King County, WA Shrink-Swell Risk
King County's SSURGO shrink-swell reading
Low
In King County, WA, 95.3% of the surveyed soil carries a "Low" shrink-swell rating, 1.38% linear extensibility on average. Among the 3,144 counties on this site, that's the clean result: little shrink-swell movement, standard construction the likely outcome.
Before you rely on this for one address
King County's reading is an average across the whole county, not a promise about any one lot inside it. 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 King County.
Budgeting for King County, WA
King County's soil reading points toward standard foundation practice as the likely outcome, not the exception. 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 King County, WA compares
Among the 3,085 rated counties on this site, King County, WA ranks 2,625 most-constrained nationally, and 35 of 39 within Washington. The county spans 2,116 square miles, home to 2,340,211 people.
See how another county compares
Orleans Parish, LA carries this site's most-constrained reading. Isabella County, MI and Pondera 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
Elsewhere in Washington
Every county in Washington is on this site, including San Juan County, WA and Jefferson County, WA. The full underlying dataset is downloadable directly, one row per county.