Score 34 · moderate · #21 of 46 in SC

Crawl space moisture in Lee County, SC

Lee County scores moderate: no single wet-soil signal dominates its mapped acres. Where a seasonal water table is reported — 81% of acres — it averages 2.3 ft below grade.

Size venting or encapsulation

1Water table 2.3 ft
2Wet soils 27%
3Moisture score 34
4EPA radon zone 3

Share of mapped soil acres in Lee County, SC by NRCS drainage class (dominant condition), bars to scale; wetter classes highlighted. Covers 100% of mapped acres.

Dominant drainage

Well drained

50% of acres

Group D soils

42%

slow infiltration

Flood-prone acres

15%

any flooding frequency

Ponding

acres where water ponds

Reading the Lee County soil survey

The score of 34 combines four parts, each from the USDA survey: wet drainage classes contribute 30.2 points of 100 on their own scale, group D soils 31.1, a shallow water table 52.6, and flooding 11.9; the weights are on the methodology page. The dominant hydrologic group is B/D (27% of acres): D when undrained, B when drained.

Hydrologic soil groups in Lee 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 2.3 ft the seasonal water table is usually below a crawl-space floor, but the 81% 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.

Lee County against the rest of South Carolina

Lee County ranks 21 of 46 South Carolina counties, 9 points above the state median of 25. That places it in the middle range, nationally and for the state. Statewide, 34% of mapped soil is in the wet drainage classes; here it is 27%, below the state figure — the score here comes from a shallow water table rather than drainage class alone. After well drained, the next most common class is poorly drained at 14%.

Flooding. 10.4% of acres with a flooding class are rated frequent; 1.5% of acres with a flooding class are rated occasional; 2.8% 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 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 Lee County by score

Allendale County 38 Darlington County 38 Marlboro County 41 Orangeburg County 41

All 46 South Carolina counties

Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area SC061; drainage covers 100% of 263,000 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.