For years, Massachusetts homeowners had to jump through hoops to get approval for an Accessory Dwelling Unit (ADU) such as an in-law apartment. Between zoning restrictions and permitting issues many great ideas never got off the ground. But that’s all changing.
Thanks to the Affordable Homes Act signed by Governor Maura Healey, it’s now easier than ever for homeowners in Belmont and surrounding communities to build an ADU—and the possibilities are exciting!
Whether you’re thinking of adding an in-law apartment, a rental unit, an art studio, or a guest cottage, the new law makes it far simpler to get started.
Understanding the New ADU Law
The new law went into effect on February 2, 2025 allowing for ADUs to be permitted “by right” statewide in single-family residential zones. Here’s what that means for you:
✅ “By Right” Permitting
While ADUs are permitted “by right” which streamlines the process and reduces red tape, building permits are still required for renovations to ensure that proper building code is followed.
📏 Size Limits
An ADU may be no larger than 900 square feet, or no more than 50% of the size of the primary home—whichever is smaller. This allows for practical, functional spaces that complement the main residence.
🏠 No Owner-Occupancy Requirement
You don’t have to live in the house yourself to build or rent out an ADU. This creates more flexibility for homeowners and opens up new possibilities for rental income or property investments.
🧭 Flexibility in Location
ADUs can be located:
- Internally, such as a basement apartment with a private entrance
- Attached, like converting a garage or building an addition
- Detached, such as a small backyard cottage or “tiny house”
🔄 Multiple Uses
ADUs can serve a wide range of purposes, depending on your needs:
- In-law apartment for aging parents or adult children
- Rental apartment for additional income (note that if the home is located within a half mile of public transportation a parking space isn’t required)
- Guest suite for visiting family or friends
- Home office or creative studio with peace and privacy
The Gallagher Remodeling team has experience converting buildings to ADUs, including this antique carriage house , which became an inspiring artist’s studio.
How Gallagher Remodeling Can Help
The new laws can be confusing and can be applied differently depending on the town. For more information on the town of Belmont, click here. The Belmont Voice also wrote an informative article.
At Gallagher Remodeling, we’ve worked with homeowners in Belmont and surrounding towns for over 39 years, designing and building beautiful, practical spaces that improve daily life. With the new ADU laws, we’re excited to help clients create:
- Comfortable, code-compliant in-law apartments for aging parents or boomeranging kids
- Thoughtfully designed rental units
- Custom studios or work-from-home spaces that inspire creativity
From initial design and permitting to construction and finish work, we handle every step of the process with care, quality, and attention to detail.
An ADU can have a full kitchen and a bathroom along with other amenities.