Gwinnett County, GA Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Freeboard
- 3 ft above base flood elevation
- Alternative
- 1 ft above future-conditions elevation
- Applies to
- residential substantial improvements
- Non-residential option
- flood-proof instead of elevate
- Proof required
- certified elevation certificate
Summary
Substantially improved residential structures in Gwinnett's flood hazard areas must set the lowest floor at least three feet above the 100-year base flood elevation, or one foot above the future-conditions flood elevation, whichever is higher.
Substantial improvements. For substantial improvements to all or part of an existing principal residential buildings, the requirements of Sections 700-20.1 through 700-20.3 and Sections 700-30.1 et seq., shall apply and the elevation of the lowest floor, including basement and access to the building, shall be elevated at least three feet above the level of the highest base flood elevation (100-year) adjacent to the building or at least 1 foot above the future conditions flood elevation whichever is highest.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 9).
Full Breakdown
For substantial improvements to existing residential buildings in an Area of Special Flood Hazard, UDO Section 700-40.2 requires the lowest floor, including the basement and building access, to sit at least three feet above the highest base flood elevation (the 100-year flood) adjacent to the building, or at least one foot above the future-conditions flood elevation, whichever is higher. Non-residential buildings may flood-proof instead of elevate under separate criteria in the same section, and openings must let floodwater move freely through any enclosed space below the elevated floor.
Violations & Fines
Building below the required freeboard elevation without an approved flood-proofing alternative violates Chapter 700; the Department of Planning and Development can withhold the framing inspection and certificate of occupancy until a certified elevation certificate confirms compliance.
Frequently Asked Questions
How high above the base flood elevation must a Gwinnett County house be built?
Can a commercial building in the floodplain skip elevating?
Sources & Official References
Other rules in Gwinnett County
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