BasementSoil

South Carolina: basement moisture and foundation risk by county

46 counties, ranked by our combined index. Highest combined risk is Florence County (52), lowest is Pickens County (26). The worst soil for foundation cracks specifically is in Cherokee County.

Where in South Carolina the ground is worse

Every county in the state, coloured by the soil values below. Click a county to open its report; switch what the colour means with the buttons. The pattern is geology, not administration — risk stops at the edge of a physiographic region, not at a county line.

Abbeville County, SC — combined 33/100, moisture 31, movement 39, water table 30Aiken County, SC — combined 31/100, moisture 37, movement 33, water table 16Allendale County, SC — combined 35/100, moisture 38, movement 34, water table 30Anderson County, SC — combined 29/100, moisture 31, movement 24, water table 30Bamberg County, SC — combined 39/100, moisture 37, movement 49, water table 30Barnwell County, SC — combined 46/100, moisture 37, movement 60, water table 46Beaufort County, SC — combined 39/100, moisture 40, movement 34, water table 46Berkeley County, SC — combined 43/100, moisture 40, movement 45, water table 46Calhoun County, SC — combined 47/100, moisture 40, movement 43, water table 66Charleston County, SC — combined 44/100, moisture 40, movement 21, water table 82Cherokee County, SC — combined 49/100, moisture 38, movement 66, water table 46Chester County, SC — combined 35/100, moisture 38, movement 33, water table 30Chesterfield County, SC — combined 49/100, moisture 42, movement 46, water table 66Clarendon County, SC — combined 42/100, moisture 42, movement 24, water table 66Colleton County, SC — combined 47/100, moisture 40, movement 42, water table 66Darlington County, SC — combined 49/100, moisture 44, movement 45, water table 66Dillon County, SC — combined 46/100, moisture 42, movement 37, water table 66Dorchester County, SC — combined 42/100, moisture 44, movement 35, water table 46Edgefield County, SC — combined 35/100, moisture 37, movement 36, water table 30Fairfield County, SC — combined 40/100, moisture 39, movement 37, water table 46Florence County, SC — combined 52/100, moisture 43, movement 44, water table 82Georgetown County, SC — combined 45/100, moisture 42, movement 35, water table 66Greenville County, SC — combined 36/100, moisture 34, movement 32, water table 46Greenwood County, SC — combined 43/100, moisture 36, movement 50, water table 46Hampton County, SC — combined 42/100, moisture 37, movement 45, water table 46Horry County, SC — combined 43/100, moisture 44, movement 39, water table 46Jasper County, SC — combined 45/100, moisture 37, movement 55, water table 46Kershaw County, SC — combined 41/100, moisture 43, movement 36, water table 46Lancaster County, SC — combined 37/100, moisture 41, movement 26, water table 46Laurens County, SC — combined 36/100, moisture 35, movement 43, water table 30Lee County, SC — combined 48/100, moisture 40, movement 36, water table 82Lexington County, SC — combined 38/100, moisture 38, movement 43, water table 30Marion County, SC — combined 49/100, moisture 43, movement 44, water table 66Marlboro County, SC — combined 45/100, moisture 42, movement 33, water table 66McCormick County, SC — combined 44/100, moisture 34, movement 57, water table 46Newberry County, SC — combined 40/100, moisture 38, movement 51, water table 30Oconee County, SC — combined 35/100, moisture 33, movement 30, water table 46Orangeburg County, SC — combined 39/100, moisture 39, movement 35, water table 46Pickens County, SC — combined 26/100, moisture 31, movement 16, water table 30Richland County, SC — combined 41/100, moisture 38, movement 42, water table 46Saluda County, SC — combined 40/100, moisture 37, movement 52, water table 30Spartanburg County, SC — combined 32/100, moisture 36, movement 37, water table 16Sumter County, SC — combined 47/100, moisture 43, movement 39, water table 66Union County, SC — combined 35/100, moisture 36, movement 47, water table 16Williamsburg County, SC — combined 37/100, moisture 42, movement 23, water table 46York County, SC — combined 47/100, moisture 37, movement 61, water table 46
  • Low (0–27)
  • Moderate (28–49)
  • Elevated (50–74)
  • High (75–100)

County boundaries: US Census TIGER (public domain), simplified for display. Colours are our index from USDA SSURGO fields where loaded, otherwise from our regional model — each county page states which. How the index is calculated.

