) | 30.1 inches [4] | | Southeast (CD-9) | 28.1 inches [4] | Losses increase from east to west and can be higher in drought years [4]. Higher evaporation in western Oklahoma means soils there face stronger drying than in the east. ## Related - Active zone and drought depth (https://terrabrain.vercel.app/data/active-zone-and-drought-depth) - Drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) - Seasonal movement calendar (https://terrabrain.vercel.app/guides/seasonal-movement-calendar) - Mesonet for foundation pros (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros) - Cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally) - Moisture index by city (https://terrabrain.vercel.app/data/moisture-index-by-city) Sources: [1] Extreme to Exceptional Drought Covers Most of Oklahoma, Oklahoma Mesonet https://mesonet.org/images/news/Extreme%20to%20Exceptional%20Drought%20Covers%20Most%20of%20Oklahoma.pdf [2] Oklahoma Monthly Climate Summary, May 2015, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2015/MCS_May_2015.pdf [3] Oklahoma Monthly Climate Summary, September 2022, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2022/MCS_September_2022.pdf [4] Evaporation Losses from Shallow Water Bodies in Oklahoma (BAE-1529), Oklahoma State University Extension https://extension.okstate.edu/fact-sheets/evaporation-losses-from-shallow-water-bodies-in-oklahoma [5] Soil matric suction and active zone depth in Oklahoma, Oklahoma State University (SHAREOK repository) https://shareok.org/handle/11244/54639 [6] Oklahoma State Climate Records, Oklahoma Climatological Survey https://climate.ok.gov/index.php/site/page/state_records [7] Oklahoma Weather Timeline: 1950-1959, Oklahoma Climatological Survey https://climate.ok.gov/index.php/climate/weather_timeline/1950_1959 [8] Hydrologic Drought of Water Year 2006 Compared with Four Major Drought Periods of the 20th Century in Oklahoma (SIR 2008-5199), U.S. Geological Survey https://pubs.usgs.gov/publication/sir20085199 [9] Oklahoma Monthly Climate Summary, July 2007, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2007/MCS_July_2007.pdf [10] Oklahoma Monthly Climate Summary, September 2014, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2014/MCS_September_2014.pdf [11] Oklahoma Monthly Climate Summary, December 2015, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2015/MCS_December_2015.pdf [12] Oklahoma Monthly Climate Summary, March 2018, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2018/MCS_March_2018.pdf [13] Oklahoma Monthly Climate Summary, May 2019, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2019/MCS_May_2019.pdf [14] Oklahoma Monthly Climate Summary, October 2022, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2022/MCS_October_2022.pdf --- # When do I need an engineer for foundation problems in Oklahoma? URL: https://terrabrain.vercel.app/guides/working-with-engineers Answer: A licensed engineer gives an independent, sealed opinion on the cause and needed repair. Lenders, insurers and buyers may ask for an engineer's report. In short: A licensed professional engineer (PE) gives an independent, sealed opinion on what is causing foundation movement and what repair is needed. In Oklahoma, engineers are licensed by the State Board of Licensure for Professional Engineers and Land Surveyors, whose guidelines say the engineer, not the repair company, controls any engineered repair plan [1]. Buyers may hire engineers, and lenders may require a professionally prepared report on abnormal settlement [5][6]. ## When is an engineer commonly involved? - **Home sales.** Oklahoma's standard sale contract lets buyers hire registered professional engineers and lists a structural inspection as a separate investigation [5]. - **Mortgage conditions.** When an appraisal shows abnormal settlement, Fannie Mae requires proof of correction or a professionally prepared report that the condition poses no threat of structural damage [6]. - **Insurance disputes.** Causation often turns on an engineer's analysis. In one federal flood-insurance appeal, an engineer attributed exterior cracks to long-term drying shrinkage and differential soil movement, and the denial was upheld [7]. - **Home inspection referrals.** Oklahoma inspectors must describe signs of foundation movement but are not required to find causes, choose repair methods or perform engineering, so reports recommend "further evaluation" by a qualified professional [4]. - **Complex conditions**, such as suspected heave, bowing basement walls, slopes or sinkholes. See heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) and gypsum karst and sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes). ## What is the difference between structural and geotechnical engineers? | | Geotechnical engineer | Structural engineer | |---|---|---| | Focus | Soil and rock | The building's load-carrying parts | | Typical work | Borings, lab tests, foundation design values, expansive-soil mitigation | Load paths, beam and pier layouts, repair design, evaluations | | Output | Written geotechnical report [3] | Sealed evaluation or repair plan [1] | A geotechnical engineer investigates site soils and recommends site preparation and foundation design; a written geotechnical report typically includes soil logs, water table, foundation recommendations, expansive-soil mitigation and expected movements [3]. Where no site testing is done, designs may rely on regional soil surveys such as the USDA NRCS Web Soil Survey [3]. Any licensed PE with board-recorded structural competence may do structural engineering in Oklahoma. The separate **S.E.** title is reserved for licensed PEs the board has authorized, and is required for analysis and design of defined "significant structures" [2]. ## How does Oklahoma's board expect repair engineering to work? The engineering board's compliance guidelines for foundation repair companies set out these steps [1]: 1. A PE (directly or through a repair company) takes responsibility for the project. 2. The PE visits the site or directs a technician to collect data following the PE's instructions. 3. The PE decides whether more information is needed, writes a repair plan, or states that no repair or a non-pier repair is needed. 4. Plans and "no repair" statements must be signed, sealed and dated. 5. The repair company carries out the PE's plan. 6. A PE may issue an engineering completion letter only if present during the work or given sufficient information by a technician under the PE's responsible charge. A repair company may send its own completion letter but may not call it an engineering completion letter. 7. The PE keeps a design file with criteria, calculations, changes, the reasons for repair and the cause of damage, and must report to the board if a company overrules the PE and endangers the public. ## What helps an engineer evaluate a house? - An elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) with the raw readings - A crack map with dated photos - The soil series from the NRCS soil survey (see soil series in the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro)) - The foundation type, age and any past repairs - Pier logs (depth and pressure) after any installation ## Related - Inspection protocol (https://terrabrain.vercel.app/guides/inspection-protocol) - Real estate disclosure and inspections (https://terrabrain.vercel.app/rules/real-estate-disclosure-and-inspections-foundation-issues-in-oklahoma) - Insurance claims (https://terrabrain.vercel.app/rules/insurance-claims) - Seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement) - Soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values) - What affects the cost of foundation repair in Oklahoma? (https://terrabrain.vercel.app/guides/what-affects-foundation-repair-cost) Sources: [1] The Board's Bulletin, Vol. 21, Issue 4 (2007): Compliance Guidelines for Foundation Repair Companies, Oklahoma State Board of Licensure for Professional Engineers and Land Surveyors https://oklahoma.gov/content/dam/ok/en/pes/documents/bulletin/Newsletter_Volume21_Issue62.pdf [2] Structural Engineer Designation, Oklahoma State Board of Licensure for Professional Engineers and Land Surveyors https://oklahoma.gov/pes/apply-for-a-license/pe-se-applications/structural-engineer-designation.html [3] Beyond the Building Code: Expansive Soils, Journal of the National Academy of Forensic Engineers https://journal.nafe.org/ojs/index.php/nafe/article/download/975/924/4846 [4] OAC 158:70 Home Inspector rules, 158:70-1-3 Standards of workmanship and practice, Oklahoma Construction Industries Board https://oklahoma.gov/content/dam/ok/en/cib/documents/your-industry/home-inspector/title_158_chapter_70.pdf [5] 2026 Residential Sale Contract, Oklahoma Real Estate Commission https://oklahoma.gov/content/dam/ok/en/orec/documents/contracts-and-forms-page/2026-contract-forms/2026%20Residential%20Sale.pdf [6] B4-1.3-06, Property Condition and Quality of Construction of the Improvements, Fannie Mae https://selling-guide.fanniemae.com/sel/b4-1.3-06/property-condition-and-quality-construction-improvements [7] Earth Movement Decision Upheld, FEMA National Flood Insurance Program https://www.floodsmart.gov/recover/how-to-write-your-appeal/earth-movement-decision-upheld --- # When do Oklahoma foundations move during the year? URL: https://terrabrain.vercel.app/guides/seasonal-movement-calendar Answer: Clay swells in wet springs, shrinks in hot, dry midsummer and partly rewets with fall rains, so cracks often open in late summer and narrow in spring. In short: Oklahoma's clay soils follow the weather through the year: they swell during wet springs, shrink in hot, dry midsummer, and partly rewet with fall rains. Foundation cracks often open in late summer and narrow in spring. The exact timing shifts from year to year with drought and wet spells. ## Why does the calendar matter? Expansive clay swells when water enters and shrinks when it dries, and uneven moisture under a house causes differential movement [7]. Because Oklahoma's rainfall and evaporation follow a seasonal rhythm, so does much foundation movement. A crack that closes in April and reopens in August is a classic sign of moisture-driven movement; see cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally). ## What is the general seasonal pattern? | Season | Weather pattern | Typical soil behavior | |---|---|---| | Winter (Dec–Feb) | Shorter, milder winters than the northern Plains; freezing rain occurs regularly, especially in the southeast [1][2] | Low evaporation; frozen soil is rare and brief [1] | | Spring (Mar–May) | Rainfall rises; three-fourths of tornadoes occur April–June [1] | Soil rewets, clay swells, cracks may narrow | | Late spring to early summer (May–Jun) | Often very wet; flooding most common in the rainy spring and fall months [1] | Highest moisture; perched water and edge lift possible | | Midsummer (Jul–Aug) | Rainfall relaxes in July and August; long, hot summers [1] | Fast drying, perimeter shrinkage, cracks widen | | Fall (Sep–Nov) | A secondary rainy and severe-weather season [1] | Partial rewetting | Most of Oklahoma's precipitation falls in spring and summer, and the state ranges from under 20 inches a year in the west to more than 50 in the southeast [2]. Average annual lake evaporation, from about 48 inches in the east to 65 inches in the southwest, exceeds average rainfall in those areas [1]. That imbalance is why soils dry so quickly in hot spells. ## How much does it vary year to year? The seasonal pattern is a tendency, not a rule: - **Wet years:** May and June 2019 together averaged 15.52 inches statewide, the fifth-wettest such period on record [5]. - **Dry years:** In 2011, Tulsa had very little rain in June and July, and the state had its third-driest summer on record [6]. More on multi-year swings is on the drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) page. ## How can soil moisture be tracked through the year? The Oklahoma Mesonet reports daily soil moisture as a fractional water index from 0 (very dry) to 1 (very wet) [3][4]. A few points from the sources: - Soil moisture falls faster in hot, dry periods [3]. - Readings at several depths show how far rain has soaked in [3]. - Winter maps can have gaps because sensors can't read frozen soil [4]. Recording the date, recent rainfall and soil moisture with each elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) makes it easier to compare measurements taken in different seasons. Details are on the Mesonet guide (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros). ## Related - Drought and Wet Cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) - Mesonet for Foundation Pros (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Freeze-Thaw and Frost Depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) - Monitoring Program (https://terrabrain.vercel.app/repairs/monitoring-program) Sources: [1] Oklahoma Climate, Oklahoma Climatological Survey https://www.ou.edu/ocs/oklahoma-climate [2] Oklahoma - State Climate Summaries 2022, NOAA National Centers for Environmental Information https://statesummaries.ncics.org/chapter/ok/ [3] Tracking Drought Using Soil Moisture Information (BAE-1541), Oklahoma State University Extension https://extension.okstate.edu/fact-sheets/tracking-drought-using-soil-moisture-information.html [4] 1-day Average 4-inch Bare Soil Fractional Water Index, Oklahoma Mesonet https://mesonet.org/weather/soil-moisture/1-day-average-4-inch-bare-soil-fractional-water-index [5] Oklahoma Monthly Climate Summary: June 2019, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2019/MCS_June_2019.pdf [6] 2011 Drought, National Weather Service, Tulsa https://www.weather.gov/tsa/weather-event_2011drought [7] Residential House Foundations on Expansive Soils in Changing Climates, HUD Office of Policy Development and Research (Cityscape, Vol. 25 No. 1) https://www.huduser.gov/PORTAL/periodicals/cityscape/vol25num1/ch10.pdf --- # When is cosmetic crack repair enough? URL: https://terrabrain.vercel.app/repairs/cosmetic-repair-only Answer: When cracks come from something other than foundation movement, or movement has stopped. If soil is still moving the house, cosmetic repairs reopen. In short: Cosmetic repair means fixing drywall, masonry, trim, doors and flooring without structural foundation work. It is the complete repair when cracks come from something other than foundation movement, or when movement has stopped. When an active soil mechanism is still moving the house, cosmetic repairs reopen, which is why the movement trend is checked first. ## When is cosmetic repair the whole answer? Not every crack means the foundation is moving. Several common causes of cracking leave the foundation sound: | Cause | Why it is not foundation movement | Page | |---|---|---| | Concrete shrinkage | Concrete shrinks as it dries; adding 2 gallons of water per cubic yard increases shrinkage about 20% [2] | Material shrinkage and thermal cracking (https://terrabrain.vercel.app/causes/material-shrinkage-and-thermal-cracking-mimic) | | Floating slab cracking | Guidance for slabs on swelling soils states that some cracking of floating slabs should be expected [4] | Visible slab cracks (https://terrabrain.vercel.app/signs/visible-slab-cracks) | | Roof truss uplift | Movement in the roof framing above the ceiling, not in the foundation | Truss uplift (https://terrabrain.vercel.app/causes/truss-uplift-mimic) | | Drywall fasteners and tape | Defects in the finish materials themselves | Nail pops and tape-joint cracks (https://terrabrain.vercel.app/signs/nail-pops-and-tape-joint-cracks) | | Movement that has stopped | The foundation moved in the past but is no longer moving | Monitoring confirms it | Truss uplift and drywall fastener problems look like foundation distress but come from the framing above or from the finishes themselves; the linked pages explain how each is recognized. ## Why does the movement trend decide? Expansive soils, usually clays, can cause excessive cracking of floors, walls and foundations as they shrink and swell [5]. In clay, moisture change follows wet and dry seasons and can reach from 3 to 40 ft deep [3]. Researchers describe corner supports that are lifted in the wet season and lose grip and drop in the dry season [3]. A crack that closes in spring and reopens in August fits that cycle. Because of that seasonal cycle, one inspection cannot show whether a house is: - **Stable:** small seasonal movement with no overall trend. - **Seasonally active:** movement that repeats each year, in step with soil moisture [3]. - **Progressively moving:** steady one-direction change, which points to an active mechanism such as settlement or a leak. Readings repeated across seasons, as described in the monitoring program (https://terrabrain.vercel.app/repairs/monitoring-program) and elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) pages, sort a house into one of these groups. Home inspection standards treat cracked drywall, cracked brick, out-of-square door frames and unlevel floors as signs of possible movement to report, and leave structural judgment out of the inspection [1]. ## What does cosmetic repair include? - Drywall crack repair and re-taping. - Brick and mortar repair (repointing) and sealing of veneer cracks. - Trim, baseboard and crown molding adjustment. - Door and window adjustment: re-hanging, planing or re-setting strikes. - Floor covering repair over slab cracks. - Keeping cracks and separations filled in the paving or moisture barriers around the foundation, which engineering guidance for swelling soils lists as a maintenance item [4]. ## When is cosmetic repair a supporting step? Cosmetic work also follows structural repair. After movement from center heave, a leak or settlement has been stopped, finishes are repaired as the last step. Finishing first and stopping movement later risks repeating the work, since cracks reopen while the mechanism is active. Cracks that open and close with the seasons are covered in detail in cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally). ## Related - Monitoring Program (https://terrabrain.vercel.app/repairs/monitoring-program) - Material Shrinkage and Thermal Cracking (Mimic) (https://terrabrain.vercel.app/causes/material-shrinkage-and-thermal-cracking-mimic) - Truss Uplift (Mimic) (https://terrabrain.vercel.app/causes/truss-uplift-mimic) - Cracks That Open and Close Seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally) - Elevation Surveys (https://terrabrain.vercel.app/guides/elevation-surveys) Sources: [1] InterNACHI Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [2] Inspecting the Concrete, Cracking, and Water Connection (IRC R406), InterNACHI https://www.nachi.org/concrete-cracking-water-connection.htm [3] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [4] Home Construction on Shrinking and Swelling Soils (Special Publication 11), Colorado Geological Survey (Holtz and Hart, 1978) https://coloradogeologicalsurvey.org/wp-content/uploads/woocommerce_uploads/SP-11.pdf [5] Guide to Use of the FHA Soil PVC Meter (HUD Handbook 4075.15), U.S. Department of Housing and Urban Development https://www.hud.gov/sites/documents/407515hsgh.pdf --- # When is foundation or slab replacement needed? URL: https://terrabrain.vercel.app/repairs/slab-or-foundation-replacement Answer: Replacement is the most disruptive repair, used when piers, lifting and moisture control cannot restore the foundation, and it follows an engineered design. In short: Slab or foundation replacement means removing damaged foundation elements and building new ones to an engineered design. It is the most disruptive repair and is generally used only when the existing foundation cannot be restored with piers, lifting and moisture control. On expansive clay, replacement designs often separate the floor from the soil — for example, a structural slab on deep piers with a void space beneath it [1][2]. ## When is replacement considered? Replacement is generally a last resort for severe cases, such as: - Major original construction deficiencies (https://terrabrain.vercel.app/causes/original-construction-deficiency) — for example, a slab too thin, under-reinforced or built on unsuitable fill. - Badly damaged post-tensioned slabs (https://terrabrain.vercel.app/foundations/post-tensioned-slabs) after tendon failure (https://terrabrain.vercel.app/causes/post-tension-tendon-failure). - Exterior slabs and flatwork broken beyond re-leveling — see flatwork and exterior slabs (https://terrabrain.vercel.app/foundations/flatwork-and-exterior-slabs). ## Why do soil conditions drive the design? Clay with a linear extensibility (an NRCS measure of shrink-swell) of more than 3% can shrink and swell enough to damage buildings, and special design is often needed [5]. Oklahoma research estimated the **active zone** — the depth of seasonal moisture change — at about 0.5 to 4 meters statewide [6]. A new foundation that rests on the same soil can move in the same way as the old one, so the design typically either reaches below that zone or isolates the floor from it. A geotechnical report for such designs reports the depth of moisture change, the probable rise and fall of the ground surface and, for suspended slabs, the recommended void height and maximum possible heave [3]. Borings for residential work are recommended to reach at least 20 feet, and at least 25 feet on wooded lots with cohesive soil [3]. ## What replacement foundation options exist? An engineering committee comparison of foundation systems on expansive clay describes the following [1]: | System | How it works | Notes from the comparison | |---|---|---| | Structural slab with void space on deep foundations | 4–8 in slab spans grade beams on piers, cast over void forms | Usually outperforms other foundation types; higher cost; forms must leave enough void | | Structural wood floor over crawl space on deep foundations | Raised floor with at least 18 in clearance | Usually highest cost; reduces vertical movement if enough crawl space is kept; plumbing accessible; needs ventilation and drainage | | Stiffened slab on grade (post-tensioned or rebar) | Slab with deepened beams resting on soil | Most common in the Houston area; may move more vertically than slabs on deep foundations; not designed to prevent tilt | | Uniform thickness slab without beams | Flat slab on soil | Faster to build; potentially more differential movement than stiffened slabs; suited to soils with low potential for volume change | Deep foundations under these systems are often drilled piers, which should have vertical reinforcement to resist tension from swelling soil gripping the shaft [1]. See drilled bell-bottom piers (https://terrabrain.vercel.app/repairs/drilled-bell-bottom-piers). ## What are void spaces and why are they used? A **void space** is a deliberate gap between swelling soil and a suspended slab or beam. It is formed with cardboard (corrugated paper) forms that hold up the wet concrete and later break down, or with plastic or metal forms [2]. - Void depth typically ranges from about 1 to 24 inches, set from the soil's potential upward movement [2]. - For isolated foundations on deep supports, voids are recommended under both grade beams and slab areas unless analysis shows otherwise [2]. - Gravel or plastic sheeting should not be placed under degradable paper forms, because it keeps them from breaking down [2]. Leaving a void matters because piers not tied to the foundation cannot resist uplift; engineering guidance recommends raising the floor above the soil's maximum potential rise or leaving a void beneath the slab [4]. ## What are the limitations? - Highest disruption of any repair, since floors, plumbing and finishes over the replaced area are removed and rebuilt. - Requires engineered design, permits and inspection — see codes and permits (https://terrabrain.vercel.app/rules/codes-and-permits) and working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). - Cost is driven by the area replaced, pier count and depth, access, and the restoration of plumbing and finishes. ## Related - Slab on Grade (https://terrabrain.vercel.app/foundations/slab-on-grade) - Post-Tensioned Slabs (https://terrabrain.vercel.app/foundations/post-tensioned-slabs) - Drilled Bell-Bottom Piers (https://terrabrain.vercel.app/repairs/drilled-bell-bottom-piers) - Method Selection Matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix) - Working with Engineers (https://terrabrain.vercel.app/guides/working-with-engineers) Sources: [1] Foundation Design Options for Residential and Other Low-Rise Buildings on Expansive Soils (FPA-SC-01-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-01-0.pdf [2] Specification and Application of Void Spaces Below Concrete Foundations (FPA-SC-11-1), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-11-1.pdf [3] Recommended Practice for Geotechnical Explorations and Reports (FPA-SC-04-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-SC-04-0.pdf [4] Post Foundation Repair Performance of Residential and Other Low-Rise Buildings on Expansive Soils (FPA-RC-01-0), Foundation Performance Association https://foundationperformance.org/projects/FPA-RC-01-0.pdf [5] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [6] Soil matric suction and active zone depth in Oklahoma, Oklahoma State University (ShareOK) https://shareok.org/handle/11244/54639 --- # Which foundation pier type is right for an Oklahoma home? URL: https://terrabrain.vercel.app/repairs/method-selection-matrix Answer: Pressed concrete, steel push, helical and drilled piers differ in installation and bearing; on clay, the key is reaching below soil that swells and shrinks. In short: The four common pier types differ in how they are installed, what they bear on, and how each pier's installation is checked. On Oklahoma clay the deciding question is whether a pier reaches below the soil that swells and shrinks with the seasons. Non-pier methods such as drainage and moisture control address the water that drives that movement, and are often paired with piers. ## How do the pier types compare? Trade words: **underpinning** means adding support under an existing foundation; **refusal** is the point where a pier will not go deeper under the applied force; **reaction** is the weight a hydraulic jack pushes against. | Factor | Pressed concrete piles | Steel push piers | Helical piers | Drilled bell-bottom piers | |---|---|---|---|---| | What it is | Short precast concrete cylinders stacked and pressed into the soil | Steel pipe sections driven down with a hydraulic jack | Steel shaft with screw plates turned into the soil | Concrete column cast in an augered hole with a widened base | | Uses building weight to install | Yes | Yes | No | No | | How each pier is checked | Pressure at refusal | Hydraulic pressure recorded at each pier [1] | Final torque recorded at each pier | Design depth and inspection of the hole | | Depth set by | Refusal, often in stiff clay | Refusal on firm strata | Target torque and depth | Engineered design below the seasonal moisture zone [2] | | Uplift resistance | Little | Little | Yes, when plates are below the moving clay | Yes, from the bell [2] | | Steel corrosion | Not applicable | Steel in soil | Steel in soil | Not applicable | Torque as a measure of soil strength also appears in federal manufactured housing rules, which classify soils by torque-probe readings [6]. ## What does Oklahoma installation data show? Oklahoma steel push pier installation records give these working figures [1]: - Typical depth **8 to 16 ft** at exterior footings and **5 to 13 ft** at interior locations. - At one large Tulsa site, **396 piers** reached a median depth of **12 ft**, with the middle half between 9 and 14 ft and a full range of 2 to 40 ft, at a median of about **9,000 psi**. - Field standard of **6,000 psi minimum**, with 8,000 to 10,000 psi as the target range. - Spacing usually about **7 ft** between piers. - Pressed concrete piles in the same records usually stopped at **5 to 12 ft**. ## Why does depth matter on clay? Seasonal moisture change can extend from 3 to 40 ft deep [3]. Engineering guidance calls for piers on swelling soil to extend well below that zone and to be anchored against uplift [2]. Researchers describe six-foot piers that handled normal annual fluctuations but did not appear adequate over a two-year drought followed by an extremely wet year [3]. A pier that stops at refusal in stiff clay during a dry spell may still be inside the moving layer, which is why depth records are compared with expected active-zone depths; see active zone and drought depth (https://terrabrain.vercel.app/data/active-zone-and-drought-depth) and depth to rock from borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings). For drilled shafts in Oklahoma's weak rock, a state-funded study load-tested eight shafts at two sites and published design relations for tip and side resistance [5]. ## What questions guide the decision? 1. **Heave or settlement?** Piers hold up settling areas; heave calls for other methods. See heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). 2. **Is a water source still active?** Grading, gutters and leaks are addressed first; the code calls for grade to fall at least 6 in within 10 ft of the foundation [7]. See drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). 3. **Is the structure heavy enough to push against?** If not, piers that do not need reaction weight apply. 4. **How deep is firm bearing?** As a minimum, NRCS soil survey reports help determine whether expansive soils are present [4]. 5. **Is resistance to upward pull needed?** Piers anchored in non-swelling soil, for example by belling the bottoms, provide it [2]; helical plates set below the moving clay are another option. 6. **What records are needed?** Push piers log pressure and helical piers log torque per pier. 7. **Access:** yard space, interior finishes and crawl clearance limit which equipment fits. ## What non-pier methods are used? | Situation | Method | |---|---| | Voids under slabs, settled flatwork | Slabjacking and polyurethane | | Sagging crawl space floors | Crawl space repair (https://terrabrain.vercel.app/repairs/crawl-space-repair) | | Bowing basement walls | Basement wall repair | | Moisture-driven movement in high-swell clay | Chemical soil stabilization, root barriers and moisture control | | Water at the foundation | Drainage solutions | Every mechanism is matched to these methods in the mechanism-method matrix (https://terrabrain.vercel.app/repairs/mechanism-method-matrix). ## Related - Mechanism-Method Matrix (https://terrabrain.vercel.app/repairs/mechanism-method-matrix) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Helical Piers (https://terrabrain.vercel.app/repairs/helical-piers) - Drilled Bell-Bottom Piers (https://terrabrain.vercel.app/repairs/drilled-bell-bottom-piers) - Pressed Concrete Piles (https://terrabrain.vercel.app/repairs/pressed-concrete-piles) - Loads Pier Spacing and Capacity (https://terrabrain.vercel.app/guides/loads-pier-spacing-and-capacity) Sources: [1] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data [2] Home Construction on Shrinking and Swelling Soils (Special Publication 11), Colorado Geological Survey (Holtz and Hart, 1978) https://coloradogeologicalsurvey.org/wp-content/uploads/woocommerce_uploads/SP-11.pdf [3] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [4] Foundations on Expansive Soils – Residential (IHB TB 10-01), Texas Department of Licensing and Regulation https://tdlr.texas.gov/ihb/pdf/TB1001.pdf [5] Probabilistic Approach for Design of Drilled Shafts Socketed in Weak Rock in Oklahoma (FHWA-OK-23-02), Oklahoma Department of Transportation and Federal Highway Administration (University of Missouri) https://rosap.ntl.bts.gov/view/dot/89161 [6] 24 CFR Part 3285 – Model Manufactured Home Installation Standards (Code of Federal Regulations, 2020), U.S. Government Publishing Office https://www.govinfo.gov/content/pkg/CFR-2020-title24-vol5/pdf/CFR-2020-title24-vol5-part3285.pdf [7] Foundation Fundamentals: Inspecting Load Paths and Water Paths (IRC R401.2 & R401.3), InterNACHI https://nachi.org/foundation-load-water.htm --- # Which foundation repair method fits each cause of movement? URL: https://terrabrain.vercel.app/repairs/mechanism-method-matrix Answer: Each repair method only works for some causes. Piers can hold up settlement, but they cannot fix heave or water problems. In short: Foundation movement has many causes, and each repair method only works on some of them. This table matches 26 causes, called mechanisms, to the methods that address them directly, the methods that support the main repair, and the methods that do not fit. The key split is between settlement, which piers can hold up, and heave or water problems, which piers cannot fix. ## How do you read the table? - **Primary:** the method acts on the cause or carries the load the cause has taken away. - **Supporting:** the method helps, protects the main repair, or controls part of the cause, but is not enough alone. - **Not suitable:** the method works against the cause, cannot act on it, or treats a symptom while the cause continues. "Piers" below means underpinning such as steel push piers, helical piers, pressed concrete piles and drilled piers. Each method has its own page; the decision factors between pier types are in the method selection matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix). ## What is the physical logic behind the table? - **Settlement vs. heave:** swelling clay lifts lightly loaded foundations, and corners tend to rise relative to the center of a slab [1]. Piers push up from below, so they suit settlement but cannot pull a heaved area down. - **Depth:** piers work against seasonal clay movement only when they reach below the zone of seasonal moisture change and are anchored against uplift [2]; that zone can range from 3 to 40 ft deep [1]. - **Water:** the code requires grade to fall at least 6 in within 10 ft of the foundation [3], and lawn watering, leaking pipes and pools create damaging moisture differences [1]. An engineering analysis compared how a slab moves and bends with and without a water line leak beneath it [8]. - **Soil treatment:** lime cut swell about 95% at 3% in one Oklahoma soil and raised it 1,237% in a high-sulfate soil [4], because of ettringite formation [5]. - **Crawl spaces:** moisture is controlled by ground cover, ventilation or conditioning, and drainage under the code's crawl space rules [6]. - **Basement walls:** the code designs walls for sideways soil pressure, with the highest design values for the clay soil classes it lists [7]; soil treatment does not reinforce a wall. ## Which methods fit which causes? | Mechanism | Primary | Supporting | Not suitable | |---|---|---|---| | Perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) | Steel push piers, helical piers | Pressed concrete, drilled piers, soil stabilization, drainage, moisture control, monitoring | Slab lifting by injection | | Perimeter wetting heave | Drainage, monitoring | Soil stabilization, moisture control | Steel push piers, slab lifting | | Center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) | Leak repair, monitoring | Steel push piers (raise low perimeter), soil stabilization, drainage, cosmetic repair | Interior piers, slab lifting | | Leak-induced heave | Leak repair, monitoring | Cosmetic repair after movement stops | Slab lifting | | Tree-root drying settlement | Steel push piers, helical piers, moisture control | Pressed concrete, monitoring, tree management | | | Post-tree-removal heave | Monitoring | Soil stabilization, drainage | Steel push piers | | Fill consolidation | Steel push piers, helical piers | Drilled piers, interior piers, slab lifting, void grouting | Pressed concrete | | Soft soil consolidation | Steel push piers, helical piers | Drilled piers | | | Hydrocollapse | Steel push piers, helical piers, leak repair | Void grouting, drainage | | | Erosion and washout voids | Slab lifting, void grouting, drainage, leak repair | Slope and erosion work | | | Slope creep | Helical piers, slope stabilization | Steel push piers, drainage | | | Frost heave | Helical piers | Slab lifting, drainage | | | Karst and sinkholes | Void grouting, drainage | Steel push piers, drilled piers | | | Earthquake shaking | Cosmetic repair | Monitoring | Steel push piers | | Wall pressure (lateral earth, swell, water) | Basement wall repair, drainage | | Soil stabilization | | Crawl moisture and wood decay | Crawl repair, encapsulation, drainage | | | | Crawl support and framing failure | Crawl repair | Helical piers, encapsulation | | | Original construction deficiency | | Steel push piers, helical piers, replacement | | | Post-tension tendon failure | | Monitoring, replacement | | | Concentrated load settlement | Steel push piers, helical piers | | | | Movement at additions | Steel push piers, helical piers | Monitoring | | | Pier uplift after repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair) | Helical piers, drilled piers | Steel push piers, soil stabilization, drainage | | | Over-lift heave after drought lift | Monitoring | Steel push piers, crawl repair, drainage | | | Truss uplift (mimic) | Cosmetic repair | | Steel push piers | | Material shrinkage (mimic) | Cosmetic repair | | Steel push piers | | Vibration cracking (rare) | Cosmetic repair | Monitoring | | A **mimic** is a crack pattern that looks like foundation movement but comes from something else, such as roof framing or concrete shrinkage; see cosmetic repair only (https://terrabrain.vercel.app/repairs/cosmetic-repair-only). Whether a house is settling or heaving is worked out in heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). ## Related - Method Selection Matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Symptom Matrix (https://terrabrain.vercel.app/guides/symptom-matrix) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Chemical Soil Stabilization (https://terrabrain.vercel.app/repairs/chemical-soil-stabilization) - Monitoring Program (https://terrabrain.vercel.app/repairs/monitoring-program) Sources: [1] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [2] Home Construction on Shrinking and Swelling Soils (Special Publication 11), Colorado Geological Survey (Holtz and Hart, 1978) https://coloradogeologicalsurvey.org/wp-content/uploads/woocommerce_uploads/SP-11.pdf [3] Foundation Fundamentals: Inspecting Load Paths and Water Paths (IRC R401.2 & R401.3), InterNACHI https://nachi.org/foundation-load-water.htm [4] Engineering Properties of Stabilized Subgrade Soils for Implementation of the AASHTO 2002 Pavement Design Guide (FHWA-OK-08-10), Oklahoma Department of Transportation (Solanki, Khoury and Zaman, University of Oklahoma) https://www.odot.org/hqdiv/p-r-div/spr-rip/library/reports/fhwa-ok0810.pdf [5] Calcium-Based Stabilizer Induced Heave in Oklahoma Sulfate-Bearing Soils (FHWA-OK-11-03), Oklahoma Department of Transportation (Cerato, Miller, Elwood-Madden, Adams and Varnier) https://rosap.ntl.bts.gov/view/dot/23202/dot_23202_DS1.pdf [6] Inspecting Under-Floor Crawl Spaces: A Guide for Home Inspectors (2024 IRC Section R408), InterNACHI https://www.nachi.org/under-floor-crawl-space.htm [7] 2007/2008 Proposed Changes to the International Residential Code (RB101–RB143), International Code Council https://www.iccsafe.org/cs/codes/Documents/2007-08cycle/ProposedChanges/V2_RB101-143.pdf [8] Investigation of a leaking water line beneath residential foundation on expansive soils, American Society of Civil Engineers, Geotechnical Special Publication 147 (Michigan Technological University Digital Commons) https://digitalcommons.mtu.edu/michigantech-p/8670 --- # Which soil series are found under Oklahoma homes? URL: https://terrabrain.vercel.app/soils/soil-series-index Answer: This index lists 55 Oklahoma soil series by region; find the soil under a house with the free Web Soil Survey map, then read the matching series page. In short: This index lists the 55 Oklahoma soil series that have their own page on this site, grouped by region of the state. Each page summarizes the USDA's Official Series Description for that soil and explains what its depth, drainage and clay content mean for foundations. To find the soil under a specific house, use the free Web Soil Survey map, then read the matching series page. ## How does soil series information work? The USDA Natural Resources Conservation Service (NRCS) publishes an Official Series Description (OSD) for every named soil series, searchable by name or list [1]. An OSD gives a soil's classification, parent material, typical layers, drainage, depth to rock and the area where it is mapped. Web Soil Survey is NRCS's online map of soil data from the National Cooperative Soil Survey, and it covers more than 95 percent of U.S. counties [2]. It lets users define an area of interest, view soil maps and explore soil data and suitability for particular uses [2]. A soil map is a starting point; it does not replace a site investigation on a single lot. ## How is shrink-swell read? NRCS rates shrink-swell using linear extensibility percent (LEP), the change in length of a soil clod as it dries from a moist to a dry state [4]. The classes are [3]: | LEP | Shrink-swell class | |---|---| | Under 3% | Low | | 3-6% | Moderate | | 6-9% | High | | More than 9% | Very high | NRCS notes that when LEP is above 3 percent, shrinking and swelling can damage buildings and roads, and special design is commonly needed [3]. Some OSDs give the same value as COLE, the coefficient of linear extensibility, which is LEP written as a fraction [4]. For example, the Summit (https://terrabrain.vercel.app/soils/summit) OSD lists a COLE of 0.09 or more, at the boundary of the very high class [8]. ### Clues in the soil name - **Vertic or Udertic:** Vertisols and vertic soils shrink and form deep cracks when dry and swell when wet, and the University of Idaho notes this creates serious engineering problems [5]. - **Smectitic:** Soils with smectite clay minerals such as montmorillonite show the most profound swelling [6]. - **Slickensides:** Polished, grooved surfaces inside the soil that form as clay repeatedly swells and shrinks [5]. In Oklahoma, the Oklahoma Geological Survey notes that more than 75 percent of the state has bedrock that can produce expansive soils [7]. Seasonal moisture change in expansive clays can reach from 3 to 40 feet deep [6]. More background is on shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) and clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy). ## Which soil series occur in each region? Many series cross regional lines, so some appear under more than one region. ### Tulsa Metro and Northeast Apperson (https://terrabrain.vercel.app/soils/apperson), Bates (https://terrabrain.vercel.app/soils/bates), Choteau (https://terrabrain.vercel.app/soils/choteau), Clarksville (https://terrabrain.vercel.app/soils/clarksville), Collinsville (https://terrabrain.vercel.app/soils/collinsville), Coweta (https://terrabrain.vercel.app/soils/coweta), Dennis (https://terrabrain.vercel.app/soils/dennis), Eram (https://terrabrain.vercel.app/soils/eram), Muskogee (https://terrabrain.vercel.app/soils/muskogee), Niotaze (https://terrabrain.vercel.app/soils/niotaze), Nixa (https://terrabrain.vercel.app/soils/nixa), Okemah (https://terrabrain.vercel.app/soils/okemah), Osage (https://terrabrain.vercel.app/soils/osage), Parsons (https://terrabrain.vercel.app/soils/parsons), Summit (https://terrabrain.vercel.app/soils/summit), Taloka (https://terrabrain.vercel.app/soils/taloka), Verdigris (https://terrabrain.vercel.app/soils/verdigris), Wynona (https://terrabrain.vercel.app/soils/wynona) ### East-Central (Arkoma) Bates (https://terrabrain.vercel.app/soils/bates), Coweta (https://terrabrain.vercel.app/soils/coweta), Dennis (https://terrabrain.vercel.app/soils/dennis), Eram (https://terrabrain.vercel.app/soils/eram), Hector (https://terrabrain.vercel.app/soils/hector), Konawa (https://terrabrain.vercel.app/soils/konawa), Muskogee (https://terrabrain.vercel.app/soils/muskogee), Okemah (https://terrabrain.vercel.app/soils/okemah), Osage (https://terrabrain.vercel.app/soils/osage), Talihina (https://terrabrain.vercel.app/soils/talihina), Wynona (https://terrabrain.vercel.app/soils/wynona) ### Southeast and South-Central Bernow (https://terrabrain.vercel.app/soils/bernow), Chickasha (https://terrabrain.vercel.app/soils/chickasha), Durant (https://terrabrain.vercel.app/soils/durant), Hector (https://terrabrain.vercel.app/soils/hector), Kiomatia (https://terrabrain.vercel.app/soils/kiomatia), Zaneis (https://terrabrain.vercel.app/soils/zaneis) ### OKC Metro Bethany (https://terrabrain.vercel.app/soils/bethany), Chickasha (https://terrabrain.vercel.app/soils/chickasha), Dale (https://terrabrain.vercel.app/soils/dale), Darnell (https://terrabrain.vercel.app/soils/darnell), Dougherty (https://terrabrain.vercel.app/soils/dougherty), Kingfisher (https://terrabrain.vercel.app/soils/kingfisher), Kirkland (https://terrabrain.vercel.app/soils/kirkland), Konawa (https://terrabrain.vercel.app/soils/konawa), Lucien (https://terrabrain.vercel.app/soils/lucien), Norge (https://terrabrain.vercel.app/soils/norge), Port (https://terrabrain.vercel.app/soils/port), Pulaski (https://terrabrain.vercel.app/soils/pulaski), Renfrow (https://terrabrain.vercel.app/soils/renfrow), Stephenville (https://terrabrain.vercel.app/soils/stephenville), Teller (https://terrabrain.vercel.app/soils/teller), Vernon (https://terrabrain.vercel.app/soils/vernon), Zaneis (https://terrabrain.vercel.app/soils/zaneis) ### North-Central (Red Prairies and Wheat Belt) Dougherty (https://terrabrain.vercel.app/soils/dougherty), Grant (https://terrabrain.vercel.app/soils/grant), Kingfisher (https://terrabrain.vercel.app/soils/kingfisher), Kirkland (https://terrabrain.vercel.app/soils/kirkland), Lucien (https://terrabrain.vercel.app/soils/lucien), Norge (https://terrabrain.vercel.app/soils/norge), Pond Creek (https://terrabrain.vercel.app/soils/pond-creek), Port (https://terrabrain.vercel.app/soils/port), Renfrow (https://terrabrain.vercel.app/soils/renfrow), Tabler (https://terrabrain.vercel.app/soils/tabler), Teller (https://terrabrain.vercel.app/soils/teller) ### Southwest (Lawton and Red Plains) Abilene (https://terrabrain.vercel.app/soils/abilene), Chickasha (https://terrabrain.vercel.app/soils/chickasha), Dale (https://terrabrain.vercel.app/soils/dale), Foard (https://terrabrain.vercel.app/soils/foard), Hollister (https://terrabrain.vercel.app/soils/hollister), Port (https://terrabrain.vercel.app/soils/port), St. Paul (https://terrabrain.vercel.app/soils/st-paul), Tillman (https://terrabrain.vercel.app/soils/tillman), Vernon (https://terrabrain.vercel.app/soils/vernon), Woodward (https://terrabrain.vercel.app/soils/woodward) ### Northwest (Gypsum Hills) Pratt (https://terrabrain.vercel.app/soils/pratt), Quinlan (https://terrabrain.vercel.app/soils/quinlan), St. Paul (https://terrabrain.vercel.app/soils/st-paul), Tivoli (https://terrabrain.vercel.app/soils/tivoli), Vernon (https://terrabrain.vercel.app/soils/vernon), Woodward (https://terrabrain.vercel.app/soils/woodward) ### Panhandle (High Plains) Dalhart (https://terrabrain.vercel.app/soils/dalhart), Richfield (https://terrabrain.vercel.app/soils/richfield), Ulysses (https://terrabrain.vercel.app/soils/ulysses) ## Related - Soil series in the Tulsa metro (https://terrabrain.vercel.app/guides/soil-series-tulsa-metro) - Soil series in the OKC metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) - Soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values) - Oklahoma geologic provinces (https://terrabrain.vercel.app/guides/oklahoma-geologic-provinces) - OK data: soil lab values (https://terrabrain.vercel.app/data/soil-lab-values) Sources: [1] USDA-NRCS Official Soil Series Description View By List, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/ [2] Web Soil Survey - Home, USDA Natural Resources Conservation Service https://websoilsurvey.nrcs.usda.gov/app/ [3] Physical Properties of the Soils (Field Office Technical Guide, Section II), USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [4] Definition: Linear Extensibility Percent (LEP), UC Davis California Soil Resource Lab https://casoilresource.lawr.ucdavis.edu/gmap/help/defn-linear-extensibility.html [5] Vertisols, University of Idaho, College of Agricultural and Life Sciences https://www.uidaho.edu/cals/soil-orders/vertisols [6] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [7] Geologic Hazards in Oklahoma (GSA South-Central Section abstract), Oklahoma Geological Survey / Geological Society of America https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [8] Official Series Description - SUMMIT Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/S/SUMMIT.html --- # Why are my cabinets or countertops pulling away from the wall? URL: https://terrabrain.vercel.app/signs/cabinets-or-countertops-separating Answer: The floor or wall may have moved; on Oklahoma clay one cause is center heave, where the slab interior rises, though cabinets also loosen for ordinary reasons. In short: Cabinets pulling away from a wall, or a countertop that has gone out of level, can mean the floor or wall beneath has moved. On Oklahoma's expansive clay, one cause is center heave, where the interior of the slab rises relative to the edges. Because cabinets can also loosen for ordinary reasons, this sign is weighed together with floor levels and other nearby clues. ## Why do cabinets show foundation movement? Base cabinets sit on the floor and are screwed to the wall; upper cabinets hang from the wall framing; countertops span across the base cabinets. When the floor under one end rises or drops, or the wall tilts, the straight lines of cabinets and counters reveal it. Gaps open between cabinet backs and the wall, between countertop and backsplash, or between cabinet sections. ## How does center heave cause it? This site links the sign to center heave (moisture build-up under slab) (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab). Center lift happens when swelling is concentrated under the middle of a building, or when the edges shrink, so the center ends up high [1]. The corners of a uniformly loaded rectangular slab exert only about one-quarter of the swelling-soil pressure of the central portion, so slab geometry and load also shape how the floor moves [2]. Kitchens and baths often sit in the interior of a house and contain plumbing; leaking pipes add water that can worsen swelling of nearby clay [2]. See leak-induced localized heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave). ### Oklahoma clay More than 75% of Oklahoma has bedrock that can produce expansive soils, and soil saturation from rain, lawn watering or sewer leaks can damage foundations as the soil expands [3]. Oklahoma State University researchers note that lightweight houses on shallow slab foundations over expansive soils are especially vulnerable to wet and dry extremes [4]. See clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy). ## What else can cause it? | Possibility | What points to it | |---|---| | Center heave | Counter and floor both rise toward the interior; nearby interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump) or floor tile cracks in a line (https://terrabrain.vercel.app/signs/floor-tile-cracks-in-a-line) | | Edge settlement | Low side is toward an exterior wall; see perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) | | Installation or fastener issues | Gap with no floor tilt and no other signs nearby | Home inspection standards list uneven floors, drywall cracks, brick cracks and out-of-square door frames as signs of possible foundation movement to report [5]. ## How can it be checked? 1. Put a level on the countertop front to back and side to side, and note the low direction. 2. Measure gaps between cabinets and wall, and between countertop and backsplash, at marked spots. 3. Photograph each gap with a ruler in view, and repeat over several months. 4. Compare the low direction with a floor elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) of the whole house. Movement on expansive clay often follows the seasons: Texas monitoring found slabs moving through the summer and partly recovering in winter [6]. A gap that changes with the seasons points to soil moisture; see seasonal movement calendar (https://terrabrain.vercel.app/guides/seasonal-movement-calendar). ## What are the next steps? Plot it on the elevation survey, compare with the distress pattern library, and use the symptom matrix to weigh likely mechanisms. ## Related - Center heave (moisture build-up under slab) (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) - Interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump) - Plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) - Heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Symptom matrix (https://terrabrain.vercel.app/guides/symptom-matrix) Sources: [1] Expansive soils (encyclopedia entry, post-review manuscript), NERC Open Research Archive https://nora.nerc.ac.uk/id/eprint/521301/1/EncyclopediaEngGeol_ExpansiveSoils_PostReview.pdf [2] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [3] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [4] Residential House Foundations on Expansive Soils in Changing Climates, HUD USER, Cityscape (Oklahoma State University authors) https://www.huduser.gov/PORTAL/node/10259 [5] Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [6] Cyclical Foundation Movements and Their Remediation, CIGMAT, University of Houston (conference presentation) https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2007/addison.pdf --- # Why are my floor tiles cracking in a straight line? URL: https://terrabrain.vercel.app/signs/floor-tile-cracks-in-a-line Answer: A crack running through several tiles usually follows a crack or bend in the slab below, often from clay swelling under part of it or edges settling. In short: A crack that runs in a line through several floor tiles usually follows a crack or bend in the concrete slab beneath. On Oklahoma's expansive clay, the slab can crack when soil under part of it swells, often in the interior or near a plumbing leak, or when the edges settle. Whether the line is growing and whether one side is higher than the other tells you most of what you need to know. ## Why does tile show slab cracks? Ceramic and stone tile is bonded tightly to the slab. Tile is stiff and brittle, so it cannot stretch across a crack that opens beneath it. When the slab cracks or bends, the tile directly above it cracks along the same path. That is why the crack forms a line through grout and tile alike, often running across a room or hallway. Swelling soils frequently cause distress in floor slabs [1]. Home inspection standards list uneven floors among the signs of possible foundation movement to report [4]. See visible slab cracks (https://terrabrain.vercel.app/signs/visible-slab-cracks). ## What can cause the slab to crack? | Mechanism | Typical pattern | |---|---| | Center heave (moisture build-up under slab) (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) | Interior of the slab rises; crack lines often near the middle of the house, sometimes with a raised edge | | Leak-induced localized heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave) | Crack near a bathroom, kitchen or water line, centered on a wet area | | Perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) | Crack runs roughly parallel to an outside wall that has dropped | ### Center lift Center lift happens when swelling is concentrated beneath the middle of a building, or when shrinkage occurs under its edges [2]. The corners of a uniformly loaded rectangular slab exert only about one-quarter of the swelling-soil pressure of the central portion, and moisture differences at the slab edge can increase the distortion [1]. Either way, the slab bends and cracks, and the tile follows. ### Leaks Leaking water and sewer pipes are a common source of extra moisture under a house, and the water they release can worsen swelling of nearby clay [1]. In Oklahoma, the Oklahoma Geological Survey lists sewer leakage, along with rain and lawn watering, as a source of soil saturation that can damage foundations as clay expands [3]. Shallow plastic pipes buried in the zone of seasonal moisture change can face large stresses from shrinking soil [1]. See plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) and unexplained high water bill (https://terrabrain.vercel.app/signs/unexplained-high-water-bill). ### Oklahoma clay More than 75% of Oklahoma has bedrock that can produce expansive soils [3]. Oklahoma State University researchers note that slab-on-ground houses on expansive soils are more vulnerable to climate-related challenges, especially extreme events such as excessive rain and drought [5]. See shrink-swell and active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). ## How do you document it? 1. Trace the line from end to end and mark the ends with tape and a date. 2. Measure the width at the widest point and check whether one side is higher than the other (a height difference, or offset). 3. Photograph with a ruler in view, including a close-up of any offset. 4. Mark the line on a floor plan, along with plumbing fixtures and any floor hump. 5. Re-measure every month or two. A line that crosses an interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump), or sits near plumbing, points toward heave. A line parallel to an outside wall that has dropped points toward edge settlement. An elevation survey shows which. ## What happens next? If a leak is suspected, plumbing leak detection and repair comes first, since the moisture source drives the heave. For other mechanisms, compare the crack map with the distress pattern library and the symptom matrix. ## Related - Visible slab cracks (https://terrabrain.vercel.app/signs/visible-slab-cracks) - Interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump) - Center heave (moisture build-up under slab) (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) - Leak-induced localized heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave) - Plumbing leaks under slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) Sources: [1] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [2] Expansive soils (encyclopedia entry, post-review manuscript), NERC Open Research Archive https://nora.nerc.ac.uk/id/eprint/521301/1/EncyclopediaEngGeol_ExpansiveSoils_PostReview.pdf [3] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [4] Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [5] Residential House Foundations on Expansive Soils in Changing Climates, HUD USER, Cityscape (Oklahoma State University authors) https://www.huduser.gov/PORTAL/node/10259 --- # Why are my foundation piers moving after repair? URL: https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair Answer: Piers that miss stable soil or rock can be lifted by swelling clay, settle when ending too shallow in shrinking clay, or be dragged down by settling fill. In short: Foundation piers installed during a repair can move later if they did not reach stable soil or rock. Swelling clay can grip a pier and lift it, shrinking clay can let a pier that ended too shallow settle, and settling fill can drag a pier down. The repaired area then shows new cracks or binding doors. ## What are the three ways piers move? ### Uplift by swelling clay Expansive clay grips the sides of a pier when it swells. Engineering literature documents drilled corner piers being lifted during wet seasons, then losing skin friction (the grip of soil along the pier's sides) in the following dry season as the soil shrinks away, after which the pier may fail [1]. For this reason, piers in expansive soil must extend well below the seasonal moisture zone and be designed assuming their upper portions lose contact with the soil [1]. ### Settlement of piers that ended too shallow A pier that stopped within the active zone, the depth of soil whose moisture changes with the climate, still rests on soil that shrinks in dry periods. In Oklahoma, the active zone has been estimated at roughly 0.5 to 4 meters (about 1.5 to 13 feet) depending on soil and climate [2], and multi-year droughts can dry soil deeper than previously believed [1]. A pier that stopped within that zone still bears on soil subject to seasonal shrinkage [1][2]. ### Downdrag in fill Where a pier passes through fill, the fill settling around it can drag on the pier. Oklahoma Department of Transportation research describes compacted fill continuing to settle after construction as its moisture content increases [6]. See fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). ## What determines how well a pier performs? | Factor | Why it matters | |---|---| | Depth relative to active zone | Foundations are extended below the zone of moisture fluctuation to avoid shrink-swell movement [3] | | Soil moisture and skin friction | Texas guidelines note underpinning performance can be affected by soil moisture changes and skin friction [4] | | Specified depth and size | Underpinning locations, sizes, depths and materials must be specified [4] | | Moisture state at installation | Seasonal moisture can extend from about 3 to 40 feet deep in expansive soils [1] | For reference, Oklahoma steel push pier installation records show typical pier depths of about 8 to 16 feet, with a median of about 12 feet in Tulsa, and installation pressures around 9,000 psi with a 6,000 psi minimum [7]. See steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers). ## What are the signs of pier movement? - doors that bind again in a previously repaired area - stair-step brick cracks wider at the bottom (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-bottom) - stair-step brick cracks wider at the top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top) - new cracks in finishes that had been repaired Texas guidelines note that previous repairs can change the shape of a foundation's elevation profile [5], so post-repair surveys are the reference point. ## How is pier movement evaluated? - **Post-repair survey.** The Texas guidelines call for floor elevations to be measured after remedial work, recorded and given to the client [5]. - **Repeated surveys.** A single survey shows shape at one moment; repeated surveys over months or years show change [5]. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) and monitoring program (https://terrabrain.vercel.app/repairs/monitoring-program). - **Installation records.** Pier logs showing depth and installation force at each pier help identify piers that ended shallow. ## How is pier movement typically addressed? The approach depends on whether piers rose or settled. Recognized principles include extending supports below the zone of moisture fluctuation [3] and designing piers in expansive soil on the assumption that their upper sections lose soil contact [1]. Options discussed on this site include drilled bell-bottom piers (https://terrabrain.vercel.app/repairs/drilled-bell-bottom-piers), helical piers (https://terrabrain.vercel.app/repairs/helical-piers) and reducing wetting of the soil around piers through drainage. ## Related - Over-Lift Heave After Drought Lift (https://terrabrain.vercel.app/causes/over-lift-heave-after-drought-lift) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Contracts, Warranties and Liens (https://terrabrain.vercel.app/rules/contracts-warranties-liens) - Active Zone and Drought Depth (https://terrabrain.vercel.app/data/active-zone-and-drought-depth) Sources: [1] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers et al.) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [2] Soil Matric Suction and Active Zone Depth in Oklahoma, Oklahoma State University (Er Yue, Ph.D. dissertation, 2017) https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf [3] Shrink-Swell Subsidence, PreventionWeb (UN Office for Disaster Risk Reduction) https://www.preventionweb.net/understanding-disaster-risk/terminology/hips/gh0025 [4] Guidelines for the Evaluation and Repair of Residential Foundations, Version 2, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2022/05/Guidelines-for-the-Evaluation-and-Repair-of-Residential-Foundations-V2-2008.pdf [5] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [6] Settlement Behavior of Compacted Oklahoma Soils (FHWA-OK-02-03), Oklahoma Department of Transportation https://rosap.ntl.bts.gov/view/dot/88914 [7] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # Why are retaining walls, fences and trees leaning on my slope? URL: https://terrabrain.vercel.app/signs/tilted-retaining-walls-fences-or-trees Answer: When they all lean the same way, the upper soil may be slowly creeping downhill, which can also pull at foundations near the slope. In short: When retaining walls, fence posts and trees on a slope all lean the same way, the upper soil may be slowly moving downhill. This slow movement, called creep, can also pull at foundations near the slope, so the leaning features are checked alongside the house itself. ## What does this sign look like? - Retaining walls tipping outward or bulging at mid-height. - Fence posts leaning downhill in a row, or fence lines that have bowed. - Trees tilted downhill. Any house on or near a slope can show these, whether it sits on a slab, crawl space or basement. ## Why does it happen? ### Creep of clay soils **Creep** is very slow downhill movement of the upper soil, often too slow to see except through its effects on things anchored in it. Inspection guidance notes that clay soils on slopes can slowly drift downhill, causing settlement [1]. Expansive clay swells as it gains moisture and shrinks as it loses moisture [5]. The mechanism is covered in slope creep and lateral movement (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement). ### Retaining walls Masonry walls that lean almost always lean outward, and leaning walls can sometimes be tied back to the structure [1]. Poor surface drainage can cause soil swelling and erosion around footings [1], and when soil particles fill the drainage path, water pressure builds up against the wall [1]. See lateral earth and hydrostatic pressure on walls (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls). ### Landslides in Oklahoma The Oklahoma Geological Survey monitors and maps landslides across the state, with research focused on the causes of shallow landslides in eastern Oklahoma, and it has produced a preliminary landslide susceptibility map of Sugarloaf Mountain using high-resolution LiDAR elevation data [2]. Creeks and steep banks are covered in erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes). ## How is it documented? | What to record | Why | |---|---| | Lean of walls, posts and trees, measured with a level or plumb line | Shows direction and amount of movement | | Whether all leaning features point the same way | A consistent downhill lean fits creep | | Wall lean compared with its base width | Used in the middle-third rule [1] | | Floor elevations in the house | Shows whether the house is dropping toward the slope | A common inspection rule says a wall is usually considered unsafe if a plumb line through its center of gravity does not fall within the middle third of its base, and that a structural engineer should be consulted in that case [1]. Floor readings are covered in elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). ## How is drainage handled on sloped lots? Building guidance calls for grassy swales (shallow drainage channels) to slope at least about 1 percent and no more than about 15 percent unless lined with riprap, meaning rock armor [3]. Foundation design guidance calls for at least a 5 percent slope away from the house in the first 10 feet and keeps drainage swales at least 4 feet from the foundation [4]. Approaches for unstable slopes are described in slope and erosion stabilization (https://terrabrain.vercel.app/repairs/slope-and-erosion-stabilization). ## Related - Slope Creep & Lateral Movement (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement) - Erosion Creeks and Slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Slope and Erosion Stabilization (https://terrabrain.vercel.app/repairs/slope-and-erosion-stabilization) - Surface Drainage and Grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Sloping Floors (https://terrabrain.vercel.app/signs/sloping-floors) Sources: [1] Inspecting Foundation Walls and Piers, International Association of Certified Home Inspectors (InterNACHI) https://www.nachi.org/documents2012/Inspecting_Foundation_Walls_and_Piers-revised-January-2013.pdf [2] Hazard Mapping, Oklahoma Geological Survey https://ou.edu/ogs/research/hazard_mapping [3] A Professional's Guide to Durable Home Design: Durability by Design, 2nd Edition, U.S. Department of Housing and Urban Development https://www.HUDUser.gov/portal/sites/default/files/pdf/Guide-Durability-by-Design.pdf [4] Recommended Practice for the Design of Residential Foundations, Version 2, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Recommended-Practice-for-the-Design-of-Residential-Foundations-V2-2007.pdf [5] The Mystery of Expansive Soils, STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf --- # Why are the floors bouncy or soft in my crawl space home? URL: https://terrabrain.vercel.app/signs/bouncy-or-soft-floors Answer: Bouncy or soft floors usually point to framing or support problems, such as moisture-damaged wood or supports that are missing, too far apart or failing. In short: A floor that bounces, flexes or feels soft underfoot is usually a framing or support problem rather than a soil problem. In crawl space and pier-and-beam homes the common causes are moisture damage to the wood and supports that are missing, too far apart or failing. The answer is found by going into the crawl space. ## Where does this sign appear? Bouncy or soft floors are a sign for houses with a wood floor system over a crawl space: pier and beam crawl space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) homes and manufactured homes on piers (https://terrabrain.vercel.app/foundations/manufactured-homes-on-piers). In these houses the floor is built from joists (parallel wood framing members) resting on beams, which rest on piers or posts. A slab-on-grade floor sits directly on the soil and does not bounce this way. ## What can bouncy floors mean? | Mechanism | How it causes bounce or softness | |---|---| | Crawl space moisture and wood decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) | Decay of joists, beams or subfloor linked to damp air, standing water or wood near soil; inspectors report wood near soil and active water penetration [1] | | Interior support and framing failure (crawl) (https://terrabrain.vercel.app/causes/interior-support-and-framing-failure-crawl) | Posts or piers that settle, tilt or were spaced too far apart leave long spans that flex | ### Wood sags under long-term load Wood framing keeps deflecting slowly under a constant load. In a U.S. Forest Products Laboratory study of wood trusses held under load for 15 years, total deflection grew to about two to three times the initial deflection, and about half of the time-related deflection happened in the first year [3]. Connection type mattered: glued joints deflected less than nailed ones [3]. Long-term sag of this kind adds to bounce when framing is already undersized or damaged. ### How decay weakens wood Decay fungi need wood wetter than its fiber saturation point, about 30% moisture content, which takes free water from rain, condensation or wet ground contact [5]. Air-dried wood usually holds no more than 20% moisture, so decay generally does not start in dry framing [5]. Strength drops early in the process [5]: - Toughness is lost first, then bending strength, then all strength properties. - A 5-10% loss of wood weight to decay matched a 20-80% drop in mechanical properties in laboratory tests. - At 10% weight loss, bending strength fell about 40%. - Decay at 10% weight loss or less may be detectable only under a microscope, and no method exists to judge strength loss by eye alone. That is why a floor can feel soft before the wood looks rotten. ### Moisture under the house Building code provisions for crawl spaces cover ventilation, access and debris removal [2]. Residential code Section R317.1 requires naturally durable or preservative-treated wood for the floor assembly (posts, girders, joists and subfloor) where joists are closer than 18 inches, or girders closer than 12 inches, to exposed ground in a crawl space [6]. Some Oklahoma soils hold water near the surface for months: the Osage soil on eastern Oklahoma floodplains has a seasonal high water table 6 to 18 inches deep from November through May in normal years [4]. On sites like that, a crawl space can stay damp much of the year. See water, condensation or mold in crawl (https://terrabrain.vercel.app/signs/water-condensation-or-mold-in-crawl) and groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water). ## What gets checked? Home inspection standards call for inspecting the crawl space and structural components and reporting [1]: - Wood in contact with or near soil. - Signs of active water penetration. - Possible foundation movement, such as drywall cracks, brick cracks, out-of-square door frames and uneven floors. - Cutting, notching or boring of framing members that may be a structural or safety concern. Inspectors are not required to enter a crawl space that is not readily accessible or is hazardous, and they do not judge the size, spacing or adequacy of joists and support systems [1]. That evaluation falls to a contractor or engineer; see working with engineers (https://terrabrain.vercel.app/guides/working-with-engineers). ### How to document it - Note where the bounce is: one room, near plumbing, or across a whole span. - Photograph framing from the crawl space: joists, beams, posts and any dark, soft or crumbly wood. - Note standing water, wet soil, condensation or mold. - Record whether floors also slope or sag; see sagging floor between supports (https://terrabrain.vercel.app/signs/sagging-floor-between-supports) and sloping floors. ## How are bouncy floors repaired? Repairs depend on which mechanism is found. Crawl space repair covers adding or replacing posts and piers, sistering or replacing damaged joists and shimming beams. Where moisture is the driver, crawl space encapsulation and drainage solutions address the source of the water. ## Related - Crawl space moisture and wood decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) - Interior support and framing failure (crawl) (https://terrabrain.vercel.app/causes/interior-support-and-framing-failure-crawl) - Sagging floor between supports (https://terrabrain.vercel.app/signs/sagging-floor-between-supports) - Crawl space repair (https://terrabrain.vercel.app/repairs/crawl-space-repair) - Pier and beam crawl space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) Sources: [1] Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [2] Inspecting Foundation Fortitude: Cracking the Code for a Solid Home (IRC R401-R408), InterNACHI https://www.nachi.org/foundation-systems-building-code.htm [3] Longtime Performance of Trussed Rafters with Different Connection Systems (Research Paper FPL 444), USDA Forest Service, Forest Products Laboratory https://apps.dtic.mil/sti/pdfs/ADA142035.pdf [4] Official Series Description: Osage Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OSAGE.html [5] Strength loss in decayed wood (McGraw-Hill Yearbook of Science & Technology 2014), USDA Forest Service, Forest Products Laboratory (R. E. Ibach and P. K. Lebow) https://www.fpl.fs.usda.gov/documnts/pdf2014/fpl_2014_ibach001.pdf [6] BDP-BLG25: Clearance and Protection Against Decay and Termites of Wood Floor Framing Members in Crawl Spaces, City of Milpitas Office of Building Safety (quoting residential code Section R317.1) https://www.milpitas.gov/DocumentCenter/View/277/BDP-BLG25-Clearance-and-Protection-Against-Decay-and-Termites-of-Wood-Floor-Framing-Members-in-Crawl-Spaces-and-Garage-Conversions-PDF --- # Why are the floors sagging over my crawl space? URL: https://terrabrain.vercel.app/causes/interior-support-and-framing-failure-crawl Answer: Interior pads settle, wood shims crush or rot, or beams and joists are too small or span too far, so the floor sags, bounces or slopes. In short: In a pier-and-beam house, the floor rests on wood beams and joists carried by interior piers or pads in the crawl space. When those pads settle, wood shims crush or rot, or beams and joists are too small or span too far, the floor sags, bounces or slopes toward the interior. It is a problem with the support system under the floor rather than with the perimeter foundation. ## How is a pier-and-beam floor supported? A pier-and-beam (crawl space) floor has three layers of support: - **Joists**, the closely spaced boards that the subfloor is nailed to. - **Beams or girders**, heavier members that carry the joists. - **Interior piers or pads**, posts or masonry piers on small footings that hold up the beams, often with wood or steel shims between the pier and the beam to set the height. A failure at any level shows up as a sag or slope in the floor above. Texas engineering guidelines treat pier-and-beam repairs, including shimming, framing repairs and added supports, as a distinct category from slab repairs [1]. ## What goes wrong with the floor supports? ### Pads moving with the soil In Oklahoma, the active zone, the depth of soil whose moisture changes with the climate, has been estimated at roughly 0.5 to 4 meters (about 1.5 to 13 feet) [5], so a shallow interior pad on clay rests within the soil that shrinks and swells. Nearly all of Oklahoma has medium or high soil swelling potential [5]. See shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). ### Shims and wood that decay Wood decay is generally understood to occur above about 30% moisture content and not below about 20% [3]. Decay requires moisture, oxygen, a suitable temperature (about 50 to 95°F) and the wood itself as food [4], and decayed wood loses strength [4]. Wood shims and posts that stay damp in a crawl space are exposed to those conditions, and as they lose strength the beam above can drop. See crawl space moisture and wood decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay). ### Beams and joists that span too far When a beam or joist spans too far for its size, or has been notched or cut for plumbing or ductwork, it bends more under load. Engineers often judge floor deflection against the L/360 live-load limit from the International Residential Code, meaning a span should not bow more than 1/360 of its length [2]; the Foundation Performance Association uses the same L/360 ratio [7]. ### Debris and site conditions The code calls for removing vegetation, organic material and wooden forms from the crawl space, and for drainage or a raised grade where groundwater can rise close to the floor [6]. ## What are the signs of interior support failure? - sagging floor between supports (https://terrabrain.vercel.app/signs/sagging-floor-between-supports) - bouncy or soft floors (https://terrabrain.vercel.app/signs/bouncy-or-soft-floors) - sloping floors (https://terrabrain.vercel.app/signs/sloping-floors) toward the interior - doors that bind and diagonal drywall cracks near the sag Texas guidelines note that signs such as cracked drywall or racked door frames do not necessarily mean the structure is performing inadequately [2]. ## How is interior sag different from perimeter settlement? When the perimeter foundation drops, floors slope outward toward the exterior walls. When the interior supports fail, the floor sags in the middle or between supports while the perimeter stays near level. A floor elevation survey records the shape of the floor so the two patterns can be compared [2]; see elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) and perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). ## How is a sagging crawl space floor typically fixed? The Texas ASCE guidelines list floor shimming, framing repairs, additional supports, restoring the open space under the floor and crawl space moisture control as pier-and-beam repair approaches [1]. Framing repairs replace or reinforce structural members that are damaged or distressed [1]. See crawl space repair (https://terrabrain.vercel.app/repairs/crawl-space-repair). ## Related - Pier and Beam Crawl Space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) - Crawl Space Moisture and Wood Decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) - Manufactured Homes on Piers (https://terrabrain.vercel.app/foundations/manufactured-homes-on-piers) - Crawl Space Encapsulation (https://terrabrain.vercel.app/repairs/crawl-space-encapsulation) - Bouncy or Soft Floors (https://terrabrain.vercel.app/signs/bouncy-or-soft-floors) Sources: [1] Guidelines for the Evaluation and Repair of Residential Foundations, Version 2, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2022/05/Guidelines-for-the-Evaluation-and-Repair-of-Residential-Foundations-V2-2008.pdf [2] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [3] Limiting Conditions for Decay in Wood Systems, USDA Forest Products Laboratory / International Research Group on Wood Protection https://www.fpl.fs.usda.gov/documnts/pdf2002/morri02a.pdf [4] Strength loss in decayed wood, USDA Forest Products Laboratory https://www.fpl.fs.usda.gov/documnts/pdf2014/fpl_2014_ibach001.pdf [5] Soil Matric Suction and Active Zone Depth in Oklahoma, Oklahoma State University (Er Yue, Ph.D. dissertation, 2017) https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf [6] Inspecting Under-Floor Crawl Spaces: A Guide for Home Inspectors (2024 IRC Section R408), InterNACHI https://www.nachi.org/under-floor-crawl-space.htm [7] Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings (FPA-SC-13-1), Foundation Performance Association https://inspectapedia.com/structure/Foundation-Movement-Evaluation-Guidelines-FPA-TX.pdf --- # Why did a 1928 Tulsa basement wall need a full rebuild? URL: https://terrabrain.vercel.app/case-studies/tulsa-1928-basement-wall-rebuild Answer: Years of lateral soil and water pressure bowed the lower block wall inward, so the engineer ruled out crack repair or bracing and called for a rebuild. In short: The north concrete-block wall of a partial basement under a 1928 Tulsa house was leaning and bulging inward at its base. It was worse than at the previous inspection, and water and soil were coming in at the bottom [1]. The engineer attributed it to long-term lateral soil and hydrostatic pressure. The engineer specified a full rebuild in reinforced, fully grouted block or cast-in-place concrete, with exterior waterproofing and a perimeter drain [1]. ## What did the house show? The house is a one-story wood-frame house without veneer, built about 1928. It has a crawl space under most of it and a partial concrete-block (CMU) basement at the west end, all on a continuous trench footing [1]. The same engineer had inspected it since 2009. A failed east foundation wall had been rebuilt and the floor re-supported. Porch column settlement was noted in 2014 and a follow-up inspection was done in 2017 [1]. At the January 2026 inspection [1]: - The **north basement wall** had significant cracking and deteriorated mortar. It showed an **inward lean and bulge in the lower wall that was worse than in 2017**. - Stormwater and **soil were entering at the base** of the wall. The silt ran to the sump and clogged the pump. - Steel tube columns along the wall were **only bolted to the masonry**, with no footing of their own, and no longer restrained it. - The crawl space was dry. Floor framing was adequately supported on steel pipe columns on precast footings. No other structural defects were found, and site drainage was judged adequate. The house has no gutters. ## What did the engineer find was causing it? The engineer concluded the wall had failed gradually over years under **long-term lateral soil pressure and hydrostatic (water) loading** [1]. The soil was presumed to be silty clay with trace sand and moderate expansive potential [1]. ## What repair was specified? The engineer stated that crack repair or more bracing would **not** be adequate [1]. The scope was: 1. **Fully reconstruct the north basement wall.