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

Section 46-119, part of the county's 2017 Floodplain Management and Flood Damage Prevention Ordinance, sets building standards for the future-conditions floodplain administered by the Clayton County Water Authority. New residential construction is barred from the future-conditions floodplain unless the engineering study, floodway-encroachment and maintenance requirements of Secs. 46-114 through 46-116 are first satisfied; once they are, the lowest floor, including basement, must sit at least three feet above the base flood elevation or one foot above the future-conditions flood elevation, whichever is higher, and the same three-foot freeboard applies to substantial improvements of existing residential structures.

Non-residential buildings need only one foot of freeboard above base flood elevation, or may be floodproofed watertight to that level instead, with a licensed professional engineer or architect certifying the design to the Department of Community Development on a FEMA Floodproofing Certificate. Manufactured homes face the same three-foot freeboard, or, in an existing manufactured home park, may instead sit on reinforced piers at least 36 inches above grade. Any solid foundation wall used to elevate a structure must include flood openings meeting Sec. 46-118(5): at least two openings totaling one square inch of net area per square foot of enclosed area, with the lowest opening no higher than one foot above grade, so floodwater can enter and exit automatically. Accessory structures like sheds and detached garages permitted in the floodplain must be built of flood-resistant materials and anchored against flotation.