Stillwater County, MT Shrink-Swell Risk

What Stillwater County, MT's soil means for a foundation

Moderate

USDA's SSURGO data puts Stillwater County, MT's soil at "Moderate" shrink-swell potential, an area-weighted linear extensibility of 4.26% across 70.8% 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 Stillwater County, MT 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 Stillwater County, MT 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, Stillwater County, MT is the 455-most-constrained of 3,085 rated counties for shrink-swell soil. Within Montana alone it ranks 9 of 54. Stillwater County, MT is 1,797 square miles with a population of 9,450.

For contrast

Orleans Parish, LA carries this site's most-constrained reading. Harrison County, TX and Dodge County, GA 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 Montana

Every county in Montana is on this site, including Judith Basin County, MT and Roosevelt County, MT. The full underlying dataset is downloadable directly, one row per county.