Score 20 · moderate · #26 of 46 in SC

Crawl space moisture in York County, SC

York County scores moderate: no single wet-soil signal dominates its mapped acres. Where a seasonal water table is reported — 24% of acres — it averages 1.8 ft below grade, shallow enough to reach a typical crawl-space footing.

Size venting or encapsulation

1Water table 1.8 ft
2Wet soils 15%
3Moisture score 20
4EPA radon zone 2

Share of mapped soil acres in York County, SC by NRCS drainage class (dominant condition), bars to scale; wetter classes highlighted. Covers 93% of mapped acres.

Dominant drainage

Well drained

76% of acres

Group D soils

36%

slow infiltration

Flood-prone acres

any flooding frequency

Ponding

acres where water ponds

Reading the York County soil survey

The score of 20 combines four parts, each from the USDA survey: wet drainage classes contribute 13 points of 100 on their own scale, group D soils 36.6, a shallow water table 17.5, and flooding 7.5; the weights are on the methodology page. The dominant hydrologic group is B (50% of acres): moderate infiltration.

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

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 24% of York County's acres. Venting cannot fix that; it needs drainage — a perimeter drain to daylight or a sump — before any liner goes down.

York County against the rest of South Carolina

York County ranks 26 of 46 South Carolina counties, 5 points below 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 15%, below the state figure — the score here comes from flooding and ponding rather than drainage class alone. After well drained, the next most common class is somewhat poorly drained at 15%.

Flooding. 6.9% of acres with a flooding class are rated frequent; 1% of acres with a flooding class are rated occasional; 0.1% 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 York County by score

Kershaw County 20 Chesterfield County 22Calhoun County 16Union County 16

All 46 South Carolina counties

Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area SC091; drainage covers 93% of 445,300 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.