Oklahoma / Craig County
Score 49 · elevated · #2 of 77 in OK
Crawl space moisture in Craig County, OK
60% of Craig 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 — 67% 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 60%
- 3Moisture score 49
- 4EPA radon zone 3
Reading the Craig County soil survey
The score of 49 combines four parts, each from the USDA survey: wet drainage classes contribute 43.9 points of 100 on their own scale, group D soils 69.3, a shallow water table 52.1, and flooding 10.6; the weights are on the methodology page. The dominant hydrologic group is D (51% 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 Craig County. Venting cannot fix that; it needs drainage — a perimeter drain to daylight or a sump — before any liner goes down.
Craig County against the rest of Oklahoma
Craig County ranks 2 of 77 Oklahoma counties, 32 points above the state median of 17. Only 1 other county in the state score higher. Statewide, 11% of mapped soil is in the wet drainage classes; here it is 60%, half again the state figure or more. After somewhat poorly drained, the next most common class is well drained at 30%.
Flooding. 6.4% of acres with a flooding class are rated frequent; 7% of acres with a flooding class are rated occasional. Flood-prone soils are a minority here, concentrated along streams; the score mostly reflects what happens between floods.
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 Craig County by score
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area OK035; drainage covers 100% of 488,282 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.