Trinity County, CA Shrink-Swell Risk
Shrink-swell potential in Trinity County, CA
Low
Soil across 70.4% of Trinity County, CA comes back "Low" in USDA's shrink-swell data, averaging 2.42% 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 this number does and doesn't tell you
This is a countywide, area-weighted figure across every soil survey map unit in Trinity County, CA - never a reading for one specific parcel. The real answer for one lot is still a site-specific geotechnical report, running about $1,000-$5,000 (typically near $2,700).
Trinity County: the real numbers
Trinity 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 Trinity County, CA compares
Among the 3,085 rated counties on this site, Trinity County, CA ranks 1,621 most-constrained nationally, and 41 of 58 within California. Trinity County covers 3,179 square miles and counts 15,642 residents.
See how another county compares
Orleans Parish, LA carries this site's most-constrained reading. Tarrant County, TX and King George County, VA 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 Ventura County, CA and Los Angeles County, CA. The full underlying dataset is downloadable directly, one row per county.