Lyman County, SD Shrink-Swell Risk

What Lyman County, SD's soil means for a foundation

Very High

USDA's SSURGO data puts Lyman County, SD's soil at "Very High" shrink-swell potential, an area-weighted linear extensibility of 10.23% across 82% of the county's surveyed land. That's the range most associated with real foundation cracking - stair-step cracks in mortar joints, sticking doors, gaps around window frames - and it typically needs an engineered foundation (post-tension slab, drilled piers), not a standard footing.

This is a county figure, not a lot figure

USDA's survey covers the whole of Lyman County, SD 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 Lyman County.

Report cost vs. repair cost

Given Lyman County's rating, spending a few thousand now is the way to avoid spending tens of thousands later. The report ($1,000-$5,000) is what tells you whether Lyman County's county-level reading applies to your lot; the repair ($5,000-$15,000) is what it costs if you skip that and find out from the cracks instead.

How Lyman County, SD compares

Nationally, Lyman County, SD is the 25-most-constrained of 3,085 rated counties for shrink-swell soil. Within South Dakota alone it ranks 1 of 66. Lyman County, SD is 1,642 square miles with a population of 3,721.

For contrast

Orleans Parish, LA carries this site's most-constrained reading. Faribault County, MN and Elkhart County, IN are worth a look for comparison.

How this reading is built, and its real limits · The warning signs of expansive-clay damage, explained

More of South Dakota

Every county in South Dakota is on this site, including Dewey County, SD and Douglas County, SD. The full underlying dataset is downloadable directly, one row per county.