The Planning Board presented proposed zoning amendments to the Select Board ahead of Town Meeting that would implement statewide changes to accessory dwelling units (ADUs), create a local inclusionary zoning bylaw to require affordable units in larger projects, and update other zoning provisions including signs, lot-shape factors and stormwater exemptions.

Acting Planning Board Chair Amy Peretzky told the Select Board the state’s Affordable Homes Act (effective August 6, 2024) created uniform ADU rules that require towns to permit ADUs more broadly. To comply, the town’s draft bylaws would allow one ADU per lot by right, increase the by-right maximum ADU size to 900 square feet or half of the principal dwelling’s gross floor area (whichever is smaller), remove the requirement that the owner must live in the principal dwelling, and forbid selling the ADU separately from the principal dwelling. ADUs would be subject to Title V septic limits; if a property’s septic could not support additional bedrooms, the owner would need to adjust the septic or the deed restrictions accordingly.

Peretzky and Planning Board staff stressed the law requires towns to accept ADUs on many lot types — including certain nonconforming lots — and that the changes will likely add rental units over time. The board noted ADUs cannot be counted as subsidized affordable housing for the state’s subsidized housing inventory, so ADU growth will affect the denominator used in Chapter 40B compliance calculations and could make it more difficult for the town to remain above the 10% threshold without other affordable-building strategies.

On inclusionary zoning, the Planning Board proposed a trigger of 10 or more new units for a project, with a 15% minimum set-aside of affordable units and an accompanying density bonus (for example, a developer who must provide two affordable units could be allowed to add two additional market-rate units as a density incentive). The board said an earlier MBTA-area feasibility study suggested a 15% requirement was economically feasible for typical multifamily projects and that the inclusionary approach is intended to capture larger projects that would otherwise increase the town’s market-rate denominator without producing subsidized units.

Other amendments presented included a lot-shape standard to manage irregular lots, a clarification that projects approved under the Conservation Commission’s stormwater management permit need not also undergo a separate land-clearing special permit, and downtown sign-code updates to add definitions and standards for projecting, awning and sandwich-board signs.

Select Board members asked about septic and Title V compliance, short-term rental (Airbnb) implications, and whether ADUs on duplexes/triplexes would be allowed; Planning Board staff confirmed ADUs can be associated with multifamily buildings under the state law change and that short-term-rental bans remain an option for a town if the town elects to adopt them separately. The Planning Board will place its recommended warrant language on the Town Meeting warrant for voter consideration.