** Remove the block and replace it with **reinforced CMU or cast-in-place concrete, fully grouted**. 2. **Excavate the exterior face** and install an exterior waterproofing membrane. 3. Install a **perimeter subsurface drain** to a proper outlet where feasible. 4. Remove the steel columns. Any interior bracing must be independently supported and engineered. 5. Clean silt out of the basement and sump after the repair. 6. Have the work designed or overseen by a qualified contractor or structural engineer. ## What does this case show about Oklahoma foundations? - **Water behind a wall adds load.** Building-science guidance for basements calls for a perimeter drain outside the foundation wrapped in geotextile and free-draining backfill or a drainage board to carry groundwater down to it. It also calls for exterior damp-proofing and runoff collected and kept away from the foundation [2]. The engineer's scope here (exterior membrane plus perimeter drain) follows the same approach [1]. - **Clay changes with moisture.** ASCE's homeowner guide on shrink-swell soils explains that clay expands when it takes on water and shrinks when it dries [3]. The engineer presumed a silty clay of moderate expansive potential against this wall [1]. - **Bracing must bear on something solid.** The failed columns were attached only to the wall they were supposed to restrain. The engineer required any future bracing to have independent support [1]. - **Progress over time matters.** Repeat inspections in 2009, 2014, 2017 and 2026 let the engineer say the inward movement had gotten worse, not just that it existed [1]. ## Related - Horizontal Crack or Inward Bow in Basement Wall (https://terrabrain.vercel.app/signs/horizontal-crack-or-inward-bow-in-basement-wall) - Lateral Earth, Swell & Hydrostatic Pressure on Walls (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls) - Basement Wall Repair (https://terrabrain.vercel.app/repairs/basement-wall-repair) - Basements (https://terrabrain.vercel.app/foundations/basements) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Groundwater and Perched Water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) Sources: [1] Engineer's evaluation report, 2026 (private client report), Licensed professional engineer, Oklahoma [2] Understanding Basements, Building Science Digest 103, Building Science Press (J. Lstiburek) https://www.greenbuildingadvisor.com/sites/default/files/Basement%20-%20Understanding%20Basements.pdf [3] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, ASCE Geo-Institute, Shallow Foundations Committee https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # Why did a 1953 Tulsa crawl space home need drainage work along with piers? URL: https://terrabrain.vercel.app/case-studies/tulsa-1953-crawl-space-water-and-failed-concrete-piers Answer: Surface water was entering the crawl space and old concrete piers at one corner had stopped holding; the engineer specified steel piers plus drainage fixes. In short: A 1953 Tulsa crawl space home had a damp crawl space, water entering through an at-grade vent, downspouts emptying at the foundation, and old concrete piers at the southeast corner that had stopped holding. The engineer named surface water and seasonal clay movement as the causes and specified new steel piers at that corner plus a vent curb, regrading with a swale, downspout extensions and removal of the vapor barrier [1]. ## What did the house show? - Wood floors slightly uneven, which the engineer considered normal long-term framing sag for the home's age [1]. - Concrete piers previously installed at the southeast corner [1]. - In the southeast bedroom, cracks and a warped wall under the east window caused by window leaks, and a corner separation at the south window from wall movement [1]. - A damp crawl space. Water entered at the north foundation vent, which sat at grade, and a little through the east stem wall. The soil under the existing vapor barrier was damp [1]. - Downspouts discharging near the foundation on the north and east sides, and planters holding water against the house [1]. ## What did the engineer find was causing it? Surface water was the main cause: the at-grade crawl vent, planters holding water against the walls, downspouts at the foundation and a flat front yard. Seasonal shrink-swell of the clay accounted for minor binding and cracking, and the old concrete piers at the southeast corner were no longer holding [1]. ## What repair was specified? - Install new steel piers at the southeast corner, replacing the old concrete piers, as the repair contractor had proposed [1]. - Build a masonry curb around the north crawl vent [1]. - Grade the north planter down toward the north and remove the east planter [1]. - Add downspout extensions at every downspout [1]. - Remove the existing vapor barrier so the crawl space soil can dry [1]. - Regrade for positive drainage with a swale along the east side, without raising grade at the perimeter or changing flow onto neighboring lots [1]. - Seal the leaking bedroom window [1]. The repair contractor's plan showed 5 new exterior steel piers, downspouts tied into buried pipe ending at pop-up emitters, and removal of the east planter [1]. ## What does this case show about Oklahoma foundations? Most of this engineer's list was water control, not structure. Federal building-science guidance recommends that downspouts discharge at least 5 ft from the foundation and that grade fall at least 1/2 in. per foot for 10 ft, and notes that unmanaged roof runoff can saturate soil around a foundation and wick into a crawl space, leading to mold and rot [2]. In this house an at-grade vent and wall planters let surface water reach the crawl directly [1]. Clay under a house changes volume as its moisture changes, and uneven wetting produces uneven movement [3]. Holding water against one side of a house is one way that happens. The engineer also told the owner to take out the vapor barrier rather than add to it, because the first goal was to stop water getting in and let the soil dry [1]. The case also shows that cracks need sorting by cause: one bedroom's damage came from a leaking window, not from the foundation [1]. ## Related - Pier and Beam Crawl Space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) - Surface Drainage and Grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Crawl Space Moisture & Wood Decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) - Pier Uplift or Movement After Repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair) - Water, Condensation or Mold in Crawl (https://terrabrain.vercel.app/signs/water-condensation-or-mold-in-crawl) Sources: [1] Engineer's evaluation report, 2025 (private client report), Licensed professional engineer, Oklahoma [2] Gutters and Downspouts (Building America Solution Center), U.S. Department of Energy / Pacific Northwest National Laboratory https://basc.pnnl.gov/resource-guides/gutters-and-downspouts [3] Shrink-Swell Subsidence (Hazard Information Profile), UN Office for Disaster Risk Reduction / British Geological Survey https://www.undrr.org/understanding-disaster-risk/terminology/hips/gh0310 --- # Why did a 1970 Claremore slab house on a sloped lot crack everywhere? URL: https://terrabrain.vercel.app/case-studies/claremore-sloped-lot-slab-piers-and-polyurethane Answer: The engineer blamed changing moisture in the clay under the footings and slab, and specified perimeter piers, polyurethane slab leveling and a leak test. In short: A 1970 slab-on-grade house near Claremore, on a lot sloping moderately to steeply east, had misaligned doors, cracks through the interior and veneer cracks on every exterior wall [1]. The engineer attributed the movement to variations in moisture content of the soil beneath the footings and slab. The scope was piers under the perimeter footings, polyurethane slab leveling, a plumbing leak test and crack stitching [1]. ## What did the house show? The engineer inspected the house in December 2025 [1]. It is a one-story timber-frame house with brick veneer and fiber siding, built about 1970. The garage had been converted to living space and a patio addition abuts the original east wall. The foundation is a slab-on-grade with continuous perimeter footings and stem walls, and HVAC ducts run under the slab [1]. Observed conditions [1]: - The site slopes **moderately to steeply down to the east** on the front, back and both ends. - Representative doors were misaligned and hitting the top and side of the frame. - **Significant interior cracks throughout**, with stem-wall-to-slab and baseboard separations in many areas. - About a **1 in. gap** between the ceiling and the fireplace veneer. - Veneer cracks and veneer-to-trim gaps on **all** exterior walls. - Floor elevations were not measured as part of the inspection. ## What did the engineer find was causing it? The engineer attributed the movement to "variations in the moisture content of the soil beneath the footings and slab," describing the soil at foundation level as a mildly active clay [1]. The report also noted the steep slope and the additions, but did not name them as the cause [1]. ## What repair was specified? - **Piers under the continuous footings** at locations shown on the engineer's drawing [1]. - **Polyurethane slab leveling** where the slab is out of level. The exact areas are to be set by the contractor from a floor survey. The engineer cautioned about sub-slab plumbing and ducts and against lifting large areas over plumbing [1]. - A **leak test of supply and drain lines** by a licensed plumber, with any leaks repaired [1]. - After leveling, **stitch slab cracks** with carbon fiber strips and self-leveling epoxy. Where a height difference remains, saw-cut 6 in. or more each side and re-pour [1]. - Tuck-point mortar joints (raked at least 1/2 in. deep) and caulk veneer-to-trim joints with silicone [1]. - Delay cosmetic repairs several weeks after stabilization [1]. ## What does this case show about Oklahoma foundations? - **Clay subsoils formed from shale are common here.** The USDA describes the Dennis series, whose type location is in Rogers County, as formed in residuum weathered from Pennsylvanian shale. Its subsoil is silty clay or clay with 28 to 50 percent clay, and a perched water table sits 12 to 30 inches deep from December through April in normal years [2]. This record does not identify the soil series at this site. The series shows the kind of clayey, seasonally wet subsoil found in the area. - **Uneven moisture causes more damage than uniform moisture.** ASCE's homeowner guide explains that clay swells when it gains water and shrinks when it dries, and that uneven moisture changes do more damage than uniform ones. It also notes that sewer or water line leaks can cause localized movement [3]. That is why the engineer paired lifting with a plumbing leak test [1]. - **Slopes and additions complicate the picture.** On this house the steep east slope and two additions were noted alongside the clay [1]. ## Related - Slab on Grade (https://terrabrain.vercel.app/foundations/slab-on-grade) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Slabjacking and Polyurethane (https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane) - Plumbing Leak Detection and Repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair) - Additions and Mixed Foundations (https://terrabrain.vercel.app/guides/additions-and-mixed-foundations) - Dennis soil series (https://terrabrain.vercel.app/soils/dennis) Sources: [1] Engineer's evaluation report, 2025 (private client report), Licensed professional engineer, Oklahoma [2] USDA Official Series Description - Dennis Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DENNIS.html [3] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, ASCE Geo-Institute, Shallow Foundations Committee https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # Why did a Bartlesville commercial building need piers and floor leveling? URL: https://terrabrain.vercel.app/case-studies/bartlesville-commercial-building-heave-and-settlement Answer: Its perimeter had settled while the interior slab heaved; the engineer specified 13 steel piers to shale or rock, then interior leveling, plus gutters. In short: A two-unit masonry commercial building in Bartlesville had floors sloping up to 3 in., cracked and displaced block on three sides of one unit, and downspouts emptying against the foundation. The engineer found perimeter settlement combined with clay heave of the interior slab and specified 13 steel piers taken to shale or rock, followed by interior piers or foam leveling, leak detection and new gutters [1]. ## What did the house show? - Interior floors out of level, sloping from 1/4 in. to 3 in.; doors had been trimmed to fit [1]. - On the east unit, cracks of 1/4 to 1 in. and displaced concrete blocks on the south, east and west walls, with soffit trim separations at the southeast and southwest corners [1]. - Incomplete, rusted guttering, with downspouts discharging directly against the foundation; spalled curbs and an aged roof [1]. ## What did the engineer find was causing it? The engineer separated two mechanisms. The perimeter of the east unit had settled on its south, east and west sides. The interior slab, by contrast, had heaved from clay expansion and contraction, with groundwater, poor drainage and a sloped or filled lot as contributors, and the report noted that plumbing leaks are commonly the cause of slab heave. The report stated that "in most foundation settlement problems water is a significant contributing factor" [1]. ## What repair was specified? 1. 13 steel piers on the south, east and west sides of the east unit, per the engineer's sketch. Caulking between veneer and windows was to be removed before lifting [1]. 2. Piers driven deep enough to reach bedrock, blue or gray shale, or dense unweathered stone. The engineer recommended inspecting the installation and the excavations before backfill, required engineer approval for any changes, and asked the contractor to submit its piering proposal at least one week before construction [1]. 3. After the perimeter work, interior piers and/or foam injection to level the floors [1]. 4. A leak-detection test of sewer, supply lines and shower pans; a new roof; repair of spalled concrete; and a new gutter system with downspout extensions [1]. The repair contractor's piering sketch for the building also called for 13 piers [1]. ## What does this case show about Oklahoma foundations? A single building can show both heave and settlement. Here the engineer ordered the work so the settled perimeter was piered first and the heaved interior was leveled afterward [1]. The water items are not cosmetic. Federal building-science guidance notes that a few inches of rain on a roof can produce thousands of gallons of runoff, and recommends downspouts discharge at least 5 ft from the foundation with the ground sloping away at least 1/2 in. per foot for 10 ft, because water pooled near a house can damage foundations on expansive soils [2]. On this building every downspout emptied at the wall [1]. The project record lists the Bates series mapped over alluvium in the area [1]. USDA describes Bates as a moderately deep soil over Pennsylvanian sandstone with thin shale beds, with the soft rock contact typically 20 to 40 in. down [3]. The engineer also noted a sloped or filled lot, and set the pier termination by bearing material (shale or unweathered stone) rather than by a fixed depth [1]. ## Related - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Slabjacking and Polyurethane (https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane) - Plumbing Leaks Under Slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Shale Weathering and Bearing Strata (https://terrabrain.vercel.app/guides/shale-weathering-and-bearing-strata) Sources: [1] Engineer's evaluation report, 2025 (private client report), Licensed professional engineer, Oklahoma [2] Gutters and Downspouts (Building America Solution Center), U.S. Department of Energy / Pacific Northwest National Laboratory https://basc.pnnl.gov/resource-guides/gutters-and-downspouts [3] USDA Official Series Description - Bates Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/B/BATES.html --- # Why did a Bixby engineer want a tree removed before piering a corner? URL: https://terrabrain.vercel.app/case-studies/bixby-tree-at-corner-remove-before-piers Answer: Cracking was worst at the corner beside a tree on active clay; the engineer listed tree removal first, then 3 steel piers at least 10 ft below the footing. In short: A Bixby slab home had veneer separations and cracks all around, largest at the northeast corner, where a tree stood. The engineer named active clay soil and the tree as the causes, and specified removing the tree first, then underpinning that corner with 3 steel piers at least 10 ft below the footing [1]. ## What did the house show? - Stone veneer separations and hairline to 1/4 in. cracks, some previously patched, around the chimney and on the north, south and west walls. The largest were at the northeast corner [1]. - Cracks in a garage wall and stem wall, and garage slab cracks rated non-structural [1]. - Interior cracks at the northeast and southeast corners and in a bedroom closet, and uneven floors [1]. - A tree close to the northeast corner, photographed in the report [1]. - Slab movement judged not severe enough to repair [1]. ## What did the engineer find was causing it? Shrink-swell movement of active clay soil, with the tree at the northeast corner as a contributor. No soil report was available [1]. ## What repair was specified? 1. Remove the tree at the northeast corner [1]. 2. Then underpin the northeast corner with 3 piers, shown at about 9 ft spacing on the plan [1]. The engineer's standard pier specification applied: steel piers only unless the engineer approved another system; each pier to penetrate at least 10 ft below the bottom of the foundation to firm, stable strata, with the detail reading "drive to refusal — bedrock (blue shale)"; a log for every pier listing depth, type, diameter, driving pressure and lift; mortar removed from patched cracks near piers before lifting; a 6 x 6 x 1/2 in. angle iron under the footing where a pier lands near a crack; and a call to the engineer if old shallow concrete piers were found. Pier locations and count could change to suit footing conditions. A repair inspection by the engineer was available on request [1]. ## What does this case show about Oklahoma foundations? On clay soils, trees draw water out of the ground beneath nearby foundations during dry spells, the clay shrinks, and the result is settlement with cracking that often shows around windows and doors [2]. Tree roots are unlikely to break sound footings directly; the damage comes from the soil drying [2]. Below the depth that weather alone dries out, a tree's water demand can be the main driver of shrink and swell in clay [3]. In this house the worst cracking was at the corner next to the tree [1]. The engineer listed the tree removal ahead of the piers [1]. Published guidance also notes that, in rare cases where clay has been kept dry at depth for years, removing a tree can let the soil re-wet and heave [2]. Only one corner was piered. Cracks elsewhere were smaller and the slab movement was judged not severe enough to repair, so the specified underpinning was limited to the corner next to the tree [1]. ## Related - Trees and Roots (https://terrabrain.vercel.app/guides/trees-and-roots) - Tree Management (https://terrabrain.vercel.app/repairs/tree-management) - Tree-Root Desiccation Settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) - Post-Tree-Removal Heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Slab on Grade (https://terrabrain.vercel.app/foundations/slab-on-grade) Sources: [1] Engineer's evaluation report, 2025 (private client report), Licensed professional engineer, Oklahoma [2] Trees near buildings, Royal Horticultural Society https://www.rhs.org.uk/plants/types/trees/near-buildings [3] Shrink-Swell Subsidence (Hazard Information Profile), UN Office for Disaster Risk Reduction / British Geological Survey https://www.undrr.org/understanding-disaster-risk/terminology/hips/gh0310 --- # Why did a Claremore church addition's floor drop 1 to 3 inches? URL: https://terrabrain.vercel.app/case-studies/claremore-church-addition-slab-drop-piers-and-foam Answer: The engineer found soil consolidation under the slab and a possible void or plumbing leak, and specified 16 steel piers at least 12 ft deep plus slab support. In short: The southeast addition of a one-story church building near Claremore had uneven floors, slab cracks and brick separations. Its floor had dropped about 1 to 3 inches [1]. The engineer attributed this to consolidation and settlement of the soil under the slab, with a possible cavity and plumbing leak. The scope was 16 perimeter steel piers at least 12 ft below the footing, slab support by helical piers or foam, and plumbing tests before and after [1]. ## What did the building show? The engineer inspected the building in April 2025, limiting the inspection to the southeast addition [1]. The building is one-story wood frame with brick veneer. The addition sits on a slab-on-grade with a continuous perimeter spread footing and stem walls [1]. Observed conditions [1]: - Uneven floors, slab cracks, and cracks around doors from floor slab and foundation settlement. - A **floor drop of about 1 to 3 in.** The engineer took this as a sign of a possible **cavity under the slab and a possible plumbing leak**. - Brick cracks and separations at the corners of the addition. ## What did the engineer find was causing it? The engineer found **consolidation and settlement of the underlying soil** beneath the slab in active clay, with a suspected void or under-slab plumbing leak [1]. ## What repair was specified? **Slab** [1]: - Lift and level the slab **to within 1/2 to 3/4 in.** - Option 1: steel helical slab piers about 6 ft on center. - Option 2: foam ports on a 6 ft grid each way, with a warranty acceptable to the owner. A few helical piers under interior bearing walls may still be needed with foam. - Fill voids larger than 3 in. with low-pressure grout. - Repair cracks with carbon fiber staples and epoxy, or by stitching: 18 in. #3 bars at 18 in. on center, 1.5 in. deep, in saw cuts. - If the slab is heavily cracked, replace it with #3 bars at 18 in. each way, doweled to the existing concrete. **Perimeter** [1]: - **16 perimeter steel piers**, penetrating **at least 12 ft below the bottom of the foundation** into firm, stable strata. - Steel piers only unless another system is approved, driven to refusal on bedrock (blue shale) per the detail. - A pier log for each pier: depth, type, diameter, driving pressure and lift. - A 6x6x1/2 in. angle iron under the footing where a pier lands near a crack. - Mortar removed from patched cracks before lifting. **Plumbing.** Test the plumbing **before and after** the repair [1]. ## What does this case show about Oklahoma foundations? - **Leaks are a known cause of localized slab movement.** ASCE's homeowner guide for shrink-swell soils states that leaks in sewer or water lines provide a localized source of water that may lead to localized foundation movements [2]. The engineer's before-and-after plumbing test reflects that concern [1]. - **Area subsoils are clay over shale.** The USDA's Dennis series, with its type location in Rogers County, formed in residuum weathered from Pennsylvanian shale. It has a clayey subsoil of 28 to 50 percent clay and a perched water table 12 to 30 inches down from December through April in normal years [3]. The record does not name the soil series at this site. - **Tolerances make a repair checkable.** The engineer set a measurable lift target of 1/2 to 3/4 in. and a minimum pier depth of 12 ft below the footing [1]. Both can be verified with an elevation survey and the pier log. ## Related - Plumbing Leaks Under Slab (https://terrabrain.vercel.app/guides/plumbing-leaks-under-slab) - Void and Compaction Grouting (https://terrabrain.vercel.app/repairs/void-and-compaction-grouting) - Helical Piers (https://terrabrain.vercel.app/repairs/helical-piers) - Slabjacking and Polyurethane (https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane) - Tolerances and Standards (https://terrabrain.vercel.app/guides/tolerances-and-standards) - Elevation Surveys (https://terrabrain.vercel.app/guides/elevation-surveys) Sources: [1] Engineer's evaluation report, 2025 (private client report), Licensed professional engineer, Oklahoma [2] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, ASCE Geo-Institute, Shallow Foundations Committee https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [3] USDA Official Series Description - Dennis Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/D/DENNIS.html --- # Why did a Tulsa house with 23 piers need pier work again in 2026? URL: https://terrabrain.vercel.app/case-studies/tulsa-slab-house-existing-piers-need-adjusting-again Answer: Footings kept moving at existing pier locations, and drainage was poor. The engineer specified adjusting the old piers or adding new steel piers, plus gutters. In short: A one-story Tulsa slab house had 23 perimeter piers installed in 2002, and 14 of them were adjusted after a 2022 inspection. By 2026 it again showed veneer movement on all four sides at the pier locations [1]. The engineer specified adjusting the existing piers, or placing new steel piers where an old pier is missing or cannot be adjusted. The scope also included re-grading and gutters with downspouts at every eave [1]. ## What did the house show? The house is a one-story wood-frame residence with brick veneer and siding. It sits on poured concrete footings with stem walls and a slab floor [1]. The file records a long repair history [1]: - **2002:** 23 perimeter piers installed by another contractor. - **2021:** that contractor proposed adjusting 14 of the piers and injecting high-density polyurethane foam. - **2022:** the same engineer inspected and recommended pier adjustment and under-slab injection. Afterward the west slab was replaced, the east slab stabilized and 14 piers adjusted. At the June 2026 inspection [1]: - Masonry veneer movement on the **north, west, south and east** sides. - Interior ceiling and wall cracks consistent with exterior footing movement at the pier locations marked on the engineer's sketch. - No excessive slab cracking. - Grades that do not slope away enough, and **missing gutters, splash pads and downspout extensions**. ## What did the engineer find was causing it? The record describes continued exterior footing movement at the existing pier locations, together with poor surface drainage around the house [1]. This was the second adjustment cycle in about four years after the 2002 installation. ## What repair was specified? - **Install steel piers or adjust existing piers** at the footings at the sketch locations. The report states that if a pier is not in place or cannot be adjusted, a new pier should be placed at that location [1]. - Full recovery to the original position is not guaranteed [1]. - Re-grade so water drains away, and install **gutters with downspouts and splash pads at all eaves** [1]. - Camera-inspect the in-slab ducts, and get a wood-destroying-organism inspection [1]. The report's general conclusion also contained standard wording that the house had not moved enough to warrant piers. That wording conflicts with the item-by-item recommendations, which do call for pier work [1]. ## What does this case show about Oklahoma foundations? - **Perimeter water is a recurring driver.** ASCE's homeowner guide for shrink-swell soils recommends keeping soil sloped away on all sides (at least 3 inches of fall in 5 feet) and discharging downspouts at least 3 feet from the foundation [2]. This house had neither adequate slope nor gutters [1]. - **The moisture zone can be deep.** Researchers writing on expansive-soil damage note that the zone of seasonal moisture change can extend from 3 to 40 feet deep. They identify differential water content as the biggest problem in expansive-soil areas [3]. - **The repair history was documented.** The file included records going back to 2002, including a seller disclosure. The engineer tied the 2026 distress to specific existing pier locations and allowed for adjustment or replacement pier by pier [1]. ## Related - Pier Uplift or Movement After Repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Surface Drainage and Grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Working with Engineers (https://terrabrain.vercel.app/guides/working-with-engineers) - Real Estate, Disclosure and Inspections - Foundation Issues in Oklahoma (https://terrabrain.vercel.app/rules/real-estate-disclosure-and-inspections-foundation-issues-in-oklahoma) Sources: [1] Engineer's evaluation report, 2026 (private client report), Licensed professional engineer, Oklahoma [2] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, ASCE Geo-Institute, Shallow Foundations Committee https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [3] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers et al.) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf --- # Why did a Tulsa slab home get wall piers but no slab repair? URL: https://terrabrain.vercel.app/case-studies/tulsa-slab-home-east-wall-seven-piers Answer: Brick cracks showed the east wall footing had moved, but floor differential was under 1 in., so the engineer specified 7 steel piers and no slab work. In short: A Tulsa slab-on-grade home had brick cracks on its east wall and cracking under the east bedroom windows. The engineer attributed it to active clay moving the perimeter footing under that wall, found the slab itself within 1 in. of level, and specified 7 steel piers along the east wall, at least 12 ft below the footing, plus a plumbing test [1]. ## What did the house show? - Brick cracks on the east wall. The veneer had been painted, and the engineer noted that paint may hide additional cracks [1]. - Inside: uneven floors, cracks at ceilings and windows, and cracks under the windows of the east bedroom [1]. - Ceiling cracks in the garage, which the engineer traced to over-loading of the attic above it rather than to the foundation [1]. - An elevation survey of the floor showed less than 1 in. of differential, with about 1 in. of settlement noted [1]. ## What did the engineer find was causing it? Shrink-swell movement of active clay soil under the east wall's perimeter footing. A plumbing leak was not confirmed, and the engineer asked for one to be ruled out [1]. ## What repair was specified? - A plumbing test of the supply and drain lines [1]. - 7 piers along the east wall at 8 ft spacing on the plan [1]. - Steel piers only; any other system needed the engineer's approval [1]. - Each pier to penetrate at least 12 ft below the bottom of the foundation to firm, stable strata; the typical detail reads "drive to refusal — bedrock (blue shale)" [1]. - A pier log for every pier: depth, type, diameter, driving pressure and amount of lift [1]. - Mortar to be removed from previously patched cracks near piers before lifting [1]. - A 6 x 6 x 1/2 in. angle iron under the footing wherever a pier fell close to a crack [1]. - The engineer to be called if old shallow concrete piers were found; locations and count could change with footing conditions [1]. - No slab repair, because the floor movement was judged minor [1]. ## What happened on the job? The repair contractor installed the piers in spring 2025, shortly after the report was issued [1]. ## What does this case show about Oklahoma foundations? On a floating slab, the perimeter footing and the interior slab are separate pieces and can move by different amounts. In this house the brick and the east-side rooms showed the footing had dropped, while the survey showed the slab itself was within 1 in. of level, so the engineer treated only the footing [1]. The engineer's spec ties the piers to depth and bearing material, not just to pressure: a 12 ft minimum below the footing and refusal on shale [1]. Seasonal moisture change is greatest in roughly the upper 1.5 to 2 m (about 5 to 6.5 ft) of soil and can reach about 5 m in some settings [2], so a 12 ft minimum below a shallow footing places the pier tip below the zone where clay moisture swings are largest. The garage ceiling cracks are a reminder that not every crack is a foundation problem. The engineer assigned them to attic loading and left them out of the foundation scope [1]. ## Related - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Elevation Surveys (https://terrabrain.vercel.app/guides/elevation-surveys) - Slab on Grade (https://terrabrain.vercel.app/foundations/slab-on-grade) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Plumbing Leak Detection and Repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair) - Diagonal Drywall Cracks at Openings (https://terrabrain.vercel.app/signs/diagonal-drywall-cracks-at-openings) Sources: [1] Engineer's evaluation report and pier location plan, 2025 (private client report), Licensed professional engineer, Oklahoma [2] Shrink-Swell Subsidence (Hazard Information Profile), UN Office for Disaster Risk Reduction / British Geological Survey https://www.undrr.org/understanding-disaster-risk/terminology/hips/gh0310 --- # Why did an Edmond slab house settle again two years after piering? URL: https://terrabrain.vercel.app/case-studies/edmond-1967-slab-settlement-after-2023-piers Answer: The engineer found more settlement at piers installed in 2023 plus erosion and poor grading. The fix: adjust or replace 7 piers, add 1, and improve drainage. In short: A small 1967 slab house in Edmond had 21 exterior piers, 1 garage pier and interior slab injection installed in 2023. By late 2025 it showed additional settlement at the front, rear and north side [1]. The engineer pointed to continued settlement at pier locations, erosion and poor grading. The engineer specified adjusting or replacing 7 piers with steel piers, adding 1 pier where spacing was excessive, and a list of drainage improvements [1]. ## What did the house show? The engineer inspected the house in November 2025 and issued the report in December [1]. It is a one-story house of about 1,035 sq ft, built about 1967, on a slab-on-grade [1]. Repair history and observations [1]: - **2023:** 21 exterior piers, 1 pier inside the garage, and interior slab injection. - Since then, **additional settlement at the front, rear and north side**, seen as drywall corner and baseboard separations. - A southwest bedroom closet door binding. - A living and kitchen ceiling crack, which the engineer attributed to truss movement and described as not structural. - **Erosion and poor grading.** A north-side walk traps water by the kitchen and utility room. ## What did the engineer find was causing it? The engineer described continued settlement at pier locations and stressed **surface water**, grading and drainage. Possible under-slab leaks were also raised [1]. ## What repair was specified? - **Adjust or replace 7 of the existing piers** shown on the report's figure. Replacement piers must be **steel** [1]. - **Add 1 new pier on the north side "due to excessive spacing"** [1]. - Afterward, repair drywall and trim, seal exterior cracks, tuck-point, and use elastomeric caulk [1]. - Suggested items [1]: - a plumbing leak test - downspout extensions of **at least 36 in.**, or underground pipe to daylight - ground sloped at **1 in. per 12 in. within 4 ft** of the house - removal of beds that trap water - surface drains - compacted fill with vegetation - an option for a sloped concrete walkway The report states its plan is not an engineered location plan. The contractor sets final pier lengths, locations and count, and any bad footing or stem wall must be repaired before piering [1]. ## What does this case show about Oklahoma foundations? - **OKC-area soils include clay subsoils over shale.** The USDA describes the Bethany series, with its type location in Oklahoma County, as formed in loess or alluvium over Permian shale. Its subsoil is silty clay loam to clay with 35 to 45 percent clay [2]. The record does not identify the soil series at this site; Bethany illustrates the clay subsoils mapped in the county. - **Drainage was part of the scope on a piered house.** ASCE's homeowner guide for shrink-swell soils recommends grade falling at least 3 inches in 5 feet and downspouts discharging at least 3 feet away. It also notes that leaks in sewer or water lines can cause localized movement [3]. The engineer's drainage list (36 in. extensions, 1 in. per 12 in. within 4 ft, leak test) covers the same items [1]. - **Spacing is part of the design.