10 counties mapped. On average, 18% of Arizona county soil area is high shrink-swell clay (USDA SSURGO).
Higher percentages mean more of a county's mapped soil is shrink-swell clay that expands and contracts with moisture. This is county-scale exposure, not a diagnosis of any single home — but it tells you whether soil movement belongs on your radar.
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Before you call a foundation company →| County | Tier | High-risk % | Moderate % |
|---|---|---|---|
| Graham | Severe | 47% | 9% |
| Yavapai | High | 30% | 16% |
| Coconino | High | 29% | 14% |
| Cochise | High | 26% | 20% |
| Pima | Moderate | 13% | 29% |
| Apache | Moderate | 11% | 34% |
| Navajo | Moderate | 8% | 24% |
| Mohave | Moderate | 6% | 12% |
| Pinal | Moderate | 6% | 33% |
| Maricopa | Low | 1% | 21% |
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.