Score 21 · moderate · #46 of 100 in NC

Crawl space moisture in Granville County, NC

Granville County scores moderate: no single wet-soil signal dominates its mapped acres. Where a seasonal water table is reported — 36% of acres — it averages 1.6 ft below grade, shallow enough to reach a typical crawl-space footing.

Size venting or encapsulation

1Water table 1.6 ft
2Wet soils 8%
3Moisture score 21
4EPA radon zone 3

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

Dominant drainage

Well drained

65% of acres

Group D soils

35%

slow infiltration

Flood-prone acres

any flooding frequency

Ponding

0.5%

acres where water ponds

Reading the Granville County soil survey

The score of 21 combines four parts, each from the USDA survey: wet drainage classes contribute 14.7 points of 100 on their own scale, group D soils 30.2, a shallow water table 27, and flooding 7; the weights are on the methodology page. The dominant hydrologic group is B (51% of acres): moderate infiltration.

Hydrologic soil groups in Granville 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 36% of Granville County's acres. Venting cannot fix that; it needs drainage — a perimeter drain to daylight or a sump — before any liner goes down.

Granville County against the rest of North Carolina

Granville County ranks 46 of 100 North Carolina counties, 4 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 8%, 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 moderately well drained at 28%.

Flooding. 6.9% of acres with a flooding class are rated frequent; 0.5% 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 3. The zone is a county-level prediction; EPA says elevated levels occur in every zone and every home should be tested.

Near Granville County by score

Person County 21 Wake County 21 Hoke County 22 Union County 22

All 100 North Carolina counties

Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area NC077; drainage covers 99% of 343,744 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.