Mahaska County, IA Shrink-Swell Risk

Mahaska County, IA's soil, for shrink-swell risk

Moderate

Mahaska County, IA: USDA's soil survey rates 85.4% of the county "Moderate" for shrink-swell potential (4.95% linear extensibility). Conventional foundations are the reasonable expectation here, with routine moisture-control practice rather than special engineering.

What Mahaska County's reading doesn't cover

Two lots a mile apart in Mahaska County can carry different soil, even though they share one countywide reading. A local geotechnical report, typically $1,000-$5,000 (around $2,700 typical), is the only way to know what one lot in Mahaska County will actually do.

What it costs to find out, versus to ignore it

With Mahaska 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, Mahaska County, IA is the 298-most-constrained of 3,085 rated counties for shrink-swell soil. Within Iowa alone it ranks 23 of 99. Mahaska County covers 571 square miles and counts 22,034 residents.

See how another county compares

Orleans Parish, LA carries this site's most-constrained reading. Henry County, AL and Sullivan County, IN 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 Webster County, IA and Grundy County, IA. The full underlying dataset is downloadable directly, one row per county.