Why are my foundation piers moving after repair?

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

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 ¹².

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.

What determines how well a pier performs?

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.

What are the signs of pier movement?

• doors that bind again in a previously repaired area
• stair-step brick cracks wider at the bottom
• stair-step brick cracks wider at the 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 and 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, helical piers and reducing wetting of the soil around piers through drainage.

Related

• Over-Lift Heave After Drought Lift
• Steel Push Piers
• Shrink-Swell and Active Zone
• Contracts, Warranties and Liens
• Active Zone and Drought Depth