BasementSoil

Connecticut: basement moisture and foundation risk by county

8 counties, ranked by our combined index. Highest combined risk is New Haven County (44), lowest is Windham County (33). The worst soil for foundation cracks specifically is in New Haven County.

Where in Connecticut 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.

Fairfield County, CT — combined 40/100, moisture 40, movement 21, water table 66Hartford County, CT — combined 35/100, moisture 43, movement 15, water table 46Litchfield County, CT — combined 39/100, moisture 44, movement 12, water table 66Middlesex County, CT — combined 37/100, moisture 40, movement 25, water table 46New Haven County, CT — combined 44/100, moisture 42, movement 31, water table 66New London County, CT — combined 35/100, moisture 39, movement 23, water table 46Tolland County, CT — combined 43/100, moisture 42, movement 27, water table 66Windham County, CT — combined 33/100, moisture 39, movement 26, water table 30
  • 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
New Haven County44423166Glaciated New England upland
Tolland County43422766Glaciated New England upland
Fairfield County40402166Glaciated New England upland
Litchfield County39441266Glaciated New England upland
Middlesex County37402546Glaciated New England upland
Hartford County35431546Glaciated New England upland
New London County35392346Glaciated New England upland
Windham County33392630Glaciated New England upland

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

The physiographic regions inside Connecticut

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

Glaciated New England upland

A hardpan under thin till creates a perched water table — water stands above an impermeable layer even though the regional water table is deep. It is the commonest cause of a wet basement in New England. Expansive clay is largely absent.

8 counties: Fairfield County, Hartford County, Litchfield County, Middlesex County, New Haven County, New London County, Tolland County, Windham County

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