** The engineer called out excessive spacing on the existing layout as a reason for an added pier [1]. ## Related - Pier Uplift or Movement After Repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair) - Loads Pier Spacing and Capacity (https://terrabrain.vercel.app/guides/loads-pier-spacing-and-capacity) - Surface Drainage and Grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Truss Uplift (Mimic) (https://terrabrain.vercel.app/causes/truss-uplift-mimic) - OKC Metro (https://terrabrain.vercel.app/regions/okc-metro) - Bethany soil series (https://terrabrain.vercel.app/soils/bethany) Sources: [1] Engineer's evaluation report, 2025 (private client report), Licensed professional engineer, Oklahoma [2] USDA Official Series Description - Bethany Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/B/BETHANY.html [3] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, ASCE Geo-Institute, Shallow Foundations Committee https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf --- # Why did an engineer pick helical piers for a Tulsa crawl space home? URL: https://terrabrain.vercel.app/case-studies/tulsa-crawl-space-home-helical-piers-clay-tile-stem-wall Answer: A clay tile stem wall and a light converted garage gave push piers little to push against, so the engineer specified 10 helical piers at least 20 ft deep. In short: An east Tulsa crawl space home with a converted garage showed veneer separations over 1/2 in. and out-of-square doors despite earlier, undocumented underpinning. The engineer presumed moisture-reactive clay and missing gutters as the cause and specified 10 exterior helical piers at least 20 ft below grade, shimming of crawl supports, and drainage maintenance [1]. ## What did the house show? - Brick veneer separations over 1/2 in. on the north side, and veneer-to-trim gaps over 1/4 in. at the northwest and southwest corners [1]. - The south door of the converted garage out of square, and interior drywall cracks [1]. - Previous underpinning along the north, west and south sides, with no documentation available [1]. - A mostly dry crawl space, loose floor supports in the south crawl, and added braces in the north crawl that the engineer judged were for floor vibration only; the 2x8 joists at 16 in. on center were adequate [1]. - Incomplete guttering and cracked exterior flatwork, which the engineer rated non-structural [1]. ## What did the engineer find was causing it? With no geotechnical data, the engineer presumed moisture-reactive clay whose shrink-swell causes loss of support and uplift at the perimeter footing. The incomplete gutter system contributed; possible fill or slope issues were noted as beyond the report's scope. The engineer's stated aim was to carry the footing down to soil "less affected by climate, soil conditions and/or homeowner's actions" [1]. ## What repair was specified? - 10 exterior piers under the perimeter footings. Helical piers were specifically recommended because of the clay tile stem wall and the light weight of the garage. Drilled concrete piers with a bell at least twice the shaft diameter, or drilled steel piers, were also acceptable [1]. - Minimum depth 20 ft below existing grade, bearing on a stronger stratum such as bedrock or weathered shale, unless the engineer approved otherwise [1]. - Jack the footings after piering, and notify the engineer if jacking was not possible [1]. - Verify the garage footing during installation; expose existing piers in at least 3 places (up to 10 ft deep) and call the engineer if a pier-and-grade-beam foundation was found [1]. - Level and tight-shim all crawl space girders and supports; rebuild or re-side the northwest veneer [1]. - Plumbing tests of supply and sewer lines after piering, and suggested before [1]. - Gutters; downspout and condensate extensions 36 to 48 in. from the foundation; grade sloped 2 to 5 percent away; low spots filled with sandy clay; no sprinkler use in wet weather [1]. - Engineer inspection before backfill (24-hour notice) if certification was wanted; any pier relocation needed the engineer's approval [1]. ## What does this case show about Oklahoma foundations? The project record lists the Coweta series mapped at the site [1]. USDA describes Coweta as a shallow, well-drained soil formed from soft Pennsylvanian sandstone interbedded with shale, with the soft rock typically about 15 in. down and harder sandstone at 2 to 5 ft in some places [2]. That is far shallower than the engineer's 20 ft default, and the spec's engineer-approval clause is how a shallower refusal on rock gets accepted [1]. The pier choice turned on the structure, not just the soil. A push pier is driven using the building's own weight as reaction, so a light garage and a fragile clay tile stem wall led the engineer to helical piers [1]. The drainage advice is close to published guidance. The engineer asked for 36 to 48 in. extensions and 2 to 5 percent grade [1]; federal building-science guidance recommends at least 5 ft of discharge distance and at least 1/2 in. per foot of fall for 10 ft [3]. ## Related - Helical Piers (https://terrabrain.vercel.app/repairs/helical-piers) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Pier and Beam Crawl Space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) - Working with Engineers (https://terrabrain.vercel.app/guides/working-with-engineers) - Soil - Coweta (https://terrabrain.vercel.app/soils/coweta) - Pier Uplift or Movement After Repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair) Sources: [1] Engineer's evaluation report, 2026 (private client report), Licensed professional engineer, Oklahoma [2] USDA Official Series Description - Coweta Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COWETA.html [3] Gutters and Downspouts (Building America Solution Center), U.S. Department of Energy / Pacific Northwest National Laboratory https://basc.pnnl.gov/resource-guides/gutters-and-downspouts --- # Why did Oklahoma earthquakes increase, and can they damage houses? URL: https://terrabrain.vercel.app/guides/induced-seismicity-in-oklahoma Answer: Quakes rose sharply after 2009, mainly linked to deep disposal of oil-and-gas wastewater; moderate quakes can crack plaster and masonry. In short: Oklahoma's earthquake activity rose sharply after 2009, and the state geological survey links that increase mainly to deep disposal of oil-and-gas wastewater. The largest recorded event was the 2016 Pawnee earthquake. Moderate quakes can crack plaster and masonry, and earthquake damage and soil movement can look alike. ## What happened to Oklahoma's earthquake activity? The Oklahoma Geological Survey (OGS) states that a large area of the state has had greatly increased seismic activity since 2009, and especially since 2013 [1]. The OGS describes these earthquakes as induced primarily by deep injection of produced water from oil and gas operations [1]. "Produced water" is the salty water that comes out of wells along with oil and gas and is pumped back underground for disposal. "Induced" means caused by human activity rather than natural processes alone. ### Wastewater disposal, not fracking itself The USGS states that disposal of waste fluids produced with oil is the primary cause of the rise in central U.S. earthquakes, and that only 1 to 2 percent of Oklahoma earthquakes can be linked to hydraulic fracturing ("fracking") [8]. Less than 10 percent of the water injected into Oklahoma disposal wells is spent fracking fluid; most is salty water produced along with oil [8]. Much of that water went into the Arbuckle, a deep rock formation under most of Oklahoma that readily absorbs fluid [9]. Researchers identified injection into the granite basement rock below it as a major risk factor for triggering earthquakes [9]. ### How regulators responded The OGS noted in 2016 that actions by the Oklahoma Corporation Commission, the state agency that regulates oil and gas wells, and changes in the oil market may already have affected seismic activity [1]. Key steps included: - **March 2015:** The Commission directed operators of 347 Arbuckle disposal wells in quake-prone areas to prove their wells did not reach basement rock, to plug back wells that did, or face a 50 percent volume cut [9]. - **March 2016:** A plan covering more than 5,200 square miles of central Oklahoma aimed to cut disposal volumes 40 percent below 2014 totals; together with a northwestern plan it covered more than 640 disposal wells [10]. ### The rise and decline in numbers | Year | Earthquakes of magnitude 3.0 or greater | |---|---| | 2015 (peak) | 903 [11] | | 2018 | 196 [11] | | 2022 | 15 (14 between 3.0 and 3.9, one between 4.0 and 4.9) [12] | The OGS detected 2,972 earthquakes of all sizes in 2022, down from 5,150 in 2021 [12]. Smaller quakes continue, so a felt earthquake today is still possible. ## What are the largest recorded Oklahoma earthquakes? | Event | Date | Magnitude | Intensity (MMI) | |---|---|---|---| | Pawnee | Sept. 3, 2016 | 5.8 | VII | | Prague | Nov. 6, 2011 | 5.7 | VII | | El Reno | Apr. 9, 1952 | 5.5 | VII | | Fairview | Feb. 13, 2016 | 5.1 | VII | Source: OGS top-ten list [2]. Four of the state's ten largest listed events occurred in 2016 [2]. ### Pawnee, 2016 The OGS fact sheet issued after the Pawnee quake listed a preliminary magnitude of 5.6, centered 9.3 miles northwest of Pawnee at a depth of about 3.5 miles, on a strike-slip fault (one where the ground slides sideways) [3]. The later top-ten list gives 5.8 [2]. The fact sheet notes that central U.S. earthquakes are felt over an area more than ten times larger than similar West Coast quakes [3]. ### Cushing, 2016 The magnitude 5.0 Cushing earthquake in November 2016 began only about 4 km (2.5 miles) deep, and nearby instruments recorded peak horizontal ground accelerations of 0.44 g to 0.58 g [15]. Century-old unreinforced brick buildings downtown were heavily damaged and some were demolished [15]. ### Fairview aftershocks The magnitude 5.1 Fairview earthquake in February 2016 was followed by aftershocks; by July 2016, eight aftershocks of magnitude 4 or larger had occurred on the same fault zone in Woods County [4]. The OGS noted that aftershock sequences tend to last longer in the middle of the continent than along plate boundaries [4]. ## How do magnitude and intensity differ? - **Magnitude** measures the energy released at the source. One number per earthquake. - **Intensity**, on the Modified Mercalli Intensity (MMI) scale, describes shaking effects at a particular place. It varies with distance and ground conditions. The OGS describes MMI VI as minor damage such as falling plaster and a few cracks [1]. The chance of MMI VII damage, comparable to the 2011 Prague earthquake, was described as very small and limited to a much smaller area [1]. The OGS also noted the 2016 USGS hazard model did not address cumulative damage from many small earthquakes over time [1]. ## Where can the earthquake record be checked? - **OGS earthquake catalogs**: yearly lists of Oklahoma events. The OGS describes them as fairly complete for magnitude 2.9 and larger since 1980 [5]. - **Report a felt quake**: the OGS asks residents to report felt earthquakes on the USGS Did You Feel It? site and on its own form [6]. - **USGS Did You Feel It?**: collects reports from people who felt a quake and turns them into maps of shaking and damage [7]. - **USGS ShakeMap**: maps of the ground shaking recorded at seismic stations soon after an earthquake, including an estimated Modified Mercalli Intensity map showing where shaking was likely felt and where damage may have occurred; accuracy is highest near stations [13]. ## Why do earthquakes matter for foundations? In the moderate Oklahoma quakes, damage concentrated in masonry. After the Pawnee earthquake, emergency managers reported no building collapses and said much of the damage was to older brick and mortar buildings from the early 1900s; stones fell from the facade of a 1902 sandstone bank building [14]. In Cushing, the worst damage was to century-old unreinforced brick buildings [15]. Earthquakes and expansive clay can both crack walls and slabs, and the patterns differ; see earthquake shaking damage (https://terrabrain.vercel.app/causes/earthquake-shaking-damage) for how shaking damage typically appears. A step-by-step comparison of timing, crack edges and elevation data is on the seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement) page. The deep geology behind these events is summarized in Oklahoma geologic provinces (https://terrabrain.vercel.app/guides/oklahoma-geologic-provinces). ## Related - Seismic Damage vs Soil Movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement) - Fresh, Clean-Edged Cracks Appearing Suddenly (https://terrabrain.vercel.app/signs/fresh-clean-edged-cracks-appearing-suddenly) - Chimney Separating or Leaning (https://terrabrain.vercel.app/signs/chimney-separating-or-leaning) - OK Data - Earthquakes Claims and Law (https://terrabrain.vercel.app/data/earthquakes-claims-and-law) - Insurance Claims (https://terrabrain.vercel.app/rules/insurance-claims) Sources: [1] Statement on USGS Hazard Assessment for Sites with Induced Seismicity, Oklahoma Geological Survey https://www.ou.edu/content/dam/ogs/documents/statements/OGS_Statement_USGS_Hazard_Assessment_2016-03-28.pdf [2] Information (Top Ten Oklahoma Earthquakes), Oklahoma Geological Survey https://www.ou.edu/ogs/research/earthquakes/Information.html [3] Fact Sheet: Pawnee Earthquake, September 3, 2016, Oklahoma Geological Survey https://www.ou.edu/content/dam/ogs/documents/statements/OGS-Fact_Sheet_Pawnee_Earthquake_2016-09-03.pdf [4] Statement on Woods County M4+ Aftershocks, July 11, 2016, Oklahoma Geological Survey https://www.ou.edu/content/dam/ogs/documents/statements/OGS-statement-woods_county_M4_aftershocks_2016-07-11.pdf [5] Earthquake Catalogs, Oklahoma Geological Survey https://www.ou.edu/ogs/research/earthquakes/catalogs.html [6] Report an Earthquake, Oklahoma Geological Survey https://www.ou.edu/ogs/research/earthquakes/report-an-earthquake.html [7] Did You Feel It? (DYFI), U.S. Geological Survey https://earthquake.usgs.gov/data/dyfi/ [8] Myths and Misconceptions About Induced Earthquakes, U.S. Geological Survey https://www.usgs.gov/programs/earthquake-hazards/myths-and-misconceptions-about-induced-earthquakes [9] Regulators Issue Tougher Disposal Well Directives as Oklahoma's Quake Risk Rises, StateImpact Oklahoma (NPR) https://stateimpact.npr.org/oklahoma/2015/03/25/regulators-issue-tougher-disposal-well-directives-as-oklahomas-quake-risk-rises/ [10] Oklahoma Unveils Earthquake Prevention Plan, High Plains Public Radio https://www.hppr.org/hppr-environment/2016-03-14/oklahoma-unveils-earthquake-prevention-plan [11] Scientists see a decline in earthquakes, magnitude 3.0 or greater, KTUL https://www.ktul.com/news/local/scientists-see-a-decline-in-earthquakes-magnitude-30-or-greater [12] Bulletin of seismic activity in Oklahoma for the Year 2022, Oklahoma Geological Survey https://www.ou.edu/content/dam/ogs/documents/information/earthquake-monthly-bulletins/2022_EQ_Summary.pdf [13] ShakeMap Manual: Background, U.S. Geological Survey https://ghsc.code-pages.usgs.gov/esi/shakemap/manual4_0/ug_background.html [14] Overview of building damages after the September 3, 2016 Oklahoma, USA Earthquake, Earthquake Engineering Research Institute, Learning from Earthquakes https://learningfromearthquakes.org/?p=54335 [15] Performance of Low-Rise Buildings with No Seismic Design in Unanticipated Earthquakes (17th World Conference on Earthquake Engineering), 17WCEE / NICEE https://wcee.nicee.org/wcee/article/17WCEE/2c-0197.pdf --- # Why did one corner of a Mannford walk-out basement house settle? URL: https://terrabrain.vercel.app/case-studies/mannford-walkout-basement-corner-settlement-roof-runoff Answer: The engineer tied it to possible fill consolidation on the south side and roof runoff concentrated at the southwest corner, and specified 8 steel piers. In short: A one-story brick-veneer house in Mannford with a partial walk-out basement had settled at its southwest corner. The engineer attributed it to possible consolidation of fill along the south side and to roof runoff concentrated at that corner [1]. The repair specified 8 exterior steel pipe piers with lift and level, solid drain lines from the south downspouts, and a rebuilt retaining wall [1]. ## What did the house show? The engineer inspected the house in April 2022 [1]. The building is a one-story timber-frame house with brick veneer, a partial walk-out basement, and an attached garage that was built as an addition. Basement and stem walls are concrete on spread footings, and the main level has a slab-on-grade [1]. Observed distress [1]: - A 1/8 in. crack in the brick on the west face and a brick crack at the southwest living-room corner. - A 1/2 in. gap between a window frame and the surrounding brick. - Ceiling and wall cracks in the southwest part of the living room, and wrinkles in the wall finish along the south living-room wall and the east garage wall. - A segmental block retaining wall that had partly collapsed. - A back balcony carried on 6 in. columns formed in PVC. ## What did the engineer find was causing it? The engineer concluded the house had minor long-term settlement along the south elevation, with **possible consolidation of fill** as a factor [1]. Roof runoff was concentrated at the southwest corner. The engineer linked that water both to the corner settlement and to the buckled block retaining wall [1]. ## What repair was specified? The report listed five items [1]: 1. **8 exterior steel pipe piers**, then lift and level the structure to close the gaps. 2. Repair the brick cracks with matching mortar. 3. Run **non-perforated gutter drain lines** from the two south downspouts to the downhill side of the retaining wall. 4. Rebuild the damaged section of the retaining wall. 5. Consider drainage improvements at the northeast corner. The drainage items address the water source the engineer identified, and the piers address the settlement it had already caused. A solid pipe carries roof water to its outlet instead of releasing it into the soil next to the footing and behind the wall. ## What happened on the job? The record shows the repair was carried out in April 2022, within about two weeks of the engineer's report [1]. ## What does this case show about Oklahoma foundations? - **Roof water is a point source.** A roof collects rain over a large area and the downspouts drop it in a few spots. ASCE's homeowner guide for shrink-swell soils recommends gutters and downspouts that discharge at least 3 feet from the foundation into well-drained areas. It also says to keep soil sloping away on all sides, with at least 3 inches of fall in 5 feet [2]. In this case the water was concentrated at one corner, and that corner is where the settlement was. - **Below-grade walls need water routed away.** Building-science guidance for basements says roof and surface runoff should be collected and carried away from the foundation, and that grade should slope away from the building [3]. On a walk-out lot the downhill side often also holds retaining walls. Here the same water that reached the corner also loaded the retaining wall below it. - **Fill can keep compressing.** The engineer listed fill consolidation as a possible factor on the south side [1]. Steel piers carry the footing load down through that fill to deeper bearing. ## Related - Fill Consolidation Settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) - Fill Soils and Lot History (https://terrabrain.vercel.app/guides/fill-soils-and-lot-history) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Brick Separating from Window or Door Frame (https://terrabrain.vercel.app/signs/brick-separating-from-window-or-door-frame) - Basements (https://terrabrain.vercel.app/foundations/basements) Sources: [1] Engineer's evaluation report, 2022 (private client report), Licensed professional engineer, Oklahoma [2] Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations, ASCE Geo-Institute, Shallow Foundations Committee https://geoinstitute.org/sites/default/files/inline-files/LivingWithShrinkSwellSoils_updated.pdf [3] Understanding Basements, Building Science Digest 103, Building Science Press (J. Lstiburek) https://www.greenbuildingadvisor.com/sites/default/files/Basement%20-%20Understanding%20Basements.pdf --- # Why did only one side of a 1958 brick home in The Village need piers? URL: https://terrabrain.vercel.app/case-studies/the-village-1958-brick-home-east-side-piers Answer: The east side had settled up to about 1.2 in. on highly plastic clay, so the engineer specified 4 steel piers there and monitoring on the west side. In short: A 1958 brick home in The Village showed its worst cracking and a 3/8 in. trim gap on the east side, and an elevation survey found the floor up to about 1.2 in. low toward the east. The engineer attributed it to consolidation and shrink-swell of highly plastic clay and specified 4 steel piers on the east side only, with the west side to be monitored [1]. ## What did the house show? On the east side the engineer recorded brick cracks of 1/32 to 1/8 in. under the windows, brick pulled about 1/8 in. off the window frame near the southeast corner, a 3/8 in. gap at the frieze trim at that same corner, and interior cracks above the east bedroom windows. The engineer classed this as significant movement [1]. The west side had smaller brick cracks (1/16 and 1/32 in.) and some previously patched interior cracks, which the engineer rated as not significant [1]. An elevation survey taken with a digital level (stated accuracy about 0.1 in. over 200 ft), zeroed at the front door, read from about 0.0 to −1.2 in., lowest toward the east. The crawl space was dry and the floor framing showed minimal deflection [1]. ## What did the engineer find was causing it? The engineer named highly plastic clay soil, settling through consolidation and moving with moisture change. Rain and drought cycles, drainage, plumbing leaks and trees were listed as the moisture drivers [1]. ## What repair was specified? - Underpin the east side with 4 steel piers, "hydraulically driven until the foundation starts lifting" [1]. - Maximum pier spacing of 8 ft; the plan was not tied to any proprietary pier system [1]. - A caution against over-lifting [1]. - Monitor the west side and re-evaluate if movement continues [1]. ## What happened on the job? The repair contractor installed the piers in 2025. Its markup of the engineer's plan logged the piers at roughly 9,500 psi driving pressure and recorded about 1/4 to 1/2 in. of lift [1]. ## What does this case show about Oklahoma foundations? The soil mapped for the area in the project record is the Renthin series [1]. USDA describes Renthin as a deep, well-drained soil weathered from Permian clayey and silty shale, with 35 to 55 percent clay in the subsoil, very slow permeability, and slickensides and shrinkage cracks typical of shrink-swell behavior; its linear extensibility is 6 cm or more within the top 100 cm [2]. Soils like this change volume as they wet and dry, and the upper 1.5 to 2 m of soil sees the most seasonal moisture change [3]. This case also shows that movement is often uneven. One side of the house had dropped more than an inch while the other side was nearly level, and the engineer treated only the side that had moved [1]. Seasonal clay movement usually lifts or drops a house unevenly rather than as a single block [3]. ## Related - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Elevation Surveys (https://terrabrain.vercel.app/guides/elevation-surveys) - Monitoring Program (https://terrabrain.vercel.app/repairs/monitoring-program) - Soil Series - OKC Metro (https://terrabrain.vercel.app/guides/soil-series-okc-metro) - R - OKC Metro (https://terrabrain.vercel.app/regions/okc-metro) - Frieze Board or Trim Separation (https://terrabrain.vercel.app/signs/frieze-board-or-trim-separation) Sources: [1] Engineer's evaluation report, 2025 (private client report), Licensed professional engineer, Oklahoma [2] USDA Official Series Description - Renthin Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/R/RENTHIN.html [3] Shrink-Swell Subsidence (Hazard Information Profile), UN Office for Disaster Risk Reduction / British Geological Survey https://www.undrr.org/understanding-disaster-risk/terminology/hips/gh0310 --- # Why do basement walls crack horizontally and bow inward? URL: https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls Answer: Soil pushes sideways on basement walls, and wet backfill and swelling clay add pressure. When the push exceeds the wall's strength, it cracks, bows or slides. In short: Basement and retaining walls hold back soil, and that soil pushes sideways on them. When the backfill is wet, the water adds pressure, and when it is expansive clay, swelling adds more. If the total push exceeds what the wall was built to resist, the wall cracks horizontally, bows inward or slides at the top. ## What kinds of sideways pressure act on walls? A below-grade wall carries a horizontal load from the ground beside it. That load has three parts: - **Lateral earth pressure.** The weight of the soil itself pushes outward against any wall holding it back. Soil, water and temperature all push horizontally on basement walls, and walls that are not properly designed for these pressures can see existing cracks grow [2]. - **Hydrostatic pressure.** This is the pressure of water in saturated soil, especially against underground walls [1]. Standing water along a foundation can push past the pressure a wall was designed for [2]. - **Swell pressure.** Expansive clay swells when it takes on water [5]. In Oklahoma benchmark soils such as Bethany, Kirkland and Norge, the fine clays are dominantly montmorillonitic (smectite), a swelling clay mineral [3], and nearly all of Oklahoma has medium or high swelling potential [4]. Clay backfill that wets and swells adds its own push to the wall. ## How do basement and retaining walls fail? When water-saturated soil presses against the outside of a foundation wall, the wall is pushed inward, and the inward bow opens a crack [1]. InterNACHI describes these cracks as usually horizontal, wider than hairline and showing signs of water intrusion, and notes that hydrostatic pressure acts particularly on underground concrete block and poured concrete walls [1]. Backfilling is also a vulnerable time. Cracks can form during backfilling if the concrete has not gained enough strength, the walls are not braced as designed, or heavy equipment works too close to the wall [2]. ## What are the signs of wall pressure damage? - a horizontal crack or inward bow in a basement wall (https://terrabrain.vercel.app/signs/horizontal-crack-or-inward-bow-in-basement-wall) - water at the cove joint or efflorescence (https://terrabrain.vercel.app/signs/water-at-cove-joint-or-efflorescence), the white mineral deposit left when water seeps through masonry and evaporates - a horizontal crack at the brick ledge or slab edge (https://terrabrain.vercel.app/signs/horizontal-crack-at-brick-ledge-or-slab-edge) - tilted retaining walls, fences or trees (https://terrabrain.vercel.app/signs/tilted-retaining-walls-fences-or-trees) where a retaining wall is involved ## How do pressure cracks differ from shrinkage cracks? Not every basement wall crack comes from soil pressure. New concrete shrinks as it dries, and temperature changes make it expand and contract; when that movement is restrained, cracks form [2]. Diagonal cracks at window, door and other opening corners usually come from shrinkage [2]. Settlement cracks can come from uneven footing support or expansive soils [2]. | Crack type | Typical cause | |---|---| | Horizontal, often with inward bow and water | Lateral soil and water pressure [1] | | Diagonal from window or door corners | Drying shrinkage [2] | | Cracks with vertical offset | Settlement of footing support [2] | The concrete industry notes that cracking is not necessarily a sign of poor materials, workmanship or a structural problem. Typical warranties require repair when cracks leak, show measurable vertical displacement or exceed 1/8 inch (3 mm) in width, and cracks that keep widening call for professional evaluation [2]. See material shrinkage and thermal cracking (https://terrabrain.vercel.app/causes/material-shrinkage-and-thermal-cracking-mimic). ## How is a pushed-in wall typically fixed? - **Reduce the water.** The concrete industry advises finishing grade so water drains away from the foundation and installing waterproofing and drainage so water does not build up against walls [2]. See drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). - **Reinforce or rebuild the wall.** Methods for bowed or cracked walls are described on the basement wall repair (https://terrabrain.vercel.app/repairs/basement-wall-repair) page. See the basements (https://terrabrain.vercel.app/foundations/basements) page for how these foundations are built. ## Related - Basement Wall Repair (https://terrabrain.vercel.app/repairs/basement-wall-repair) - Horizontal Crack or Inward Bow in Basement Wall (https://terrabrain.vercel.app/signs/horizontal-crack-or-inward-bow-in-basement-wall) - Groundwater and Perched Water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Basements (https://terrabrain.vercel.app/foundations/basements) - Clay Mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) Sources: [1] Foundation Crack from Lateral Movement and Hydrostatic Pressure, InterNACHI https://nachi.org/gallery/settlement-and-cracks/lateral-movement-foundation-cracks [2] CIP 7 - Cracks in Residential Basement Walls, National Ready Mixed Concrete Association https://www.nrmca.org/wp-content/uploads/2021/01/07pr.pdf [3] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [4] Soil Matric Suction and Active Zone Depth in Oklahoma, Oklahoma State University (Er Yue, Ph.D. dissertation, 2017) https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf [5] The Mystery of Expansive Soils, STRUCTURE magazine (NCSEA / CASE / SEI) https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf --- # Why do cracks open and close with the seasons? URL: https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally Answer: Expansive clay shrinks as it dries and swells as it rewets, so the house moves with it and cracks widen in dry months and tighten in wet months. In short: A crack that widens in the dry months and tightens again in the wet months is the classic sign of soil moisture driving foundation movement. On Oklahoma's expansive clay, the soil shrinks as it dries and swells as it rewets, and the house rides that cycle. Tracking the crack through a full year shows the pattern and its size. ## Why do cracks open and close? Expansive clay swells when it gets wet and shrinks when it dries, creating a repeating cycle of movement in the upper soil [2]. The zone of seasonal moisture change can extend from 3 to 40 feet deep depending on the site [2]. Because the edges, corners and areas near trees dry and rewet differently from the middle of the house, the movement is uneven, and uneven movement is what cracks walls, brick and slabs. Texas monitoring of houses on expansive clay found average out-of-levelness growing from about 2-1/4 inches to 3-3/4 inches as the growing season progressed, with partial recovery when winter dormancy, rain and lower evaporation returned moisture to the soil [1]. Droughts during the growing season made settlement worse, and above-normal rainfall slowed it [1]. UK guidance likewise notes that soil shrinkage typically peaks in late summer [3]. ## What is Oklahoma's seasonal cycle? More than 75% of Oklahoma has bedrock that can produce expansive soils, including clay-rich shales that can swell to 1.5 to 2 times their dry volume when wet [6]. Soil moisture drops faster during hot, dry periods than during cool, wet ones [4]. The Oklahoma Mesonet measures soil moisture at depths of 5, 25, 60 and 75 centimeters (about 2 to 30 inches) at stations covering all 77 counties [5], so readings from a nearby station can be lined up with crack measurements. See Mesonet for foundation pros (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros) and seasonal movement calendar (https://terrabrain.vercel.app/guides/seasonal-movement-calendar). ## What mechanisms produce it? | Mechanism | Typical seasonal pattern | |---|---| | Perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) | Edges drop in late summer and drought; cracks at outside walls widen | | Perimeter wetting heave (edge lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) | Edges rise in wet periods; cracks change in the opposite direction | | Tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) | Settlement toward a tree grows through the growing season [1] | Engineering guidance on expansive soil notes that lack of watering in drought, which dries the clay, can be more damaging than overwatering, and that the goal is steady soil moisture [7]. ## How do you track a seasonal crack? 1. Mark the ends of the crack and two or three measuring points along it. 2. Measure width at the same points with a crack gauge or ruler, or install a crack monitor across it. 3. Photograph each point with a scale in view. 4. Record readings every month or two for at least 12 months. 5. Note rainfall, drought and watering changes alongside each reading; the U.S. Drought Monitor and Mesonet data (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) give context. A plot of width against date shows whether the crack follows the seasons, is steadily growing, or is stable. Seasonal cracks that also grow larger each year point to ongoing net movement. ## What does it rule in and out? Seasonal opening and closing points toward moisture-driven soil movement. It argues against causes that happen once, such as a single earthquake or impact, which tend to leave fresh, clean-edged cracks that do not cycle; see fresh, clean-edged cracks appearing suddenly (https://terrabrain.vercel.app/signs/fresh-clean-edged-cracks-appearing-suddenly). It also differs from truss uplift (https://terrabrain.vercel.app/causes/truss-uplift-mimic), which opens ceiling-to-wall joints in winter rather than in late summer. ## What are the next steps? Plot the cracks on an elevation survey, compare them with the distress pattern library, and use the symptom matrix. ## Related - Shrink-swell and active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) - Perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Monitoring program (https://terrabrain.vercel.app/repairs/monitoring-program) - Drought and wet years data (https://terrabrain.vercel.app/data/drought-and-wet-years) Sources: [1] Cyclical Foundation Movements and Their Remediation, CIGMAT, University of Houston (conference presentation) https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2007/addison.pdf [2] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [3] Trees near buildings, Royal Horticultural Society https://www.rhs.org.uk/plants/types/trees/near-buildings [4] Tracking Drought Using Soil Moisture Information (BAE-1541), Oklahoma State University Extension https://extension.okstate.edu/fact-sheets/tracking-drought-using-soil-moisture-information.html [5] The Oklahoma Mesonet (fact sheet), Oklahoma Mesonet https://www.mesonet.org/common/pubs/factsheets/Mesonet%20Fact%20Sheet.pdf [6] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [7] Irrigation, Drainage, and Landscaping for Expansive Soil, Journal of Irrigation and Drainage Engineering (ASCE) https://ascelibrary.com/doi/10.1061/%28ASCE%290733-9437%281992%29118%3A2%28285%29 --- # Why do driveways, patios and sidewalks move in Oklahoma? URL: https://terrabrain.vercel.app/foundations/flatwork-and-exterior-slabs Answer: Flatwork is thin, lightly loaded and sits on the soil, so swelling clay lifts it and drying or washed-out soil lets it drop more readily than the house. In short: Flatwork is the concrete outside the house: driveways, sidewalks, patios, porches, stoops and garage aprons. It is thin, lightly loaded and usually sits directly on the soil, so Oklahoma's swelling clay lifts it and drying or washed-out soil lets it drop more readily than the house itself. Flatwork also matters to the foundation because it decides where roof and yard water goes. ## What counts as flatwork? - Driveways and garage aprons - Sidewalks and front walks - Patios and back slabs - Porches and stoops at doors - Pool decks and pads for equipment Unlike a house foundation, most flatwork has no thickened beam or footing reaching below the surface soil. Where a porch or stoop does have footings, the general code minimum for footings is 12 in below the ground surface, with added frost protection (such as going below the local frost line) where frost requires it [8]. ## Why does flatwork move so much? Swelling soils lift and crack lightly loaded strip footings and frequently cause distress in floor slabs [2]. Clay-rich soils can swell 10% or more by volume when wetted, and cracked garage slabs, driveways, sidewalks and patios are among the most common signs of swelling soil [1]. Colorado State University Extension reports swelling pressures up to 15,000 lb per square foot in expansive soils, enough to crack walks and drives [7]. The main mechanisms behind flatwork movement are: | Mechanism | What happens | Typical look | |---|---|---| | Perimeter wetting heave (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) | Clay under the slab takes on water and swells [1] | Slab edge or joint raised; trip edges | | Drying settlement | Clay loses moisture and shrinks [2] | Slab tipped down at the outer edge | | Shrinkage cracking | Concrete shrinks as it cures; extra mixing water increases shrinkage [4] | Fine random or regularly spaced cracks | Washout of soil from under slab edges and frost heave are covered on their own pages under erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) and frost heave. ## Which concrete details matter? - Adding 2 gallons of water per cubic yard makes concrete about 10% weaker and increases shrinkage about 20% [4]. - Exterior exposed slabs carry a minimum strength of 3,000 psi in the residential code, compared with 2,500 psi for interior footings and basement slabs [4]. - Oklahoma's 2024 code adoption exempts interior slabs on grade and enclosed garage slabs from the air-entrainment requirement [5]. Air entrainment means tiny bubbles mixed into concrete to help it resist freeze-thaw damage, so exterior flatwork remains subject to it. - Water that freezes inside concrete expands about 9%, which can crack and spall it [4]. ## How does flatwork affect foundation drainage? The residential code requires the ground to fall at least 6 in within the first 10 ft from the foundation, and requires impervious surfaces such as concrete within 10 ft of the building to slope at least 2% away from it [3]. A patio or walk that has settled toward the house reverses that slope and can send water to the foundation edge, which is why flatwork is checked during a surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) review. Engineering guidance for swelling soils treats impermeable surfaces such as concrete around a foundation as an added moisture precaution, and calls for keeping cracks and separations filled [6]. Floating slabs that are not tied to the house are expected to crack somewhat and are kept isolated from walls, columns and utilities [6]. ## What are the repair options for flatwork? - Lifting settled slabs by injection: slabjacking and polyurethane (https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane) - Filling voids from washout: void and compaction grouting - Re-sloping or redirecting water: drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Reducing clay swell: chemical soil stabilization (https://terrabrain.vercel.app/repairs/chemical-soil-stabilization) - Removing and repouring: slab or foundation replacement ## Related - Heaved or Settled Flatwork (https://terrabrain.vercel.app/signs/heaved-or-settled-flatwork) - Water Ponding Near Foundation (https://terrabrain.vercel.app/signs/water-ponding-near-foundation) - Surface Drainage and Grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Slabjacking and Polyurethane (https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane) - Freeze-Thaw and Frost Depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) Sources: [1] Expansive Soil, Colorado Geological Survey https://coloradogeologicalsurvey.org/hazards/expansive-soil/ [2] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers, Robert Olshansky, Robert B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [3] Foundation Fundamentals: Inspecting Load Paths and Water Paths (IRC R401.2 & R401.3), InterNACHI https://nachi.org/foundation-load-water.htm [4] Inspecting the Concrete, Cracking, and Water Connection (IRC R406), InterNACHI https://www.nachi.org/concrete-cracking-water-connection.htm [5] Adoption of International Residential Code 2024 (IRC 2024), Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2024%20IRC%20Code%20Changes%20Summary%20-%20for%20website.pdf [6] Home Construction on Shrinking and Swelling Soils (Special Publication 11), Colorado Geological Survey (Holtz and Hart, 1978) https://coloradogeologicalsurvey.org/wp-content/uploads/woocommerce_uploads/SP-11.pdf [7] Landscaping on Expansive Soils (Fact Sheet 7.236), Colorado State University Cooperative Extension https://ca-montereypark.civicplus.com/DocumentCenter/View/487 [8] Inspecting Footings: The Unsung Heroes Beneath a House (IRC R403), InterNACHI https://www.nachi.org/foundation-footings.htm --- # Why do foundation edges rise after heavy rain? URL: https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift Answer: When soil at the perimeter gets wetter than soil under the middle, expansive clay swells and lifts the foundation edges, leaving a dish shape. In short: Perimeter wetting heave, or edge lift, happens when the soil around the outside of a house gets wetter than the soil under the middle. Expansive clay at the edges swells and pushes the foundation perimeter up, leaving the center relatively low in a dish shape. It is tied to moisture gain, such as wet seasons and rain after a dry spell. ## How does edge lift happen? Heave is soil expanding as water is added to expansive clay [6]. Engineers describe seasonal moisture gain causing the soil to swell and push the perimeter of a slab up [1]. Clay soils do not move if their moisture stays constant; it is changes in moisture that cause the movement [1]. ### Why the edges move first In a uniformly loaded rectangular slab, the corners press on the soil with about one-fourth the pressure of the central portion, so the corners tend to lift relative to the center, and moisture differences at the slab edge can make this worse [2]. Swelling soils can lift lightly loaded strip footings, and because resisting forces vary around a foundation, the uplift is usually differential [7]. ### Where the water comes from Common sources of moisture change include groundwater, landscape irrigation, poor drainage, leaking pipes, trees and plantings, and extended wet weather [1]. Lawn and garden watering can wet the soil outside a house while the soil under it stays drier [2]. At the perimeter of a house, these sources can take forms such as: - downspouts that discharge next to the foundation - ground that slopes toward the house instead of away - sprinkler zones and watered beds along the walls ## What happens when trees near the house are removed? When established trees near a house are removed, the soil they had been drying can rewet. Texas engineering guidelines note that tree removal may stop shrinkage or partly restore lowered areas but can also cause upheaval, and that a waiting period may be recommended [5]. The Foundation Performance Association also lists removal of established trees as a cause of movement [6]. See post-tree-removal heave (https://terrabrain.vercel.app/causes/post-tree-removal-heave). ## What Oklahoma conditions lead to edge lift? Nearly all of Oklahoma has medium or high soil swelling potential [3], and OSU testing of western Oklahoma benchmark soils found their fine clays dominantly montmorillonite, a smectite clay that swells strongly when wet, most of all in the Kirkland soil [4]. Oklahoma's climate ranges from humid subtropical in the east to semi-arid in the west [3]. ## What are the signs of edge lift? - stair-step brick cracks wider at the bottom (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-bottom) - water ponding near the foundation (https://terrabrain.vercel.app/signs/water-ponding-near-foundation) - cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally) - gaps under baseboards, binding doors and diagonal drywall cracks - heaved or settled flatwork near wet areas ## How is edge lift told apart from look-alikes? | Pattern | What moved | Related page | |---|---|---| | Dish shape from edge lift | Edges rose with wetting [1] | This page | | Dish shape from interior settlement | Center dropped, for example over a washout void | Erosion and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) | | Dome shape | Opposite shape: center high | Center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) | A single elevation survey shows shape at one moment; repeated surveys show how it is changing [5]. ## How is edge lift typically addressed? - **Remove the perimeter water.