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Westwood Ahead of the Curve on ADUs

A study published by the Pioneer Institute and the Massachusetts Smart Growth Coalition lists Westwood among a small group of municipalities in the Greater Boston area with zoning bylaws that adopt best practices in permitting Accessory Dwelling Units.

Known as accessory apartments, in-law apartments or even granny flats, ADUs are small dwellings located within or behind a single family home. Although ADUs are widely considered by housing experts, sustainable development advocates and community planning organizations to be a beneficial mode of residential development to both municipalities and homeowners, nearly 2/3 of the 100 cities and towns in the Metropolitan Area Planning Council (MAPC) region outside Boston restrict development of ADUs.

By contrast, Westwood’s Bylaw allows accessory apartments to be constructed via special permit, awarded at the discretion of the Zoning Board of Appeals and subject to restrictions that seek to preserve neighborhood character and the appearance of a single family home. For example, accessory apartments in Westwood must adhere to maximum size requirements and cannot contain exterior staircases. The Bylaw also requires owner occupancy in either the apartment or the primary dwelling unit, which inherently maintains owner investment in the property and safeguards against common concerns such as noise. Provided the owner resides onsite, our Bylaw allows rental use in accessory apartments, a practice the study strongly encourages due to legality, enforcement, safety, and local housing shortages. Finally, permits promote safety: the unit must have two forms of egress and receive the benefit of a full inspection by the Building Department before a Certificate of Occupancy is issued.

According to the study, the benefit to homeowners and municipalities is considerable. In Westwood, we observe accessory apartments being used to care for aging relatives, provide live-in space for caretakers, comfortably house young adult children, or generate rental income that allows residents to stay in their hometown. The Town’s creation of a legal permitting process for accessory apartments results in safer units and allows for incremental production of housing that is affordable.

With an aging population and soaring housing market, accessory apartments are a sustainable way to offer property owners the flexibility they need with minimal impact on existing neighborhoods or town resources. Westwood is proud to have incorporated this innovative housing development tool into its Bylaw over 20 years ago. Residents voted at Town Meeting in 2017 to raise the maximum number of accessory apartment special permits, and many are still available.

If you are interested in learning more about accessory apartments, or wish to obtain a permit to add one to your home, please contact Sarah Bouchard, Housing & Zoning Agent, at or 781-251-2598.

You can read the study, “The State of Zoning for Accessory Dwelling Units” by Amy Dain of the Pioneer Institute, co-sponsored by the Massachusetts Smart Growth Alliance, at: