4 county-level rules, plus city-specific rules for 1 city in Oakland County, Michigan.
Verified from official government sources
Michigan has no statewide accessory dwelling unit (ADU) law, and Oakland County does not regulate residential zoning — each city, village, and township sets its own ADU rules under the Michigan Zoning Enabling Act (MCL 125.3201 et seq.). Approaches differ sharply across Oakland County: Pontiac's zoning ordinance allows only 'one dwelling unit structure' per lot (effectively prohibiting detached ADUs without rezoning), while Farmington has adopted an express ADU framework allowing detached backyard cottages subject to lot-size, parking, and design standards.
Pontiac Zoning Ordinance §2.505 (One and Two Family Dwelling Unit Structures)
Only one dwelling unit structure shall occupy a lot or site condominium unit.
Michigan's Residential Code (adopted statewide) requires a building permit for any detached accessory structure larger than 200 square feet. Sheds 200 sq ft or smaller are exempt from a state building permit but must still meet the zoning rules of the Oakland County municipality. Typical Oakland County standards: minimum 5 ft setback from side/rear lot lines, 10 ft separation from the principal dwelling, rear-yard only, and one-story max height (commonly 14–15 ft).
Rochester Hills Accessory Structures Guidebook (2026)
A building permit is not required for Detached Accessory Structures 200 sq. ft. or less, however, they shall comply with the following: Structures shall be more than 10 feet from the main building or any other Accessory Structure. Structures may be located in the side or rear yards of the property only, no closer than 5 feet from the property line and not in the front yard or within an easement...
Converting a garage to living space in Oakland County requires (a) a zoning determination that the conversion is permitted in the district, (b) a building permit reviewed against the Michigan Residential Code, and (c) replacement of any required off-street parking the garage previously satisfied. Most Oakland County zoning codes (Pontiac, Royal Oak Ch. 770, Troy Ch. 39) require single-family lots to provide a minimum of 2 off-street parking spaces — converting the only enclosed garage typically forces the owner to add a new parking pad or detached garage.
No Oakland County municipality has adopted an express tiny-home ordinance. Tiny houses on permanent foundations must meet the Michigan Residential Code (MRC) and the host city's minimum dwelling-unit floor area — commonly 800–1,200 sq ft in single-family districts. Tiny houses on wheels (THOWs) are treated as recreational vehicles or manufactured housing and are generally prohibited as full-time residences in residential zones; they are permitted only in licensed mobile-home parks under MCL 125.2301 (Mobile Home Commission Act).
1 cities in Oakland County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
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