Wisconsin / Wood County
Score 57 · elevated · #2 of 72 in WI
Crawl space moisture in Wood County, WI
73% of Wood 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 — 87% of acres — it averages 1 ft below grade, shallow enough to reach a typical crawl-space footing.
- 1Water table 1 ft
- 2Wet soils 73%
- 3Moisture score 57
- 4EPA radon zone 1
Reading the Wood County soil survey
The score of 57 combines four parts, each from the USDA survey: wet drainage classes contribute 63.9 points of 100 on their own scale, group D soils 48.6, a shallow water table 73.4, and flooding 5.3; the weights are on the methodology page. The dominant hydrologic group is C/D (39% 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 Wood County. Venting cannot fix that; it needs drainage — a perimeter drain to daylight or a sump — before any liner goes down.
Wood County against the rest of Wisconsin
Wood County ranks 2 of 72 Wisconsin counties, 24 points above the state median of 33. Only 1 other county in the state score higher. Statewide, 32% of mapped soil is in the wet drainage classes; here it is 73%, half again the state figure or more. After somewhat poorly drained, the next most common class is poorly drained at 22%.
Flooding. 4.1% of acres with a flooding class are rated frequent; 2% 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. Wood County is in EPA radon zone 1, the highest predicted potential. A sealed crawl space and a radon system share most of their parts — the liner, the sealed seams, a fan — so if you are encapsulating, test for radon first and design both together. EPA itself says the zone map is not a reason to skip testing in zones 2 and 3.
Near Wood County by score
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area WI141; drainage covers 97% of 517,613 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.