Marietta, GA Accessory Structures: ADU Rules (2026)

01(C)(2) of the R-1 zoning district lets a property owner build one accessory dwelling unit as a conditional use approved administratively by the Director rather than through a public hearing. The ADU must be located to the rear of the principal structure and set back at least 10 feet from any property line, and the lot must carry 5,000 square feet dedicated to the ADU on top of the district's normal lot-area requirement for the main house. No paying guests or tenants may occupy the unit, and no second similar accessory structure can exist on the same lot.

Height is capped at whatever the principal structure measures, and the ADU's footprint cannot exceed 50 percent of the principal structure's footprint. Once the structure passes 15 feet in height, the setback tightens: it must sit at least 10 feet from the side property line and 35 feet from the rear property line, or a distance equal to its own height, whichever is smaller. On corner lots, the ADU cannot sit closer to the abutting right-of-way than the principal house does. 01(C)(2)(i) requires the property owner to occupy either the main house or the accessory unit, so a Marietta ADU can never be a purely rental, absentee-owner setup. 04 for the R-2, R-3 and R-4 districts, so the ADU rules track Marietta's single-family residential zoning generally rather than one district alone.