Sioux County, IA Shrink-Swell Risk

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

Moderate

USDA's SSURGO data puts Sioux County, IA's soil at "Moderate" shrink-swell potential, an area-weighted linear extensibility of 4.12% across 93.1% of the county's surveyed land. That's a middle reading: not the sharp swings that crack a foundation outright, but enough that grading and drainage are worth getting right.

This is a county figure, not a lot figure

USDA's survey covers the whole of Sioux 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 Sioux County will actually do.

Report cost vs. repair cost

With Sioux 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, Sioux County, IA is the 512-most-constrained of 3,085 rated counties for shrink-swell soil. Within Iowa alone it ranks 40 of 99. The county spans 768 square miles, home to 36,554 people.

See how another county compares

Orleans Parish, LA carries this site's most-constrained reading. Oceana County, MI and Athens County, OH 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 Clinton County, IA and Carroll County, IA. The full underlying dataset is downloadable directly, one row per county.