** Drainage changes address the source of wetting; see drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). - **Monitor.** Texas guidelines note that non-structural measures and monitoring may be prudent before or instead of structural repairs [5]. - **Limit soil swelling.** Using non-expansive soils or soil stabilizers is one recognized way to manage shrink-swell ground [7]; see chemical soil stabilization (https://terrabrain.vercel.app/repairs/chemical-soil-stabilization). Methods that lift a slab, such as mudjacking [5], add elevation to areas that are already high. ## Related - Perimeter Drying Settlement (Edge Drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Over-Lift Heave After Drought Lift (https://terrabrain.vercel.app/causes/over-lift-heave-after-drought-lift) - Surface Drainage and Grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Water Ponding Near Foundation (https://terrabrain.vercel.app/signs/water-ponding-near-foundation) - Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro) Sources: [1] The Mystery of Expansive Soils, STRUCTURE magazine (NCSEA / CASE / SEI) https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [2] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers et al.) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [3] Soil Matric Suction and Active Zone Depth in Oklahoma, Oklahoma State University (Er Yue, Ph.D. dissertation, 2017) https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf [4] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [5] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [6] Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings (FPA-SC-13-1), Foundation Performance Association https://inspectapedia.com/structure/Foundation-Movement-Evaluation-Guidelines-FPA-TX.pdf [7] Shrink-Swell Subsidence, PreventionWeb (UN Office for Disaster Risk Reduction) https://www.preventionweb.net/understanding-disaster-risk/terminology/hips/gh0025 --- # Why do houses on Oklahoma hillsides slowly move downhill? URL: https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement Answer: Clay on a slope creeps downhill a little each wet-dry season, and creeks cutting the toe remove support, pulling a house outward and down on its downhill side. In short: Soil on a slope can move downhill very slowly, a process geologists call creep. Each wet-dry season can nudge clay a little farther downslope, and creeks that cut into the toe of a slope remove support. A house on or near that slope can be pulled outward and down on its downhill side. ## What is slope creep? Creep is an imperceptibly slow, steady downhill movement of soil or rock. It happens when the stress on a slope is large enough to deform the soil permanently but too small to cause a sudden slide [1]. The U.S. Geological Survey describes three kinds [1]: - **Seasonal creep:** movement within the surface layer whose moisture and temperature change through the year. - **Continuous creep:** the stress constantly exceeds the strength of the material. - **Progressive creep:** the slope is approaching a larger failure such as a landslide. Seasonal creep is limited to the soil layer affected by seasonal changes in moisture and temperature [1]. See shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). ## What drives slope creep? | Driver | How it acts | |---|---| | Water saturation | Slope saturation by water is a primary cause of landslides; sources include heavy rain and changing groundwater or stream levels [1] | | Stream erosion at the toe | Creeks wearing away the base or sides of a slope remove support [1] | | Cutting into the slope | Excavating the slope or its toe is a listed human cause [1] | | Loading the top | Adding weight at the crest of a slope is a listed human cause [1] | | Utility leaks | Leaking water lines are a listed human cause [1] | For creek-side lots, see erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) and creeks and flood history (https://terrabrain.vercel.app/data/creeks-and-flood-history). ## What are the warning signs of slope creep? Signs of creep include curved tree trunks, bent fences or retaining walls, tilted poles or fences, and small ripples or ridges in the soil [1][2]. In a house, field notes link slope movement to tilted retaining walls, fences or trees (https://terrabrain.vercel.app/signs/tilted-retaining-walls-fences-or-trees), stair-step brick cracks wider at the top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top), sloping floors (https://terrabrain.vercel.app/signs/sloping-floors) and diagonal drywall cracks at openings (https://terrabrain.vercel.app/signs/diagonal-drywall-cracks-at-openings). Creep shows sideways displacement and tilting, while fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) moves mostly straight down. ## How common is slope movement in Oklahoma? The Oklahoma Geological Survey reports that most landslides occur in the eastern third of Oklahoma, where the wetter climate and steeper terrain make them more likely [3]. Survey researchers mapping shallow landslides in eastern Oklahoma and western Arkansas counted about 25 events before 2000 and 62 during 2010-2016 in their inventory; they found a qualitative match with the rise in Oklahoma earthquakes but did not confirm that specific quakes triggered specific slides [4]. An Oklahoma Department of Transportation study identified and mapped 113 historic and current landslides statewide [5]. At its monitored site near Idabel in McCurtain County, the slope was a high-plasticity clay with a plasticity index of 46 on a roughly 3:1 slope, and rainfall drove the sliding as the clay absorbed water [5]. The study found slope, soil texture and land cover strongly affected landslide susceptibility [5]. ## What setbacks from slopes do codes require? Building codes based on the International Residential Code (Section R403.1.7) set two common distances [6]: - **Top of a slope:** footings set back one-third of the slope height, but no more than 40 feet is required. - **Bottom of a slope:** buildings set back one-half of the slope height, but no more than 15 feet is required. Check local adoption with the city; see codes and permits. ## How is slope movement repaired? Slope movement is treated as both a slope problem and a foundation problem. Options matched to this mechanism include engineered slope and erosion stabilization, helical piers designed for sideways loads, vertical steel push piers combined with lateral design, and drainage solutions. On highway slopes, ODOT lists rock drains to remove water faster and laying slopes back to flatter angles as mitigation methods [5]. ## Related - Erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Tilted retaining walls, fences or trees (https://terrabrain.vercel.app/signs/tilted-retaining-walls-fences-or-trees) - Erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) - Slope and erosion stabilization (https://terrabrain.vercel.app/repairs/slope-and-erosion-stabilization) - Southeast (Ouachitas and Red River) (https://terrabrain.vercel.app/regions/southeast-ouachitas-and-red-river) - Tulsa Metro (https://terrabrain.vercel.app/regions/tulsa-metro) Sources: [1] Landslide Types and Processes (Fact Sheet 2004-3072), U.S. Geological Survey https://pubs.usgs.gov/fs/2004/3072/fs-2004-3072.html [2] Creep, U.S. Geological Survey https://www.usgs.gov/media/images/creep [3] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [4] Detailed mapping of shallow landslides in eastern Oklahoma and western Arkansas and potential triggering by Oklahoma earthquakes, Geomorphology (Oklahoma Geological Survey authors) https://www.jakewalter.net/papers/Regmi_Walter_2019.pdf [5] Real Time Monitoring of Slope Stability in Eastern Oklahoma (FHWA-OK-14-06), Oklahoma Department of Transportation https://aem-prod.oklahoma.gov/content/dam/ok/en/odot/documents/research/highlighter-2241-fhwa-ok-14-06.pdf [6] Development on or Near Steep Slopes, Roanoke County (Virginia) Development Services https://roanokecountyva.gov/DocumentCenter/View/1021 --- # Why do Oklahoma basement walls crack and bow? URL: https://terrabrain.vercel.app/foundations/basements Answer: Most trouble comes from sideways pressure: clay that swells when wet and water that builds up in the backfill behind the wall. In short: A basement is a set of below-grade walls that hold back soil, with a concrete floor slab inside. In Oklahoma the walls face sideways pressure from clay that swells when wet and from water that builds up in the backfill. Most basement problems here trace back to those two loads, and the residential code's drainage and dampproofing rules exist to limit the water side of them. ## Why are basements less common in Oklahoma? A University of Oklahoma geology professor interviewed by NPR described how Oklahoma's red clay expands and contracts with soil moisture, cracking basement walls so they leak [1]. The same report notes that northern codes require footings below a deep frost line, so the digging for a basement is largely done anyway, while southern codes do not, so a basement here means extra excavation [1]. ## What types of basement walls are there? Foundation walls can be built from concrete, masonry, wood or insulated concrete forms [2]. The types most often seen are: | Wall type | Plain-English description | |---|---| | Concrete block (CMU) | Hollow concrete units laid in mortar; joints are the weak line | | Poured concrete | Concrete cast in forms, with or without steel reinforcement | | Stone or brick | Older walls laid in lime or cement mortar | The code's prescriptive wall tables place a horizontal reinforcing bar within 12 inches of the top of a wall, plus one near mid-height for walls under 8 ft [3]. ## What forces act on a basement wall? ### Soil pressure **Lateral earth pressure** means the sideways push of soil against a wall. The residential code's wall tables group soils by design pressure of 30, 45 or 60 pounds per square foot for each foot of depth, and inorganic clays fall in the highest, 60 psf group [3]. Walls retaining 4 ft or more of unbalanced backfill must be braced at top and bottom before the backfill is placed [3]. ### Swelling clay Clay-rich soils can swell 10% or more by volume when wetted and push on foundations at 20,000 lb per square foot or more [6]. The Colorado Geological Survey lists failing to allow for basement or ground-floor movement as a common source of damage on swelling soils [6]. ### Water pressure **Hydrostatic pressure** is the push of water trapped in saturated soil. Water in concrete's tiny capillary pathways can exert hydrostatic pressure and draw dissolved salts deep into the concrete [8]. Water that freezes inside concrete expands about 9%, which can crack and spall it [8]. ## What does the code require for water? - **Footing drains (IRC R405):** required around concrete or masonry walls that retain earth and enclose habitable or usable space below grade, placed at or below the top of the footing and discharged by gravity or a pump [4]. - **Gravel and pipe:** a gravel drain extends at least 1 ft beyond the footing and 6 in above its top; perforated pipe sits on at least 2 in of washed gravel with 6 in of cover [4]. - **Exception:** drains are not required on well-drained Group I sand and gravel soils [4]; clay soils are not part of that group. - **Dampproofing (IRC R406.1):** resists vapor and incidental moisture but is not designed for significant water pressure [5]. - **Waterproofing (IRC R406.2):** required where a high water table or other severe soil-water conditions are known to exist [5]. ## What are the signs of basement trouble? - Water at the joint between wall and floor slab, or seepage through cracks; the NPR report notes that cracked basement walls leak [1]. - White crystalline residue (**efflorescence**), which forms when water moves through masonry, dissolves salts and evaporates at the surface [7]. - Cracked basement floors, a common sign of swelling soil [6]. - Horizontal cracking or inward bowing of the wall, the pattern covered in horizontal crack or inward bow in basement wall (https://terrabrain.vercel.app/signs/horizontal-crack-or-inward-bow-in-basement-wall). ## How are basement walls repaired? Wall movement is handled under basement wall repair (https://terrabrain.vercel.app/repairs/basement-wall-repair); water is handled under drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). Perched water behind walls in wet seasons is explained in groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water), and the mechanism is described in lateral earth, swell and hydrostatic pressure on walls (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls). ## Related - Basement Wall Repair (https://terrabrain.vercel.app/repairs/basement-wall-repair) - Water at Cove Joint or Efflorescence (https://terrabrain.vercel.app/signs/water-at-cove-joint-or-efflorescence) - Groundwater and Perched Water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Freeze-Thaw and Frost Depth (https://terrabrain.vercel.app/guides/freeze-thaw-and-frost-depth) Sources: [1] Why Oklahomans Don't Like Basements, NPR (via WFAE 90.7) https://www.wfae.org/2013-05-21/why-oklahomans-dont-like-basements [2] Inspecting Foundation Fortitude: Cracking the Code for a Solid Home (IRC R401-R408), InterNACHI https://www.nachi.org/foundation-systems-building-code.htm [3] 2007/2008 Proposed Changes to the International Residential Code (RB101–RB143), International Code Council https://www.iccsafe.org/cs/codes/Documents/2007-08cycle/ProposedChanges/V2_RB101-143.pdf [4] Inspecting Foundation Drainage: Essential Guidelines for Below-Grade Spaces (IRC R405), InterNACHI https://www.nachi.org/foundation-drainage-below-grade.htm [5] Inspecting Foundation Dampproofing and Waterproofing (IRC R406), InterNACHI https://www.nachi.org/foundation-dampproofing-waterproofing.htm [6] Expansive Soil, Colorado Geological Survey https://coloradogeologicalsurvey.org/hazards/expansive-soil/ [7] Understanding Efflorescence and Spalling: Critical Assessment Points for Home Inspectors, InterNACHI https://www.nachi.org/efflorescence-capillary-osmosis-spalling [8] Inspecting the Concrete, Cracking, and Water Connection (IRC R406), InterNACHI https://www.nachi.org/concrete-cracking-water-connection.htm --- # Why do Oklahoma foundations move, in plain English? URL: https://terrabrain.vercel.app/guides/homeowner-explanations Answer: Most Oklahoma foundation movement comes from clay that swells when wet and shrinks when dry. Repair aims to stop damaging movement, not reach a level floor. In short: Most Oklahoma foundation movement comes from clay soil that swells when wet and shrinks when dry [1][2]. Foundations are not built perfectly level [5], so the goal of a repair is to stop damaging movement, not to reach a perfectly flat floor. The explanations below put the main ideas in everyday terms. ## Why does clay move like a sponge? Picture the clay under a house as a stack of microscopic sheets. In the most active clays, water slips into the spaces between those sheets, and the soil swells; when it dries, it shrinks [1]. Clay minerals such as montmorillonite (a type of smectite) swell this way, and over 75% of Oklahoma contains bedrock that can be a source of such expansive soils [2]. The director of the Oklahoma Geological Survey has described the state's red clay as expanding and contracting with the moisture in the soil [3]. More detail: clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy). ## Why is the house moving now? Dry spells pull water out of the soil. Summer heat and drought dry the ground under homes, and one foundation repair contractor reported more calls during summer drought [4]. Commonly reported signs include new or widening cracks, sticking doors and windows, sloping floors and a visible gap between the soil and the house [4]. Problems are not limited to old homes; some houses built within the past five years have shown movement too [4]. Local soil moisture data is covered in Mesonet for foundation pros (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros). ## Why is "level" not the goal? No foundation is built perfectly level, and patios, porches and garages are often sloped on purpose for drainage [5]. Engineers look at overall **tilt** (an even slope across the house) and **deflection** (bowing between two points), plus cracks and other damage, rather than a single number [5]. A repair aims for the best practical lift without harming the house. See tolerances and standards (https://terrabrain.vercel.app/guides/tolerances-and-standards). ## What is a floor-level map? An elevation survey measures the floor height at many points and draws lines connecting equal heights, like a topographic map. Engineers use these relative elevation surveys to evaluate tilt, deflection and distress, and a new survey after a repair becomes the baseline for future comparison [5]. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). ## What is heave? Not every problem is sinking. When water collects under a slab, the clay there swells and pushes that area up; this is **heave**. Forensic engineers describe water collecting in permeable fill and seeping into the surrounding clay (a "bathtub effect") and list remedies such as sub-surface drainage, moisture barriers and changes to watering [5]. Because the cause is added water rather than lost support, heave and settlement call for different responses. See heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). ## Why are piers paired with water control? Piers carry the house down to firmer ground. Water control, including gutters, grading, drainage and moisture barriers, addresses the soil movement that caused the problem in the first place; engineers list both structural and non-structural repairs as options [5]. See drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). ## How deep will the piers go? In the Tulsa area, steel push piers usually stop around 12 feet; on one large logged job, half of the piers stopped between 9 and 14 feet, and the full range ran from 2 to 40 feet [6]. That matches public borings: a City of Tulsa geotechnical report found weathered shale at about 13.5 feet at one south Tulsa site [7]. Each pier is pushed with a hydraulic ram until the soil resists with at least 6,000 psi of pressure, and the depth and pressure of every pier is written down [6]. More: bedrock in the Tulsa metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro). ## What happens after the repair? Lifting can disturb plumbing, so forensic engineers recommend plumbing tests after any lift and a new elevation survey as a baseline [5]. See lifting procedure and restoration (https://terrabrain.vercel.app/guides/lifting-procedure-and-restoration). ## Related - Clay mineralogy (https://terrabrain.vercel.app/guides/clay-mineralogy) - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Trees and roots (https://terrabrain.vercel.app/guides/trees-and-roots) - Heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Inspection protocol (https://terrabrain.vercel.app/guides/inspection-protocol) Sources: [1] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [2] Geologic Hazards in Oklahoma, Geological Society of America (abstract by K. V. Luza, Oklahoma Geological Survey) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [3] Why Oklahomans Don't Like Basements, NPR (via WFAE) https://www.wfae.org/2013-05-21/why-oklahomans-dont-like-basements [4] Is Oklahoma's drought damaging your foundation? Warning signs to watch for, News 9 (KWTV) https://www.news9.com/oklahoma-city-news/is-oklahomas-drought-damaging-your-foundation-warning-signs-to-watch-for [5] Beyond the Building Code: Expansive Soils, Journal of the National Academy of Forensic Engineers https://journal.nafe.org/ojs/index.php/nafe/article/download/975/924/4846 [6] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data [7] Geotechnical Engineering Report, Retaining Walls A and B Along 91st Street South from South Memorial Drive to South Mingo Road, City of Tulsa https://www.cityoftulsa.org/media/25588/geotechnical-report-retaining-walls.pdf --- # Why do Oklahoma houses settle on floodplains and soft wet clay? URL: https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays Answer: Soft river alluvium and wet clay compress under a house as water squeezes out, causing gradual, largely permanent settlement, most under heavy walls. In short: Some natural soils, especially wet clay and silt deposited by rivers, are soft enough to compress under the weight of a house. As the load slowly squeezes water out of the soil, the ground settles, usually most under heavy walls and chimneys. This settlement is gradual and largely permanent. ## How does soil consolidation work? Clay and silt have tiny pores filled with water. When a load is added, the soil can only compress as that water drains out, so the process is slow. The U.S. Geological Survey describes the same basic mechanism in land subsidence: fine-grained silt and clay layers compact as water leaves their pores, the change is slow, and it is largely permanent because the collapsed pore space does not come back [1]. Engineers measure this with a laboratory consolidation test. ASTM D2435 loads a laterally confined, saturated sample of fine-grained soil in steps and records both how much and how fast it compresses [2]. Settlement over time can also be tracked in the field with repeated elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). ### Typical sequence 1. A house is built on soft alluvium (river-deposited sediment) or saturated clay. 2. The weight of the house slowly squeezes water out of the soil. 3. The heaviest parts, such as bearing walls, masonry and chimneys, settle the most. ## Where do soft soils occur in Oklahoma? ### River alluvium Oklahoma's major rivers are lined with alluvium and terrace deposits, mainly sand and gravel with some clay and silt [5]. Reported thicknesses include [5]: | River | Alluvium thickness (USGS) | Depth to water | |---|---|---| | Arkansas | about 40-50 ft on average | generally less than 20 ft | | North Canadian (Oklahoma City to Canadian River) | 30-40 ft | not given | | Canadian near Norman | up to 80 ft | not given | | Washita | about 64 ft average, 120 ft maximum | generally less than 20 ft | See Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces). ### Wet clay soils Floodplain soils differ a great deal. The Osage series, found on floodplains in eastern Oklahoma, formed in thick clayey alluvium with an average of 35 to 60% clay in the subsoil. It is poorly drained, water moves through it very slowly, and its seasonal high water table sits 6 to 18 inches below the surface from November through May in normal years [3]. The Verdigris series, also on northeastern Oklahoma floodplains, is a well-drained silty alluvium that is subject to flooding [4]. See the soil pages for Osage (https://terrabrain.vercel.app/soils/osage) and Verdigris (https://terrabrain.vercel.app/soils/verdigris). A high water table keeps soils like Osage wet for much of the year [3]. ## How does flood exposure affect these sites? FEMA's Flood Map Service Center is the official public source for flood hazard maps and can be searched by address [6]. In Oklahoma, the Oklahoma Water Resources Board is the state coordinating agency for the National Flood Insurance Program [7]. See creeks and flood history (https://terrabrain.vercel.app/data/creeks-and-flood-history). ## What does soft soil settlement look like? Field notes associate soft-soil settlement with sloping floors (https://terrabrain.vercel.app/signs/sloping-floors), stair-step brick cracks wider at the top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top), sticking doors and, under heavy masonry, a chimney separating or leaning (https://terrabrain.vercel.app/signs/chimney-separating-or-leaning). The pattern is often similar to fill consolidation settlement; lot history and soil borings separate natural soft soil from placed fill. ## How is soft soil settlement repaired? Repairs for this mechanism transfer the load through the soft layer to firmer soil or rock below. Options include steel push piers and helical piers. Drilled bell-bottom piers are listed as a supporting option, but shallow groundwater, which is common in alluvium [5], can make drilled holes harder to keep open. In Oklahoma steel push pier records, pier depths typically ranged from about 8 to 16 feet, with a median of about 12 feet in the Tulsa area [8]. Sites on deep alluvium may need deeper piers; see depth to rock from borings. ## Related - Fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) - Groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) - Soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values) - Steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) - Sloping floors (https://terrabrain.vercel.app/signs/sloping-floors) Sources: [1] Land Subsidence in the United States (Fact Sheet 165-00), U.S. Geological Survey https://water.usgs.gov/ogw/pubs/fs00165/SubsidenceFS.v7.PDF [2] Standard Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental Loading (ASTM D2435/D2435M-25), ASTM International https://store.astm.org/d2435_d2435m-25.html [3] Official Series Description: Osage Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OSAGE.html [4] Official Series Description: Verdigris Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/V/VERDIGRIS.html [5] Ground Water Atlas of the United States (HA 730-E), U.S. Geological Survey https://pubs.usgs.gov/ha/ha730/ch_e/E-text1.html [6] FEMA Flood Map Service Center, Federal Emergency Management Agency https://msc.fema.gov/ [7] Floodplain Management (fact sheet), Oklahoma Water Resources Board https://www.oklahoma.gov/content/dam/ok/en/owrb/documents/floodplain-management/floodplain-management-fact-sheet.pdf [8] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # Why do the edges of a house sink in dry Oklahoma weather? URL: https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop Answer: Expansive clay around the outside of a house dries and shrinks while soil under the middle stays moist, so the edges sink. It is worst in drought. In short: Perimeter drying settlement, or edge drop, happens when expansive clay around the outside of a house dries out and shrinks while the soil under the middle stays moist. The edges of the foundation lose support and sink, leaving the center relatively high. It is seasonal, worst in dry periods and drought, and partly recovers when rain returns. ## How does edge drop happen? Expansive clay shrinks as it loses moisture and swells as it gains it. Engineers describe seasonal moisture loss letting the perimeter of a slab settle, and seasonal moisture gain pushing it back up [1]. Ground-supported slabs are flexible and tend to follow the shape of the soil beneath them [1], so when the soil at the edges shrinks, the edges come down with it. There is frequently a moisture difference between the soil beneath a house and soil more exposed to the weather [2]. A frequent source of damage is differential swelling where pockets of moist soil sit next to dry soil [2], which is the situation at a drying perimeter. ### Step by step 1. Heatwaves, drought and the water demand of vegetation pull moisture from the clay around the house [5]. 2. The clay shrinks, leaving voids and cracks in the soil [2]. 3. The perimeter beam loses support and drops with the soil beneath it [1]. 4. The center, still near its original moisture, is left relatively high compared with the edges [1]. 5. The cycle repeats with the seasons, since shrink-swell cycles occur annually in climates with pronounced wet and dry seasons [2]. ## How deep does the drying go? The zone of soil whose moisture changes with the weather is called the active zone. - In Oklahoma, it has been estimated at roughly 0.5 to 4 meters (about 1.5 to 13 feet), depending on soil properties and climate [3]. - A PreventionWeb hazard profile puts the zone of seasonal moisture change usually in the upper 1.5 to 2 meters, reaching about 5 meters in some cases [5]. - Engineering literature reports seasonal fluctuation from about 3 to 40 feet deep in expansive soils, with cracks reaching deeper than often assumed and multi-year droughts drying soil deeper than previously believed [2]. See shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). ## Why do Oklahoma soils and climate cause edge drop? Nearly all of Oklahoma has medium or high soil swelling potential, based on USDA soil survey data [3]. OSU testing of benchmark soils found the fine clay in Bethany, Kirkland-like and Norge-like subsoils dominantly montmorillonite (smectite), a strongly swelling clay mineral, with coefficients of linear extensibility up to about 0.095 in Bethany and 0.090 in Kirkland [4]. Oklahoma's climate ranges from humid subtropical in the east to semi-arid in the west [3]. ## How do trees and drought affect edge drop? Below the depth reached by surface drying, the water demand of vegetation, particularly trees on clay soils, drives the moisture changes that cause shrinking and swelling [5]. Soil drying from trees and other large vegetation, especially during drought, is a common cause of foundation subsidence [6]. Texas engineering guidelines note that removing trees may stop the shrinkage or partly restore lowered areas, but can also cause upheaval, and that pruning may reduce future settlement without restoring elevation [7]. See tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement). ## What are the signs of edge drop? - stair-step brick cracks wider at the top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top) - soil pulled away from the foundation (https://terrabrain.vercel.app/signs/soil-pulled-away-from-foundation) - cracks that open and close seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally) - brick separating from window or door frames, frieze board or trim separation - doors that bind, diagonal drywall cracks and sloping floors toward exterior walls ## How is edge drop different from center heave? Both can leave a floor high in the middle. In edge drop, the edges went down; in center heave, the center came up. Engineers associate center lift with long-term moisture gain, typically in older foundations, and edge movement with seasonal moisture changes [1]. A single elevation survey shows the foundation's shape at one moment, while repeated surveys over months or years show how it is changing [7]. Without a baseline survey, movement cannot be determined accurately [6]. Compare center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab). ## How is edge drop typically fixed? - **Underpinning below the active zone.** A standard risk-reduction measure for shrink-swell ground is extending foundations below the zone of moisture fluctuation, adjusted for vegetation [5]. In Oklahoma steel push pier installation records, typical pier depths were about 8 to 16 feet, with a median of about 12 feet in Tulsa; piers were installed at about 7-foot spacing, with installation pressures around 9,000 psi and a 6,000 psi minimum [8]. See steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers). - **Moisture control.** Non-structural measures and monitoring may be prudent before or instead of structural repairs [7]. See root barriers and moisture control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control). - **Monitoring through a cycle.** Repeated elevation surveys show whether movement is seasonal and how large it is [7]. ## Related - Perimeter Wetting Heave (Edge Lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) - Tree-Root Desiccation Settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) - Seasonal Movement Calendar (https://terrabrain.vercel.app/guides/seasonal-movement-calendar) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Helical Piers (https://terrabrain.vercel.app/repairs/helical-piers) - OKC Metro (https://terrabrain.vercel.app/regions/okc-metro) Sources: [1] The Mystery of Expansive Soils, STRUCTURE magazine (NCSEA / CASE / SEI) https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [2] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers et al.) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [3] Soil Matric Suction and Active Zone Depth in Oklahoma, Oklahoma State University (Er Yue, Ph.D. dissertation, 2017) https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf [4] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [5] Shrink-Swell Subsidence, PreventionWeb (UN Office for Disaster Risk Reduction) https://www.preventionweb.net/understanding-disaster-risk/terminology/hips/gh0025 [6] Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings (FPA-SC-13-1), Foundation Performance Association https://inspectapedia.com/structure/Foundation-Movement-Evaluation-Guidelines-FPA-TX.pdf [7] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [8] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # Why does a chimney or column settle more than the rest of the house? URL: https://terrabrain.vercel.app/causes/concentrated-load-settlement Answer: A heavy chimney, column or added story can press on the soil harder than it can support, so that spot sinks. It is a soil-strength problem, not a seasonal one. In short: Concentrated load settlement happens when one heavy part of a house, such as a masonry chimney, a column or an added second story, presses on the soil harder than the soil can support, so that area sinks relative to the rest. It is a structural and soil-strength problem rather than a seasonal moisture problem. It is evaluated by looking at the load, the footing under it and the strength of the soil. ## What is concentrated load settlement? Engineers describe three common kinds of foundation movement: heave (expansive clay swelling as it takes on water), subsidence (soil shrinking as moisture is withdrawn) and settlement, which is soil compressing because it is loaded beyond its bearing capacity [1]. Bearing capacity is the pressure a soil can carry without excessive compression or failure. Concentrated load settlement is a form of settlement in which the load at one spot is high enough, or the footing small enough, that the soil under that spot compresses more than the soil elsewhere. The same guidelines recommend taking floor measurements near masonry fireplaces and other heavily loaded areas [1]. Texas engineering guidelines list "unanticipated loads" and inadequate design or construction alongside soil movement as causes of residential foundation distress [2]. Concrete members also deflect under load, and cracks form when a design does not allow for that movement [5]. ## Which parts of a house are heavy spots? Examples of concentrated loads in a home include: - masonry chimneys and fireplaces - interior columns and posts that carry beams - second stories added after the original construction - heavy fixtures or masonry features resting on a slab When an addition or second story has been built, Texas guidelines say evaluations should look at each separate foundation element as well as the foundation as a whole [2]. See additions and mixed foundations (https://terrabrain.vercel.app/guides/additions-and-mixed-foundations) for more. ## What are the signs of concentrated load settlement? The most typical sign is a chimney separating or leaning (https://terrabrain.vercel.app/signs/chimney-separating-or-leaning) away from the house, with a gap at the wall or roofline. Floors near a heavy column or wall may also slope toward it, showing up as sloping floors (https://terrabrain.vercel.app/signs/sloping-floors). ## Which Oklahoma soil conditions make it worse? Weak, compressible soils are found in parts of Oklahoma, particularly in river-bottom alluvium (soil laid down by streams). An Oklahoma Department of Transportation study characterized compressible clayey and silty alluvial soils in two Oklahoma river systems where settlement of fill was a known problem [4]. Pages on soft soil consolidation (https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays) and Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) describe where these soils occur. ## How is concentrated load settlement evaluated? - **Load and footing.