New Jersey / Atlantic County
Score 46 · elevated · #2 of 21 in NJ
Crawl space moisture in Atlantic County, NJ
52% of Atlantic County's mapped soil is somewhat poorly to very poorly drained, which means ground that stays wet near the surface for significant periods. Where a seasonal water table is reported — 58% of acres — it averages 0.7 ft below grade, shallow enough to reach a typical crawl-space footing.
- 1Water table 0.7 ft
- 2Wet soils 52%
- 3Moisture score 46
- 4EPA radon zone 3
Reading the Atlantic County soil survey
The score of 46 combines four parts, each from the USDA survey: wet drainage classes contribute 53.1 points of 100 on their own scale, group D soils 34.9, a shallow water table 51.3, and flooding 28.4; the weights are on the methodology page. The dominant hydrologic group is A/D (45% of acres): D when undrained, A when drained.
A water table under two feet is the single most important number here. A crawl-space floor is usually 18 to 36 inches below the joists and often below outside grade, so in a wet season groundwater can stand at or above the crawl-space floor on the soils that report a water table — about 58% of Atlantic County's acres. Venting cannot fix that; it needs drainage — a perimeter drain to daylight or a sump — before any liner goes down.
Atlantic County against the rest of New Jersey
Atlantic County ranks 2 of 21 New Jersey counties, 16 points above the state median of 30. Only 1 other county in the state score higher. Statewide, 30% of mapped soil is in the wet drainage classes; here it is 52%, half again the state figure or more. After well drained, the next most common class is very poorly drained at 29%.
Flooding. 9.1% of acres with a flooding class are rated frequent; 0.8% of acres with a flooding class are rated occasional; 4.1% of acres with a flooding class are rated rare. That is a large flood-prone share; a crawl space in the floodplain needs flood vents under most local floodplain ordinances, which is a separate rule from R408 and can rule out a fully sealed design.
What it means for a crawl space here
In an elevated county the soil supplies more moisture than average, but a vented crawl space can work if the ground is covered: the code lets vent area drop from 1 sq ft per 150 to 1 per 1500 with a Class I vapor retarder on the ground, which is an admission of how much moisture comes from below. Grading, gutters and a ground cover usually decide whether a crawl space here stays dry before any decision about sealing it.
Radon. EPA radon zone 3. The zone is a county-level prediction; EPA says elevated levels occur in every zone and every home should be tested.
Near Atlantic County by score
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area NJ001; drainage covers 89% of 430,378 mapped acres); EPA Map of Radon Zones, county table (June 2024 JSON); IRC R408.3 Unvented crawl space, as adopted in S.C. Code Regs. 8-1221 (LII). Checked 2026-10-23.