Polk County, OR Shrink-Swell Risk

Shrink-swell potential in Polk County, OR

Moderate

Soil across 47.7% of Polk County, OR comes back "Moderate" in USDA's shrink-swell data, averaging 3.29% linear extensibility. That's a middle reading: not the sharp swings that crack a foundation outright, but enough that grading and drainage are worth getting right.

What this number does and doesn't tell you

This is a countywide, area-weighted figure across every soil survey map unit in Polk County, OR - never a reading for one specific parcel. 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 Polk County.

Polk County: the real numbers

Polk 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.

Where this sits nationally

Among the 3,085 rated counties on this site, Polk County, OR ranks 981 most-constrained nationally, and 8 of 36 within Oregon. Polk County, OR is 741 square miles with a population of 90,549.

See how another county compares

Orleans Parish, LA carries this site's most-constrained reading. Russell County, KY and Meigs County, OH 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 Oregon

Every county in Oregon is on this site, including Morrow County, OR and Douglas County, OR. The full underlying dataset is downloadable directly, one row per county.