Kentucky / Graves County
Score 39 · moderate · #4 of 49 in KY
Crawl space moisture in Graves County, KY
50% of Graves 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 — 80% of acres — it averages 2.1 ft below grade.
- 1Water table 2.1 ft
- 2Wet soils 7%
- 3Moisture score 39
- 4EPA radon zone 3
Reading the Graves County soil survey
The score of 39 combines four parts, each from the USDA survey: wet drainage classes contribute 30.5 points of 100 on their own scale, group D soils 45.7, a shallow water table 54.3, and flooding 17.1; the weights are on the methodology page. The dominant hydrologic group is B (32% of acres): moderate infiltration.
At 2.1 ft the seasonal water table is usually below a crawl-space floor, but the 80% 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.
Graves County against the rest of Kentucky
Graves County ranks 4 of 49 Kentucky counties, 24 points above the state median of 15. That puts it in the wettest quarter of the state. Statewide, 6% of mapped soil is in the wet drainage classes; here it is 7%. After moderately well drained, the next most common class is well drained at 18%.
Flooding. 6.7% of acres with a flooding class are rated frequent; 17.4% of acres with a flooding class are rated occasional. 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 a moderate county the soil record is mixed rather than uniformly wet, so conditions vary from lot to lot. Where the lot drains, the model-code default — a vented crawl space with 1 sq ft of net vent per 150 sq ft of floor, or 1 per 1500 with a Class I vapor retarder on the ground — is a reasonable starting point; where the sections above point to a shallow water table or flood-prone soil on your lot, plan as for an elevated county. Either way, check the site first: grading that falls away from the foundation, gutters and downspouts that discharge well clear of it, and a ground cover over bare earth. A wet crawl space in a moderate county points to one of those first.
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 Graves County by score
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area KY083; drainage covers 99% of 356,358 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.