Why did a Claremore church addition's floor drop 1 to 3 inches?

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

rural Claremore area20251-story wood frame church building, brick veneer; inspection limited to the southeast additionslab-on-grade with continuous perimeter spread footing and stem walls (floating slab)

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
• Void and Compaction Grouting
• Helical Piers
• Slabjacking and Polyurethane
• Tolerances and Standards
• Elevation Surveys