DeKalb County, IL Shrink-Swell Risk

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

Moderate

USDA's SSURGO data puts DeKalb County, IL's soil at "Moderate" shrink-swell potential, an area-weighted linear extensibility of 3.83% across 90% 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 DeKalb 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 DeKalb 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, DeKalb County, IL is the 659-most-constrained of 3,085 rated counties for shrink-swell soil. Within Illinois alone it ranks 40 of 101. DeKalb County, IL is 631 square miles with a population of 101,335.

See how another county compares

Orleans Parish, LA carries this site's most-constrained reading. Wilson County, TN and Carlisle County, KY 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 Piatt County, IL and Wayne County, IL. The full underlying dataset is downloadable directly, one row per county.