Cobb County, GA Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Buildable area rule
- 12,500 sq ft at least 18 in. above BFE
- Smaller-lot exception
- Director may allow less, still 18 in. above BFE
- Roadway freeboard
- Public/private roads 3 ft above BFE at centerline
- Building freeboard
- Lowest floor 3 ft above BFE or 1 ft above future-conditions
- Civil penalty
- Up to $1,000 per day unremedied
- Criminal penalty
- Up to $1,000 fine or 60 days jail
- Scope
- Unincorporated Cobb County only
Summary
In unincorporated Cobb County, new residential development in the floodplain must keep at least 12,500 square feet of contiguous buildable land 18 inches above the base flood elevation, and new construction's lowest floor must sit three feet above base flood elevation or one foot above the future-conditions flood elevation, whichever is higher. The Community Development Agency and Water System Stormwater Management Division administer Chapter 58's floodplain rules.
Sec. 58-67. - Development standards. The following development standards shall apply: ... (2) In districts which permit residential use, not less than 12,500 square feet of a single contiguous area of one zoning classification shall be at least 18 inches above the effective base flood elevation such that encroachments into the future-conditions "built-out" conditions floodplain for residential structures will not be required. A smaller such area of less than 12,500 square feet but still at least 18 inches above the future-conditions flood elevation may be permitted at the sole discretion of the director upon petition supported by documentation in conformance with subsection 58-68(3). (3) ... Unless a variance is granted both public and private roadways shall be constructed not less than three feet above the base flood elevation measured at the centerline of the road.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 53).
Full Breakdown
Section 58-67 of the Cobb County Code sets the development standards that apply to any parcel touching the floodplain, working alongside the elevation rules in sections 58-70 and 58-53 that the county's community development agency and Water System Stormwater Management Division enforce. Under 58-67(2), any district that permits residential use must keep at least 12,500 square feet of a single, contiguous zoning area at least 18 inches above the effective base flood elevation, so a house can be sited without encroaching into the future-conditions built-out floodplain.
If a lot cannot meet the 12,500-square-foot threshold, the director of community development may approve a smaller area, still 18 inches above the future-conditions flood elevation, but only on a petition backed by the documentation required under section 58-68(3), which also requires a plat notation of the base flood water surface elevation and a drainage easement over any land below it. Roads serving the site carry their own freeboard: 58-67(3) requires public and private roadways, other than a single-residence driveway, to sit at least three feet above base flood elevation at the road centerline unless a variance is granted, and utility access points must clear the base flood elevation entirely.
Section 58-70(b)(1) sets the building-level freeboard: new construction and substantial improvements must have the lowest floor, including any basement, elevated no lower than three feet above base flood elevation or one foot above the future-conditions flood elevation, whichever is higher; nonresidential buildings may floodproof to the same level instead, certified by a Georgia-licensed engineer or architect. Before any of this can be built, section 58-52 requires a floodplain management/flood damage prevention plan stamped by a professional engineer, plus an as-built elevation certificate after the lowest floor is set and a final certificate after construction; owners in flood zones A or AE must obtain a FEMA letter of map revision before occupying the building.
Section 58-67(1)a also lets an owner request an administrative variance of up to 100 percent of a setback or lot-size requirement in exchange for donating or dedicating land for stormwater quantity or quality purposes, processed under section 134-35 and reported to the district commissioner.
Violations & Fines
The community development agency issues a written notice of violation identifying the defect and a compliance deadline; unresolved violations can trigger a stop-work order, a withheld certificate of occupancy, or permit suspension. Civil penalties run up to $1,000 per day the violation continues after notice, under section 58-57(4). Intentional or flagrant violations are prosecuted in magistrate court as a misdemeanor, punishable by a fine up to $1,000, up to 60 days' imprisonment, or both, with each day treated as a separate offense; repeat violators risk losing their county business licenses.
Frequently Asked Questions
Does this floodplain elevation rule apply inside Marietta or Smyrna?
How much higher than the base flood elevation must my house sit?
What happens if I build without meeting the elevation standard?
Can I get a variance from the 18-inch buildable-area requirement?
Sources & Official References
Other rules in Cobb County
Compare Cobb County to another location·View the Georgia environmental rules overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.