Check the soil under your address

How to read the result

Shrink-swell soil, also called expansive soil, is clay-rich ground that swells when it takes on water and shrinks as it dries; a foundation sitting on it rides up and down with the seasons, and that movement is a leading cause of foundation repair in the South and Plains. Shrink-swell class is the NRCS rating of how much a soil changes volume between wet and dry, measured as linear extensibility (LEP). We weight it over the top 60 inches, the zone a slab or pier-and-beam foundation actually sits in. Low is under 3%, moderate 3–6%, high 6–9%, very high above 9%.

Address-level vs. neighborhood estimate. In dense urban cores the survey often records the ground as “Urban land” with no measured properties. When that happens under your point we widen the search (400 m, then 800, 1,600 and 3,200) and report the surveyed ground around you, weighted by how much of the area each soil covers. We tell you the radius, what share of that area actually has data, and the split by class — because in downtown Dallas the answer moves from “low” to “very high” between 400 m and 1,600 m.

What it does not say. We are not engineers and this is not an engineering opinion. We report public soil-survey data and published price ranges. Nothing here states that a specific house is or is not structurally sound; a licensed structural engineer who has seen the house can.

Full method, data provenance and the traps we hit: methodology.