St. Charles County, MO Shrink-Swell Risk

St. Charles County, MO's soil, for shrink-swell risk

Moderate

St. Charles County, MO: USDA's soil survey rates 38.7% of the county "Moderate" for shrink-swell potential (4.92% 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 St. Charles County's reading doesn't cover

Two lots a mile apart in St. Charles 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 St. Charles County will actually do.

What it costs to find out, versus to ignore it

With St. Charles County, MO 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, St. Charles County, MO is the 304-most-constrained of 3,085 rated counties for shrink-swell soil. Within Missouri alone it ranks 42 of 114. St. Charles County, MO is 560 square miles with a population of 423,726.

For contrast

Orleans Parish, LA carries this site's most-constrained reading. Miller County, GA and Sublette County, WY 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 Missouri

Every county in Missouri is on this site, including Caldwell County, MO and Perry County, MO. The full underlying dataset is downloadable directly, one row per county.