Pennsylvania / Warren County
Score 43 · elevated · #11 of 67 in PA
Crawl space moisture in Warren County, PA
66% of Warren County's soil falls in hydrologic group D or a dual D group: clays and high water tables that shed water slowly. Where a seasonal water table is reported — 72% of acres — it averages 1.4 ft below grade, shallow enough to reach a typical crawl-space footing.
- 1Water table 1.4 ft
- 2Wet soils 33%
- 3Moisture score 43
- 4EPA radon zone 2
Reading the Warren County soil survey
The score of 43 combines four parts, each from the USDA survey: wet drainage classes contribute 35.5 points of 100 on their own scale, group D soils 56.3, a shallow water table 56.6, and flooding 3.5; the weights are on the methodology page. The dominant hydrologic group is C/D (32% of acres): D when undrained, C 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 across much of Warren County. Venting cannot fix that; it needs drainage — a perimeter drain to daylight or a sump — before any liner goes down.
Warren County against the rest of Pennsylvania
Warren County ranks 11 of 67 Pennsylvania counties, 18 points above the state median of 25. That puts it in the wettest quarter of the state. Statewide, 16% of mapped soil is in the wet drainage classes; here it is 33%, half again the state figure or more. After well drained, the next most common class is moderately well drained at 33%.
Flooding. 2.7% of acres with a flooding class are rated frequent; 1.1% of acres with a flooding class are rated occasional; 0.6% of acres with a flooding class are rated rare. Flood-prone soils are a minority here, concentrated along streams; the score mostly reflects what happens between floods. Ponding — water standing at the surface with nowhere to go — affects 1.2% of acres.
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 2. The zone is a county-level prediction; EPA says elevated levels occur in every zone and every home should be tested.
Near Warren County by score
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area PA123; drainage covers 98% of 575,181 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.