Fairfax County, VA Shrink-Swell Risk

Fairfax County, VA's soil, for shrink-swell risk

Low

Fairfax County, VA: USDA's soil survey rates 78.9% of the county "Low" for shrink-swell potential (2.29% 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 Fairfax County's reading doesn't cover

Two lots a mile apart in Fairfax County can carry different soil, even though they share one countywide reading. A local geotechnical report, typically $1,000-$5,000 (around $2,700 typical), is the only way to know what one lot in Fairfax County will actually do.

What it costs to find out, versus to ignore it

With Fairfax County, VA 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.

Fairfax County's rank among Virginia counties

Nationally, Fairfax County, VA is the 1,729-most-constrained of 3,085 rated counties for shrink-swell soil. Within Virginia alone it ranks 54 of 114. Fairfax County covers 391 square miles and counts 1,160,925 residents.

See how another county compares

Orleans Parish, LA carries this site's most-constrained reading. Riley County, KS and Ohio County, WV 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 Virginia

Every county in Virginia is on this site, including Hampton city, VA and Lee County, VA. The full underlying dataset is downloadable directly, one row per county.