Michigan / Luce County
Score 43 · elevated · #31 of 79 in MI
Crawl space moisture in Luce County, MI
57% of Luce County's soil falls in hydrologic group D or a dual D group: clays and high water tables that shed water slowly. Where a seasonal water table is reported — 59% of acres — it averages 0.1 ft below grade, shallow enough to reach a typical crawl-space footing.
- 1Water table 0.1 ft
- 2Wet soils 43%
- 3Moisture score 43
- 4EPA radon zone 3
Reading the Luce County soil survey
The score of 43 combines four parts, each from the USDA survey: wet drainage classes contribute 45.6 points of 100 on their own scale, group D soils 40.9, a shallow water table 57.5, and flooding 0.1; the weights are on the methodology page. The dominant hydrologic group is A (34% of acres): high infiltration, low runoff (sands, gravels).
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 on the soils that report a water table — about 59% of Luce County's acres. Venting cannot fix that; it needs drainage — a perimeter drain to daylight or a sump — before any liner goes down.
Luce County against the rest of Michigan
Luce County ranks 31 of 79 Michigan counties, 6 points above the state median of 37. Wetter counties exist in Michigan, but the soil here still sits well above the national middle. Statewide, 45% of mapped soil is in the wet drainage classes; here it is 43%, below the state figure — the score here comes from heavy group D soils rather than drainage class alone. After very poorly drained, the next most common class is well drained at 17%.
Flooding. No mapped soil in Luce County carries a flooding frequency above "none", so the score here is about water held in and under the soil rather than water arriving over it. Ponding still affects 9.3% 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. 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 Luce County by score
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area MI095; drainage covers 97% of 593,319 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.