Expansive Soil in Alabama: County Ratings
2 of the 67 rated counties in Alabama have a dominant shrink-swell rating of High or Very High. Each rating below is the NRCS shrink-swell class covering the largest share of the county's mapped soil acres, computed from USDA SSURGO data. Open a county for the full class breakdown and what it means for a slab foundation.
| County | Dominant class | High + Very High share | Survey coverage |
|---|---|---|---|
| Autauga County | Low | 0% | 96% |
| Baldwin County | Low | 0% | 94% |
| Barbour County | Low | 5% | 98% |
| Bibb County | Low | 2% | 100% |
| Blount County | Low | 5% | 99% |
| Bullock County | Low | 39% | 100% |
| Butler County | Low | 14% | 100% |
| Calhoun County | Low | 8% | 99% |
| Chambers County | Low | 0% | 99% |
| Cherokee County | Low | 10% | 92% |
| Chilton County | Low | 0% | 99% |
| Choctaw County | Low | 15% | 98% |
| Clarke County | Low | 10% | 98% |
| Clay County | Low | 3% | 100% |
| Cleburne County | Low | 0% | 100% |
| Coffee County | Low | 4% | 100% |
| Colbert County | Low | 30% | 94% |
| Conecuh County | Low | 12% | 100% |
| Coosa County | Low | 2% | 98% |
| Covington County | Low | 2% | 99% |
| Crenshaw County | Low | 11% | 99% |
| Cullman County | Low | 0% | 98% |
| Dale County | Low | 2% | 100% |
| Dallas County | Low | 22% | 98% |
| DeKalb County | Low | 2% | 100% |
| Elmore County | Low | 2% | 94% |
| Escambia County | Low | 0% | 100% |
| Etowah County | Low | 4% | 97% |
| Fayette County | Low | 2% | 100% |
| Franklin County | Low | 17% | 97% |
| Geneva County | Low | 1% | 100% |
| Greene County | Low | 33% | 95% |
| Hale County | Moderate | 19% | 97% |
| Henry County | Low | 2% | 98% |
| Houston County | Low | 0% | 99% |
| Jackson County | Low | 27% | 95% |
| Jefferson County | Low | 2% | 96% |
| Lamar County | Moderate | 0% | 100% |
| Lauderdale County | Low | 0% | 92% |
| Lawrence County | Low | 24% | 97% |
| Lee County | Low | 1% | 99% |
| Limestone County | Low | 1% | 93% |
| Lowndes County | High | 59% | 99% |
| Macon County | Low | 18% | 99% |
| Madison County | Low | 23% | 98% |
| Marengo County | Low | 32% | 99% |
| Marion County | Low | 0% | 100% |
| Marshall County | Low | 7% | 91% |
| Mobile County | Low | 0% | 93% |
| Monroe County | Low | 11% | 99% |
| Montgomery County | High | 55% | 99% |
| Morgan County | Low | 23% | 96% |
| Perry County | Low | 23% | 100% |
| Pickens County | Low | 6% | 98% |
| Pike County | Low | 7% | 100% |
| Randolph County | Low | 0% | 97% |
| Russell County | Low | 19% | 97% |
| Shelby County | Low | 2% | 98% |
| St. Clair County | Low | 0% | 97% |
| Sumter County | Moderate | 38% | 99% |
| Talladega County | Low | 2% | 98% |
| Tallapoosa County | Low | 1% | 94% |
| Tuscaloosa County | Low | 1% | 99% |
| Walker County | Low | 0% | 99% |
| Washington County | Low | 4% | 99% |
| Wilcox County | Moderate | 31% | 97% |
| Winston County | Low | 0% | 97% |
How these ratings are computed
Ratings come from USDA NRCS SSURGO soil survey data: for each soil component we take the maximum linear extensibility percent (lep_r) in the top 100 cm, apply the NRCS Handbook Part 618 class limits (Low under 3 percent, Moderate 3 to 6, High 6 to 9, Very High 9 and above), assign map units by plurality of component percent, and roll acres up to the county. Full details on the methodology section of the lookup page. A county rating is not a parcel-level geotechnical assessment.