** An inspection identifies what the heavy element is and, where possible, how large and deep its footing is. - **Soil strength.** The ODOT study used continuous undisturbed sampling, standard penetration tests (a test that counts hammer blows needed to drive a sampler), unconfined compression tests and consolidation tests to characterize weak soils [4]. - **Elevations.** A floor elevation survey shows whether the heavy area is low relative to the rest of the house; repeated surveys show whether it is still moving [2]. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). ## How is concentrated load settlement typically fixed? Underpinning, which means adding piers or piles under an existing foundation, is the usual structural approach for a settled heavy element. Texas guidelines state that underpinning locations, sizes, depths and materials must be specified, and that underpinning does not improve the areas of a foundation that are not underpinned [3]. That is why piers for this problem are placed under the heavy element itself. In Oklahoma steel push pier installation records, typical pier depths ranged from about 8 to 16 feet, with a median of about 12 feet in Tulsa [6]. Actual depth depends on where the pier reaches load-bearing soil or rock at each location. The steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) and helical piers (https://terrabrain.vercel.app/repairs/helical-piers) pages explain these methods. ## Related - Chimney Separating or Leaning (https://terrabrain.vercel.app/signs/chimney-separating-or-leaning) - Differential Movement at Additions (https://terrabrain.vercel.app/causes/differential-movement-at-additions) - Loads, Pier Spacing and Capacity (https://terrabrain.vercel.app/guides/loads-pier-spacing-and-capacity) - Original Construction Deficiency (https://terrabrain.vercel.app/causes/original-construction-deficiency) - Steel Push Piers (https://terrabrain.vercel.app/repairs/steel-push-piers) Sources: [1] Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings (FPA-SC-13-1), Foundation Performance Association https://inspectapedia.com/structure/Foundation-Movement-Evaluation-Guidelines-FPA-TX.pdf [2] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [3] Guidelines for the Evaluation and Repair of Residential Foundations, Version 2, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2022/05/Guidelines-for-the-Evaluation-and-Repair-of-Residential-Foundations-V2-2008.pdf [4] Bearing capacities and characterization of compressible clayey and silty foundation soils in Oklahoma (FHWA-OK-81-3), Oklahoma Department of Transportation (via ShareOK) https://shareok.org/items/20dbaccf-8026-43bf-8b75-88314f3f3a6e/full [5] CIP 4 - Cracking Concrete Surfaces, National Ready Mixed Concrete Association https://www.prairie.com/wp-content/uploads/sites/4/2024/12/04p_CrackingConcreteSurfaces.pdf [6] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # Why does a home addition crack away from the original house? URL: https://terrabrain.vercel.app/guides/additions-and-mixed-foundations Answer: An addition is often a separate foundation at a different depth on different soil prep, so on Oklahoma clay the two move differently and crack at the joint. In short: An addition and the house it is attached to are often two different foundations built years apart, at different depths and on differently prepared soil. Expansive clay can move ground-supported structures by different amounts, and that movement does not settle out on its own [4]; at an addition, the crack shows up at the joint. Repair either ties the two parts together or lets them move independently. ## Why do the two parts move differently? - **Different foundation types.** A slab addition attached to a crawl-space house, or a new slab poured beside an old one, rests on the soil in different ways. - **Different depths.** Frost depth, which sets the minimum footing depth, is filled in by each local jurisdiction rather than the state [7]. Oklahoma's engineering board has described some shallow pier-and-grade-beam foundations with grade beam bottoms only 1 to 8 inches below finished grade, which allows water under the foundation [3]. - **Different soil preparation.** Forensic engineers note that contractors are expected to follow the geotechnical report and plans for fill and site preparation, and that moisture barriers are recommended between native soil and select fill [4]. Fill placed beside an existing house without that control can settle. - **Different code eras.** Oklahoma's code now requires two #4 reinforcing bars in all footings and #4 bars tying footings to stem walls at corners [1]. Those Oklahoma amendments were in the 2018-edition rule effective in 2022 [2], so additions built before then may not have them. - **Different moisture.** Expansive clay changes volume as its moisture changes, and the depth of that seasonal change is called the **active zone** [4]. A shallow addition footing sits higher in that zone than a deeper original footing. ## What are the signs at the junction? - A crack running along the line where old and new meet - A step or separation in the roofline or siding at the joint - A floor height change or door misalignment at the doorway between old and new rooms - The addition tipping away from the house These match the pattern on the differential movement at additions (https://terrabrain.vercel.app/causes/differential-movement-at-additions) page. Distress patterns are compared with an elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) to see which part is moving. ## How are additions and mixed foundations repaired? | Approach | How it works | Typical use | |---|---|---| | Tie together | Support both sides of the joint and connect them so they move as one | When both parts can be brought to a common, stable support | | Separate | Support the addition on its own and leave a flexible joint between the two | When the parts sit on very different foundations | Supporting a shallow addition often means piers along the addition's perimeter down to firmer soil. See steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) and helical piers (https://terrabrain.vercel.app/repairs/helical-piers). Forensic engineers also list non-structural measures such as gutters, grading and sub-surface drainage alongside structural repairs [4]; see drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). ## What about permits and disclosure? Cities control permits for additions and repairs. In Tulsa, construction plans are required when damage is extensive or structural, as decided by the plans examiner [5]. Oklahoma's 2026 seller disclosure form asks about previous foundation repairs and about defects affecting walls, slabs and foundations [6], which covers movement at an addition. ## Related - Construction era by decade (https://terrabrain.vercel.app/guides/construction-era-by-decade) - Distress pattern library (https://terrabrain.vercel.app/guides/distress-pattern-library) - Method selection matrix (https://terrabrain.vercel.app/repairs/method-selection-matrix) - Fill soils and lot history (https://terrabrain.vercel.app/guides/fill-soils-and-lot-history) - Stem wall and grade beam (https://terrabrain.vercel.app/foundations/stem-wall-and-grade-beam) Sources: [1] Oklahoma Uniform Building Code Commission, Adoption of International Residential Code 2024: Code Changes Summary, Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2024%20IRC%20Code%20Changes%20Summary%20-%20for%20website.pdf [2] 748:20-6-9. IRC 2018 Chapter 4 Foundations (Permanent Rule), Oklahoma Uniform Building Code Commission https://oklahoma.gov/content/dam/ok/en/oubcc/documents/rules/2022%2009%2014%20IRC%202018%20Permanent%20Rule.pdf [3] The Board's Bulletin, Vol. 21, Fourth Quarter 2007: Residential Foundation Public Meeting, Oklahoma State Board of Licensure for Professional Engineers and Land Surveyors https://oklahoma.gov/content/dam/ok/en/pes/documents/bulletin/Newsletter_Volume21_Issue62.pdf [4] Beyond the Building Code: Expansive Soils, Journal of the National Academy of Forensic Engineers https://journal.nafe.org/ojs/index.php/nafe/article/download/975/924/4846 [5] Residential Building Permit Process, City of Tulsa Development Services https://www.cityoftulsa.org/media/10918/residential2019.pdf [6] 2026 Appendix A: Residential Property Condition Disclosure Statement, Oklahoma Real Estate Commission https://oklahoma.gov/content/dam/ok/en/orec/documents/contracts-and-forms-page/2026-contract-forms/2026%20Appendix%20A%20Residential%20Property%20Condition.pdf [7] Oklahoma Administrative Code 748:20-6-8, IRC 2018 Chapter 3 Building Planning, Justia (Oklahoma Administrative Code) https://regulations.justia.com/states/oklahoma/title-748/chapter-20/subchapter-6/section-748-20-6-8/ --- # Why does dry silty soil in Oklahoma sink when it gets wet? URL: https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil Answer: Loose, dry silts hold together only while dry; when water first reaches them under a house, the bonds weaken and the soil compacts, causing sudden settlement. In short: Collapsible soils are loose, dry silts and similar deposits that hold together only while they stay dry. When water reaches them for the first time under the weight of a house, the bonds between grains weaken and the soil compacts, causing sudden local settlement. The trigger is almost always added water, such as a leak, new irrigation or ponding. ## What is collapsible soil? Collapsible soils are geologically recent, loosely packed sediments that can settle or collapse suddenly [1]. In their dry state the grains are held apart by small amounts of clay, silt and suction (the pull of thin water films between grains), and water weakens those bonds [1]. When the soil is wetted, the grains shift into a denser arrangement, the soil's volume drops, and the surface settles [1]. This is called hydrocollapse or hydrocompaction. The Colorado Geological Survey reports volume reductions of 10 to 15 percent and documented settlements of more than six feet [1]. These soils form in semi-arid to arid climates [1]. ## How does collapsible soil damage a house? 1. A house is built on loose, dry silt that is strong enough while dry. 2. Water is added, usually from a human source. 3. The bonds weaken, the soil compacts under the load, and the area over the wetted zone drops [1]. Collapse can damage foundations, concrete slabs, pavements and utilities [1]. Once the soil is wetted, it can settle or collapse rapidly [1]. ### Common triggers Most collapse is attributed to human activity that raises subsurface moisture [1], including: - watering lawns and shrubs - leaking water lines, particularly along utility trenches - ponded or impounded water - blocked drainage paths ## Where does collapsible soil occur in Oklahoma? The Oklahoma Panhandle has tableland plains covered by loess, a wind-deposited silt. The Richfield soil series, mapped in the Panhandle, formed in calcareous loess 1 to more than 3 meters thick, with silt loam at the surface [2]. See the Panhandle region page (https://terrabrain.vercel.app/regions/panhandle-high-plains), the Ogallala Formation and loess page (https://terrabrain.vercel.app/geology/ogallala-formation-and-loess) and collapsible and loess soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils). Collapse is not limited to natural deposits. An Oklahoma Department of Transportation study described collapse settlement in compacted Oklahoma soils as a time-dependent process resulting from increases in moisture content after construction, and examined how soil type affects collapse potential [3]. Poorly placed fills are also prone to settling [1]; see fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). ## What are the signs of soil collapse? - stair-step brick cracks wider at the top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top) over the wetted area - sloping floors (https://terrabrain.vercel.app/signs/sloping-floors) - visible slab cracks - an exposed slab edge or a gap under a footing ## How is collapse different from leak heave? Water under a slab can make the floor go either up or down depending on the soil. On expansive clay, added water causes swelling and a hump; on collapsible silt, it causes the soil to compact and drop [1]. See leak-induced localized heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave) for the clay version. ## How is collapsible soil typically addressed? - **Stop the water.** The EPA's whole-house meter test (read the meter, use no water for two hours, read it again) checks for supply leaks [4], and Texas engineering guidelines call for testing supply and drain lines whenever a foundation is lifted [5]. - **Monitor.** Non-structural measures followed by monitoring may be prudent before or instead of structural repair [5]. - **Underpin.** Underpinning places supports below the affected soil; the Texas guidelines state that plans should specify the locations, sizes and depths of underpinning elements, and that underpinning will not improve the foundation's performance in areas that are not underpinned [6]. See helical piers (https://terrabrain.vercel.app/repairs/helical-piers). ## Related - Collapsible and Loess Soils (https://terrabrain.vercel.app/guides/collapsible-and-loess-soils) - Panhandle (High Plains) (https://terrabrain.vercel.app/regions/panhandle-high-plains) - Fill Consolidation Settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) - Plumbing Leak Detection and Repair (https://terrabrain.vercel.app/repairs/plumbing-leak-detection-and-repair) - Void and Compaction Grouting (https://terrabrain.vercel.app/repairs/void-and-compaction-grouting) Sources: [1] Collapsible Soils, Colorado Geological Survey https://coloradogeologicalsurvey.org/hazards/collapsible-soils/ [2] Richfield Series (Official Series Description), USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/R/RICHFIELD.html [3] Settlement Behavior of Compacted Oklahoma Soils (FHWA-OK-02-03), Oklahoma Department of Transportation https://rosap.ntl.bts.gov/view/dot/88914 [4] WaterSense Challenges Homeowners: Take 10 Minutes to Find and Fix a Leak this Week, U.S. Environmental Protection Agency https://www.epa.gov/node/265001 [5] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [6] Guidelines for the Evaluation and Repair of Residential Foundations, Version 2, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2022/05/Guidelines-for-the-Evaluation-and-Repair-of-Residential-Foundations-V2-2008.pdf --- # Why does fill soil under a house cause settlement? URL: https://terrabrain.vercel.app/guides/fill-soils-and-lot-history Answer: Poorly compacted fill, or fill with organic material or debris, can keep settling for years, often on one side of the house, apart from the seasonal pattern. In short: Many house lots are built partly on fill, soil that was moved or brought in to make a level pad. Fill that wasn't well compacted, or that contains organic material or debris, can keep settling for years, often on one side of the house. Knowing a lot's history helps explain settlement that doesn't follow the usual wet-dry seasonal pattern. ## What is fill and why does it settle? **Fill** is any soil, rock or debris placed by people rather than left in place by nature. On a sloping lot, builders often cut into the uphill side and push that soil to the downhill side to make a flat pad, a "cut-and-fill" lot. The cut side sits on undisturbed native soil or rock; the fill side sits on loosened, re-placed material. **Consolidation** is the slow squeezing-down of soil under load as air and water are pushed out. Fill that was not compacted in controlled layers consolidates under the weight of a house and when it gets wet, producing settlement that is typically steady rather than seasonal. The U.S. Geological Survey lists hydrocompaction (compaction of loose deposits when wetted) and drainage of organic soils among the causes of land subsidence [1]. ## Where does fill matter in Oklahoma? ### Hillside lots with shallow rock Upland sandstone soils such as Collinsville sit on hillslopes and reach hard rock within about 4 to 20 inches [5]. Building a flat pad on this kind of slope can leave part of a house on rock or a thin soil and part on placed fill, two materials that behave very differently. See Bedrock - Tulsa Metro (https://terrabrain.vercel.app/guides/bedrock-tulsa-metro). ### Clay used as fill Clay dug on site is often reused as fill. An Oklahoma State University study rated Kirkland soil very poor as road fill because its material is unstable and has high shrink-swell, while sandy soils in the same study rated as good sources of construction material [3]. Clay fill can both settle and swell. ### Select fill under slabs Engineers note that slabs built directly on the ground in expansive-clay areas are often placed on select fill, a chosen low-swell material, or on moisture-conditioned subgrade [2]. That is engineered fill, placed and tested for the job, rather than the uncontrolled fill described above. ## What are the red flags for a filled lot? | Clue | What it may suggest | |---|---| | Flat pad on an otherwise sloping lot | Cut on the uphill side, fill on the downhill side | | Settlement concentrated on one side and not changing with seasons | Ongoing consolidation of fill | | Brick, concrete, wood, trash or roots in auger samples | Uncontrolled or debris fill | | Lot near a former pond, ravine or creek channel | Low area filled in before construction | | Demolished-house or infill lot | Old foundations or backfilled basements below | These patterns are compared with seasonal clay movement on heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement), and the mechanism is described on fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement). ## How is fill investigated? Borings and lab samples are the direct way to see what is under a house. As an example of a written standard, one county policy for expansive-soil areas requires at least two borings in the footprint, taken at least 5 feet deep or to auger refusal on non-shrink-swell strata, with lab testing of the weakest soil just below footing level [4]. ## What does fill mean for repair? - Piers have to pass **through** fill to reach native soil or rock that can carry the load; see steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) and helical piers (https://terrabrain.vercel.app/repairs/helical-piers). - Settling fill can drag down on the sides of a pier, an added load engineers call **downdrag**. - Interior slab areas over fill may continue to settle after the perimeter is supported; options include slabjacking and polyurethane (https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane) and interior piers (https://terrabrain.vercel.app/repairs/interior-piers-tunnel-or-core). ## Related - Construction Era by Decade (https://terrabrain.vercel.app/guides/construction-era-by-decade) - Erosion Creeks and Slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Fill Consolidation Settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) - Heave vs Settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - OK Data - Construction History (https://terrabrain.vercel.app/data/construction-history) Sources: [1] Land Subsidence in the United States (Circular 1182), U.S. Geological Survey https://pubs.usgs.gov/circ/circ1182/ [2] Expansive Soils (The Mystery), STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [3] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma Agricultural Experiment Station, Oklahoma State University https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [4] County Expansive Soils Policy & Procedures (Commercial & Residential Projects), Roanoke County, Virginia, Development Services https://roanokecountyva.gov/DocumentCenter/View/1020 [5] Official Series Description - COLLINSVILLE Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/C/COLLINSVILLE.html --- # Why does my ceiling crack in winter and close in summer? URL: https://terrabrain.vercel.app/causes/truss-uplift-mimic Answer: Often truss uplift: roof trusses bow up in cold weather and lift the ceiling off interior walls. It mimics heave, but the floor has not moved. In short: Truss uplift happens when roof trusses bow upward in cold weather and pull the ceiling up off interior walls. It leaves a crack or gap where ceiling meets wall that usually opens in winter and closes in summer. It can look like foundation heave, but the floor has not moved. ## What is a roof truss? Roof trusses are factory-built triangles of lumber. The sloped top members (top chords) carry the roof, and the flat bottom member (bottom chord) doubles as the ceiling joist that the ceiling drywall is fastened to [4]. The ends of each truss bear on the exterior walls. ## How does truss uplift happen? The two chords live in different conditions. The bottom chord is buried in ceiling insulation, where it stays warmer and drier, while the top chords are exposed to the ventilated attic air [1]. Wood changes size with moisture, so the two parts of the truss move by different amounts. Published explanations describe the bottom chord shrinking as it dries [1] and the top chords swelling as they take on moisture [2]; either way, the truss arches and its middle rises [1][3]. Because the truss ends are held by the exterior walls, the center is pushed upward [3]. Interior partitions do not move with the truss, so the ceiling separates from them and the drywall cracks or screws pop [2]. A partition fastened to the bottom chord can even be lifted slightly off the floor [1]. ### When does it happen? The cracks typically open in winter and close in summer [3]. In summer, both chords reach similar temperature and moisture and the truss returns to its original shape [1]. The cycle may occur only once or recur every year [1]. Juvenile wood from near the center of a tree changes dimension more with moisture than mature wood, which affects how much a given truss moves [1]. Oklahoma's winter cold sets up the temperature difference between attic air and insulated ceiling. Oklahoma Mesonet stations record air temperature and humidity every 5 minutes in all 77 counties, which can be used to line up crack changes with the season [5]. ## Where does truss uplift show up? - Cracks along the ceiling-to-wall corner over interior, non-load-bearing partitions, especially walls running across the trusses [3][4]. - Tape torn through at the ceiling corner, rather than a crack along the edge of the tape, which may point to poor taping instead [3]. - Popping or snapping noises from the ceiling [3]. - In one reported case, cracks appeared at interior partitions but not at exterior walls, where the truss ends bear [4]. ## How can truss uplift be told from foundation heave? | Clue | Truss uplift | Foundation heave | |---|---|---| | Where the gap is | Ceiling corner at interior partitions [3] | Often with cracks in walls, floors and brick | | Season | Opens in winter, closes in summer [3] | Follows soil moisture; see center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) | | Floor level | Unchanged | Raised area or hump on an elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) | | Attic framing | Framing above the crack is checked and photographed from the attic [3] | Not the source of the gap | Inspecting the attic framing above the crack is part of diagnosis [3]. A floor elevation survey separates the two: truss uplift is in the roof, so the floor stays put. See ceiling-wall separation at interior walls (https://terrabrain.vercel.app/signs/ceiling-wall-separation-at-interior-walls) and heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement). ## How is truss uplift usually handled? Because the truss is moving rather than failing, trade literature describes uplift as a cosmetic problem, not a structural one [1]. Common approaches: - **Let the ceiling float:** do not fasten ceiling drywall to the truss near interior partitions. Sources give distances of about 12 to 18 inches [2] and 18 inches [4]. - **Drywall clips or backing angles:** support the ceiling edge from the wall so the drywall can flex [1][3]. - **Slotted connectors:** attach the partition top plate to the truss while allowing vertical movement [1][4]. - **Trim on one surface only:** crown or cornice trim nailed to either the wall or the ceiling, not both, can hide the seasonal gap [3]. Pier work does not address truss uplift because the foundation is not the source. See cosmetic repair only (https://terrabrain.vercel.app/repairs/cosmetic-repair-only). ## Related - Ceiling-wall separation at interior walls (https://terrabrain.vercel.app/signs/ceiling-wall-separation-at-interior-walls) - Center heave (moisture build-up under slab) (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) - Material shrinkage and thermal cracking (mimic) (https://terrabrain.vercel.app/causes/material-shrinkage-and-thermal-cracking-mimic) - Nail pops and tape-joint cracks (https://terrabrain.vercel.app/signs/nail-pops-and-tape-joint-cracks) - Cosmetic repair only (https://terrabrain.vercel.app/repairs/cosmetic-repair-only) - Elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) Sources: [1] Q&A: Truss Uplift Causes & Cures, Journal of Light Construction https://www.jlconline.com/?p=41555 [2] How Does Truss Uplift Work?, Pro Trade Craft https://www.protradecraft.com/how-does-truss-uplift-work [3] Arching roof truss uplift & drywall cracks at the ceiling-wall joint: cause, prevention, repair, InspectAPedia https://inspectapedia.com/interiors/Roof_Truss_Uplift.php [4] Cracks at walls, ceiling may be a truss problem, HeraldNet (The Daily Herald, Everett, WA) https://www.heraldnet.com/?p=373914 [5] The Oklahoma Mesonet (fact sheet), Oklahoma Mesonet https://www.mesonet.org/common/pubs/factsheets/Mesonet%20Fact%20Sheet.pdf --- # Why does my floor sag between piers in a crawl space? URL: https://terrabrain.vercel.app/signs/sagging-floor-between-supports Answer: It is usually a framing and support problem: interior piers that settled or tilted, spans too long for the load, or wood damaged by moisture. In short: A floor that dips between beams or piers in a crawl space home is usually a framing and support problem rather than a whole-house foundation problem. Interior piers that have settled or tilted, spans that are too long for the load, and wood damaged by moisture are the usual causes, and each is found by going into the crawl space. ## What does a sagging floor look like? The floor feels soft or low in the middle of a room or along a hallway, then firms up near walls or over a beam. Furniture may rock, and a level laid across the floor shows a dip rather than a steady slope in one direction. This sign applies to pier-and-beam and crawl space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) houses and to manufactured homes on piers (https://terrabrain.vercel.app/foundations/manufactured-homes-on-piers). **Pier-and-beam** means the floor sits on wood beams (girders) that rest on short interior piers or posts, with joists spanning between the beams. ## Why do floors sag between supports? ### Interior piers settle or tilt Interior piers that settle or rotate drop or lean, which reduces their bearing capacity, and a wood frame tends to flex or sag to follow them [1]. Where the outside foundation wall and the interior piers settle by different amounts, beams and joists can shift and should be checked for lost bearing [1]. Inspectors also check that piers are plumb and that their width-to-height ratio does not exceed 1:10 [1]. See interior support and framing failure (https://terrabrain.vercel.app/causes/interior-support-and-framing-failure-crawl). ### Spans too long for the load When beams or joists span farther than their size allows, they deflect under normal use. The building code sets L/360 (the span divided by 360) as the live-load deflection limit for floor members [3]. Engineering repair guidance describes adding supports where spans are too long for the loads, as long as they are compatible with the existing system [2]. ### Moisture and wood decay Unmanaged crawl space moisture can damage wood flooring and create health and property problems [1]. Rotting wood members are cited as a structural integrity concern, and treated lumber is recommended where members are replaced [2]. EPA states that the key to mold control is moisture control and recommends keeping indoor humidity below 60 percent [5]. See crawl space moisture and wood decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) and water, condensation or mold in the crawl (https://terrabrain.vercel.app/signs/water-condensation-or-mold-in-crawl). ## How is a sagging floor documented? - **Floor survey.** An elevation survey shows whether the low areas sit between supports (a framing pattern) or along one side of the house (a perimeter foundation pattern). See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). - **Crawl space inspection.** Check each pier for settlement and whether it is plumb; check beams and joists for loss of bearing and fractures [1]. - **Moisture conditions.** Look for standing water, damp soil and missing or torn ground cover. A solid 6-mil vapor barrier covering the crawl floor, overlapped and taped, is the inspection standard described [1]. ## How is a sagging floor repaired? Engineering guidance for crawl space floors lists [2]: - adding hardwood or steel shims on top of pier caps to adjust framing - replacing or reinforcing damaged or distressed members - adding supports where spans are too long - moisture controls such as cross ventilation, underfloor drainage, ground clearance for beams and joists, and treated lumber Federal building guidance also places a ground vapor barrier under crawl space construction to limit ground moisture entering the house [4]. See crawl space repair (https://terrabrain.vercel.app/repairs/crawl-space-repair). ## Related - Pier and Beam Crawl Space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) - Interior Support & Framing Failure (Crawl) (https://terrabrain.vercel.app/causes/interior-support-and-framing-failure-crawl) - Bouncy or Soft Floors (https://terrabrain.vercel.app/signs/bouncy-or-soft-floors) - Crawl Space Repair (https://terrabrain.vercel.app/repairs/crawl-space-repair) - Crawl Space Encapsulation (https://terrabrain.vercel.app/repairs/crawl-space-encapsulation) Sources: [1] Inspecting Foundation Walls and Piers, International Association of Certified Home Inspectors (InterNACHI) https://www.nachi.org/documents2012/Inspecting_Foundation_Walls_and_Piers-revised-January-2013.pdf [2] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [3] Guidelines for the Evaluation and Repair of Residential Foundations, Version 2, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2022/05/Guidelines-for-the-Evaluation-and-Repair-of-Residential-Foundations-V2-2008.pdf [4] A Professional's Guide to Durable Home Design: Durability by Design, 2nd Edition, U.S. Department of Housing and Urban Development https://www.HUDUser.gov/portal/sites/default/files/pdf/Guide-Durability-by-Design.pdf [5] A Brief Guide to Mold, Moisture and Your Home, U.S. Environmental Protection Agency https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home --- # Why does some Oklahoma clay swell more than others? URL: https://terrabrain.vercel.app/guides/clay-mineralogy Answer: Swelling depends mostly on clay minerals. Montmorillonite, a smectite, takes water between its layers and swells most; kaolinite swells much less. In short: How much a clay soil swells depends mostly on which clay minerals it contains [1]. Montmorillonite (a smectite) takes water between its layers and swells the most; kaolinite swells much less [1][2]. Much of Oklahoma's soil is rich in these swelling clays, which is why so many Oklahoma foundations move with the seasons [1][3]. ## What are clay minerals? Clay minerals are microscopic, plate-shaped crystals built from layers of silica and alumina. Soil scientists group them by how those layers stack: - **2:1 clays** (two silica layers around one alumina layer), which include montmorillonite and illite. - **1:1 clays** (one silica layer and one alumina layer), such as kaolinite. An Oklahoma State University bulletin identifies water absorbed into the interlayers of 2:1 clays as the main mechanism of shrink and swell, and notes that kaolinite-type 1:1 clays swell much less [1]. Forensic engineers describe montmorillonite's structure as loosely bound, letting water into the spaces between its layers and giving it more expansion capacity than illite [2]. ## What are the main clay minerals? | Mineral | Layer type | Swell behavior | |---|---|---| | Montmorillonite (smectite) | 2:1, loosely bound | Highest; greater expansion capacity than illite [2], can swell to about 1.5 to 2 times its dry volume [3] | | Illite | 2:1 | Less than montmorillonite [2] | | Kaolinite | 1:1 | Much lower than 2:1 clays [1] | | Mixed-layer clays (for example illite-montmorillonite or chlorite-vermiculite) | Mixed | Reported in some Oklahoma shales [4] | ## What have Oklahoma studies found? - **Soils on Permian red beds.** In central and western Oklahoma soils formed from Permian shales, the fine clay was dominantly montmorillonite, with a mix of illite and montmorillonite, plus small amounts of kaolinite, in the coarser clay [1]. Kirkland soil, with montmorillonite-dominated fine clay, had high shrink-swell and was judged unstable for most engineering uses [1]. - **Shrink-swell numbers.** The study measured COLE (coefficient of linear extensibility, how much a soil clod shrinks from wet to dry). Values above 0.03 indicated substantial smectite; Bethany, Kirkland and Norge soils reached 0.095, 0.090 and 0.066 [1]. - **Rock vs soil.** Hennessey shale cored near Oklahoma City was mainly illite and kaolinite with low shrink-swell potential, as were shale cores from two other Oklahoma sites; other studies have reported montmorillonite and mixed-layer clays in the same units elsewhere [4]. - **Statewide.** More than 75% of Oklahoma's bedrock can produce expansive soils [3]. ## Can soil color show how much a clay will swell? High-plasticity clays occur in both red and gray soils. Red Permian soils such as Kirkland are montmorillonite-rich [1], and a south Tulsa report on a site underlain by Nowata Unit shales found olive, brown and gray fat clay with plasticity indices up to about 39 [7]. Lab tests, not color, are used to judge swell. ## Which lab tests stand in for mineralogy? Mineral analysis is rarely run for a house. Engineers instead use index tests. The residential code treats soil as expansive when it has a plasticity index of 15 or more, more than 10% passing a No. 200 sieve, more than 10% finer than 5 micrometers, and an expansion index above 20; if the expansion index is run, the other three are not required [6]. See soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values) and soil lab values data (https://terrabrain.vercel.app/data/soil-lab-values). ## How does mineralogy relate to chemical treatment? Chemical treatments work on the clay itself. Forensic engineers list lime, cement, potassium and other chemicals among soil injection options [2]. Oklahoma pavement research found that stabilizers react with soil particles to form cementing compounds that add strength [5]. Sulfate is a known exception: in a soil with about 15,400 ppm soluble sulfate, adding 3% lime increased swell by more than 1,200% because it formed ettringite, an expansive mineral [5]. See chemical soil stabilization (https://terrabrain.vercel.app/repairs/chemical-soil-stabilization) and stabilization research (https://terrabrain.vercel.app/data/stabilization-research). ## Related - Shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Soil testing and lab values (https://terrabrain.vercel.app/guides/soil-testing-and-lab-values) - Hennessey shale (https://terrabrain.vercel.app/geology/hennessey-shale-group) - Kirkland soil (https://terrabrain.vercel.app/soils/kirkland) - Bethany soil (https://terrabrain.vercel.app/soils/bethany) Sources: [1] Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150), Oklahoma State University Agricultural Experiment Station https://shareok.org/bitstream/11244/302205/1/oksd_TB_T-0150.pdf [2] Beyond the Building Code: Expansive Soils, Journal of the National Academy of Forensic Engineers https://journal.nafe.org/ojs/index.php/nafe/article/download/975/924/4846 [3] Geologic Hazards in Oklahoma, Geological Society of America (abstract by K. V. Luza, Oklahoma Geological Survey) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [4] Geologic and Hydraulic Characteristics of Selected Shaly Geologic Units in Oklahoma (Water-Resources Investigations Report 96-4303), U.S. Geological Survey, with the Oklahoma Geological Survey https://pubs.usgs.gov/wri/1996/4303/report.pdf [5] Engineering Properties of Stabilized Subgrade Soils for Implementation of the AASHTO 2002 Pavement Design Guide (FHWA-OK-08-10), Oklahoma Department of Transportation / University of Oklahoma https://www.odot.org/hqdiv/p-r-div/spr-rip/library/reports/fhwa-ok0810.pdf [6] Seattle Residential Code 2018, Chapter 4 Foundations (IRC-based text of R403.1.8.1), City of Seattle Department of Construction and Inspections https://seattle.gov/Documents/Departments/SDCI/Codes/SeattleResidentialCode/2018SRCChapter4.pdf [7] Geotechnical Engineering Report, Retaining Walls A and B Along 91st Street South from South Memorial Drive to South Mingo Road, City of Tulsa https://www.cityoftulsa.org/media/25588/geotechnical-report-retaining-walls.pdf --- # Why does Tulsa's flood history matter for Oklahoma foundations? URL: https://terrabrain.vercel.app/data/creeks-and-flood-history Answer: Tulsa's floods, peaking in 1984 on Mingo Creek, led to buyouts and floodplain rules. Creek corridors hold deep, soft deposits and shallow water. In short: Tulsa has a long record of creek and river floods, peaking with the 1984 Memorial Day flood on Mingo Creek. Those floods led to buyouts, floodplain rules in 1977 and a stormwater fee in 1986. For foundations, creek corridors matter because they hold deep, soft deposits and water close to the surface, unlike nearby upland ground on shale. ## What were Tulsa's major floods? The City of Tulsa's flooding history lists these events [1]: | Date | Water body | What happened | |---|---|---| | 1908 | Arkansas River | Flood a year after statehood [1] | | June 13, 1923 | Arkansas River | Waterworks flooded; 4,000 left homeless [1] | | 1943 | Arkansas River | Led to Corps of Engineers levees around refineries [1] | | Mother's Day 1970 | Mingo and Joe creeks | Creek flooding [1] | | Labor Day and Dec. 1971 | Flat Rock, Bird and Haikey creeks | Bird Creek flooded twice [1] | | 1974 | Bird, Joe, Fry, Haikey and Mingo creeks | Mingo Creek flooded in June and again in September; some residents had their third flood in a year [1] | | Memorial Day 1976 | Mingo, Joe and Haikey creek headwaters | About 10 inches in 3 hours; 3 deaths; over 3,000 buildings damaged [1] | | Memorial Day 1984 | Mingo Creek mainly | About 15 inches overnight; 14 killed, 288 injured; nearly 7,000 buildings damaged or destroyed [1] | | 1986 | Arkansas River | Keystone Reservoir releases of 310,000 cubic feet per second; 64 buildings damaged [1] | The city describes the 1984 flood as the worst in its history [1]. ### What changed after the floods? - **1971:** Tulsa adopted a 100-year flood standard [1]. A 100-year flood has a 1% chance of happening in any year. - **1974:** 33 houses were cleared from the Mingo Creek right-of-way [1]. - **1977:** comprehensive floodplain regulations adopted [1]. - **1984:** 300 flooded homes relocated, plus a 228-pad mobile home park [1]. - **1986:** a stormwater utility fee created by ordinance, and 13 substantially damaged structures cleared [1]. - **Early 1990s:** FEMA ranked Tulsa first in the nation for its floodplain management program [1]. ## What about flooding in Oklahoma City? Flooding is a statewide hazard; an Oklahoma Geological Survey summary lists floods among Oklahoma's six main natural hazards [4]. Heavy rain also hits central Oklahoma: in May 2015 Oklahoma City received 19.48 inches, its wettest month on record [5]. For more on rain extremes, see drought and wet years (https://terrabrain.vercel.app/data/drought-and-wet-years). ## Why do creek corridors matter for foundations? ### Deep soft ground near water Creeks and rivers lay down alluvium, loose