Which foundation pier type is right for an Oklahoma home?

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

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.

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 and 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.
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.
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?

Every mechanism is matched to these methods in the mechanism-method matrix.

Related

• Mechanism-Method Matrix
• Steel Push Piers
• Helical Piers
• Drilled Bell-Bottom Piers
• Pressed Concrete Piles
• Loads Pier Spacing and Capacity