Alleghany County, NC Shrink-Swell Risk

What Alleghany County, NC's soil means for a foundation

Low

USDA's SSURGO data puts Alleghany County, NC's soil at "Low" shrink-swell potential, an area-weighted linear extensibility of 1.58% across 95.8% of the county's surveyed land. That's the easiest starting point on this site's scale - a standard foundation is the reasonable default here, though any one lot can still differ.

This is a county figure, not a lot figure

USDA's survey covers the whole of Alleghany County, NC at once, not any single address. A local geotechnical report, typically $1,000-$5,000 (around $2,700 typical), is the only way to know what one lot in Alleghany County will actually do.

Report cost vs. repair cost

With Alleghany County, NC rating "Low", 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, Alleghany County, NC is the 2,405-most-constrained of 3,085 rated counties for shrink-swell soil. Within North Carolina alone it ranks 63 of 100. Alleghany County, NC is 235 square miles with a population of 11,379.

See how another county compares

Orleans Parish, LA carries this site's most-constrained reading. Pike County, AL and Stillwater County, MT 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 North Carolina

Every county in North Carolina is on this site, including Graham County, NC and Mitchell County, NC. The full underlying dataset is downloadable directly, one row per county.