Georgia / Twiggs County
Score 22 · moderate · #22 of 59 in GA
Crawl space moisture in Twiggs County, GA
Twiggs County scores moderate: no single wet-soil signal dominates its mapped acres. Where a seasonal water table is reported — 38% of acres — it averages 2.4 ft below grade.
- 1Water table 2.4 ft
- 2Wet soils 25%
- 3Moisture score 22
- 4EPA radon zone 3
Reading the Twiggs County soil survey
The score of 22 combines four parts, each from the USDA survey: wet drainage classes contribute 21 points of 100 on their own scale, group D soils 23.4, a shallow water table 24, and flooding 20.6; the weights are on the methodology page. The dominant hydrologic group is B (45% of acres): moderate infiltration.
At 2.4 ft the seasonal water table is usually below a crawl-space floor, but the 38% 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.
Twiggs County against the rest of Georgia
Twiggs County ranks 22 of 59 Georgia counties, 7 points above the state median of 15. That places it in the middle range, nationally and for the state. Statewide, 25% of mapped soil is in the wet drainage classes; here it is 25%. After well drained, the next most common class is poorly drained at 12%.
Flooding. 18.1% of acres with a flooding class are rated frequent; 4.3% of acres with a flooding class are rated occasional. 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 Twiggs County by score
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area GA289; drainage covers 97% of 232,000 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.