Why does a chimney or column settle more than the rest of the house?

Reviewed by Preston, Oklahoma foundation repair consultant · Updated 2026-10-14

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of foundation movement: heave (expansive clay swelling as it takes on water), subsidence (soil shrinking as moisture is withdrawn) and settlement, which is soil compressing because it is loaded beyond its bearing capacity ¹.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 for more.

What are the signs of concentrated load settlement?

The most typical sign is a 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.

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 and 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.

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 and helical piers pages explain these methods.

Related

• Chimney Separating or Leaning
• Differential Movement at Additions
• Loads, Pier Spacing and Capacity
• Original Construction Deficiency
• Steel Push Piers