Crawl space moisture in Sevier County, TN

56% of Sevier 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 — 13% of acres — it averages 2.9 ft below grade.

Size venting or encapsulation

1Water table 2.9 ft
2Wet soils 1%
3Moisture score 20
4EPA radon zone 2

Share of mapped soil acres in Sevier County, TN by NRCS drainage class (dominant condition), bars to scale; wetter classes highlighted. Covers 99% of mapped acres.

Dominant drainage

Well drained

57% of acres

Group D soils

56%

slow infiltration

Flood-prone acres

14%

any flooding frequency

Ponding

acres where water ponds

Reading the Sevier County soil survey

The score of 20 combines four parts, each from the USDA survey: wet drainage classes contribute 4.2 points of 100 on their own scale, group D soils 61.2, a shallow water table 7.2, and flooding 7.7; the weights are on the methodology page. The dominant hydrologic group is D (55% of acres): very slow infiltration, high runoff (clays, high water table).

Hydrologic soil groups in Sevier County by share of acres, columns to scale. Group D and dual groups (x/D) shed water slowly and hold it near the surface.

At 2.9 ft the seasonal water table is usually below a crawl-space floor, but the 13% 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.

Sevier County against the rest of Tennessee

Sevier County ranks 26 of 88 Tennessee counties, 8 points above the state median of 12. That places it in the middle range, nationally and for the state. Statewide, 9% of mapped soil is in the wet drainage classes; here it is 1%, below the state figure — the score here comes from heavy group D soils rather than drainage class alone. After well drained, the next most common class is excessively drained at 21%.

Flooding. 12.4% of acres with a flooding class are rated occasional; 1.4% of acres with a flooding class are rated rare. 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 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 2. The zone is a county-level prediction; EPA says elevated levels occur in every zone and every home should be tested.

Near Sevier County by score

Bedford County 20 Lincoln County 20Rutherford County 19Cannon County 22

All 88 Tennessee counties

Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area TN608; drainage covers 99% of 255,100 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.