Score 37 · moderate · #35 of 100 in NC

Crawl space moisture in Greene County, NC

Greene County scores moderate: no single wet-soil signal dominates its mapped acres. Where a seasonal water table is reported — 91% of acres — it averages 2.5 ft below grade.

Size venting or encapsulation

1Water table 2.5 ft
2Wet soils 36%
3Moisture score 37
4EPA radon zone 3

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

Dominant drainage

Well drained

47% of acres

Group D soils

38%

slow infiltration

Flood-prone acres

25%

any flooding frequency

Ponding

0.7%

acres where water ponds

Reading the Greene County soil survey

The score of 37 combines four parts, each from the USDA survey: wet drainage classes contribute 37.3 points of 100 on their own scale, group D soils 26, a shallow water table 56.6, and flooding 11.9; the weights are on the methodology page. The dominant hydrologic group is B (33% of acres): moderate infiltration.

Hydrologic soil groups in Greene 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 2.5 ft the seasonal water table is usually below a crawl-space floor, but the 91% 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.

Greene County against the rest of North Carolina

Greene County ranks 35 of 100 North Carolina counties, 20 points above the state median of 17. That places it in the middle range, nationally and for the state. Statewide, 30% of mapped soil is in the wet drainage classes; here it is 36%. After well drained, the next most common class is poorly drained at 21%.

Flooding. 8.7% of acres with a flooding class are rated frequent; 15.9% 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 Greene County by score

Durham County 37 Johnston County 36 Sampson County 39 Wayne County 39

All 100 North Carolina counties

Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area NC079; drainage covers 99% of 170,580 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.