Washington County, IA Shrink-Swell Risk

What Washington County, IA's soil means for a foundation

Moderate

USDA's SSURGO data puts Washington County, IA's soil at "Moderate" shrink-swell potential, an area-weighted linear extensibility of 4.96% across 85.6% of the county's surveyed land. A real but modest amount of movement - standard foundations usually hold up, but drainage and moisture control around the foundation still matter more than on low-risk soil.

This is a county figure, not a lot figure

USDA's survey covers the whole of Washington County, IA at once, not any single address. A local geotechnical report, typically $1,000-$5,000 (around $2,700 typical), is the only way to know what one lot in Washington County will actually do.

Report cost vs. repair cost

With Washington County, IA rating "Moderate", a geotechnical report is still worthwhile before a build, just less urgent than in a high-risk county. A geotechnical report runs $1,000-$5,000, typically around $2,700. Foundation repair, if a specific lot turns out to differ from the county average, runs $5,000-$15,000.

Where this sits nationally

Nationally, Washington County, IA is the 295-most-constrained of 3,085 rated counties for shrink-swell soil. Within Iowa alone it ranks 22 of 99. Washington County, IA is 569 square miles with a population of 22,631.

Before you act on this

Orleans Parish, LA carries this site's most-constrained reading. Macon County, TN and Kingsbury County, SD are worth a look for comparison.

How this reading is built, and its real limits · Moisture management: the cheap fix that works on any soil

More of Iowa

Every county in Iowa is on this site, including Lyon County, IA and Davis County, IA. The full underlying dataset is downloadable directly, one row per county.