Tennessee: basement moisture and foundation risk by county
95 counties, ranked by our combined index. Highest combined risk is Obion County (51), lowest is Blount County (24). The worst soil for foundation cracks specifically is in McMinn County.
| County | Index | Moisture | Cracks | Water table | Region |
|---|---|---|---|---|---|
| Obion County | 51 | 43 | 39 | 82 | Gulf Coastal Plain |
| Weakley County | 49 | 42 | 48 | 66 | Gulf Coastal Plain |
| Chester County | 48 | 43 | 32 | 82 | Gulf Coastal Plain |
| Hardeman County | 48 | 40 | 34 | 82 | Gulf Coastal Plain |
| Henry County | 46 | 44 | 33 | 66 | Gulf Coastal Plain |
| Carroll County | 45 | 42 | 34 | 66 | Gulf Coastal Plain |
| Smith County | 45 | 38 | 53 | 46 | Appalachian Plateau |
| Crockett County | 44 | 40 | 34 | 66 | Gulf Coastal Plain |
| McNairy County | 44 | 44 | 44 | 46 | Gulf Coastal Plain |
| Wilson County | 44 | 38 | 50 | 46 | Appalachian Plateau |
| Bledsoe County | 43 | 34 | 52 | 46 | Ridge and Valley |
| Benton County | 42 | 42 | 39 | 46 | Gulf Coastal Plain |
| Decatur County | 42 | 41 | 27 | 66 | Gulf Coastal Plain |
| Hardin County | 42 | 40 | 43 | 46 | Gulf Coastal Plain |
| Loudon County | 42 | 36 | 48 | 46 | Ridge and Valley |
| Marion County | 42 | 38 | 44 | 46 | Appalachian Plateau |
| Meigs County | 42 | 36 | 49 | 46 | Ridge and Valley |
| Moore County | 42 | 36 | 46 | 46 | Appalachian Plateau |
| Robertson County | 42 | 35 | 48 | 46 | Interior Low Plateau karst |
| Houston County | 41 | 34 | 48 | 46 | Interior Low Plateau karst |
| Madison County | 41 | 43 | 21 | 66 | Gulf Coastal Plain |
| McMinn County | 41 | 35 | 57 | 30 | Ridge and Valley |
| Monroe County | 41 | 34 | 46 | 46 | Ridge and Valley |
| Pickett County | 41 | 36 | 55 | 30 | Ridge and Valley |
| Sequatchie County | 40 | 36 | 52 | 30 | Ridge and Valley |
| Coffee County | 39 | 35 | 39 | 46 | Appalachian Plateau |
| Dickson County | 39 | 32 | 43 | 46 | Interior Low Plateau karst |
| Franklin County | 39 | 38 | 48 | 30 | Appalachian Plateau |
| Gibson County | 39 | 40 | 43 | 30 | Gulf Coastal Plain |
| Macon County | 39 | 38 | 48 | 30 | Appalachian Plateau |
| Morgan County | 39 | 36 | 50 | 30 | Ridge and Valley |
| Rhea County | 39 | 37 | 48 | 30 | Ridge and Valley |
| Rutherford County | 39 | 34 | 52 | 30 | Interior Low Plateau karst |
| Humphreys County | 38 | 34 | 50 | 30 | Interior Low Plateau karst |
| Lawrence County | 38 | 33 | 39 | 46 | Interior Low Plateau karst |
| Maury County | 38 | 32 | 52 | 30 | Interior Low Plateau karst |
| Montgomery County | 38 | 32 | 42 | 46 | Interior Low Plateau karst |
| Overton County | 38 | 35 | 48 | 30 | Ridge and Valley |
| Perry County | 38 | 33 | 38 | 46 | Interior Low Plateau karst |
| Grainger County | 37 | 31 | 40 | 46 | Blue Ridge Mountains |
| Henderson County | 37 | 42 | 25 | 46 | Gulf Coastal Plain |
| Marshall County | 37 | 32 | 38 | 46 | Interior Low Plateau karst |
| Putnam County | 37 | 35 | 33 | 46 | Appalachian Plateau |
| Trousdale County | 37 | 37 | 31 | 46 | Appalachian Plateau |
| Bedford County | 36 | 32 | 35 | 46 | Interior Low Plateau karst |
| Bradley County | 36 | 38 | 46 | 16 | Ridge and Valley |
| Jackson County | 36 | 35 | 30 | 46 | Appalachian Plateau |
| Lauderdale County | 36 | 36 | 40 | 30 | Loess hills |
| Stewart County | 36 | 33 | 34 | 46 | Interior Low Plateau karst |
| Van Buren County | 36 | 34 | 31 | 46 | Appalachian Plateau |
| White County | 36 | 36 | 28 | 46 | Appalachian Plateau |
| Cannon County | 35 | 36 | 38 | 30 | Appalachian Plateau |
| Giles County | 35 | 35 | 26 | 46 | Interior Low Plateau karst |
| Grundy County | 35 | 34 | 39 | 30 | Appalachian Plateau |
| Hamilton County | 35 | 36 | 37 | 30 | Ridge and Valley |
| Roane County | 35 | 34 | 40 | 30 | Ridge and Valley |
| Warren County | 35 | 35 | 28 | 46 | Appalachian Plateau |
| Williamson County | 35 | 32 | 43 | 30 | Interior Low Plateau karst |
| Jefferson County | 34 | 32 | 28 | 46 | Blue Ridge Mountains |
| Carter County | 33 | 32 | 25 | 46 | Blue Ridge Mountains |
| Cumberland County | 33 | 35 | 32 | 30 | Ridge and Valley |
| DeKalb County | 33 | 36 | 30 | 30 | Appalachian Plateau |
| Johnson County | 33 | 30 | 28 | 46 | Blue Ridge Mountains |
| Lewis County | 33 | 31 | 48 | 16 | Interior Low Plateau karst |
| Polk County | 33 | 37 | 41 | 16 | Ridge and Valley |
| Sevier County | 33 | 32 | 26 | 46 | Blue Ridge Mountains |
| Claiborne County | 32 | 33 | 31 | 30 | Blue Ridge Mountains |
