Missouri / Moniteau County
Score 44 · elevated · #46 of 113 in MO
Crawl space moisture in Moniteau County, MO
Moniteau County scores elevated because several moderate signals stack up rather than one dominant one. Where a seasonal water table is reported — 83% of acres — it averages 1.8 ft below grade, shallow enough to reach a typical crawl-space footing.
- 1Water table 1.8 ft
- 2Wet soils 30%
- 3Moisture score 44
- 4EPA radon zone 2
Reading the Moniteau County soil survey
The score of 44 combines four parts, each from the USDA survey: wet drainage classes contribute 40.8 points of 100 on their own scale, group D soils 47.4, a shallow water table 59.7, and flooding 12.3; the weights are on the methodology page. The dominant hydrologic group is C (44% of acres): slow infiltration (clay layers).
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 Moniteau County. Venting cannot fix that; it needs drainage — a perimeter drain to daylight or a sump — before any liner goes down.
Moniteau County against the rest of Missouri
Moniteau County ranks 46 of 113 Missouri counties, 5 points above the state median of 39. Wetter counties exist in Missouri, but the soil here still sits well above the national middle. Statewide, 32% of mapped soil is in the wet drainage classes; here it is 30%, below the state figure — the score here comes from a shallow water table rather than drainage class alone. After moderately well drained, the next most common class is somewhat poorly drained at 21%.
Flooding. 10.1% of acres with a flooding class are rated frequent; 3.3% of acres with a flooding class are rated occasional; 1.1% 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 2. The zone is a county-level prediction; EPA says elevated levels occur in every zone and every home should be tested.
Near Moniteau County by score
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area MO135; drainage covers 100% of 268,103 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.