Putnam County, IL Shrink-Swell Risk

Putnam County, IL's soil, for shrink-swell risk

Moderate

Putnam County, IL: USDA's soil survey rates 70.7% of the county "Moderate" for shrink-swell potential (3.4% 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 Putnam County's reading doesn't cover

Two lots a mile apart in Putnam 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 Putnam County will actually do.

What it costs to find out, versus to ignore it

With Putnam 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.

Putnam County's rank among Illinois counties

Nationally, Putnam County, IL is the 908-most-constrained of 3,085 rated counties for shrink-swell soil. Within Illinois alone it ranks 73 of 101. The county spans 160 square miles, home to 5,633 people.

For contrast

Orleans Parish, LA carries this site's most-constrained reading. Seminole County, OK and Saline County, NE 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 Clinton County, IL and Adams County, IL. The full underlying dataset is downloadable directly, one row per county.