Pottawattamie County, IA Shrink-Swell Risk

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

Moderate

USDA's SSURGO data puts Pottawattamie County, IA's soil at "Moderate" shrink-swell potential, an area-weighted linear extensibility of 3.64% across 62.6% 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 Pottawattamie County, IA at once, not any single address. A site-specific soil report, usually $1,000-$5,000, is what an engineer would actually pull before designing a foundation on a lot in Pottawattamie County.

Report cost vs. repair cost

With Pottawattamie 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, Pottawattamie County, IA is the 765-most-constrained of 3,085 rated counties for shrink-swell soil. Within Iowa alone it ranks 58 of 99. The county spans 951 square miles, home to 93,529 people.

For contrast

Orleans Parish, LA carries this site's most-constrained reading. Burke County, ND and San Juan County, WA 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 Howard County, IA and Ringgold County, IA. The full underlying dataset is downloadable directly, one row per county.