Union County, IL Shrink-Swell Risk

What Union County, IL's soil means for a foundation

Moderate

USDA's SSURGO data puts Union County, IL's soil at "Moderate" shrink-swell potential, an area-weighted linear extensibility of 3.52% across 61.3% 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 Union County, IL at once, not any single address. The real answer for one lot is still a site-specific geotechnical report, running about $1,000-$5,000 (typically near $2,700).

Report cost vs. repair cost

With Union 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.

Union County's rank among Illinois counties

Nationally, Union County, IL is the 832-most-constrained of 3,085 rated counties for shrink-swell soil. Within Illinois alone it ranks 59 of 101. Union County, IL is 413 square miles with a population of 16,886.

Before you act on this

Orleans Parish, LA carries this site's most-constrained reading. Summers County, WV and Osborne County, KS 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 Crawford County, IL and Edgar County, IL. The full underlying dataset is downloadable directly, one row per county.