Planning board narrows ADU bylaw debate; schedules public hearing

The Planning Board on July 9 agreed to move the town’s ADU bylaw to public hearing after months of drafting and detailed debate over size, ownership and enforcement.

The Chair opened the discussion on the proposed maximum size, and a Committee member said, "I wanted to discuss the 1,200 square foot maximum size," questioning whether that scale was appropriate for backyard accessory units. Several members pressed for the state standard; one board member said, "I would prefer that we go to the state 900 square feet," noting that 900 is the state-prescribed maximum or half the principal dwelling, whichever is smaller.

Why it matters: board members split along a housing-versus-scale axis. Supporters of 1,200 square feet argued it would increase housing options and allow families to occupy ADUs, while others warned a 1,200-square-foot unit would be out of scale with typical neighborhood homes and could allow conversions that undermine single-family character.

Board discussion then focused on what counts toward an ADU’s gross floor area. A staff member explained that "gross floor area is defined in state regulations," and that the definition typically excludes garages but can include basements and lofts under certain conditions. Members flagged an enforcement risk: building a detached garage that was later converted to living space could effectively expand an ADU beyond permitted size. The board asked staff to draft clearer gross-floor-area language and permit checks to reduce that loophole.

On ownership and process, members debated whether to require ADUs to remain in common ownership with the principal dwelling. Legal counsel told the board zoning typically cannot regulate ownership form but acknowledged that preserving an accessory relationship argues for ownership constraints or special findings; one member warned attorneys could condominiumize properties to avoid restrictions. The board asked staff to explore a bylaw finding or other drafting approaches to preserve ADU accessory status without running afoul of state rules.

The board also discussed whether to permit a second ADU on large lots and whether septic capacity should be a limiting factor. Speakers noted septic sizing is typically bedroom-based and that an additional septic or system upgrade may be required; on balance, members favored not allowing a second ADU by right and raised the option of limited exceptions.

On short-term rentals, multiple members supported retaining a prohibition on vacation/short-term use of ADUs. A Committee member said the "purpose of the state bylaw is to create housing, not short-term, vacation rentals," and the board agreed to keep the restriction.

After refining language and identifying the chief issues—maximum gross floor area, common-ownership provisions, number of ADUs and enforcement—the board voted to schedule a public hearing on the ADU bylaw. The motion to advertise and set the hearing passed by voice vote.

Next steps: staff will draft clarified definitions and reconcile language about nonconforming structures; the board will carry the ADU bylaw to a publicly noticed hearing for further comment and potential revision.