Randolph County, IL Shrink-Swell Risk

Shrink-swell potential in Randolph County, IL

Moderate

Soil across 68% of Randolph County, IL comes back "Moderate" in USDA's shrink-swell data, averaging 4.19% linear extensibility. That's a middle reading: not the sharp swings that crack a foundation outright, but enough that grading and drainage are worth getting right.

What this number does and doesn't tell you

This is a countywide, area-weighted figure across every soil survey map unit in Randolph County, IL - never a reading for one specific parcel. A local geotechnical report, typically $1,000-$5,000 (around $2,700 typical), is the only way to know what one lot in Randolph County will actually do.

Randolph County: the real numbers

Randolph 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.

How Randolph County, IL compares

Among the 3,085 rated counties on this site, Randolph County, IL ranks 478 most-constrained nationally, and 20 of 101 within Illinois. The county spans 575 square miles, home to 29,903 people.

See how another county compares

Orleans Parish, LA carries this site's most-constrained reading. Teton County, ID and Webb County, TX 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 Illinois

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