Alabama: basement moisture and foundation risk by county
67 counties, ranked by our combined index. Highest combined risk is Montgomery County (71), lowest is Franklin County (30). The worst soil for foundation cracks specifically is in Autauga County.
| County | Index | Moisture | Cracks | Water table | Region |
|---|---|---|---|---|---|
| Montgomery County | 71 | 52 | 100 | 66 | Blackland Prairie and Black Belt |
| Tallapoosa County | 71 | 53 | 100 | 66 | Blackland Prairie and Black Belt |
| Autauga County | 70 | 51 | 100 | 66 | Blackland Prairie and Black Belt |
| Marengo County | 70 | 51 | 99 | 66 | Blackland Prairie and Black Belt |
| Dallas County | 69 | 53 | 95 | 66 | Blackland Prairie and Black Belt |
| Pike County | 69 | 49 | 100 | 66 | Blackland Prairie and Black Belt |
| Crenshaw County | 67 | 54 | 100 | 46 | Blackland Prairie and Black Belt |
| Elmore County | 66 | 51 | 100 | 46 | Blackland Prairie and Black Belt |
| Hale County | 66 | 52 | 100 | 46 | Blackland Prairie and Black Belt |
| Lowndes County | 66 | 53 | 100 | 46 | Blackland Prairie and Black Belt |
| Perry County | 66 | 51 | 100 | 46 | Blackland Prairie and Black Belt |
| Chilton County | 65 | 49 | 100 | 46 | Blackland Prairie and Black Belt |
| Choctaw County | 65 | 49 | 100 | 46 | Blackland Prairie and Black Belt |
| Greene County | 65 | 50 | 100 | 46 | Blackland Prairie and Black Belt |
| Sumter County | 65 | 50 | 100 | 46 | Blackland Prairie and Black Belt |
| Coosa County | 63 | 50 | 94 | 46 | Blackland Prairie and Black Belt |
| Wilcox County | 63 | 54 | 100 | 30 | Blackland Prairie and Black Belt |
| Bullock County | 62 | 51 | 100 | 30 | Blackland Prairie and Black Belt |
| Macon County | 62 | 52 | 100 | 30 | Blackland Prairie and Black Belt |
| Covington County | 54 | 40 | 55 | 82 | Gulf Coastal Plain |
| Cullman County | 50 | 41 | 50 | 66 | Gulf Coastal Plain |
| Dale County | 50 | 41 | 39 | 82 | Gulf Coastal Plain |
| Conecuh County | 49 | 40 | 50 | 66 | Gulf Coastal Plain |
| Butler County | 48 | 39 | 48 | 66 | Gulf Coastal Plain |
| Jefferson County | 48 | 43 | 32 | 82 | Gulf Coastal Plain |
| Walker County | 48 | 42 | 57 | 46 | Gulf Coastal Plain |
| Winston County | 48 | 41 | 45 | 66 | Gulf Coastal Plain |
| Pickens County | 47 | 42 | 40 | 66 | Gulf Coastal Plain |
| Escambia County | 46 | 40 | 41 | 66 | Gulf Coastal Plain |
| Geneva County | 46 | 42 | 37 | 66 | Gulf Coastal Plain |
| Mobile County | 46 | 41 | 52 | 46 | Gulf Coastal Plain |
| Monroe County | 46 | 40 | 53 | 46 | Gulf Coastal Plain |
| Coffee County | 45 | 41 | 51 | 46 | Gulf Coastal Plain |
| Fayette County | 45 | 39 | 26 | 82 | Gulf Coastal Plain |
| Washington County | 45 | 41 | 49 | 46 | Gulf Coastal Plain |
| Baldwin County | 44 | 42 | 30 | 66 | Gulf Coastal Plain |
| Clarke County | 44 | 40 | 33 | 66 | Gulf Coastal Plain |
| Cleburne County | 44 | 36 | 54 | 46 | Ridge and Valley |
| Shelby County | 44 | 39 | 51 | 46 | Gulf Coastal Plain |
| Tuscaloosa County | 44 | 41 | 48 | 46 | Gulf Coastal Plain |
| Barbour County | 43 | 39 | 31 | 66 | Gulf Coastal Plain |
| Blount County | 43 | 37 | 48 | 46 | Ridge and Valley |
| Marion County | 43 | 40 | 44 | 46 | Gulf Coastal Plain |
| Bibb County | 41 | 39 | 39 | 46 | Gulf Coastal Plain |
| Chambers County | 41 | 40 | 23 | 66 | Gulf Coastal Plain |
| Lawrence County | 41 | 37 | 43 | 46 | Appalachian Plateau |
| Clay County | 39 | 35 | 52 | 30 | Ridge and Valley |
| Lamar County | 39 | 39 | 34 | 46 | Gulf Coastal Plain |
| Lee County | 39 | 43 | 29 | 46 | Gulf Coastal Plain |
