Detroit, MI Accessory Structures: ADU Permits (2026)

Detroit's zoning is codified at Chapter 50 of the City Code (the 2019 Zoning Ordinance), administered by the Buildings, Safety Engineering, and Environmental Department (BSEED) and the Planning and Development Department. Under the existing code, accessory dwelling units are not a by-right use in single-family (R1) or two-family (R2) districts. The narrow path for an ADU has been preservation of historic carriage houses and accessory structures legally established before 1940 — these may be reactivated as a dwelling with a building permit, a certificate of occupancy, and review by the Historic District Commission if in a designated historic district. In October 2025 the Detroit City Council took up the 'Let's Build More Housing' zoning reform package, which proposes legalizing ADUs by-right in additional residential zones citywide; that ordinance was still moving through Council and the Planning Commission as of the date of this article, so applicants should confirm current status with BSEED before designing a project. All ADU work requires a building permit, plan review for the Michigan Residential Code (egress, ceiling height, smoke/CO alarms, light/ventilation), and a separate certificate of occupancy because adding a dwelling unit is a change of use.