Are accessory dwelling units (ADUs) allowed in Troy, Michigan?

No. The Troy Zoning Ordinance does not permit accessory dwelling units, and the text does not mention them at all. The use schedule in Section 4.21 has no ADU category, and Section 7.02.B.1 allows only one single-family or two-family dwelling per lot.

That means a second dwelling unit on a one-family lot, whether a backyard cottage, a garage conversion with its own kitchen, or a separate basement apartment, is not permitted under the current ordinance.

The available paths are limited:

• Use variance from the Zoning Board of Appeals, which requires an unnecessary hardship showing and a two-thirds vote (Section 15.04.F).
• Rezoning, where the Planning Commission recommends and City Council decides (Article 11).

Both are significant undertakings with no promised outcome. Confirm the current rules with the Planning Department at 248-524-3364 before planning a project.