Alpharetta, GA Building Setbacks & Zoning: Lot Coverage Limits (2026)

The Unified Development Code limits how much of a residential lot a house's footprint may occupy. In the R-10 district, Section 2.2.7 sets a 10,000-square-foot minimum lot size and caps 'Maximum Ground Coverage By Principal Buildings' at 25%, meaning the ground-floor footprint of the house and any attached garage cannot exceed a quarter of the lot area. That same 25% figure is not unique to R-10: the AG, RE, R, R-22, R-15 and R-12 districts carry the identical 25% ground-coverage cap even though their minimum lot sizes range from 5 acres down to 10,000 square feet, so a larger AG lot simply allows a larger house footprint at the same ratio.

Coverage is calculated on principal buildings only; accessory structures such as sheds, detached garages and pools are addressed separately under the accessory-structure setback rules referenced in Section 2.3(c). A related but distinct limit, 'Maximum impervious area,' governs the total hardscape (driveways, patios, walkways) on a lot and is one of the standards a property owner may seek relief from as an exception under Section 4.5.5; exceptions up to 50% of the stipulated requirement go to the Board of Appeals, while larger relief requires City Council approval.

A homeowner who exceeds the 25% building-coverage cap without an approved variance is in violation of the zoning ordinance, and the Director of Community Development can order construction stopped and refuse a certificate of occupancy until the footprint is brought into compliance.