What are foundation conditions like in Edmond, Oklahoma?

Reviewed by Preston · Updated 2026-11-11

In short: About half of Edmond, 51%, is mapped in soils rated low shrink-swell, because sandy soils over soft Permian sandstone dominate ¹. That does not make Edmond trouble-free: about 16% is still high shrink-swell clay ¹, hillside lots bring fill and runoff problems, and firm rock under the sandstone can be very deep.

How much of Edmond has expansive soil?

Edmond covers about 84 square miles ² across the Oklahoma and Logan county soil surveys ¹. Only about 1.5% of the city is poorly drained ¹.

Which Edmond soils matter most for houses?

• Stephenville, about 20% of the city, is moderately deep and well drained, formed from Permian sandstone, with soft sandstone typically 20 to 40 inches down ³.
• Harrah is very deep to sandstone and well drained, in sandy and loamy colluvium on low hills with slopes of 3 to 45 percent ⁴.
• Darnell is shallow and sandy, with sandstone 10 to 20 inches down ⁵.
• Renthin is a clay soil, deep and very slowly permeable, formed from clayey and silty Permian shale ⁶. Newalla formed in sandstone material over shale and is very slowly permeable ⁷. Soils like these hold most of Edmond's expansive ground.
• Pulaski is a sandy floodplain soil of small creeks that floods occasionally to frequently for very brief periods between March and October ⁸.

How deep is firm rock in Edmond?

Borings for the Interstate 35 bridge over Waterloo Road, on Edmond's north side, found competent rock in the Garber sandstone at 20.5 to 95 feet, far deeper and more variable than under upland shale in Tulsa ⁹. Where a sandy soil sits over soft sandstone and shale, the depth at which a pier stops can change a lot over short distances. See Garber sandstone and depth to rock in Tulsa and OKC.

What causes foundation problems on Edmond's sandy hills?

Sandy, well drained soils swell little, so movement there more often comes from fill settlement, slope creep, erosion and undermining or a plumbing leak than from clay.

Which soils cover Edmond?

ZIP codes in Edmond

ZIP 73003, ZIP 73007, ZIP 73025, ZIP 73034

Looking for a foundation company near Edmond?

Companies that serve Edmond can appear on the company map in the Homeowner Hub. Paid listings there are marked Sponsored; the library and the AI guide don't rank or recommend any of them.

Buying or selling a house in Edmond? Realtors who serve the area can be on the same map, also marked Sponsored, and for realtors covers the seller disclosure form, inspections and the sale timeline. Seeing cracks at home? Start with for homeowners.

How were these numbers measured?

We overlaid the city's current limits from the Census Bureau ² on the USDA soil survey's map units ¹ and added up the area of each soil. Where a map unit is a mix of soils, its area was split by the percentages the survey lists for its major soils, so the shares above leave out minor inclusions and do not add to 100%. A soil counts as high, moderate or low shrink-swell by the linear extensibility of its most expansive layer, the survey's measure of how much a soil changes length between wet and dry (6% or more is rated high). Water table, bedrock and flooding come from the survey's map-unit summaries: the shallowest water table in any month, the shallowest bedrock, and the most common flooding frequency. Bedrock here includes soft, weathered sandstone and shale that a pier can push through, so it is not the depth where piers stop. These are mapped averages for the whole city, not a test of any one lot. Fill, grading and the soil actually under a house can differ, which is why a site visit or soil boring still decides a repair.

Related

• OKC metro soils
• Garber sandstone
• Shrink-swell and the active zone
• Compare Oklahoma cities