Effingham County, GA Accessory Structures: ADU Rules (2026)

Effingham County added a full accessory dwelling unit framework to its zoning ordinance at Appendix C § 3.46. Section 3.46.2 defines an ADU as a subordinate, self-contained dwelling on the same lot as a principal home with its own permanent kitchen and bathroom facilities, capped at two bedrooms, and limits every lot of record to one ADU that must stay in common ownership with the principal dwelling rather than being platted or sold separately. Section 3.46.3 opens ADUs to every residential (R) and agricultural-residential (AR) district where detached single-family homes are permitted, but the unit counts as an accessory use and cannot push the lot over the district's normal density.

The size and height caps differ by district. In AR districts, § 3.46.4 limits a detached ADU to 75 percent of the principal dwelling's livable floor area or 1,200 square feet, whichever is less, with a maximum height of 35 feet, and requires the ADU to meet every accessory-structure setback in the applicable AR district, or a stricter buffer, easement, or overlay standard if one applies. Section 3.46.5 sets a tighter cap in R districts: 75 percent of the principal home's floor area or 1,000 square feet, whichever is less, and a 25-foot height limit.

Other sections in the same article cover septic and water capacity, a ban on new driveway curb cuts, design compatibility with the main house, and a requirement that recreational vehicles, campers, and shipping containers cannot serve as ADUs unless fully converted to meet building code.