Sonoma County, CA Shrink-Swell Risk

Sonoma County's SSURGO shrink-swell reading

Moderate

In Sonoma County, CA, 56.7% of the surveyed soil carries a "Moderate" shrink-swell rating, 3.98% linear extensibility on average. A real but modest amount of movement - standard foundations usually hold up, but drainage and moisture control around the foundation still matter more than on low-risk soil.

Before you rely on this for one address

Sonoma County's reading is an average across the whole county, not a promise about any one lot inside it. The real answer for one lot is still a site-specific geotechnical report, running about $1,000-$5,000 (typically near $2,700).

Budgeting for Sonoma County, CA

Sonoma 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.

Sonoma County's rank among California counties

Among the 3,085 rated counties on this site, Sonoma County, CA ranks 574 most-constrained nationally, and 10 of 58 within California. Sonoma County, CA is 1,575 square miles with a population of 485,375.

Before you act on this

Orleans Parish, LA carries this site's most-constrained reading. Starke County, IN and Kenosha County, WI 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 California

Every county in California is on this site, including Plumas County, CA and Yolo County, CA. The full underlying dataset is downloadable directly, one row per county.