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The Troy Zoning Ordinance does not permit or mention accessory dwelling units. The May 2026 text contains no ADU provisions, and the Section 4.21 use schedule has no ADU row. Section 7.02.B.1 allows one single-family or two-family dwelling per lot.
Treat a second dwelling unit on a one-family lot as not permitted absent a rezoning or a use variance (Section 15.04.F). That conclusion is drawn from the ordinance's silence rather than an express prohibition, so confirm it with the Planning Department before planning a project.