Shelby County, IA Shrink-Swell Risk

Shrink-swell potential in Shelby County, IA

Moderate

Soil across 88.1% of Shelby County, IA comes back "Moderate" in USDA's shrink-swell data, averaging 3.94% linear extensibility. 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.

What this number does and doesn't tell you

This is a countywide, area-weighted figure across every soil survey map unit in Shelby County, IA - never a reading for one specific parcel. 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 Shelby County.

Shelby County: the real numbers

Shelby County's soil reading points toward standard foundation practice as the likely outcome, not the exception. 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

Among the 3,085 rated counties on this site, Shelby County, IA ranks 607 most-constrained nationally, and 48 of 99 within Iowa. The county spans 591 square miles, home to 11,821 people.

For contrast

Orleans Parish, LA carries this site's most-constrained reading. Caddo Parish, LA and Del Norte County, CA 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

Elsewhere in Iowa

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