Score 57 · elevated · #20 of 100 in NC

Crawl space moisture in Hertford County, NC

72% of Hertford 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 — 92% of acres — it averages 1.5 ft below grade, shallow enough to reach a typical crawl-space footing.

Size venting or encapsulation

1Water table 1.5 ft
2Wet soils 49%
3Moisture score 57
4EPA radon zone 3

Share of mapped soil acres in Hertford County, NC by NRCS drainage class (dominant condition), bars to scale; wetter classes highlighted. Covers 98% of mapped acres.

Dominant drainage

Poorly drained

30% of acres

Group D soils

72%

slow infiltration

Flood-prone acres

18%

any flooding frequency

Ponding

acres where water ponds

Reading the Hertford County soil survey

The score of 57 combines four parts, each from the USDA survey: wet drainage classes contribute 55.6 points of 100 on their own scale, group D soils 62.2, a shallow water table 71.4, and flooding 15.6; the weights are on the methodology page. The dominant hydrologic group is D (43% of acres): very slow infiltration, high runoff (clays, high water table).

Hydrologic soil groups in Hertford 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 across much of Hertford County. Venting cannot fix that; it needs drainage — a perimeter drain to daylight or a sump — before any liner goes down.

Hertford County against the rest of North Carolina

Hertford County ranks 20 of 100 North Carolina counties, 40 points above the state median of 17. That puts it in the wettest quarter of the state. Statewide, 30% of mapped soil is in the wet drainage classes; here it is 49%, half again the state figure or more. After poorly drained, the next most common class is moderately well drained at 29%.

Flooding. 14.5% of acres with a flooding class are rated frequent; 0.8% of acres with a flooding class are rated occasional; 3.1% 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 an elevated county the soil supplies more moisture than average, but a vented crawl space can work if the ground is covered: the code lets vent area drop from 1 sq ft per 150 to 1 per 1500 with a Class I vapor retarder on the ground, which is an admission of how much moisture comes from below. Grading, gutters and a ground cover usually decide whether a crawl space here stays dry before any decision about sealing it.

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 Hertford County by score

Dare County 57 Pitt County 57 Brunswick County 58 Carteret County 59

All 100 North Carolina counties

Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area NC091; drainage covers 98% of 231,738 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.