99 counties mapped. On average, 24% of Iowa 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.
Foundation repair is one of the most over-sold jobs in home services — quotes for the same house can vary 3×. Before you sign anything, learn how to get honest bids and what a fair price looks like.
Before you call a foundation company →| County | Tier | High-risk % | Moderate % |
|---|---|---|---|
| Henry | Severe | 73% | 20% |
| Jefferson | Severe | 69% | 25% |
| Wayne | Severe | 69% | 30% |
| Van Buren | Severe | 68% | 24% |
| Davis | Severe | 66% | 32% |
| Lucas | Severe | 66% | 33% |
| Clarke | Severe | 64% | 34% |
| Madison | Severe | 63% | 32% |
| Mahaska | Severe | 63% | 32% |
| Appanoose | Severe | 62% | 33% |
| Keokuk | Severe | 62% | 31% |
| Washington | Severe | 62% | 33% |
| Warren | Severe | 61% | 34% |
| Lee | Severe | 61% | 24% |
| Wapello | Severe | 61% | 31% |
| Ringgold | Severe | 59% | 35% |
| Monroe | Severe | 59% | 39% |
| Adams | Severe | 58% | 37% |
| Des Moines | Severe | 56% | 33% |
| Decatur | Severe | 55% | 38% |
| Marion | Severe | 55% | 35% |
| Union | Severe | 51% | 44% |
| Taylor | Severe | 51% | 46% |
| Adair | Severe | 51% | 47% |
| Iowa | Severe | 39% | 55% |
| Monona | Severe | 36% | 37% |
| Page | Severe | 35% | 62% |
| Guthrie | Severe | 35% | 50% |
| Louisa | Severe | 31% | 50% |
| Hamilton | Severe | 30% | 58% |
| Poweshiek | Severe | 30% | 67% |
| O'Brien | Severe | 30% | 66% |
| Allamakee | High | 28% | 59% |
| Clay | High | 28% | 55% |
| Webster | High | 24% | 62% |
| Wright | High | 24% | 63% |
| Cass | High | 24% | 71% |
| Clayton | High | 20% | 64% |
| Johnson | High | 20% | 63% |
| Jasper | High | 20% | 72% |
| Jackson | High | 19% | 63% |
| Winnebago | High | 17% | 59% |
| Harrison | High | 17% | 54% |
| Montgomery | High | 17% | 80% |
| Winneshiek | High | 16% | 60% |
| Sioux | High | 16% | 77% |
| Sac | High | 16% | 69% |
| Woodbury | High | 16% | 48% |
| Kossuth | High | 15% | 70% |
| Buena Vista | Moderate | 15% | 74% |
| Osceola | Moderate | 15% | 75% |
| Dubuque | Moderate | 14% | 61% |
| Hancock | Moderate | 14% | 68% |
| Fremont | Moderate | 14% | 69% |
| Dallas | Moderate | 12% | 45% |
| Pocahontas | Moderate | 12% | 81% |
| Cherokee | Moderate | 11% | 81% |
| Audubon | Moderate | 11% | 87% |
| Lyon | Moderate | 11% | 83% |
| Mills | Moderate | 10% | 71% |
| Calhoun | Moderate | 10% | 81% |
| Palo Alto | Moderate | 10% | 71% |
| Emmet | Moderate | 10% | 68% |
| Humboldt | Moderate | 9% | 80% |
| Dickinson | Moderate | 9% | 61% |
| Worth | Moderate | 9% | 67% |
| Pottawattamie | Moderate | 8% | 72% |
| Greene | Moderate | 8% | 61% |
| Cerro Gordo | Moderate | 7% | 68% |
| Polk | Moderate | 7% | 50% |
| Delaware | Moderate | 6% | 69% |
| Howard | Moderate | 6% | 69% |
| Story | Moderate | 6% | 55% |
| Boone | Moderate | 6% | 59% |
| Clinton | Moderate | 6% | 71% |
| Fayette | Moderate | 6% | 70% |
| Tama | Moderate | 6% | 88% |
| Franklin | Low | 5% | 66% |
| Jones | Low | 5% | 67% |
| Plymouth | Low | 5% | 74% |
| Hardin | Low | 4% | 55% |
| Marshall | Low | 4% | 86% |
| Floyd | Low | 4% | 68% |
| Ida | Low | 4% | 89% |
| Muscatine | Low | 4% | 70% |
| Shelby | Low | 4% | 88% |
| Carroll | Low | 3% | 73% |
| Grundy | Low | 3% | 92% |
| Mitchell | Low | 3% | 78% |
| Scott | Low | 3% | 80% |
| Butler | Low | 3% | 67% |
| Cedar | Low | 3% | 90% |
| Benton | Low | 2% | 86% |
| Crawford | Low | 2% | 88% |
| Linn | Low | 2% | 64% |
| Bremer | Low | 1% | 75% |
| Buchanan | Low | 1% | 71% |
| Chickasaw | Low | 1% | 73% |
| Black Hawk | Low | 0% | 70% |
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.