Massachusetts Home Buyer Guide

Massachusetts homeowners and prospective home buyers should expect to see thousands more accessory dwelling units (ADUs) in neighborhoods throughout the state in the coming years after the signing of a new law.

ADUs, sometimes called an in-law apartment or a "granny flat," are secondary dwellings on a primary residential property. Some also call an ADU an accessory apartment, guest apartment, family apartment, or a "mother-in-law house."

For a time, ADUs fell out of fashion.  In recent years, ADUs have come back into focus as an effective avenue for homeowners to increase the value or utility of their property and a way for state and local governments to increase housing units.

Massachusetts Governor Maura Healey signed a $5.16 billion housing bond bill on Tuesday, August 6, 2024 ("the Affordable Homes Act" [the "Act"]). A key provision allows ADUs, by right, in single-family zoned neighborhoods statewide. ADUs can be basement or attic apartments, home additions, or small detached dwellings on the primary property. There are still rules and regulations governing ADUs, but the new law allows homeowners more flexibility and options.

Local governments can impose reasonable regulations, such as, but not limited to, site plan review, dimensional setbacks, restrictions on the bulk and height of structures, and restrictions on and prohibition of short-term rental ADUs.

The new provisions in the Act supersede any inconsistent local bylaws already in existence, although the ADU provision will not be in effect until February 2, 2025, 180 days after the Act became law.

Key Points of the Law to Know:

• No Local Zoning Approval Needed: ADUs can be up to 900 square feet or half the size of the primary home, whichever is smaller. Homeowners are not required to obtain a special permit for one ADU.
  
  
• Occupancy Flexibility: ADU occupants are not required to be related to the property owner, which is a common restriction. An owner does not have to occupy the property, another often-seen restriction. The ADUs may require one parking space per unit; however, the law does not require any parking spaces if the unit is within 1/2 mile of a commuter rail station, subway station, ferry terminal, or bus station.
  
  
• Short-Term Rentals Still Regulated: Local laws on short-term rentals, such as Airbnb, still apply, but municipalities cannot unreasonably restrict ADUs.

ADUs were legal in Massachusetts; however, zoning varied widely by city and town. Some communities, such as Haverhill and Burlington, had looser ADU regulations. Other municipalities had onerous restrictions, making adding an ADU to a property cumbersome and frustrating. State officials believe the new law will add 8,000-10,000 ADUs over five years.

Supporters of the new law argue, among other things, the ability of homeowners to utilize their property and add more housing in a community. Opponents point to how adding units in quiet single-family residential locations will effectively change neighborhoods to multi-family zones.