Snohomish County, WA Shrink-Swell Risk

What Snohomish County, WA's soil means for a foundation

Low

USDA's SSURGO data puts Snohomish County, WA's soil at "Low" shrink-swell potential, an area-weighted linear extensibility of 1.43% across 90.3% of the county's surveyed land. That's as favorable a county-level reading as this dataset produces - standard foundation practice, pending one lot's own geotechnical report.

This is a county figure, not a lot figure

USDA's survey covers the whole of Snohomish County, WA at once, not any single address. The real answer for one lot is still a site-specific geotechnical report, running about $1,000-$5,000 (typically near $2,700).

Report cost vs. repair cost

With Snohomish County, WA 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 Snohomish County, WA compares

Nationally, Snohomish County, WA is the 2,579-most-constrained of 3,085 rated counties for shrink-swell soil. Within Washington alone it ranks 34 of 39. The county spans 2,087 square miles, home to 864,113 people.

See how another county compares

Orleans Parish, LA carries this site's most-constrained reading. Dewey County, SD and Madison County, AR 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 Washington

Every county in Washington is on this site, including Whitman County, WA and Skamania County, WA. The full underlying dataset is downloadable directly, one row per county.