Rockdale County, GA Environmental Rules: Flood Elevation Requirements (2026)

The Code of Rockdale County's flood damage prevention chapter, Ch. 320, sets the freeboard, the extra elevation cushion above the base flood elevation (BFE), that new buildings must clear. Sec. 320-2 defines base flood elevation as the highest water surface elevation anticipated at any given location during the base flood. Under Sec. 320-5(b)(1)a, once a residential development has cleared the no-rise and encroachment tests of Sec. 320-4(c) through (e), the lowest floor, including any basement, must sit no lower than three feet above the base flood elevation, or one foot above the future-conditions flood elevation (a county-specific standard projecting flooding under future watershed build-out), whichever number is higher.

Substantial improvements to existing residential structures carry the identical three-foot standard under Sec. 320-5(b)(1)b. Nonresidential buildings get a lower one-foot freeboard requirement under Sec. 320-5(b)(2)a, but may floodproof instead of elevate if a licensed engineer or architect certifies the structure watertight to that same one-foot level using a FEMA floodproofing certificate. Manufactured homes placed or substantially improved in the floodplain must meet the same three-foot residential standard under Sec. 320-5(b)(5)a; recreational vehicles are exempt only if left on site fewer than 180 consecutive days and kept licensed and ready for highway use.

Any enclosed area below the elevated lowest floor must be an unfinished, flood-resistant enclosure with flood vents, at least two openings totaling one square inch of net area per square foot of enclosed space, with the lowest opening no higher than one foot above grade. Buildings authorized adjacent to, but outside, the mapped floodplain must still clear three feet (residential) or one foot (nonresidential) above the BFE under Sec. 320-5(c). The county's floodplain manager in the Department of Planning and Development reviews elevation certificates and as-built surveys before issuing a certificate of occupancy.