Mobile, AL Accessory Structures: ADU Permits (2026)

Alabama has not enacted statewide ADU-by-right legislation comparable to California Government Code §65852.2. As a Dillon Rule state, Mobile exercises zoning powers delegated by the Alabama Legislature under Title 11 Chapter 52 of the Alabama Code. The Mobile Unified Development Code (UDC), codified as Chapter 64 of the City Code and adopted on June 7, 2022, contains ADU provisions for residential districts (R-1 and R-2 series). Industry guidance summarizing Mobile's ADU rules describes a footprint cap roughly in the 800-1,000 square-foot range or about 40 percent of the primary structure, one ADU per lot, a required permanent foundation, one off-street parking space, and architectural compatibility with the principal dwelling. ADUs cannot be sold separately from the main dwelling. Building permits are reviewed by Build Mobile (Permitting & Inspections Division) under Code Chapter 11 (Buildings) and the Alabama Building Commission-adopted International Residential Code, which includes high-velocity wind-load amendments for the Gulf Coast hurricane region (Mobile County). Properties within Mobile's locally designated historic districts also require a Certificate of Appropriateness from the Mobile Architectural Review Board. Properties in FEMA Special Flood Hazard Areas trigger additional flood-resistant construction standards under Mobile's floodplain ordinance.