Sangamon County, IL Shrink-Swell Risk

Shrink-swell potential in Sangamon County, IL

Moderate

Soil across 95.1% of Sangamon County, IL comes back "Moderate" in USDA's shrink-swell data, averaging 4.34% 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 Sangamon County, IL - never a reading for one specific parcel. The real answer for one lot is still a site-specific geotechnical report, running about $1,000-$5,000 (typically near $2,700).

Sangamon County: the real numbers

Sangamon 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.

Sangamon County's rank among Illinois counties

Among the 3,085 rated counties on this site, Sangamon County, IL ranks 424 most-constrained nationally, and 11 of 101 within Illinois. The county spans 868 square miles, home to 194,345 people.

Before you act on this

Orleans Parish, LA carries this site's most-constrained reading. Brooke County, WV and Russell 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

Elsewhere in Illinois

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