Crawl space moisture in Cavalier County, ND

Reading the Cavalier County soil survey

The score of 44 combines four parts, each from the USDA survey: wet drainage classes contribute 49.3 points of 100 on their own scale, group D soils 32.9, a shallow water table 64.5, and flooding 1.3; the weights are on the methodology page. The dominant hydrologic group is C (44% of acres): slow infiltration (clay layers).

At 2 ft the seasonal water table is usually below a crawl-space floor, but the 93% of acres that report one are by definition the wettest parts of the county; on those lots, a wet spring can bring water close to the footings.

Cavalier County against the rest of North Dakota

Cavalier County ranks 7 of 53 North Dakota counties, 20 points above the state median of 24. That puts it in the wettest quarter of the state. Statewide, 23% of mapped soil is in the wet drainage classes; here it is 46%, half again the state figure or more. After moderately well drained, the next most common class is somewhat poorly drained at 29%.

Flooding. 1% of acres with a flooding class are rated frequent; 0.4% 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. Ponding — water standing at the surface with nowhere to go — affects 3.2% 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. Cavalier 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 Cavalier County by score

All 53 North Dakota counties

Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area ND019; drainage covers 100% of 966,400 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.