Cobb County, GA Building Setbacks & Zoning: Setback Rules (2026)

Cobb County's zoning code splits setback rules two ways: the summary of bulk regulations at section 134-191 tabulates minimum lot width, front yard, major side yard, side yard, rear yard, lot coverage and height for every district, and each district's own section (134-193 through 134-207) restates and applies those numbers with a labeled diagram. The code itself resolves any mismatch between the two: the summary table's closing notes state that in the event of a conflict between the summary charts or diagrams, the chart shall prevail, so the section 134-191 table controls.

For R-20, the county's most common half-acre single-family district, section 134-197(4) sets a 20,000-square-foot minimum lot size, 75 feet of lot width at the front setback line (50 feet on a cul-de-sac), and building setbacks of 40 feet on an arterial or collector frontage, 35 feet on a local street, 10 feet on the side yard, 35 feet on the rear yard, and 25 or 35 feet on the major side yard, with the 35-foot figure applying once a structure fronts that major side. The larger-lot RR district requires 50-foot front, 25-foot side and 35-foot rear yards on a 40,000-square-foot lot, while the denser R-15 district drops the rear yard to 30 feet on a 15,000-square-foot lot. Every setback is measured from the future right-of-way rather than the existing curb line, and on a lot with unequal road frontage, the side with the shorter frontage becomes the front setback for locating the other yards.

Section 134-197(4)a also caps how far the board of zoning appeals can go on its own authority: it is not authorized to recommend a variance for more than 25 percent of the minimum lot size, so a bigger reduction needs a rezoning application to the board of commissioners rather than a routine BZA hearing. These figures govern unincorporated Cobb County only. Marietta, Smyrna, Kennesaw, Acworth, Powder Springs and Austell each administer their own zoning code and setback tables.