| Talladega County | 39 | 33 | 41 | 46 | Ridge and Valley |
| Madison County | 38 | 36 | 35 | 46 | Appalachian Plateau |
| Russell County | 38 | 40 | 30 | 46 | Gulf Coastal Plain |
| Calhoun County | 37 | 33 | 48 | 30 | Ridge and Valley |
| DeKalb County | 37 | 37 | 52 | 16 | Appalachian Plateau |
| Jackson County | 37 | 37 | 51 | 16 | Appalachian Plateau |
| Limestone County | 37 | 37 | 42 | 30 | Appalachian Plateau |
| Henry County | 36 | 40 | 22 | 46 | Gulf Coastal Plain |
| Houston County | 36 | 39 | 26 | 46 | Gulf Coastal Plain |
| Morgan County | 36 | 34 | 33 | 46 | Appalachian Plateau |
| Randolph County | 36 | 34 | 53 | 16 | Ridge and Valley |
| St. Clair County | 36 | 36 | 29 | 46 | Ridge and Valley |
| Cherokee County | 35 | 33 | 42 | 30 | Ridge and Valley |
| Etowah County | 34 | 35 | 36 | 30 | Ridge and Valley |
| Lauderdale County | 32 | 37 | 25 | 30 | Appalachian Plateau |
| Colbert County | 31 | 36 | 36 | 16 | Appalachian Plateau |
| Marshall County | 31 | 35 | 26 | 30 | Appalachian Plateau |
| Franklin County | 30 | 35 | 34 | 16 | Appalachian Plateau |
Values from USDA NRCS SSURGO where available, otherwise our regional model — each county page states which. Methodology.
The physiographic regions inside Alabama
State lines are political; soil follows geology. These are the distinct ground types inside Alabama and why each behaves the way it does.
Gulf Coastal Plain
Extremely variable over short distances: deep sand on the ridges, saturated clay in the flats between them. High rainfall and a seasonally high water table make crawlspace and slab moisture the dominant complaint rather than structural movement.
29 counties: Baldwin County, Barbour County, Bibb County, Butler County, Chambers County, Clarke County, Coffee County, Conecuh County, Covington County, Cullman County, Dale County, Escambia County, Fayette County, Geneva County, Henry County, Houston County, Jefferson County, Lamar County, Lee County, Marion County, Mobile County, Monroe County, Pickens County, Russell County, Shelby County, Tuscaloosa County, Walker County, Washington County, Winston County
Blackland Prairie and Black Belt
The foundation repair capital of the United States. These are Vertisols: clays so expansive that the ground itself opens fissures you can put an arm into during drought, then swells shut after rain. Slabs crack here in houses with faultless drainage, because water is not the mechanism — volume change is.
19 counties: Autauga County, Bullock County, Chilton County, Choctaw County, Coosa County, Crenshaw County, Dallas County, Elmore County, Greene County, Hale County, Lowndes County, Macon County, Marengo County, Montgomery County, Perry County, Pike County, Sumter County, Tallapoosa County, Wilcox County
Appalachian Plateau
Water travels over bedrock under a thin skin of colluvium. A house cut into a hillside has an entire catchment behind its uphill wall — what decides the outcome here is a daylight drain, not a coating.
10 counties: Colbert County, DeKalb County, Franklin County, Jackson County, Lauderdale County, Lawrence County, Limestone County, Madison County, Marshall County, Morgan County
Ridge and Valley
Limestone valleys mean karst: permeability is excellent until it is not. Sinkhole activity is an underrated cause of foundation failure here.
9 counties: Blount County, Calhoun County, Cherokee County, Clay County, Cleburne County, Etowah County, Randolph County, St. Clair County, Talladega County
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