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The Zoning Ordinance has no accessory dwelling unit provision. We searched the current ordinance (effective March 8, 2018, amended through February 1, 2024) and found no ADU, granny flat, or second-kitchen allowance. What the text does say points the other way: only one principal building is allowed per lot in the one- and two-family districts (Section 3.29.A; Section 5.12), a dwelling unit is defined as housing one family (Section 2.2), home occupations cannot occupy accessory structures (Section 4.2.E), and accessory buildings may not involve any business or separate use (Section 5.2.A.7).
If you want a second unit for a relative, talk to the Planning and Zoning Department (586-726-7243) about rezoning to R-2 or a multiple-family district. Note that the temporary dwelling provision (Section 7.22) is only a disaster-recovery tool: the building director may allow temporary occupancy of a mobile home or trailer after a house fire, tornado, or similar act of God, for up to six months with one extension. Treat any online claim that Shelby Township allows ADUs as unverified.