13 counties mapped. On average, 1% of Washington county soil area is high shrink-swell clay (USDA SSURGO).
Foundation problems get more expensive the longer they wait. Get an assessment and repair quotes from independent local pros.
Get repair quotes →| County | Tier | High-risk % | Moderate % |
|---|---|---|---|
| Cowlitz | Low | 4% | 34% |
| Spokane | Low | 4% | 22% |
| Clark | Low | 3% | 39% |
| Whitman | Low | 3% | 39% |
| Lincoln | Low | 1% | 8% |
| Stevens | Low | 1% | 8% |
| Douglas | Low | 1% | 16% |
| Mason | Low | 0% | 13% |
| Adams | Low | 0% | 0% |
| Franklin | Low | 0% | 2% |
| Grant | Low | 0% | 3% |
| Island | Low | 0% | 20% |
| San Juan | Low | 0% | 28% |
Risk metrics are computed from USDA SSURGO soil survey data (linear extensibility of soil components, area-weighted by county). Soil varies lot to lot — this is county-scale context, not a substitute for a site-specific geotechnical or structural assessment.