| Clay County | 32 | 36 | 29 | 30 | Appalachian Plateau |
| Lake County | 32 | 35 | 30 | 30 | Loess hills |
| Scott County | 32 | 34 | 32 | 30 | Ridge and Valley |
| Sullivan County | 32 | 33 | 33 | 30 | Blue Ridge Mountains |
| Cheatham County | 31 | 32 | 31 | 30 | Interior Low Plateau karst |
| Fayette County | 31 | 36 | 24 | 30 | Loess hills |
| Greene County | 31 | 32 | 30 | 30 | Blue Ridge Mountains |
| Hickman County | 31 | 34 | 28 | 30 | Interior Low Plateau karst |
| Sumner County | 31 | 35 | 27 | 30 | Interior Low Plateau karst |
| Dyer County | 30 | 36 | 32 | 16 | Loess hills |
| Fentress County | 30 | 35 | 33 | 16 | Ridge and Valley |
| Knox County | 30 | 30 | 20 | 46 | Blue Ridge Mountains |
| Lincoln County | 30 | 33 | 25 | 30 | Interior Low Plateau karst |
| Shelby County | 30 | 33 | 27 | 30 | Loess hills |
| Cocke County | 29 | 33 | 23 | 30 | Blue Ridge Mountains |
| Davidson County | 29 | 36 | 28 | 16 | Interior Low Plateau karst |
| Hawkins County | 29 | 34 | 20 | 30 | Blue Ridge Mountains |
| Haywood County | 29 | 37 | 27 | 16 | Loess hills |
| Tipton County | 29 | 34 | 21 | 30 | Loess hills |
| Unicoi County | 29 | 29 | 16 | 46 | Blue Ridge Mountains |
| Campbell County | 28 | 33 | 20 | 30 | Blue Ridge Mountains |
| Union County | 28 | 30 | 35 | 16 | Blue Ridge Mountains |
| Washington County | 28 | 31 | 22 | 30 | Blue Ridge Mountains |
| Wayne County | 28 | 32 | 30 | 16 | Interior Low Plateau karst |
| Hamblen County | 27 | 30 | 22 | 30 | Blue Ridge Mountains |
| Hancock County | 27 | 30 | 31 | 16 | Blue Ridge Mountains |
| Anderson County | 25 | 30 | 25 | 16 | Blue Ridge Mountains |
| Blount County | 24 | 32 | 20 | 16 | Blue Ridge Mountains |
Values from USDA NRCS SSURGO where available, otherwise our regional model — each county page states which. Methodology.
The physiographic regions inside Tennessee
State lines are political; soil follows geology. These are the distinct ground types inside Tennessee and why each behaves the way it does.
Interior Low Plateau karst
Cave country. Infiltration is excellent until it changes: sinkhole activity and collapse are an underrated cause of foundation damage here, and no amount of waterproofing addresses them.
21 counties: Bedford County, Cheatham County, Davidson County, Dickson County, Giles County, Hickman County, Houston County, Humphreys County, Lawrence County, Lewis County, Lincoln County, Marshall County, Maury County, Montgomery County, Perry County, Robertson County, Rutherford County, Stewart County, Sumner County, Wayne County, Williamson County
Blue Ridge Mountains
Steep ground with deep weathering. Volume change is low, but slope stability is not: colluvium on a mountainside can creep, and debris flows during hurricane rainfall are a documented hazard. A house benched into a slope collects water behind its uphill wall.
19 counties: Anderson County, Blount County, Campbell County, Carter County, Claiborne County, Cocke County, Grainger County, Greene County, Hamblen County, Hancock County, Hawkins County, Jefferson County, Johnson County, Knox County, Sevier County, Sullivan County, Unicoi County, Union County, Washington 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.
17 counties: Bledsoe County, Bradley County, Cumberland County, Fentress County, Hamilton County, Loudon County, McMinn County, Meigs County, Monroe County, Morgan County, Overton County, Pickett County, Polk County, Rhea County, Roane County, Scott County, Sequatchie 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.
17 counties: Cannon County, Clay County, Coffee County, DeKalb County, Franklin County, Grundy County, Jackson County, Macon County, Marion County, Moore County, Putnam County, Smith County, Trousdale County, Van Buren County, Warren County, White County, Wilson County
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.
14 counties: Benton County, Carroll County, Chester County, Crockett County, Decatur County, Gibson County, Hardeman County, Hardin County, Henderson County, Henry County, Madison County, McNairy County, Obion County, Weakley County
Loess hills
Loess is permeable and the water table is deep, but it is prone to erosion and to collapse under load when wetted — a different failure mode from expansive clay. A broken downspout can undermine a loess footing.
7 counties: Dyer County, Fayette County, Haywood County, Lake County, Lauderdale County, Shelby County, Tipton County
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