Arkansas / Greene County
Score 59 · elevated · #18 of 67 in AR
Crawl space moisture in Greene County, AR
59% of Greene 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 — 83% of acres — it averages 1.2 ft below grade, shallow enough to reach a typical crawl-space footing.
- 1Water table 1.2 ft
- 2Wet soils 59%
- 3Moisture score 59
- 4EPA radon zone 3
Reading the Greene County soil survey
The score of 59 combines four parts, each from the USDA survey: wet drainage classes contribute 63 points of 100 on their own scale, group D soils 63, a shallow water table 67.7, and flooding 14.6; the weights are on the methodology page. The dominant hydrologic group is D (47% of acres): very slow infiltration, high runoff (clays, high water table).
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 Greene County. Venting cannot fix that; it needs drainage — a perimeter drain to daylight or a sump — before any liner goes down.
Greene County against the rest of Arkansas
Greene County ranks 18 of 67 Arkansas counties, 25 points above the state median of 34. Wetter counties exist in Arkansas, but the soil here still sits well above the national middle. Statewide, 33% of mapped soil is in the wet drainage classes; here it is 59%, half again the state figure or more. After poorly drained, the next most common class is moderately well drained at 25%.
Flooding. 11.9% of acres with a flooding class are rated frequent; 4.1% of acres with a flooding class are rated occasional; 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 Greene County by score
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area AR055; drainage covers 98% of 370,829 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.