sediment of clay, silt and sand. Along the Arkansas River in Tulsa County, shale lies about 5 to 10 feet below the river bottom but generally 20 to 30 feet below the banks [2]. Borings at the Sand Springs and South Tulsa/Jenks sites found 18 to 35 feet of soil over rock along the banks [2]. On 91st St South between Memorial and Mingo, borings for one retaining wall hit weathered shale near 13.5 feet, while borings for a second wall went through clay to 30 and 35 feet without finding shale, and hit water at 13.5 to 15 feet [3]. See Quaternary alluvium and terraces (https://terrabrain.vercel.app/geology/quaternary-alluvium-and-terraces) and soft soil consolidation (https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays). ### Bank erosion and slope movement Floodwater and fast creek flow can cut into banks and undermine nearby yards, fences and slabs. The Oklahoma Geological Survey notes that most Oklahoma landslides occur in the eastern third of the state, where wetter climate and steeper terrain raise the risk [4]. Related pages: - Erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) - Slope creep and lateral movement (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement) ### Piers near creeks Because depth to rock can change sharply over short distances near water, from about 5 to 10 feet under the Arkansas River bottom to 20 to 30 feet under its banks [2], and from about 13.5 feet at one 91st Street wall to deeper than 35 feet at the other [3], foundation piers on creek-side lots may need to go deeper or stop on friction in soil rather than on rock. Boring comparisons are in borings: depth to rock in Tulsa and OKC (https://terrabrain.vercel.app/data/borings-depth-to-rock-in-tulsa-and-okc). ## Related - Erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes) - Groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Depth to rock from borings (https://terrabrain.vercel.app/data/depth-to-rock-from-borings) - Slope and erosion stabilization (https://terrabrain.vercel.app/repairs/slope-and-erosion-stabilization) - Tulsa metro region (https://terrabrain.vercel.app/regions/tulsa-metro) Sources: [1] Flooding History, City of Tulsa https://www.cityoftulsa.org/government/departments/water-and-sewer/flood-control/flooding-history/ [2] Arkansas River Corridor Projects: Existing Geotechnical Resource Review, Tulsa County River Projects https://riverprojectstulsa.info/wp-content/uploads/2014/Appendix_Q_Final_Geotech.pdf [3] Geotechnical Engineering Report, Retaining Walls A and B Along 91st Street South from South Memorial Drive to South Mingo Road, City of Tulsa https://www.cityoftulsa.org/media/25588/geotechnical-report-retaining-walls.pdf [4] Abstract: Geologic Hazards in Oklahoma, Geological Society of America (Oklahoma Geological Survey author) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [5] Oklahoma Monthly Climate Summary, May 2015, Oklahoma Climatological Survey https://m.climate.ok.gov/summaries/monthly/2015/MCS_May_2015.pdf --- # Why does western Oklahoma gypsum cause sinkholes? URL: https://terrabrain.vercel.app/geology/permian-gypsum-units-e-g-blaine Answer: Gypsum beds like the Blaine Formation, and deeper salt, dissolve in groundwater and form caves, sinkholes and voids, a different risk from clay movement. In short: Western Oklahoma's Permian rocks include thick beds of gypsum, such as the Blaine Formation, and deeper layers of salt. Both dissolve in groundwater, creating caves, sinkholes and hidden voids, a landscape geologists call evaporite karst. On this ground, sudden settlement over a void is a different concern from ordinary clay movement. ## What are the gypsum and salt beds? **Gypsum** is a soft mineral (calcium sulfate) that forms when seawater evaporates. Rocks formed this way, including gypsum, anhydrite and rock salt, are called **evaporites**. Western Oklahoma has enormous gypsum reserves, mined for wallboard, plaster, cement and soil amendment [5]. Thick rock salt underlies much of western Oklahoma at depths from about 30 to 3,000 feet, and natural brine springs feed several salt plains [5]. ### The Blaine Formation The Permian Blaine Formation in southwestern Oklahoma is about 60 meters (roughly 200 feet) of gypsum with thin dolomite and shale beds between the gypsum layers [1][2]. Near Mangum, it contains caves, sinkholes, disappearing streams and springs [1][2]. ## What is evaporite karst? **Karst** is ground shaped by rock that dissolves in water. The Oklahoma Geological Survey notes that karst occurs in many areas of western Oklahoma where gypsum and shallow salt deposits are common [3]. It describes the resulting sinkholes and caverns as potential hazards, with possible settlement or collapse of the land surface, and notes that contaminants can move quickly through karst groundwater with little filtering [3]. An Oklahoma Geological Survey compilation on evaporite karst includes Oklahoma studies on Blaine Formation karst, gypsum caves, cavity detection, a highway right-of-way, and regional karst mapping for avoiding engineering problems [4]. ### A case study: the Mangum dam sites A proposed earth-fill dam near Mangum would have rested on the Blaine gypsum [1]. Borings in 1999 found abundant open and clay-filled cavities in and near the abutments, and pressure tests lost large amounts of water [1][2]. The geologist recommended abandoning the site because fixing the karst would be costly and still might not guarantee the dam [1]. A site about 6 miles downstream on thick Flowerpot Shale showed favorable foundation conditions in testing [2]. ## What soils lie above gypsum country? Woodward soils formed in residuum from soft, calcareous Permian sandstone or siltstone over a large area of western Oklahoma, with soft rock at 20 to 40 inches [6]. Gypsum appears only in small amounts in Woodward profiles, up to about 3 percent in some subsoil layers and as thin seams in some deeper layers [6]. A soil map alone therefore may not show gypsum or voids deeper below. ## What does gypsum karst mean for foundations? | Concern | Why it matters here | |---|---| | Hidden voids | Open and clay-filled cavities occur in Blaine gypsum [1] | | Sudden collapse | Sinkholes and collapse are recognized hazards [3] | | Water concentration | Groundwater flow drives dissolution, and fluids moved readily through cavities in tests [2][3] | | Soil maps miss depth | Surface soils may show only minor gypsum [6] | - Distinguish slow seasonal cracking from a sudden local drop. See sudden depression or sinkhole (https://terrabrain.vercel.app/signs/sudden-depression-or-sinkhole) and karst subsidence and sinkholes (https://terrabrain.vercel.app/causes/karst-subsidence-and-sinkholes). - Circulating groundwater is what dissolves soluble rock [3], so where roof water, pool water and plumbing leaks go is part of the picture on gypsum ground. - For voids under footings, see void and compaction grouting (https://terrabrain.vercel.app/repairs/void-and-compaction-grouting). ## Related - Gypsum karst and sinkholes (https://terrabrain.vercel.app/guides/gypsum-karst-and-sinkholes) - Northwest (Gypsum Hills) (https://terrabrain.vercel.app/regions/northwest-gypsum-hills) - Southwest (Lawton and Red Plains) (https://terrabrain.vercel.app/regions/southwest-lawton-and-red-plains) - Western Permian red beds (https://terrabrain.vercel.app/geology/western-permian-red-beds) - Woodward soil (https://terrabrain.vercel.app/soils/woodward) Sources: [1] Gypsum Karst Leads to Abandonment of a Proposed Damsite in Oklahoma, Geological Society of America (Oklahoma Geological Survey author) https://gsa.confex.com/gsa/2001AM/webprogram/Paper16911.html [2] Gypsum Karst Is a Major Factor in Siting of a Proposed Dam in Southwestern Oklahoma, Geological Society of America (Oklahoma Geological Survey author) https://gsa.confex.com/gsa/2002AM/webprogram/Paper40278.html [3] Mapping of Karst Terranes in Oklahoma to Identify Potential Environmental and Hydrologic Problems, AAPG Search and Discovery / Oklahoma Geological Survey https://www.searchanddiscovery.com/abstracts/html/1995/midcon/abstracts/1403b.htm [4] Evaporite Karst and Engineering/Environmental Problems in the United States (Circular 109), excerpt and contents, Oklahoma Geological Survey (copy hosted by U.S. DOE WIPP library) https://wipp.energy.gov/library/CRA/CRA-2019/N%20-%20S/Powers%20%202003%20%20OGS%20Circular%20109.pdf [5] Industrial Minerals, Oklahoma Geological Survey https://www.ou.edu/ogs/research/minerals.html [6] Official Soil Series Description: WOODWARD Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/W/WOODWARD.html --- # Why is brick pulling away from my window or door frame? URL: https://terrabrain.vercel.app/signs/brick-separating-from-window-or-door-frame Answer: Usually the foundation edge carrying the brick has dropped, often as perimeter clay dries and shrinks. The gap tends to be widest in late summer and drought. In short: When brick veneer pulls away from a window or door frame, the usual reason is that the edge of the foundation carrying the brick has dropped. On Oklahoma's expansive clay, this often happens when soil at the perimeter dries and shrinks. The gap tends to be widest in late summer and in drought years. ## Why does the gap open? Brick veneer is a single layer of brick tied to the wood-framed wall behind it and resting on a ledge at the edge of the foundation. Windows and doors are attached to the wood framing. When the foundation edge settles, the brick goes down with it, but the frame does not follow in the same way, so the brick separates from the side or top of the frame. On shrinkable clay, drying soil contracts and the building can sink, often cracking around windows and doors [1]. Cracks usually need about 5 to 10 millimeters (roughly 1/4 to 3/8 inch) of movement before they show [1]. ### Edge drop on expansive clay The mechanism this site links to this sign is perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop): 1. Soil just outside the foundation dries in hot, dry weather. 2. The clay shrinks and the outer beam settles relative to the interior. 3. Brick and openings along that wall distort. Engineering guidance on expansive soil notes that lack of watering during drought, which dries out the clay, could be more damaging than overwatering [3]. Texas slab monitoring found out-of-levelness growing from about 2-1/4 to 3-3/4 inches on average as the growing season progressed, with droughts making settlement worse and winter rain allowing partial recovery [2]. ## How do Oklahoma soils cause it? More than 75% of Oklahoma has bedrock that can produce expansive soils, and clay-rich shales can swell to 1.5 to 2 times their dry volume when wet [5]. Soil surveys rate this with linear extensibility; above 3%, shrinking and swelling can damage buildings and special design is commonly needed [6]. Dry-season cracks in expansive clay can be about an inch wide at the surface, and one documented crack ran at least 32 inches deep [4]. See shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) and the soil series index (https://terrabrain.vercel.app/soils/soil-series-index). ## What else should you look for? Separation at frames rarely appears alone. Check the same wall for: - Stair-step brick cracks wider at the top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top), which point toward a dropping corner or edge. - Frieze board or trim separation (https://terrabrain.vercel.app/signs/frieze-board-or-trim-separation) at the top of the brick. - Windows sticking or cracked glass (https://terrabrain.vercel.app/signs/windows-sticking-or-cracked-glass) in the affected openings. - Soil pulled away from the foundation (https://terrabrain.vercel.app/signs/soil-pulled-away-from-foundation), a sign of drying at the perimeter. Home inspection standards list brick cracks, drywall cracks, out-of-square door frames and uneven floors as signs of possible foundation movement to report [7]. ## How do you document it? - Measure gap width at the same points on each frame, top and sides. - Photograph each gap with a ruler or crack gauge in view. - Repeat every month or two through at least one summer and winter. - Plot the locations on a floor plan with an elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) to see which corner or edge is low. A gap that widens in late summer and narrows in wet months points toward moisture-driven soil movement; see cracks that open and close seasonally. ## What are the next steps? Plot the sign on an elevation survey, compare it with the patterns in the distress pattern library, and use the symptom matrix to weigh likely mechanisms. ## Related - Perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Stair-step brick crack wider at top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top) - Vertical brick or veneer crack (https://terrabrain.vercel.app/signs/vertical-brick-or-veneer-crack) - Distress pattern library (https://terrabrain.vercel.app/guides/distress-pattern-library) - Symptom matrix (https://terrabrain.vercel.app/guides/symptom-matrix) Sources: [1] Trees near buildings, Royal Horticultural Society https://www.rhs.org.uk/plants/types/trees/near-buildings [2] Cyclical Foundation Movements and Their Remediation, CIGMAT, University of Houston (conference presentation) https://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2007/addison.pdf [3] Irrigation, Drainage, and Landscaping for Expansive Soil, Journal of Irrigation and Drainage Engineering (ASCE) https://ascelibrary.com/doi/10.1061/%28ASCE%290733-9437%281992%29118%3A2%28285%29 [4] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [5] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [6] Alabama FOTG Section II: Physical Properties of the Soils, USDA Natural Resources Conservation Service https://efotg.sc.egov.usda.gov/references/Public/AL/Physical.pdf [7] Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm --- # Why is my chimney pulling away from the house or leaning? URL: https://terrabrain.vercel.app/signs/chimney-separating-or-leaning Answer: Its heavy footing at the edge of the house can settle, or the soil under it can be soft or drying. Earthquake shaking is another possible cause in Oklahoma. In short: An exterior masonry chimney is a tall, heavy column, usually on its own footing at the edge of the house. When that footing settles, or the soil under it is soft or drying, the chimney can lean away and open a gap at the wall or roofline. Earthquake shaking is another possible cause in Oklahoma, which has had several moderate earthquakes [2]. ## Why do chimneys move differently from the house? Most of a house is light wood framing spread along long foundation beams. A brick or stone chimney concentrates a great deal of weight on a small footing. That difference means the chimney can settle or tilt on its own even when the rest of the foundation is moving only a little. When it does, the gap typically shows at the side wall, at the roof flashing, or as cracks in the chimney itself. ### What the code requires under a masonry chimney The residential code calls for footings under masonry fireplaces and their chimneys to be concrete or solid masonry at least 12 inches thick, extending at least 6 inches beyond the face of the fireplace [7]. The footing must bear on natural, undisturbed soil or engineered fill below frost depth, or at least 12 inches below finished grade where the ground does not freeze [7]. In higher seismic design categories (D0 to D2), the code also requires masonry chimneys to be reinforced with vertical steel bars and anchored to the floor, ceiling or roof framing [7]. Outside those categories, these reinforcing and anchorage rules do not apply [7]. ## What can make a chimney separate or lean? | Mechanism | How it moves the chimney | |---|---| | Concentrated load settlement (https://terrabrain.vercel.app/causes/concentrated-load-settlement) | A heavy load on a small footing compresses the soil beneath more than the lighter wall foundation | | Earthquake shaking damage (https://terrabrain.vercel.app/causes/earthquake-shaking-damage) | Shaking cracks masonry and can loosen the chimney from the wall | | Perimeter drying settlement (edge drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) | Clay at the outside of the house dries and shrinks under the chimney footing | | Soft soil consolidation (https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays) | Soft, wet clay slowly compresses under the chimney's weight | ### Heavier loads compress soil more Engineers test how much a soil compresses by loading a confined sample in increasing steps and measuring the settlement at each step [4]. In eastern Oklahoma, for example, the Osage floodplain soil is a poorly drained clay with a seasonal high water table 6 to 18 inches below the surface from November through May [5]. A chimney footing on soil like that carries its load into ground that stays soft for much of the year. ### Drying clay at the perimeter A chimney stands at the outside edge of the house, where soil dries the most in summer. Expansive clay shrinks as it dries, and dry-season cracks in such soil can be about an inch wide at the surface [6]. See shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone). ### Earthquakes in Oklahoma Oklahoma's earthquake activity rose sharply after 2009: about two magnitude 3.0+ events per year before then, compared with 903 in 2015 [2]. Notable events include the magnitude 5.7 Prague earthquake (2011), the magnitude 5.8 Pawnee earthquake (2016) and the magnitude 5.0 Cushing earthquake (2016) [2]. Historically mapped seismic areas include El Reno-Mustang, central Oklahoma, Love and Carter counties and the Arkoma Basin [3]. After the 2016 Pawnee earthquake, a Pawnee resident was injured by bricks falling from his chimney [8]. A chimney that cracked or separated right after a felt earthquake, with fresh crack faces, points toward shaking; see seismic damage vs soil movement (https://terrabrain.vercel.app/guides/seismic-damage-vs-soil-movement). ## How should it be documented? 1. Measure how far the chimney is out of plumb over a known height with a level or plumb line. 2. Measure the gap between chimney and wall at the bottom, middle and top. 3. Photograph cracks in the chimney with a scale, and note whether crack edges are clean or weathered. 4. Note when the gap was first seen, and whether it followed a dry summer, a wet season or an earthquake. 5. Include the chimney on a whole-house elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys). Home inspection standards include inspecting the chimney from ground level or the eaves and reporting signs of possible foundation movement, such as brick cracks [1]. ## What are the next steps? Compare the pattern with the distress pattern library (https://terrabrain.vercel.app/guides/distress-pattern-library) and the symptom matrix. For a chimney that continues to move, see working with engineers. ## Related - Concentrated load settlement (https://terrabrain.vercel.app/causes/concentrated-load-settlement) - Earthquake shaking damage (https://terrabrain.vercel.app/causes/earthquake-shaking-damage) - Induced seismicity in Oklahoma (https://terrabrain.vercel.app/guides/induced-seismicity-in-oklahoma) - Fresh, clean-edged cracks appearing suddenly (https://terrabrain.vercel.app/signs/fresh-clean-edged-cracks-appearing-suddenly) - Steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) Sources: [1] Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [2] Detailed mapping of shallow landslides in eastern Oklahoma and western Arkansas and potential triggering by Oklahoma earthquakes, Geomorphology (Oklahoma Geological Survey authors) https://www.jakewalter.net/papers/Regmi_Walter_2019.pdf [3] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [4] Standard Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental Loading (ASTM D2435/D2435M-25), ASTM International https://store.astm.org/d2435_d2435m-25.html [5] Official Series Description: Osage Series, USDA Natural Resources Conservation Service https://soilseries.sc.egov.usda.gov/OSD_Docs/O/OSAGE.html [6] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [7] International Residential Code 2006, New Jersey Edition, Chapter 10: Chimneys and Fireplaces, International Code Council https://www3.iccsafe.org/states/newjersey/NJ_Residential/PDFs/NJ_Res_Chapter10.pdf [8] Pawnee Diagnosing Damage After Earthquake, News 9 (Oklahoma City) https://news9.com/story/5e3608002f69d76f6203516e/pawnee-diagnosing-damage-after-earthquake --- # Why is my driveway or patio lifting, sinking or cracking? URL: https://terrabrain.vercel.app/signs/heaved-or-settled-flatwork Answer: Thin slabs on Oklahoma clay lift when soil swells and sink when it washes out, compresses or dries. This alone does not mean the house foundation moved. In short: Driveways, sidewalks and patios are thin slabs resting directly on the soil, so they show soil movement quickly. On Oklahoma clay they can lift when the soil swells, sink when soil washes out, compresses or dries, and crack in either case. Their movement is a clue about water and soil around the house, but it does not by itself mean the house foundation has moved. ## Why does flatwork move so easily? "Flatwork" means exterior concrete slabs: driveways, walks, patios, porches and pool decks. They are usually a few inches thick, carry little weight and sit on the top layer of soil, the layer whose moisture changes most. That makes them more sensitive to soil movement than a house foundation. In Oklahoma, the Oklahoma Geological Survey lists sidewalks and highways, along with foundations and utilities, among the things damaged when expansive soil swells after saturation from rain, lawn watering or sewer leaks [2]. More than 75% of the state has bedrock that can produce expansive soils [2]. ## What causes can produce flatwork movement? | Mechanism | Typical result | |---|---| | Erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) | Slab sinks or cracks where water has carried soil away | | Frost heave (https://terrabrain.vercel.app/causes/frost-heave) | Slab or steps lifted in freezing weather | | Perimeter wetting heave (edge lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) | Slab lifted by swelling clay after wet periods | | Fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) | Slab over backfill sinks over time, often next to the house | ### Swelling and shrinking clay Expansive soil swells when wet and shrinks when dry [3]. Swelling soils frequently cause distress in floor slabs, and water from a pool can differentially lift the adjacent pool deck [1]. Fissures in expansive soil can be up to about 20 centimeters (8 inches) wide and 4 meters (13 feet) deep [6]. ### Water and erosion The U.S. Geological Survey lists subterranean erosion, such as piping, and water leakage from utilities among the causes of landslides [4]. Swelling clays can crack concrete drainage ditches, and the voids that form can lead to piping and erosion [1]. Leaking pipes and pools are common sources of uneven moisture [1]. ### Tree roots Root growth can physically disturb the ground, which is often seen as damage to pavements and walls [3]. Trees also dry clay; see tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement). ## Does flatwork movement mean the house moved? Engineering guidance on expansive soil recommends keeping soil moisture steady around a building and mentions surrounding it with concrete paving as one way to limit moisture changes [5]. When flatwork next to the house settles or tilts toward it, rain can collect against the foundation instead; see water ponding near foundation (https://terrabrain.vercel.app/signs/water-ponding-near-foundation) and surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). ## How do you document flatwork movement? 1. Note which way each slab has moved: lifted, sunk or tilted, and toward or away from the house. 2. Measure height differences at joints and cracks with a ruler or level. 3. Photograph with a ruler in view, and record the season and recent weather. 4. Look for voids at slab edges, downspouts discharging onto or under slabs, and nearby trees. 5. Include key points on an elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) if the house is being surveyed. ## How is flatwork repaired? Options matched to flatwork include slabjacking and polyurethane to raise settled slabs, void and compaction grouting, and drainage solutions to deal with the water. Lifting slabs that rose from swelling clay is not the same problem as raising sunken ones; see flatwork and exterior slabs. ## Related - Flatwork and exterior slabs (https://terrabrain.vercel.app/foundations/flatwork-and-exterior-slabs) - Slabjacking and polyurethane (https://terrabrain.vercel.app/repairs/slabjacking-and-polyurethane) - Frost heave (https://terrabrain.vercel.app/causes/frost-heave) - Erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) - Surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) Sources: [1] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [2] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [3] Expansive soils (encyclopedia entry, post-review manuscript), NERC Open Research Archive https://nora.nerc.ac.uk/id/eprint/521301/1/EncyclopediaEngGeol_ExpansiveSoils_PostReview.pdf [4] Landslide Types and Processes (Fact Sheet 2004-3072), U.S. Geological Survey https://pubs.usgs.gov/fs/2004/3072/fs-2004-3072.html [5] Irrigation, Drainage, and Landscaping for Expansive Soil, Journal of Irrigation and Drainage Engineering (ASCE) https://ascelibrary.com/doi/10.1061/%28ASCE%290733-9437%281992%29118%3A2%28285%29 [6] Fundamental Building Solutions for Expansive Soils, Encyclopedia MDPI https://encyclopedia.pub/entry/history/show/99164 --- # Why is my garage door gap uneven or the header sagging? URL: https://terrabrain.vercel.app/signs/uneven-garage-door-or-sagging-header Answer: One side of the garage foundation may have dropped, or the lintel or door hardware may be at fault, so floor level, opening and brick are checked together. In short: A garage door that closes with a tapered gap at the bottom, or a header that dips over the opening, can mean one side of the garage foundation has dropped. It can also be a lintel or door-hardware issue, so the floor level, the opening and the brick above are checked together. ## What does an uneven garage door look like? - The closed door touches the floor on one side and leaves a wedge-shaped gap on the other. - The weather seal is crushed at one end and open at the other. - The **header**, the beam that spans over the door opening, dips in the middle or is visibly lower at one end. - Brick above the opening has cracked, often at the corners of the opening. This applies mostly to attached garages on slab-on-grade (https://terrabrain.vercel.app/foundations/slab-on-grade) and post-tensioned (https://terrabrain.vercel.app/foundations/post-tensioned-slabs) houses. ## Why does it happen? ### Foundation settlement at one side Expansive soils are common across most of Oklahoma, and seasonal moisture loss lets the clay shrink and the foundation edge move downward [4]. If one side of the garage door opening drops more than the other, the opening tilts and the door no longer closes evenly. This is covered in perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). Engineering guidance lists racking of door and window frames among visible indications of foundation movement, and also uses poor door alignment and brick coursing that is not level as clues to movement [1]. Inspector training material lists warped openings and sticking doors and windows among signs of settlement [5]. Building officials note that foundation movement often cracks walls near window and door corners and can crack garage slabs, walkways and driveways [3]. ### Lintel and header deflection A wide garage opening in brick veneer is spanned by a steel angle called a **lintel**. Brick industry guidance describes the crack pattern when a lintel is undersized: the crack is widest at the steel angle and tapers to nothing [2]. That pattern differs from foundation settlement, which tends to produce diagonal or stepped cracks in the brick directly above the foundation [2]. ### Door hardware Garage doors run on adjustable tracks and springs, and an uneven gap can come from the door itself rather than the structure. Measuring the floor and the opening separates the two. ## How is it documented? | Measurement | What it shows | |---|---| | Gap under the closed door at each end | Size of the tilt across the opening | | Floor elevation at each side of the door | Whether the slab itself has dropped | | Header level across the span | Whether the header dips (deflection) or tilts (settlement) | | Crack shape in brick above | Lintel taper vs stepped settlement crack [2] | A relative floor elevation survey is the engineering step beyond a visual first impression [1]. Readings at the two sides of the opening are compared with each other and with the house floor, since a garage floor is not always built level. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys) and visible slab cracks (https://terrabrain.vercel.app/signs/visible-slab-cracks). ## Related - Perimeter Drying Settlement (Edge Drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Brick Separating from Window or Door Frame (https://terrabrain.vercel.app/signs/brick-separating-from-window-or-door-frame) - Stair-Step Brick Crack Wider at Top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top) - Visible Slab Cracks (https://terrabrain.vercel.app/signs/visible-slab-cracks) - Elevation Surveys (https://terrabrain.vercel.app/guides/elevation-surveys) Sources: [1] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [2] Volume Changes – Analysis and Effects of Movement (Technical Note 18), Brick Industry Association https://gobrick.com:443/media/file/18-tn18.pdf [3] County Expansive Soils Policy & Procedures, Roanoke County Development Services https://roanokecountyva.gov/DocumentCenter/View/1020 [4] The Mystery of Expansive Soils, STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [5] Inspecting Foundation Walls and Piers, International Association of Certified Home Inspectors (InterNACHI) https://www.nachi.org/documents2012/Inspecting_Foundation_Walls_and_Piers-revised-January-2013.pdf --- # Why is my home addition cracking or pulling away from the house? URL: https://terrabrain.vercel.app/causes/differential-movement-at-additions Answer: An addition often sits on its own foundation at a different depth or on fill, so it settles or heaves differently and the joint with the house opens up. In short: An addition usually sits on its own foundation, built at a different time, often to a different depth and sometimes on backfill. When the addition and the original house settle or heave by different amounts, the line where they meet opens up, causing cracks, sloping floors and separation. Engineers evaluate each foundation separately as well as the house as a whole. ## Why do additions move differently from the house? An addition is a second structure attached to the first. Its foundation can differ from the original house in several ways, and any of them can make the two parts respond differently to the same soil: - **Different soil under it.** Additions are often built over ground that was disturbed or backfilled during construction. Poorly placed fill is prone to settling [3], and Oklahoma transportation research describes compacted fill continuing to compress after construction as its moisture content increases [4]. - **Different depth.** Oklahoma research estimates the active zone, the depth of soil whose moisture changes with the weather, at roughly 0.5 to 4 meters (about 1.5 to 13 feet) [6]. A foundation sitting higher within that zone experiences more of the seasonal shrink and swell than one bearing deeper. - **Different age.** The original house has had years for its soil to adjust, while compacted fill under a newer addition can still settle after construction if it gets wetter [4]. - **Different design and construction.** Texas engineering guidelines list inadequate design or construction among the causes of residential foundation distress [1]. ### The joint between them Where new concrete meets old, movement concentrates at the connection. Concrete cracks where its movement is restrained, and isolation joints are used where slabs meet walls or other elements whose movement may differ [7]. ## What are the signs of an addition moving? The distress usually lines up with the junction between the original house and the addition. Common signs include: - diagonal drywall cracks at openings (https://terrabrain.vercel.app/signs/diagonal-drywall-cracks-at-openings) near the connecting wall - sloping floors (https://terrabrain.vercel.app/signs/sloping-floors) that change grade at the addition - stair-step cracks in brick that are wider at the top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top) at the corner where the two structures meet - a gap or crack along the roofline or ceiling where the two parts join Texas guidelines note that a tilt of more than about 1% is usually noticeable [1], and the Foundation Performance Association uses 1% tilt and a deflection ratio of L/360 as performance limits [2]. Deflection ratio compares the amount a floor bows to the length over which it bows. ## How is addition movement evaluated? - **Separate checks.** When additions have been made, the Texas guidelines say the overall foundation dimensions should be checked for each separate foundation element as well as for the whole foundation [1]. - **Elevation surveys.** A single survey shows the foundation's shape at one moment, while repeated surveys show change over time [1]. Without a baseline survey, movement cannot be determined accurately [2]. See elevation surveys (https://terrabrain.vercel.app/guides/elevation-surveys). - **Lot and fill history.** Records, aerial photos and soil borings can show whether the addition was built over fill. See fill soils and lot history (https://terrabrain.vercel.app/guides/fill-soils-and-lot-history). ## How is addition movement typically addressed? Where the addition has settled, underpinning (installing piers or piles under the foundation) is the usual structural method. Texas guidelines state that repair plans should show or specify underpinning locations, sizes, depths and materials and that underpinning does not improve areas that are not underpinned [5]. The guidelines also note that non-structural measures and monitoring may be prudent before or instead of structural repair [1]. See steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) and helical piers (https://terrabrain.vercel.app/repairs/helical-piers), and the additions and mixed foundations guide (https://terrabrain.vercel.app/guides/additions-and-mixed-foundations). ## Related - Additions and Mixed Foundations (https://terrabrain.vercel.app/guides/additions-and-mixed-foundations) - Fill Consolidation Settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) - Concentrated Load Settlement (https://terrabrain.vercel.app/causes/concentrated-load-settlement) - Monitoring Program (https://terrabrain.vercel.app/repairs/monitoring-program) - Stem Wall and Grade Beam (https://terrabrain.vercel.app/foundations/stem-wall-and-grade-beam) Sources: [1] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [2] Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings (FPA-SC-13-1), Foundation Performance Association https://inspectapedia.com/structure/Foundation-Movement-Evaluation-Guidelines-FPA-TX.pdf [3] Collapsible Soils, Colorado Geological Survey https://coloradogeologicalsurvey.org/hazards/collapsible-soils/ [4] Settlement Behavior of Compacted Oklahoma Soils (FHWA-OK-02-03), Oklahoma Department of Transportation https://rosap.ntl.bts.gov/view/dot/88914 [5] Guidelines for the Evaluation and Repair of Residential Foundations, Version 2, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2022/05/Guidelines-for-the-Evaluation-and-Repair-of-Residential-Foundations-V2-2008.pdf [6] Soil Matric Suction and Active Zone Depth in Oklahoma, Oklahoma State University (Er Yue, Ph.D. dissertation, 2017) https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf [7] CIP 4 - Cracking Concrete Surfaces, National Ready Mixed Concrete Association https://www.prairie.com/wp-content/uploads/sites/4/2024/12/04p_CrackingConcreteSurfaces.pdf --- # Why is my house rising after foundation repair done in a drought? URL: https://terrabrain.vercel.app/causes/over-lift-heave-after-drought-lift Answer: If piers set a house level while clay is dry and shrunken, returning rain swells the soil under unpiered areas, lifting them above the piered edges. In short: When a house on expansive clay is lifted on piers during a drought, the perimeter is set at its new height while the soil under the rest of the house is still dry and shrunken. When rain returns, that soil swells and lifts the unpiered areas, often the interior, above the piered edges. The result is new humps, binding doors and cracks after a repair that looked level when it was finished. ## How does over-lift happen? Expansive clay shrinks when it dries and swells when it wets; seasonal moisture loss lets the perimeter of a slab settle, and seasonal moisture gain pushes it back up [1]. Clay does not move if its moisture stays constant, but moisture rarely stays constant [1]. 1. **Lift during dry conditions.** In a drought, the perimeter can drop as the clay beneath it shrinks [1]. Piers are installed and the perimeter is raised toward level. 2. **Rain returns.** The clay under the house, including under areas without piers, takes on water and swells [1]. 3. **Unpiered areas rise.** The piered perimeter is held at its set height, while the interior and any unpiered sections rise with the swelling soil. Texas engineering guidelines note that underpinning does not improve areas that are not underpinned and that its performance can be affected by soil moisture changes [5]. 4. **New distress appears.** The interior ends up higher than the edges. ## Why does dry-season timing matter? The depth and degree of drying set the stage for later swelling: - In Oklahoma, the active zone, the depth of soil whose moisture changes with the climate, has been estimated at roughly 0.5 to 4 meters (about 1.5 to 13 feet), with shallow soil responding most strongly to weather [3]. - Engineering literature reports seasonal moisture fluctuation in expansive soils ranging from about 3 to 40 feet deep, and multi-year droughts show the zone can be deeper than previously believed [2]. - Expansive soils are most damaging where climates have pronounced wet and dry seasons, with shrink-swell cycles repeating each year [2]. Texas guidelines also caution that lifting is governed by field judgment to limit damage and that it is unlikely an elevation adjustment will result in a level foundation [4]. See drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) and the seasonal movement calendar (https://terrabrain.vercel.app/guides/seasonal-movement-calendar). ### Documenting moisture at the time of lift The Oklahoma Mesonet's network of about 120 automated stations collects soil and weather observations statewide, including soil moisture [6]. Records from the nearest station show whether a lift was done in a dry period. See Mesonet for foundation pros (https://terrabrain.vercel.app/guides/mesonet-for-foundation-pros). ## What are the signs of over-lift? - an interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump) that was not there before the repair - doors that bind or show tapered gaps - ceiling-wall separation at interior walls (https://terrabrain.vercel.app/signs/ceiling-wall-separation-at-interior-walls) The pattern resembles center heave (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab); Texas guidelines note that previous foundation repairs can change elevation shapes, so repair history should be considered when interpreting a survey [4]. ## How is over-lift evaluated? Texas guidelines say floor elevations should be measured after remedial work and given to the client [4], and that a single survey shows shape at one moment while repeated surveys show change over time [4]. Comparing the post-repair survey with a new one after rain shows how much the unpiered areas rose. Plumbing should also be checked: the guidelines call for supply and drain lines to be tested for leaks when lifting is done [4]. For reference, Oklahoma steel push pier installation records show typical pier depths of about 8 to 16 feet, with a median of about 12 feet in Tulsa [7]. ## How is over-lift typically addressed? - **Monitor first.