Won’t You Be My Neighbor? ADUs Now Permitted by Right in Massachusetts

Accessory Dwelling Units (ADUs) — small, independent living spaces on the same property as a main home — just got a big green light in Massachusetts. Thanks to the Healey-Driscoll Administration’s “Affordable Homes Act,” homeowners can now build or convert ADUs by right in many communities, making it easier to add housing and income flexibility.

If you’re a Realtor®, lender, or homeowner, here’s what you need to know to make sense of the new rules — and how they impact your property or transactions.

What’s an ADU?

An ADU is a secondary living unit with its own sleeping, eating, cooking, and bathroom facilities. Think: a converted garage, a backyard cottage, or a finished basement with a separate entrance.

New Rules (Effective 2024):

The updated state law allows ADUs:

As detached structures
As additions to existing homes
As conversions of garages, attics, or basements

To qualify, the ADU must be:

Less than half the size of the primary residence or under 900 square feet
Located in a single-family zoning district
Code-compliant with a separate entrance

Key Protections for Homeowners

The new law, under MGL Chapter 40A, Section 3, overrides local zoning if the ADU meets minimum state standards:

Cities cannot ban single ADUs
Owner occupancy is not required
ADUs can be rented for long-term housing
Only one extra parking spot can be required

Local Nuances Still Apply:

Municipalities can:

Ban short-term rentals (Airbnb, etc.)
Restrict ADUs in flood zones or historic districts
Require compliance with Title V septic and environmental regulations

Zoning Still Matters

Each of Massachusetts’ 351 towns has its own zoning quirks. While ADUs are protected, local rules may shape your options. Thinking of building one? Start by calling your local planning board.

At The Law Office of David R. Rocheford, Jr., P.C., we help clients navigate land use, permitting, and local regulations with confidence. Whether you’re buying, building, or advising, we’re here to help.

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