Housing and Community Development

Accessory Dwelling Units

Accessory dwelling units (ADUs), also called "accessory apartments," are small, secondary living spaces located on the same lot as a principal dwelling unit. ADUs can be attached to an existing home or detached on the same lot.

Accessory dwelling units can support downsizing seniors, recent graduates, small families, and individuals with disabilities.

As a part of the Affordable Homes Act, signed into law on August 6th, 2024, ADUs are now allowed by right in Massachusetts. The amendments to Chapter 40A Section 3 will become effective on February 2nd, 2025.

ADUs allow homeowners to create secondary living spaces on their property. ADUs broaden the range of housing choices in a community by increasing the number of small dwelling units available for rent.

SRPEDD staff are in touch with the Executive Office of Housing and Livable Communities (EOHLC) regarding the new legislation. More information regarding by-right ADUs is expected to come in Fall 2024. In the interim, municipal staff should consult with their City Solicitor or Town Counsel for legal advice.

Do you have a question about the new law or are you interested in modifying your community's ADU bylaw?

Please email one of our staff contacts with your question and we will be in touch.

Important Links

EOHLC AHA Resource Page

Stay up to date on updates from EOHLC on the Affordable Homes Act.

APA MA Webinars on ADUs

Read the AHA Fact Sheet

Read the fact sheet on the recently passed Affordable Homes Act.

The Affordable Homes Act

Read the full text of the Affordable Homes Act (Bill H.4138).

What can Communities Regulate?

Under the new law (which amends § 1A and § 3 of Chapter 40A "the Zoning Act"), communities cannot unreasonably restrict or require a special permit or other discretionary zoning approval process to construct an ADU. EOHLC may issue guidelines or promulgate regulations on further administration of by right ADUs.

Communities can regulate ADUs by:

Imposing Site Plan Review;
Imposing restrictions on short-term rentals;
Setting basic size and dimensional standards; and
Setting "other reasonable restrictions."

Communities cannot regulate ADUs by:

Requiring a special permit;
Requiring more than 1 parking space for an ADU within a half-mile of a transit station, including commuter rail;
Imposing owner-occupancy restrictions;
Prohibiting rentals (except for short-term rentals); or
Setting other unreasonable restrictions.

Under the law, a special permit is required to construct a second ADU on a property in a single-family residential zoning district. ADUs are subject to reasonable regulations, including 310 CMR 15.000 ("Title 5") and MGL c. 131 § 40 / 310 CMR 10.00 ("The Wetlands Protection Act" and associated regulations).