Texas / Chambers County
Score 72 · high · #1 of 209 in TX
Crawl space moisture in Chambers County, TX
92% of Chambers County's mapped soil is somewhat poorly to very poorly drained, which means ground that stays wet near the surface for significant periods. Where a seasonal water table is reported — 92% of acres — it averages 2 ft below grade.
- 1Water table 2 ft
- 2Wet soils 92%
- 3Moisture score 72
- 4EPA radon zone 3
Reading the Chambers County soil survey
The score of 72 combines four parts, each from the USDA survey: wet drainage classes contribute 75.8 points of 100 on their own scale, group D soils 93.7, a shallow water table 63.5, and flooding 26.6; the weights are on the methodology page. The dominant hydrologic group is D (88% of acres): very slow infiltration, high runoff (clays, high water table).
At 2 ft the seasonal water table is usually below a crawl-space floor, but the 92% 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.
Chambers County against the rest of Texas
Chambers County ranks 1 of 209 Texas counties, 54 points above the state median of 18. Only no other county in the state scores higher. Statewide, 6% of mapped soil is in the wet drainage classes; here it is 92%, half again the state figure or more. After somewhat poorly drained, the next most common class is poorly drained at 19%.
Flooding. 18.5% of acres with a flooding class are rated frequent; 3.8% of acres with a flooding class are rated occasional; 29.2% 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. Ponding — water standing at the surface with nowhere to go — affects 17.8% of acres.
What it means for a crawl space here
In a high county, the model-code default of a vented crawl space over bare earth works against the soil: outside air brings humidity in all summer, and the ground underneath keeps supplying moisture from below. The R408 alternative — an unvented crawl space with a sealed vapor retarder lapped 6 inches and turned 6 inches up the stem wall, plus conditioned or exhaust air at 1 cfm per 50 sq ft or a dehumidifier — is built for exactly this. If the water table is shallow, drainage comes 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 Chambers County by score
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area TX071; drainage covers 93% of 409,721 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.