CountyIndexMoistureCracksWater tableRegion
Florence County52434482Southern Atlantic Coastal Plain
Cherokee County49386646Piedmont
Chesterfield County49424666Southern Atlantic Coastal Plain
Darlington County49444566Southern Atlantic Coastal Plain
Marion County49434466Southern Atlantic Coastal Plain
Lee County48403682Southern Atlantic Coastal Plain
Calhoun County47404366Southern Atlantic Coastal Plain
Colleton County47404266Southern Atlantic Coastal Plain
Sumter County47433966Southern Atlantic Coastal Plain
York County47376146Piedmont
Barnwell County46376046Piedmont
Dillon County46423766Southern Atlantic Coastal Plain
Georgetown County45423566Southern Atlantic Coastal Plain
Jasper County45375546Piedmont
Marlboro County45423366Southern Atlantic Coastal Plain
Charleston County44402182Southern Atlantic Coastal Plain
McCormick County44345746Piedmont
Berkeley County43404546Southern Atlantic Coastal Plain
Greenwood County43365046Piedmont
Horry County43443946Southern Atlantic Coastal Plain
Clarendon County42422466Southern Atlantic Coastal Plain
Dorchester County42443546Southern Atlantic Coastal Plain
Hampton County42374546Piedmont
Kershaw County41433646Southern Atlantic Coastal Plain
Richland County41384246Piedmont
Fairfield County40393746Piedmont
Newberry County40385130Piedmont
Saluda County40375230Piedmont
Bamberg County39374930Piedmont
Beaufort County39403446Southern Atlantic Coastal Plain
Orangeburg County39393546Piedmont
Lexington County38384330Piedmont
Lancaster County37412646Southern Atlantic Coastal Plain
Williamsburg County37422346Southern Atlantic Coastal Plain
Greenville County36343246Blue Ridge Mountains
Laurens County36354330Piedmont
Allendale County35383430Piedmont
Chester County35383330Piedmont
Edgefield County35373630Piedmont
Oconee County35333046Blue Ridge Mountains
Union County35364716Piedmont
Abbeville County33313930Blue Ridge Mountains
Spartanburg County32363716Piedmont
Aiken County31373316Piedmont
Anderson County29312430Blue Ridge Mountains
Pickens County26311630Blue Ridge Mountains

Values from USDA NRCS SSURGO where available, otherwise our regional model — each county page states which. Methodology.

The physiographic regions inside South Carolina

State lines are political; soil follows geology. These are the distinct ground types inside South Carolina and why each behaves the way it does.

Piedmont

Saprolite is weathered rock that keeps its structure, so water moves through it along relict joints unpredictably. The Triassic basins inside the Piedmont are islands of strongly expansive clay.

21 counties: Aiken County, Allendale County, Bamberg County, Barnwell County, Cherokee County, Chester County, Edgefield County, Fairfield County, Greenwood County, Hampton County, Jasper County, Laurens County, Lexington County, McCormick County, Newberry County, Orangeburg County, Richland County, Saluda County, Spartanburg County, Union County, York County

Southern Atlantic Coastal Plain

Low, flat and wet. Groundwater sits close to the surface for much of the year, which is why houses here sit on slabs or piers rather than over basements. Where clays are present they are moderately expansive; where sand dominates, the risk is moisture, not movement.

20 counties: Beaufort County, Berkeley County, Calhoun County, Charleston County, Chesterfield County, Clarendon County, Colleton County, Darlington County, Dillon County, Dorchester County, Florence County, Georgetown County, Horry County, Kershaw County, Lancaster County, Lee County, Marion County, Marlboro County, Sumter County, Williamsburg 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.

5 counties: Abbeville County, Anderson County, Greenville County, Oconee County, Pickens County

Page data updated