Commissioners back drafting rules to allow accessory dwelling units in Mount Clemens

At a Mount Clemens work session, commissioners discussed drafting local rules to allow accessory dwelling units (ADUs) in neighborhoods now zoned for single-family housing and directed staff to prepare a model ordinance for the planning commission to consider.

Eric (speaker 2), who presented the item, framed ADUs — also called grandmother flats or mother-in-law apartments — as a practical way to add smaller, flexible housing without radically changing neighborhood character. He said two competing bills in Lansing could alter local options: one would require ADUs in single-family zones statewide; another would make ADUs one selectable option that, if adopted, could unlock state or developer investment. "There is a requirement for owner occupancy of either the primary residence or the ADU, which I think is important because we don't want to try to solve a housing problem and have it be replaced with short-term rentals," Eric said, noting Dexter's ordinance explicitly prohibits ADUs being used as short-term rentals.

The presentation highlighted key regulatory elements commissioners would likely weigh: a minimum lot area example of 5,000 square feet; an example rule that an 800-square-foot ADU may require a larger lot (Dexter uses lot-size or lot-coverage alternatives); a 20-foot height limit for ADUs (including garage-top units); distinctions for attached versus detached units; design standards that match neighborhood character; and a neighbor-notification requirement. Eric said Dexter, a smaller community, has approved six ADUs since adopting its ordinance and had at least one additional permit request.

Commissioners raised potential local consequences. One asked whether permitted ADUs would trigger property reassessments; Greg (staff, speaker 4) responded that "every time a building permit is pulled, it triggers assessment to look at it," though he could not say exactly how assessments would change. Commissioners also flagged enforcement and capacity concerns: the city currently has one rental inspector, and a substantial increase in rental units would increase inspection workload and require registration processes. "We would need to monitor because we have a significant rental population now, and we have one rental inspector," the Chair (speaker 1) said, underscoring the need to account for inspection caseloads.

Several commissioners said they supported moving forward cautiously. One suggested staff adapt the Dexter model and return with a draft for the planning commission to review before the commission votes on any local ordinance. Speaker 3 recommended, "take the model that you have for Dexter...present something back to Greg to give to the planning commission and see what their thoughts are," and Eric agreed to prepare that draft.

The work session ended with the commission directing staff to develop a refined proposal for the planning commission that would include lot-size options, owner-occupancy language, short-term rental prohibitions, and necessary administrative steps (inspector capacity and notification requirements). The matter will next move to the planning commission for review.