Millis planning board refers revised accessory-dwelling-unit bylaw edits to select board ahead of anticipated Attorney General decision

The Millis Planning Board on Tuesday reviewed recommended edits to the town’s accessory dwelling unit (ADU) bylaw and voted to refer the revised draft to the select board for further action.

Attorney Jay (presenting to the board) told members the state Attorney General’s office has signaled it will disallow some language several towns had included when they adopted ADU bylaws, and said Millis should make targeted changes now to avoid a later partial disapproval. Board counsel and planners have discussed anticipatory edits that track AG and state guidance, Jay said; the AG is expected to issue a decision on the matter on Aug. 26.

Key points discussed: - Definition and scope: The board’s original language described ADUs as accessory to single-family homes. The AG and state implementing guidance treat ADUs as potentially accessory to any residential structure; counsel recommended removing the single-family limitation and instead tying dimensional rules to the most permissive residential form in the town’s zoning code. Presenters said that change is expected to be largely technical in Millis because current dimensional standards are already keyed to single-family settings. - Preexisting nonconforming structures: Counsel explained the tension between the ADU statute and preexisting-nonconforming rules under state law (Chapter 40A/Chapter 48 references). The AG indicated towns cannot require a special permit for ADU use in many cases; instead, Millis can rely on a “favorable finding” standard (a less rigorous administrative finding used for expansions of nonconforming structures) to evaluate conversions of carriage houses, garages and similar features. The board’s draft was edited to replace a special-permit requirement with language allowing a favorable finding by the Zoning Board of Appeals where appropriate. - Parking and site plan provisions: The draft will specify that one off-street parking space must be provided for an ADU (the AG flagged language that said “at least one” and asked for “one”), and the bylaw will retain site-plan review provisions for architectural compatibility and screening while removing unnecessary special-permit barriers. The town will continue to disallow tandem spaces for ADU parking in the draft.

Board member Alan raised an issue about a remaining reference to "single-family" in a parking clause; counsel agreed to remove it. Members discussed 40B developments and whether ADUs would be permitted to attach to or modify units covered by Chapter 40B permits; counsel said outcomes depend on the 40B permit language.

After discussion the board voted to refer the revised ADU bylaw language, including the additional change noted by member Alan, to the select board and to schedule a public hearing in September. Several members said they preferred to move sooner rather than later to give the building department and homeowners predictability ahead of the AG’s decision.

Why it matters: ADU rules increase opportunities for smaller rental or owner-occupied units; changes the AG requires could affect how many and which property owners can add units, and how local boards apply dimensional and nonconformity standards.

What’s next: Planning staff will transmit the updated draft and a memo describing changes to the select board; the planning board plans a public hearing in September and expects to adjust minor text after the AG issues its formal decision.