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.
| County | Index | Moisture | Cracks | Water table | Region |
|---|---|---|---|---|---|
| New Haven County | 44 | 42 | 31 | 66 | Glaciated New England upland |
| Tolland County | 43 | 42 | 27 | 66 | Glaciated New England upland |
| Fairfield County | 40 | 40 | 21 | 66 | Glaciated New England upland |
| Litchfield County | 39 | 44 | 12 | 66 | Glaciated New England upland |
| Middlesex County | 37 | 40 | 25 | 46 | Glaciated New England upland |
| Hartford County | 35 | 43 | 15 | 46 | Glaciated New England upland |
| New London County | 35 | 39 | 23 | 46 | Glaciated New England upland |
| Windham County | 33 | 39 | 26 | 30 | Glaciated 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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