Clayton County, GA Accessory Structures: ADU Rules (2026)

Clayton County's zoning ordinance treats a garage apartment, guest house, caretaker house or mother-in-law suite as an accessory dwelling under Sec. 9 (AS-05), and it only reaches conditional-use status in three zoning districts: AG (agricultural), ER (estate residential) and RS-180 (large-lot single-family). Outside those districts, adding a second dwelling unit to a residential lot is not on the table. Two configurations are allowed, and each caps out at one unit per lot. An accessory dwelling built inside the primary house, such as basement quarters, cannot rely on a separate exterior entrance as its only access point, must add one parking space beyond what the house already needs, and has to meet the same building and health code standards as the main residence.

A freestanding accessory dwelling, such as a garage apartment over a detached garage, must sit only in the rear yard, meet the Article 3 setbacks for accessory structures, and sit on a lot of at least 12,000 square feet, larger than the ordinance's baseline minimum lot size for many residential districts. A freestanding unit also requires its own extra parking space. Because AS-05 lists accessory dwellings as a conditional use, an applicant cannot simply pull a building permit. The request has to go through the conditional-use process set out in Article 3, which means a hearing before the Zoning Advisory Group and, ultimately, the Board of Commissioners, where the county weighs neighborhood impact, traffic and parking before approval.

A Zoning Administrator determination governs what counts as basement quarters, caretaker quarters or a similar accessory dwelling if a proposal does not fit neatly into the listed categories.