Dunwoody, GA Environmental Rules: Flood Elevation Requirements (2026)

Section 16-140(a)(6) requires all heating and air conditioning equipment and components including ductwork, plus electrical, ventilation, plumbing and other service facilities, to be designed or located at least three feet above the base flood elevation or one foot above the future-conditions flood elevation, whichever is higher, to keep water from entering or accumulating in them during flooding. Section 16-140(b)(1)a applies the same three-foot-or-one-foot freeboard standard to the lowest floor, including any basement, of new residential construction within the future-conditions floodplain, but only once the no-rise and storage-capacity conditions of section 16-139(c), (d) and (e) have been satisfied; new construction that cannot meet those conditions is barred from the floodplain outright.

Section 16-140(c) extends elevation duties to lots adjacent to, but outside, the floodplain: three feet above base flood elevation for residential buildings and one foot for nonresidential buildings. Nonresidential structures get an alternative under section 16-140(b)(2)a: instead of elevating, they may be floodproofed watertight to one foot above the base flood elevation, or the future-conditions elevation if higher, with a registered engineer or architect certifying the design. Manufactured homes carry their own version of the same freeboard in section 16-140(b)(5), either elevating the lowest floor three feet above base flood elevation or setting the chassis on reinforced piers at least 36 inches above grade.