Charleston, SC Accessory Structures: ADU Permits (2026)

The Charleston Zoning Ordinance (Title 54) regulates accessory dwelling units as accessory uses to single-family residential dwellings. Permitted zones, dimensional standards, and design requirements are set in the underlying district regulations and in the accessory-uses provisions. Applicants must submit a zoning permit application demonstrating compliance with use, lot coverage, setback, and height limits, followed by a building permit through the Charleston Permit Center. Construction follows the 2021 IRC and 2021 IBC as adopted by the South Carolina Building Codes Council under SC Code Title 6, Chapter 9. Properties located within the Old & Historic District or the Old City District (the largest US historic district covering pre-1810 architecture) must obtain Board of Architectural Review approval under Title 54 before a building permit may be issued; the BAR-Large oversees major projects and BAR-Small oversees minor work. Properties on the National Register or in National Register districts may also trigger review. ADUs in flood-hazard areas must comply with Charleston's Flood Damage Prevention Ordinance and elevation standards. Detached ADUs are typically subject to single-family setbacks and rear-yard placement.