What did an engineer specify for a south Tulsa slab with failing walls?

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

south Tulsa20262-story wood frame, brick veneer, attached 2-car garage, partly converted attic; pool and retaining walls on the lotslab-on-grade with continuous perimeter footings (floating floor slab)

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
• Interior Piers (Tunnel or Core)
• Slabjacking and Polyurethane
• Tilted Retaining Walls, Fences or Trees
• Water Ponding Near Foundation
• Tulsa Metro