Above: When the Town sought approval for its ADU bylaw, voters were shown a variety of styles that would be allowed. The version approved by the AG’s office adds mobile homes to allowed uses, though not trailers. (image cropped from past presentation)
This week, the Attorney General’s office issued its finding on the Town’s bylaws allowing, but limiting, the by-right use of Accessory Dwelling Units. The version overwhelmingly passed by Town Meeting voters last fall is only “partially” approved as complying with state laws.
The AG’s office made one exception, striking the bylaw’s ban on allowing “mobile homes” to qualify as ADUs.1
Based on information from the Executive Office of Housing & Liveable Communities, the Planning Board had believed that the Town was allowed Towns to restrict mobile homes from being used as ADUs.
The letter from an Assistant Attorney General clarifies that the issue with Southborough’s ban is the pre-existing definition for “mobile homes” under the Town’s bylaws. The bylaw would have banned some types of ADUs that the AAG opines are protected by state law.
According to AAG Nicole B. Caprioli, the ban would have illegally disqualified some manufactured homes. The version approved by the AAG, and now in effect as a Town bylaw, does still include the ban on using travel trailers as ADUs.
Caprioli highlighted that under the state’s law to expand housing opportunities, the Town isn’t allowed to “unreasonably” regulate ADUs. She then pointed to the Town’s zoning use definitions for “mobile homes”:
A structure, transportable in one or more units, built on a permanent chassis, equipped with wheels for towing to its destination, provided with internal heating, plumbing and electrical systems and designed to be used as a dwelling when connected to the required utilities, with or without a foundation.
She followed with the definition for Modular Dwelling Units under the state regulations:
A pre-designed Dwelling Unit assembled and equipped with internal plumbing, electrical or similar systems prior to movement to the site where such Dwelling Unit is affixed to a foundation and connected to external utilities; or any portable structure with walls, a floor, and a room, designed or used as a Dwelling Unit, transportable in one or more sections and
affixed to a foundation an connected to external utilities.
Caprioli determined:
with regards to a “Modular Dwelling Unit,” the Regulations 760 CMR 71.03 (3)(b)(7) provide that “[a]ny requirement that prohibits, regulates or restricts a Modular Dwelling Unit from being used as a Protected Use ADU that is more restrictive than the Building Code” is an unreasonable regulation. As defined under the Regulations, Modular Dwelling Units may be transported in one or more sections, must be affixed to a foundation that meets the building code and connected to external utilities at the site. A Modular Dwelling Unit could therefore include a manufactured home, and thus could include a “mobile home” particularly given the Town’s definition of “mobile home.
You can read the full letter here.
The Planning Board had already been charged with holding hearings on proposed revisions to the ADU bylaw in time for Annual Town Meeting this April.
That work is based on the Zoning Board of Appeals’ proposal to expand allowed ADU uses. The main focus has been on allowing owners of small homes to have more options for adding ADUs.
Now, the Planning Board will likely discuss whether or not to propose a revised definition of mobile homes and a second attempt at restricting their use as ADUs.
As of Planning’s most recent meeting, the intent was to advertise the public hearing for the ADU zoning by February 18th for opening on March 9th. In between, they did plan to continue discussing the zoning at their next meeting on February 23rd.
Stay tuned for more news on the ADU bylaw and other zoning changes headed to Town Meeting.

