Can I build an accessory dwelling unit (ADU) or in-law suite in Canton Township?

Only on rural acreage, and only with special approval. Canton Township permits accessory apartments as a special land use in the RA, RE, and RR districts, with four conditions: a lot of at least 2 acres, apartment floor area of no more than 600 square feet, a design that keeps the single-family look, and one extra parking space (Section 9.02.B.1; Section 10.02.B.1). Occupancy is limited by definition to relatives, domestic servants, or unpaid guests (Section 1.03), so it cannot be a rental unit. A detached guesthouse for temporary sleeping use is a separate special land use in the same districts (Section 9.02.B.2).

In the subdivision districts, R-1 through R-5, R-6, MR, and RMH, accessory apartments are not in the use lists, and the general provisions block the workarounds: accessory buildings may not be dwellings (Section 2.03.D.4), one principal building per lot (Section 2.09.A.2), and no basement-only dwellings (Section 2.04).

An in-law suite inside your existing house that shares the kitchen and never becomes a separate unit is generally a building-code question rather than a zoning one, but the line between suite and second dwelling is an interpretation call. Approval runs through the Township Board special land use process with a public hearing (Section 27.03). Start with Planning Services at 734-394-5170.