Coos County, NH Shrink-Swell Risk

Coos County, NH's soil, for shrink-swell risk

Low

Coos County, NH: USDA's soil survey rates 99.5% of the county "Low" for shrink-swell potential (0.91% linear extensibility). 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.

What Coos County's reading doesn't cover

Two lots a mile apart in Coos County can carry different soil, even though they share one countywide reading. 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 Coos County.

What it costs to find out, versus to ignore it

With Coos County, NH 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.

How Coos County, NH compares

Nationally, Coos County, NH is the 2,937-most-constrained of 3,085 rated counties for shrink-swell soil. Within New Hampshire alone it ranks 6 of 10. Coos County, NH is 1,795 square miles with a population of 31,094.

For contrast

Orleans Parish, LA carries this site's most-constrained reading. Karnes County, TX and Baldwin County, AL 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 New Hampshire

Every county in New Hampshire is on this site, including Grafton County, NH and Carroll County, NH. The full underlying dataset is downloadable directly, one row per county.