1 county-level rule, plus city-specific rules for 1 city in Montgomery County, Ohio.
Verified from official government sources
Ohio has no statewide ADU mandate. In unincorporated Montgomery County, ADU permissibility is set by individual township zoning resolutions adopted under R.C. Chapter 519 (township zoning) - not by the county. Building permits for one-, two-, and three-family dwellings (including detached accessory structures) are issued by Montgomery County Building Regulations under the Residential Code of Ohio (RCO, OAC 4101:8). Cities such as Dayton, Kettering, and Centerville set their own ADU rules under R.C. Chapter 713 (municipal zoning).
1 cities in Montgomery County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
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