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

UDO Sec. B sets separate freeboard standards by building type once the general floodplain development requirements of Sec. C, D and E are met. Principal residential structures, including manufactured homes under Sec. 5, must have their lowest floor, including any basement, elevated no lower than three feet above the base flood elevation, or one foot above the future-conditions flood elevation, whichever is higher; homes on existing manufactured home lots can instead rest on reinforced piers at least 36 inches above grade. Principal non-residential structures need only one foot of freeboard above the base flood elevation, or the future-conditions elevation if higher, under Sec.

2, and may floodproof to a watertight standard in lieu of elevating, provided a licensed engineer or architect certifies the design on a FEMA Flood-proofing Certificate. Sec. C applies the same three-foot residential and one-foot non-residential freeboard to buildings sited adjacent to, rather than inside, the future-conditions floodplain. Where solid perimeter walls are used to elevate a structure, Sec. 5 requires flood vents providing at least one square inch of net opening per square foot of enclosed area, with the lowest opening no higher than one foot above grade. Accessory structures permitted in the floodplain must use flood-resistant materials and the same venting standard.