Rock Island County, IL Shrink-Swell Risk

Rock Island County, IL's soil, for shrink-swell risk

Moderate

Rock Island County, IL: USDA's soil survey rates 52.2% of the county "Moderate" for shrink-swell potential (3.13% linear extensibility). Conventional foundations are the reasonable expectation here, with routine moisture-control practice rather than special engineering.

What Rock Island County's reading doesn't cover

Two lots a mile apart in Rock Island 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 Rock Island County will actually do.

What it costs to find out, versus to ignore it

With Rock Island County, IL 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, Rock Island County, IL is the 1,091-most-constrained of 3,085 rated counties for shrink-swell soil. Within Illinois alone it ranks 84 of 101. Rock Island County, IL is 427 square miles with a population of 142,731.

For contrast

Orleans Parish, LA carries this site's most-constrained reading. Bee County, TX and Clarion County, PA 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 Illinois

Every county in Illinois is on this site, including Henderson County, IL and Clay County, IL. The full underlying dataset is downloadable directly, one row per county.