** The Texas guidelines note that non-structural measures and monitoring may be prudent before or instead of further structural repair [4]. See monitoring program (https://terrabrain.vercel.app/repairs/monitoring-program). - **Re-set adjustable supports.** In crawl spaces, shims can be adjusted; floor shimming is a recognized pier-and-beam repair [5]. See lifting procedure and restoration (https://terrabrain.vercel.app/guides/lifting-procedure-and-restoration). ## Related - Lifting Procedure and Restoration (https://terrabrain.vercel.app/guides/lifting-procedure-and-restoration) - Pier Uplift or Movement After Repair (https://terrabrain.vercel.app/causes/pier-uplift-or-movement-after-repair) - Perimeter Wetting Heave (Edge Lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) - Drought and Wet Cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles) - Monitoring Program (https://terrabrain.vercel.app/repairs/monitoring-program) Sources: [1] The Mystery of Expansive Soils, STRUCTURE magazine (NCSEA / CASE / SEI) https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [2] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. David Rogers et al.) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [3] Soil Matric Suction and Active Zone Depth in Oklahoma, Oklahoma State University (Er Yue, Ph.D. dissertation, 2017) https://shareok.org/bitstream/11244/54639/1/Yue_okstate_0664D_15062.pdf [4] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [5] Guidelines for the Evaluation and Repair of Residential Foundations, Version 2, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2022/05/Guidelines-for-the-Evaluation-and-Repair-of-Residential-Foundations-V2-2008.pdf [6] Drought monitoring: a system for tracking plant available soil moisture based on the Oklahoma Mesonet, Oklahoma State University https://apps.dasnr.okstate.edu/SSL/soilphysics.okstate.edu/research/droughtmonitoring.htm [7] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # Why is my house settling on fill dirt in Oklahoma? URL: https://terrabrain.vercel.app/causes/fill-consolidation-settlement Answer: Loose fill, or fill with debris or organic matter, slowly compresses under a house. Wetting speeds it up, and it is worst where the fill is deepest. In short: Fill consolidation settlement happens when soil that was brought in or pushed around to level a lot was placed too loosely, or with debris and organic material, and then slowly compresses under the house. Getting wet speeds it up. The settlement is one-directional and tends to be worst where the fill is deepest, such as on the downhill side of a cut-and-fill lot or over an old filled ditch or pond. ## What is fill and why does it settle? Fill is soil placed by people rather than left where nature deposited it. Builders use it to level sloping lots, raise building pads, and fill ravines, ditches and old ponds. Engineers define settlement as downward movement of the supporting soil due to loading from above, such as when loads exceed the soil's bearing capacity [4]. Poorly placed fills are prone to settling [3]. Compaction alone does not guarantee stability: an Oklahoma Department of Transportation study of compacted Oklahoma soils describes collapse settlement as a time-dependent process caused by increases in moisture content after construction, and examines how soil type influences collapse potential [1]. ### Where the fill is deepest On a lot that was cut on the uphill side and filled on the downhill side, the house sits partly on undisturbed soil and partly on fill. Because the settlement comes from the fill itself compressing [3], it shows up where the fill is, and filled ponds, creek channels and ravines create similar pockets. See fill soils and lot history (https://terrabrain.vercel.app/guides/fill-soils-and-lot-history). ## Where is fill settlement common in Oklahoma? ODOT research has also characterized compressible clayey and silty alluvial soils in Oklahoma river systems at sites where settlement of fill was a known problem [2]. Fill placed over soft river-bottom soil can settle both because the fill compresses and because the soft soil beneath it consolidates. See soft soil consolidation (https://terrabrain.vercel.app/causes/soft-soil-consolidation-alluvium-and-wet-clays). ## What are the signs of fill settlement? - stair-step brick cracks wider at the top (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top), on the side over the fill - sloping floors (https://terrabrain.vercel.app/signs/sloping-floors) that fall toward the fill side - diagonal drywall cracks at doors and windows - visible slab cracks (https://terrabrain.vercel.app/signs/visible-slab-cracks) Concrete industry guidance lists poor subgrade preparation among the main construction causes of slab cracking [5]. ## How is fill settlement different from look-alikes? Collapse and consolidation of fill reduce the soil's volume [1][3], so the movement is downward and does not reverse when the soil dries. Expansive clay behaves differently, shrinking and swelling as its moisture changes; compare perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). ## How is fill settlement evaluated? - **History.** Texas engineering guidelines list cut-and-fill observations among the items in a detailed foundation report [6]. - **Elevation surveys.** Repeated surveys over months or years show whether the settlement is continuing [6]. - **Soil testing.** Borings and laboratory tests, like the sampling and consolidation testing used in ODOT's Oklahoma studies, characterize how compressible the soil is [2]. ## How is fill settlement typically fixed? Underpinning with piers or piles that pass through the fill to firmer native soil or rock is the common structural approach. Texas guidelines state that underpinning locations, sizes, depths and materials must be specified and that underpinning does not improve areas that are not underpinned [7], which matters when interior slab areas also sit on fill. In Oklahoma steel push pier installation records, typical pier depths were about 8 to 16 feet, with a median of about 12 feet in Tulsa [8]. See steel push piers (https://terrabrain.vercel.app/repairs/steel-push-piers) and void and compaction grouting (https://terrabrain.vercel.app/repairs/void-and-compaction-grouting). ## Related - Fill Soils and Lot History (https://terrabrain.vercel.app/guides/fill-soils-and-lot-history) - Differential Movement at Additions (https://terrabrain.vercel.app/causes/differential-movement-at-additions) - Slope Creep and Lateral Movement (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement) - Helical Piers (https://terrabrain.vercel.app/repairs/helical-piers) - Hydrocollapse (Collapsible Soil) (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil) Sources: [1] Settlement Behavior of Compacted Oklahoma Soils (FHWA-OK-02-03), Oklahoma Department of Transportation https://rosap.ntl.bts.gov/view/dot/88914 [2] Bearing capacities and characterization of compressible clayey and silty foundation soils in Oklahoma (FHWA-OK-81-3), Oklahoma Department of Transportation (via ShareOK) https://shareok.org/items/20dbaccf-8026-43bf-8b75-88314f3f3a6e/full [3] Collapsible Soils, Colorado Geological Survey https://coloradogeologicalsurvey.org/hazards/collapsible-soils/ [4] Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings (FPA-SC-13-1), Foundation Performance Association https://inspectapedia.com/structure/Foundation-Movement-Evaluation-Guidelines-FPA-TX.pdf [5] CIP 4 - Cracking Concrete Surfaces, National Ready Mixed Concrete Association https://www.prairie.com/wp-content/uploads/sites/4/2024/12/04p_CrackingConcreteSurfaces.pdf [6] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [7] Guidelines for the Evaluation and Repair of Residential Foundations, Version 2, American Society of Civil Engineers, Texas Section https://www.texasce.org/wp-content/uploads/2022/05/Guidelines-for-the-Evaluation-and-Repair-of-Residential-Foundations-V2-2008.pdf [8] Oklahoma steel push pier installation records, 2025 (unpublished field data), TerraBrain field data --- # Why is the soil pulling away from my foundation? URL: https://terrabrain.vercel.app/signs/soil-pulled-away-from-foundation Answer: Clay along the house has dried and shrunk. The gap is a moisture sign, not proof of damage, but the same drying under the slab edge lets the perimeter settle. In short: A gap between the soil and the foundation, often with a network of cracks in the yard, means the clay along the house has dried and shrunk. It is a moisture indicator, not proof of damage, but the same drying under the slab edge is what lets the perimeter of a house settle. ## What does a soil gap look like? The soil has separated from the foundation beam or stem wall, leaving a gap you can put a finger or a probe into. The ground nearby may be broken into many-sided blocks by cracks. These are dry-season features of clay soil [1]. The sign shows up on slab-on-grade (https://terrabrain.vercel.app/foundations/slab-on-grade), stem wall (https://terrabrain.vercel.app/foundations/stem-wall-and-grade-beam), crawl space and manufactured homes. ## Why does clay pull away? **Expansive clay** swells when water enters it and shrinks as it dries out [3]. Most of Oklahoma has these soils [2]. In the dry season they form deep cracks in roughly polygonal patterns; one documented crack was at least 32 inches deep [1]. The **active zone**, meaning the depth of soil whose moisture changes with the seasons, can run from about 3 to 40 feet deep, and successive droughts have shown it can reach deeper than once believed [1]. In one documented case, piers 6 feet deep handled normal yearly cycles but not a two-year drought followed by an extremely wet year [1]. See shrink-swell and the active zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) and drought and wet cycles (https://terrabrain.vercel.app/guides/drought-and-wet-cycles). Oklahoma State University researchers have used Oklahoma Mesonet climate data to map equilibrium soil suction, a moisture-related measure, across the state [3]. ## What can it mean for the house? | Observation | What it suggests | |---|---| | Gap along most of the perimeter after a dry spell | General drying of perimeter soil [1] | | Gap widest near a tree or large shrub | Root moisture withdrawal [4] | | Gap plus cracks and floors sloping toward that wall | Slab edge dropping as soil shrinks [2] | | Gap at a pier-supported house | Soil can pull away from piers and reduce their skin friction (side grip) [1] | The slab-edge pattern works in both directions: the perimeter drops when the soil shrinks and rises when it swells [2]. It is covered in perimeter drying settlement (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop). ### Trees Trees and large shrubs withdraw water from soil, which can cause downward foundation movement [4]. Repair guidance notes that pruning may reduce future movement but will not likely restore elevation, and that root barriers or periodic root pruning may reduce vegetation effects, with an arborist consulted because barriers can harm the tree [5]. See tree-root desiccation settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement). ## How is it documented? - **Gap size.** Record the width and the depth a probe reaches, and where along the house the gap is largest. - **Timing.** Note the season and recent rainfall, since the gap reflects current moisture. - **Floor survey.** Compare with an elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) to see whether the floor is low on the same side. ## How do moisture and grading around the house matter? Uneven moisture from lawn watering is one cause of differential movement [1]. Federal building guidance calls for the ground next to a house to slope away, typically about 6 inches of fall over the first 10 feet, and for the grade near the foundation to be kept from settling [6]. Moisture control options are described in root barriers and moisture control (https://terrabrain.vercel.app/repairs/root-barriers-and-moisture-control). ## Related - Perimeter Drying Settlement (Edge Drop) (https://terrabrain.vercel.app/causes/perimeter-drying-settlement-edge-drop) - Tree-Root Desiccation Settlement (https://terrabrain.vercel.app/causes/tree-root-desiccation-settlement) - Shrink-Swell and Active Zone (https://terrabrain.vercel.app/guides/shrink-swell-and-active-zone) - Cracks That Open and Close Seasonally (https://terrabrain.vercel.app/signs/cracks-that-open-and-close-seasonally) - Trees and Roots (https://terrabrain.vercel.app/guides/trees-and-roots) Sources: [1] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [2] The Mystery of Expansive Soils, STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [3] Residential House Foundations on Expansive Soils in Changing Climates, U.S. Department of Housing and Urban Development, Cityscape https://www.huduser.gov/PORTAL/periodicals/cityscape/vol25num1/ch10.pdf [4] Recommended Practice for the Design of Residential Foundations, Version 2, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Recommended-Practice-for-the-Design-of-Residential-Foundations-V2-2007.pdf [5] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [6] A Professional's Guide to Durable Home Design: Durability by Design, 2nd Edition, U.S. Department of Housing and Urban Development https://www.HUDUser.gov/portal/sites/default/files/pdf/Guide-Durability-by-Design.pdf --- # Why is there a gap between my ceiling and an interior wall? URL: https://terrabrain.vercel.app/signs/ceiling-wall-separation-at-interior-walls Answer: Either swelling soil has pushed the floor and wall up (foundation heave) or roof trusses have bowed up and lifted the ceiling (truss uplift). In short: A gap where the ceiling meets an interior wall has two common explanations. Either swelling soil has pushed the floor and wall up toward the ceiling, which is foundation heave, or the roof trusses have bowed upward and lifted the ceiling, which is truss uplift. The season the gap appears, the floor levels and a look in the attic usually tell them apart. ## What are the two possible causes? ### Foundation heave Heave is upward movement of the foundation as clay soil absorbs water and swells. When swelling is concentrated under the middle of a house, the interior rises relative to the edges, which is called center lift [4]. An interior wall standing on that raised area moves relative to the ceiling framing, and the joint between wall and ceiling can crack or separate. Mechanisms that can do this include: - Center heave (moisture build-up under slab) (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) - Perimeter wetting heave (edge lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) - Leak-induced localized heave (https://terrabrain.vercel.app/causes/leak-induced-localized-heave), since leaking pipes can worsen swelling of nearby clay [5] - Over-lift heave after drought lift (https://terrabrain.vercel.app/causes/over-lift-heave-after-drought-lift) More than 75% of Oklahoma has bedrock that can produce expansive soils [6]. ### Truss uplift Roof trusses are factory-built frames whose bottom member also serves as the ceiling joist. In winter, the bottom chord, buried in insulation, stays warmer and drier than the top chords in the cold attic air; the difference in moisture makes the truss arch upward and lift the ceiling off interior walls [2]. See truss uplift (mimic) (https://terrabrain.vercel.app/causes/truss-uplift-mimic). ## How do you tell them apart? | Clue | Truss uplift | Foundation heave | |---|---|---| | Season | Opens in winter, closes in summer [1][2] | Follows soil moisture, often after wet periods or leaks | | Which walls | Interior, non-load-bearing partitions, often running across the trusses [1] | Interior walls over the raised area | | Floor | Level | Raised area on an elevation survey (https://terrabrain.vercel.app/guides/elevation-surveys) | | Attic | Truss bottom chord bowed up above the wall [1] | Truss sits normally | | Other signs | Few; possibly popping noises [1] | Interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump), floor tile cracks in a line (https://terrabrain.vercel.app/signs/floor-tile-cracks-in-a-line), sticking doors | A crack where the tape is torn through at the corner, with the ceiling fastened to the truss bottoms, points toward uplift; a crack running along the edge of the tape may instead be a taping problem [1]. See nail pops and tape-joint cracks. ## How do you document it? 1. Measure the gap at marked points along each affected wall. 2. Note the date and repeat monthly through a winter and a summer. 3. Look in the attic above the gap for trusses lifted off the top of the wall [1]. 4. Have a floor elevation survey done to see whether the interior is high. A gap that only opens in winter, with a level floor, fits truss uplift. A gap that appears with a floor rise, or after a wet spell or leak, fits heave. See heave vs settlement. ## What happens next? For truss uplift, trade and inspection literature describes the problem as not structural [1][2], and fixes involve letting the ceiling drywall float near interior walls with clips or slotted connectors [2][3]. For heave, the next step is finding the moisture source; see plumbing leak detection and repair and the symptom matrix. ## Related - Truss uplift (mimic) (https://terrabrain.vercel.app/causes/truss-uplift-mimic) - Center heave (moisture build-up under slab) (https://terrabrain.vercel.app/causes/center-heave-moisture-build-up-under-slab) - Interior floor hump (https://terrabrain.vercel.app/signs/interior-floor-hump) - Heave vs settlement (https://terrabrain.vercel.app/guides/heave-vs-settlement) - Distress pattern library (https://terrabrain.vercel.app/guides/distress-pattern-library) Sources: [1] Arching roof truss uplift & drywall cracks at the ceiling-wall joint: cause, prevention, repair, InspectAPedia https://inspectapedia.com/interiors/Roof_Truss_Uplift.php [2] Q&A: Truss Uplift Causes & Cures, Journal of Light Construction https://www.jlconline.com/?p=41555 [3] How Does Truss Uplift Work?, Pro Trade Craft https://www.protradecraft.com/how-does-truss-uplift-work [4] Expansive soils (encyclopedia entry, post-review manuscript), NERC Open Research Archive https://nora.nerc.ac.uk/id/eprint/521301/1/EncyclopediaEngGeol_ExpansiveSoils_PostReview.pdf [5] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [6] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html --- # Why is there a gap under my slab edge or footing? URL: https://terrabrain.vercel.app/signs/exposed-slab-edge-or-void-under-footing Answer: Supporting soil has been removed, most often by running water, though settling fill, collapsing soil and slope movement can also leave a void. In short: When the edge of a slab or the bottom of a footing is exposed, or a gap opens beneath it, soil that used to support the foundation has been removed. Running water is the most common cause, but settling fill, collapsing soil and slope movement can do the same. The size of the void and where the water comes from guide what happens next. ## What are you seeing? A slab-on-grade foundation has a thickened outer beam that is meant to be buried in soil, and footings under other foundation types are meant to bear on soil. When soil is lost from beside or beneath that beam, part of the concrete normally below grade becomes visible, or a gap appears where a probe or hand can reach under the edge. ## What can cause it? | Mechanism | How the void forms | |---|---| | Erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) | Roof runoff, poor grading or a leak carries soil away along or under the foundation | | Fill consolidation settlement (https://terrabrain.vercel.app/causes/fill-consolidation-settlement) | Loose fill under or beside the slab compresses and drops away | | Hydrocollapse (collapsible soil) (https://terrabrain.vercel.app/causes/hydrocollapse-collapsible-soil) | Certain dry, loose soils lose volume suddenly when wetted | | Slope creep and lateral movement (https://terrabrain.vercel.app/causes/slope-creep-and-lateral-movement) | Soil on the downhill side moves away from the foundation | ### Water as the usual driver The U.S. Geological Survey lists subterranean erosion, such as piping (soil carried away by water flowing underground), as a cause of ground movement, along with water leakage from utilities and stream erosion of the base of slopes [1]. Swelling clays can crack concrete drainage channels, and the resulting voids can lead to piping and erosion [2]. Leaking pipes, pools and similar sources add water that can also worsen swelling damage on clay [2]. In Oklahoma, soil saturation from rain, lawn watering or sewer leakage is a recognized source of damage through the expansion of soils beneath sidewalks, utility lines and foundations [5]. Engineering guidance for houses on expansive soil recommends keeping soil moisture steady, and suggests surrounding the building with paving or removing perimeter planter beds to limit moisture changes [3]. See surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) and water ponding near foundation (https://terrabrain.vercel.app/signs/water-ponding-near-foundation). ### Slopes and creeks On sloped or creek-side lots, soil on the downhill side can erode or move away. An Oklahoma Department of Transportation study found that slope, soil texture and land cover strongly affect landslide susceptibility in Oklahoma, and that at one southeastern Oklahoma site, a fat clay slope absorbed rainwater, grew heavy and slid [6]. See erosion, creeks and slopes (https://terrabrain.vercel.app/guides/erosion-creeks-and-slopes). ## How is it documented? 1. Probe the void with a thin rod or tape and record how far it reaches under the slab and how tall it is, at several points. 2. Measure the length of exposed or undermined edge. 3. Photograph each point with a ruler or tape in view. 4. Note where downspouts discharge, where the yard slopes toward the house, and any wet spots or leaks. 5. Re-check after heavy rain to see whether the void is growing. Home inspection standards call for reporting signs of active water penetration and of possible foundation movement [4]. ## What can it lead to? Where support is lost, that section of the foundation can settle or crack. Check nearby walls and floors for stair-step brick cracks (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-top), horizontal cracks at the brick ledge or slab edge and sloping floors. ## How is it repaired? Repair usually has two parts: stopping the water or soil loss, and restoring support. Options include drainage solutions, void and compaction grouting, slope and erosion stabilization, and piering where the edge has already settled. ## Related - Erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids) - Surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Soil pulled away from foundation (https://terrabrain.vercel.app/signs/soil-pulled-away-from-foundation) - Void and compaction grouting (https://terrabrain.vercel.app/repairs/void-and-compaction-grouting) - Drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) Sources: [1] Landslide Types and Processes (Fact Sheet 2004-3072), U.S. Geological Survey https://pubs.usgs.gov/fs/2004/3072/fs-2004-3072.html [2] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology (J. D. Rogers, R. Olshansky, R. B. Rogers) https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [3] Irrigation, Drainage, and Landscaping for Expansive Soil, Journal of Irrigation and Drainage Engineering (ASCE) https://ascelibrary.com/doi/10.1061/%28ASCE%290733-9437%281992%29118%3A2%28285%29 [4] Home Inspection Standards of Practice, InterNACHI https://www.nachi.org/sop.htm [5] Geologic Hazards in Oklahoma, Oklahoma Geological Survey (GSA South-Central Section abstract, 2008) https://gsa.confex.com/gsa/2008SC/webprogram/Paper135817.html [6] Real Time Monitoring of Slope Stability in Eastern Oklahoma (FHWA-OK-14-06), Oklahoma Department of Transportation https://aem-prod.oklahoma.gov/content/dam/ok/en/odot/documents/research/highlighter-2241-fhwa-ok-14-06.pdf --- # Why is there water, condensation or mold in my crawl space? URL: https://terrabrain.vercel.app/signs/water-condensation-or-mold-in-crawl Answer: Moisture under the house is not being controlled. Keeping humidity below 60 percent helps limit mold, along with a vapor barrier, drainage and ventilation. In short: Standing water, damp soil, condensation or mold in a crawl space all mean moisture is not being controlled under the house. EPA cites keeping humidity below 60 percent to limit mold, and guidance for crawl spaces centers on a sealed ground vapor barrier, good drainage around the house, and ventilation or other moisture controls. ## What does crawl space moisture look like? - Puddles or saturated soil on the crawl space floor, especially after rain. - Water droplets on pipes, ductwork or the underside of the floor. - White, green or black growth on joists, beams or insulation, and a musty smell. - Torn, missing or loose plastic ground cover. This sign applies to pier-and-beam and crawl space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) houses and manufactured homes on piers (https://terrabrain.vercel.app/foundations/manufactured-homes-on-piers). ## Why do crawl spaces get wet? ### Ground moisture Federal building guidance states that ground moisture will enter any foundation unless measures are taken, and it places a ground vapor barrier under crawl space construction [4]. For crawl spaces built on a slightly raised mound, a vapor barrier is always recommended [5]. Where the site may get wet, a perimeter drain is needed [4]. ### Surface water and drainage Most damp foundations are traced to improper surface drainage and poor backfill [4]. Water that ponds against the house can find its way into the crawl space; see water ponding near the foundation (https://terrabrain.vercel.app/signs/water-ponding-near-foundation) and surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading). ### Humid air and condensation Condensation on windows, walls or pipes is a sign of high humidity [1]. EPA recommends keeping indoor relative humidity below 60 percent, ideally between 30 and 50 percent, and insulating cold surfaces such as cold water pipes to reduce condensation [1]. Plumbing leaks are another source, and EPA advises fixing them as soon as possible [1]. ## Why does it matter for the structure? Unmanaged crawl space moisture can damage wood flooring and create health and property problems [2]. Engineering repair guidance cites rotting wood members as a structural integrity concern and recommends treated lumber where members are replaced [3]. Decayed beams and joists are one cause of sagging floors between supports (https://terrabrain.vercel.app/signs/sagging-floor-between-supports); the mechanism is covered in crawl space moisture and wood decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay). EPA states that the key to mold control is moisture control, and that water-damaged areas should be dried within 24 to 48 hours to prevent mold growth [1]. EPA describes mold areas smaller than about 10 square feet as a size most people can clean up themselves, with larger areas referred to its remediation guidance [1]. ## What moisture controls does guidance describe? | Control | What guidance says | |---|---| | Ground vapor barrier | Solid 6-mil sheet over the whole floor, overlapped at least 6 inches, taped, and run about 6 inches up the walls [2] | | Vents | Vents should not be blocked [2] | | Cross ventilation and underfloor drainage | Listed as crawl space moisture controls [3] | | Ground clearance for wood | Beams and joists kept clear of the soil [3] | | Treated lumber | Used for repairs to framing [3] | Sealing and conditioning the crawl space is covered in crawl space encapsulation (https://terrabrain.vercel.app/repairs/crawl-space-encapsulation). ## How is it documented? - **Humidity.** A hygrometer (humidity meter) reading in the crawl space and in the house, compared with EPA's 60 percent guideline [1]. - **Wood moisture and condition.** A moisture meter on joists and beams, and probing for soft or decayed wood. - **Water sources.** Note where standing water collects, whether it follows rain, and whether any plumbing is dripping. ## Related - Crawl Space Moisture & Wood Decay (https://terrabrain.vercel.app/causes/crawl-space-moisture-and-wood-decay) - Crawl Space Encapsulation (https://terrabrain.vercel.app/repairs/crawl-space-encapsulation) - Crawl Space Repair (https://terrabrain.vercel.app/repairs/crawl-space-repair) - Sagging Floor Between Supports (https://terrabrain.vercel.app/signs/sagging-floor-between-supports) - Pier and Beam Crawl Space (https://terrabrain.vercel.app/foundations/pier-and-beam-crawl-space) Sources: [1] A Brief Guide to Mold, Moisture and Your Home, U.S. Environmental Protection Agency https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home [2] Inspecting Foundation Walls and Piers, International Association of Certified Home Inspectors (InterNACHI) https://www.nachi.org/documents2012/Inspecting_Foundation_Walls_and_Piers-revised-January-2013.pdf [3] Guidelines for the Evaluation and Repair of Residential Foundations, Version 3, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Texas-Residential-Foundations-Master-Repair-Guidelines-Ver-3-FINAL-latest.pdf [4] A Professional's Guide to Durable Home Design: Durability by Design, 2nd Edition, U.S. Department of Housing and Urban Development https://www.HUDUser.gov/portal/sites/default/files/pdf/Guide-Durability-by-Design.pdf [5] Durability by Design: A Guide for Residential Builders and Designers, U.S. Department of Housing and Urban Development https://www.huduser.gov/publications/pdf/durability_by_design.pdf --- # Why is water ponding next to my foundation after rain? URL: https://terrabrain.vercel.app/signs/water-ponding-near-foundation Answer: The ground is not carrying water away. On expansive clay, uneven wetting can swell soil and lift part of the foundation, and running water can erode soil. In short: Water that stands next to a house after rain means the ground is not carrying water away from the foundation. On Oklahoma's expansive clay that matters, because uneven wetting along one side can swell the soil and lift that part of the foundation, and running water can erode soil from around footings. ## What does this sign look like? Puddles stay along the foundation for hours or days after rain, often at inside corners, under roof valleys, at downspouts that empty against the wall, or where flower beds sit higher than the lawn. Mulch or soil may be washed against the siding. Any foundation type can be affected, from slab-on-grade (https://terrabrain.vercel.app/foundations/slab-on-grade) to crawl spaces and basements. ## Why does ponding water matter? ### Uneven wetting of expansive clay Soil only moves when its moisture content changes unevenly across a site, and poor drainage is a named contributor [4]. Expansive clay is widespread across Oklahoma, and when it swells under the slab edge, the perimeter can rise [4]. Researchers recommend positive surface drainage away from foundations and identify uneven moisture from sources such as lawn watering as a cause of damage [5]. The mechanism is covered in perimeter wetting heave (edge lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift). ### Erosion and settlement Poor surface drainage can cause soil swelling and erosion around footings, which can lead to settlement [6]. See erosion, undermining and washout voids (https://terrabrain.vercel.app/causes/erosion-undermining-and-washout-voids). ### Damp foundations and basements Federal building guidance states that most damp foundations are caused by improper surface drainage and poor backfill [3]. Standing water against a basement or crawl space wall adds to water at the cove joint (https://terrabrain.vercel.app/signs/water-at-cove-joint-or-efflorescence) and crawl space moisture (https://terrabrain.vercel.app/signs/water-condensation-or-mold-in-crawl). ## What do code and guidance say about grading? | Item | Requirement or guidance | |---|---| | Grade next to the foundation | Fall at least 6 inches within the first 10 feet (IRC R401.3) [1] | | Where barriers prevent 6 inches | Slope at least 5 percent toward drains or swales [1] | | Elsewhere on the lot | At least 2 percent slope [2] | | Planting beds | Slope away at least 2 inches per foot [2] | | Drainage swales | At least 4 feet from the foundation [2]; about 1 to 15 percent slope [3] | | Flatwork next to the house | Slope at least 2 percent away [3] | | Top of slab above grade | At least 8 inches [2] | ## How do gutters and downspouts factor in? - Downspouts that discharge at the surface should release water at least 2 feet from the building [3][2]. - Each downspout should serve no more than about 50 feet of gutter [3]. - Gutter drains should not be connected to the perforated foundation drain [3]. Grading near the foundation should also be kept from settling over time, without piling soil so high that it comes within 6 inches of the wall's bottom plate [3]. More detail is in surface drainage and grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) and drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). ## How is ponding documented? Photograph where water stands and for how long after a rain, note where each downspout discharges, and measure how far the grade falls over the first 10 feet from the wall. ## Related - Perimeter Wetting Heave (Edge Lift) (https://terrabrain.vercel.app/causes/perimeter-wetting-heave-edge-lift) - Surface Drainage and Grading (https://terrabrain.vercel.app/guides/surface-drainage-and-grading) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) - Soil Pulled Away from Foundation (https://terrabrain.vercel.app/signs/soil-pulled-away-from-foundation) - Stair-Step Brick Crack Wider at Bottom (https://terrabrain.vercel.app/signs/stair-step-brick-crack-wider-at-bottom) Sources: [1] Building Elevation Plan Requirements, Maricopa County, Arizona https://www.maricopa.gov/6349/100261/Building-Elevation-Plan-Requirements [2] Recommended Practice for the Design of Residential Foundations, Version 2, Texas Section, American Society of Civil Engineers https://www.texasce.org/wp-content/uploads/2025/05/Recommended-Practice-for-the-Design-of-Residential-Foundations-V2-2007.pdf [3] A Professional's Guide to Durable Home Design: Durability by Design, 2nd Edition, U.S. Department of Housing and Urban Development https://www.HUDUser.gov/portal/sites/default/files/pdf/Guide-Durability-by-Design.pdf [4] The Mystery of Expansive Soils, STRUCTURE magazine https://structuremag.org/wp-content/uploads/2014/10/Mysterysoil1.pdf [5] Damage to Foundations from Expansive Soils, Missouri University of Science and Technology https://web.mst.edu/rogersda/expansive_soils/DAMAGE%20TO%20FOUNDATIONS%20FROM%20EXPANSIVE%20SOILS.pdf [6] Inspecting Foundation Walls and Piers, International Association of Certified Home Inspectors (InterNACHI) https://www.nachi.org/documents2012/Inspecting_Foundation_Walls_and_Piers-revised-January-2013.pdf --- # Why is water seeping where my basement floor meets the wall? URL: https://terrabrain.vercel.app/signs/water-at-cove-joint-or-efflorescence Answer: Water at the cove joint and white deposits mean water is moving through the foundation, usually from poor grading, downspouts or a high water table outside. In short: Water seeping in where the basement floor meets the wall, and white powdery deposits on the wall, both mean water is moving through or around the foundation. The usual cause is water outside the wall, from poor grading, downspouts or a high water table, and guidance focuses on fixing those outside sources before treating the inside surface. ## What does this sign look like? - **Water at the cove joint.** The **cove joint** is the seam where the basement floor slab meets the foundation wall. After rain, a wet line, puddle or trickle appears along that seam. - **Efflorescence.** A white, powdery or crusty deposit on concrete or block walls, often in a band low on the wall or around cracks. - **Water marks.** Stains or tide lines on the walls or floor. Inspection guidance treats white powder stains and musty odors as signs of a moisture problem, and water marks on floors and walls as evidence that waterproofing is not working [1]. This sign applies to basements (https://terrabrain.vercel.app/foundations/basements). ## Why does water get in? ### Saturated soil and water pressure **Hydrostatic pressure** is the push of water held in saturated soil. Saturated soil against the outside of a foundation wall can push it inward, producing a horizontal crack along with signs of water intrusion [2]. Clogged drains let water pressure build up against the wall [1]. When the pressure is high enough to crack or bow the wall, see horizontal crack or inward bow in a basement wall (https://terrabrain.vercel.app/signs/horizontal-crack-or-inward-bow-in-basement-wall) and lateral earth and hydrostatic pressure (https://terrabrain.vercel.app/causes/lateral-earth-swell-and-hydrostatic-pressure-on-walls). ### Surface drainage and backfill Federal building guidance states that most damp foundations are caused by improper surface drainage and poor backfill procedures [3]. It advises against silt, heavy clay or expansive clay backfill at basement walls [3]. The International Residential Code requires the grade to fall at least 6 inches within the first 10 feet from the foundation [5]. See water ponding near the foundation (https://terrabrain.vercel.app/signs/water-ponding-near-foundation). ### High groundwater Below-grade space should not be built below the highest seasonal water table, and waterproofing does not protect against flooding or a high water table [4]. On wet sites, guidance calls for waterproofed basement walls and a sump pump [3]. See groundwater and perched water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water). ### How common it is A federal housing guide found that typical construction practices could produce some water problem in as many as 1 in 3 basements within two years [4]. ## What does the guidance say about fixes? - The source of condensation or exterior water intrusion is corrected before a crystalline waterproofing coating is applied to the concrete [1]. - Surface sealants are rarely effective and can trap moisture; water is redirected away from masonry and mortar joints repointed where needed [1]. - Basement floors should slope toward drains so water can leave if the space floods [1]. - In finished basements, wall finishes are held about 1/2 inch above the slab so they do not wick water [3]. Drainage options are described in drainage solutions (https://terrabrain.vercel.app/repairs/drainage-solutions). ## How is it documented? Observe and photograph the wall and cove joint during and after a soaking rain, note which walls are wet, and check where downspouts discharge and how the yard slopes on those sides. ## Related - Basements (https://terrabrain.vercel.app/foundations/basements) - Horizontal Crack or Inward Bow in Basement Wall (https://terrabrain.vercel.app/signs/horizontal-crack-or-inward-bow-in-basement-wall) - Groundwater and Perched Water (https://terrabrain.vercel.app/guides/groundwater-and-perched-water) - Basement Wall Repair (https://terrabrain.vercel.app/repairs/basement-wall-repair) - Drainage Solutions (https://terrabrain.vercel.app/repairs/drainage-solutions) Sources: [1] Inspecting Foundation Walls and Piers, International Association of Certified Home Inspectors (InterNACHI) https://www.nachi.org/documents2012/Inspecting_Foundation_Walls_and_Piers-revised-January-2013.pdf [2] Foundation Crack from Lateral Movement and Hydrostatic Pressure, International Association of Certified Home Inspectors (InterNACHI) https://nachi.org/gallery/settlement-and-cracks/lateral-movement-foundation-cracks [3] A Professional's Guide to Durable Home Design: Durability by Design, 2nd Edition, U.S. Department of Housing and Urban Development https://www.HUDUser.gov/portal/sites/default/files/pdf/Guide-Durability-by-Design.pdf [4] Durability by Design: A Guide for Residential Builders and Designers, U.S. Department of Housing and Urban Development https://www.huduser.gov/publications/pdf/durability_by_design.pdf [5] Building Elevation Plan Requirements, Maricopa County, Arizona https://www.maricopa.gov/6349/100261/Building-Elevation-Plan-Requirements