BasementSoil

Maryland: basement moisture and foundation risk by county

24 counties, ranked by our combined index. Highest combined risk is Prince George's County (47), lowest is Garrett County (31). The worst soil for foundation cracks specifically is in Prince George's County.

Where in Maryland 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.

Allegany County, MD — combined 41/100, moisture 34, movement 47, water table 46Anne Arundel County, MD — combined 40/100, moisture 41, movement 34, water table 46Baltimore County, MD — combined 40/100, moisture 43, movement 30, water table 46Baltimore City, MD — combined 38/100, moisture 40, movement 28, water table 46Calvert County, MD — combined 43/100, moisture 41, movement 30, water table 66Caroline County, MD — combined 44/100, moisture 40, movement 34, water table 66Carroll County, MD — combined 41/100, moisture 39, movement 39, water table 46Cecil County, MD — combined 35/100, moisture 38, movement 34, water table 30Charles County, MD — combined 44/100, moisture 35, movement 56, water table 46Dorchester County, MD — combined 43/100, moisture 39, movement 32, water table 66Frederick County, MD — combined 32/100, moisture 37, movement 37, water table 16Garrett County, MD — combined 31/100, moisture 34, movement 39, water table 16Harford County, MD — combined 35/100, moisture 35, movement 48, water table 16Howard County, MD — combined 43/100, moisture 39, movement 48, water table 46Kent County, MD — combined 41/100, moisture 39, movement 25, water table 66Montgomery County, MD — combined 39/100, moisture 39, movement 46, water table 30Prince George's County, MD — combined 47/100, moisture 34, movement 66, water table 46Queen Anne's County, MD — combined 31/100, moisture 39, movement 20, water table 30Somerset County, MD — combined 41/100, moisture 39, movement 25, water table 66St. Mary's County, MD — combined 38/100, moisture 39, movement 18, water table 66Talbot County, MD — combined 33/100, moisture 39, movement 14, water table 46Washington County, MD — combined 35/100, moisture 33, movement 31, water table 46Wicomico County, MD — combined 40/100, moisture 41, movement 21, water table 66Worcester County, MD — combined 36/100, moisture 39, movement 26, 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
Prince George's County47346646Piedmont
Caroline County44403466Atlantic coastal plain
Charles County44355646Piedmont
Calvert County43413066Atlantic coastal plain
Dorchester County43393266Atlantic coastal plain
Howard County43394846Piedmont
Allegany County41344746Ridge and Valley
Carroll County41393946Piedmont
Kent County41392566Atlantic coastal plain
Somerset County41392566Atlantic coastal plain
Anne Arundel County40413446Atlantic coastal plain
Baltimore County40433046Atlantic coastal plain
Wicomico County40412166Atlantic coastal plain
Montgomery County39394630Piedmont
Baltimore City38402846Atlantic coastal plain
St. Mary's County38391866Atlantic coastal plain
Worcester County36392646Atlantic coastal plain
Cecil County35383430Piedmont
Harford County35354816Piedmont
Washington County35333146Ridge and Valley
Talbot County33391446Atlantic coastal plain
Frederick County32373716Piedmont
Garrett County31343916Appalachian Plateau
Queen Anne's County31392030Atlantic coastal plain

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

The physiographic regions inside Maryland

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

Atlantic coastal plain

Extremely variable over short distances: sand and saturated clay side by side. A county figure means less here than anywhere else we cover — the individual parcel decides.

13 counties: Anne Arundel County, Baltimore County, Baltimore City, Calvert County, Caroline County, Dorchester County, Kent County, Queen Anne's County, Somerset County, St. Mary's County, Talbot County, Wicomico County, Worcester County

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.

8 counties: Carroll County, Cecil County, Charles County, Frederick County, Harford County, Howard County, Montgomery County, Prince George's 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.

2 counties: Allegany County, Washington 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.

1 counties: Garrett County

Page data updated