Carbon County, MT Shrink-Swell Risk

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

Moderate

USDA's SSURGO data puts Carbon County, MT's soil at "Moderate" shrink-swell potential, an area-weighted linear extensibility of 4.15% across 38.6% 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 Carbon County, MT at once, not any single address. A site-specific soil report, usually $1,000-$5,000, is what an engineer would actually pull before designing a foundation on a lot in Carbon County.

Report cost vs. repair cost

With Carbon 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, Carbon County, MT is the 501-most-constrained of 3,085 rated counties for shrink-swell soil. Within Montana alone it ranks 11 of 54. Carbon County, MT is 2,048 square miles with a population of 11,498.

See how another county compares

Orleans Parish, LA carries this site's most-constrained reading. Pipestone County, MN and Chisago County, MN 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 Prairie County, MT and Blaine County, MT. The full underlying dataset is downloadable directly, one row per county.