What are foundation conditions like in Lawton, Oklahoma?

Reviewed by Preston · Updated 2026-11-11

In short: About 54% of Lawton is mapped in soils rated high shrink-swell, one of the highest shares of the Oklahoma cities compared ¹. Red clays such as Foard, Vernon and Tillman cover about half the city ¹, and southwest Oklahoma's high summer evaporation dries them hard ⁹. Deep summer shrinkage and swelling when rain returns drive most Lawton foundation movement.

How much of Lawton has expansive soil?

Lawton covers about 82 square miles ², in the Comanche County soil survey ¹. Poorly drained soils are almost absent ¹.

Which Lawton soils matter most for houses?

• Foard, about 22% of the city, is a clay soil formed in old alluvium from the Wichita Mountains over Permian red beds; its subsoil holds 35 to 45 percent smectitic clay, shows slickensides from shrink-swell, and is affected by sodium linked to very slow water movement ³.
• Ashport, about 19%, is very deep and well drained, formed in loamy alluvium on floodplains along small streams ⁴.
• Vernon is a red clay that formed in place from Permian claystone over dense claystone 20 to 40 inches down, with 40 to 60 percent clay in the subsoil ⁵.
• Tillman is a very deep clay whose official description records cracks more than 48 inches deep and a linear extensibility above 6 percent ⁶.
• Knoco is very shallow to shallow, formed from claystone over dense claystone bedrock ⁷. Lawton soils, named for the city, are very deep and well drained, formed in loamy old alluvium from granitic material on stream terraces and alluvial fans of the Wichita Mountains ⁸.

Why does climate matter so much in Lawton?

Oklahoma State University Extension lists average May to October evaporation of about 40.3 inches in the southwest climate division, compared with about 30.1 inches in the northeast ⁹. Higher evaporation dries clay deeper and harder each summer, so on Lawton's clays edge drop during drought, tree-root drying and heave when rain returns are the typical patterns. See the moisture index by city.

Which soils cover Lawton?

Looking for a foundation company near Lawton?

Companies that serve Lawton 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 Lawton? 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

• Southwest Lawton and Red Plains
• Western Permian red beds
• Shrink-swell and the active zone
• Compare Oklahoma cities