Snellville

Gwinnett County, GA (957,000 residents) administers the Gwinnett County Unified Development Ordinance (UDO) for unincorporated territory. ADUs are conditionally permitted in some residential districts. Major incorporated cities include Lawrenceville, Duluth, Norcross, Snellville, Suwanee, Lilburn, Buford (portion), Sugar Hill, Loganville (portion).

• Gwinnett County Unified Development Ordinance

State-floor overlay: No GA statewide ADU preemption.

Gwinnett County administers flood-hazard, and (where mapped) coastal, wildland-fire, historic, and airport overlays that shape ADU project feasibility. The most consistent overlay across the county is FEMA NFIP floodplain regulation; other overlays apply to specific geographies inside the county.

• FEMA NFIP Special Flood Hazard Areas in Gwinnett County — A new ADU in a mapped SFHA must be elevated to or above the Base Flood Elevation; cost impact on the project is often material.
• Historic districts and individually-listed historic resources

Gwinnett County issues building permits for parcels in unincorporated territory through its development services / planning department, with separate review tracks for zoning conformance, building-code compliance, on-site sewage where applicable, floodplain compliance, and addressing. Inside incorporated municipalities, city departments handle their own permits; the county's authority is geographically limited to unincorporated territory. An ADU permit application is typically processed as a residential building permit with a zoning verification step against the county's ordinance for the parcel's zoning district.