What is an ADU?
An Accessory Dwelling Unit is a secondary residential living space located on the same lot of a single-family home. ADUs can play a significant role in our housing crisis. The ADU policy recently signed by the governor allows property owners to build an ADU without having to get special or discretionary approval from the local zoning board.
ADUs can be within an existing primary residence, like converting a basement into an apartment, attached to a primary residence as a new construction addition, or completely detached, like a cottage or converted detached garage in a backyard.
The Affordable Homes Act amends the definition of “Accessory Dwelling Unit” under Section 1A of Chapter 40A of the General Laws to clarify that the maximum size of an ADU is no more than half of the gross floor area of the principal dwelling, or 900 square feet, whichever is smaller. The definition was also amended to prohibit owner-occupancy requirements and unreasonably restricting the creation or rental of an ADU that is not being used as a short-term rental, as that term is defined in room occupancy excise laws (Section 1 of Chapter 64G of the General Laws).
What is the law?
On August 6, 2024, Governor Healey signed the Affordable Homes Act into law (Chapter 150 of the Acts of 2024). Section 8 of the Affordable Homes Act amends the Zoning Act to allow ADUs up to 900 square feet to be built by right in single-family zoning districts. The historic legislation authorized $5.16 billion in spending over five years along with nearly 50 policy initiatives to counter rising housing costs. The new law on ADUs is an example of a small policy change that will make a big difference. Massachusetts is a leader in finding innovative solutions to our biggest challenges. Rising housing costs and homelessness are not unique challenges for our state, but we can lead the way in solving them.
An ADU must:
- Maintain a separate entrance, either directly from the outside or through an entry hall or corridor shared with the principal dwelling sufficient to meet the requirements of the state building code for safe egress;
- Be either no larger than half the gross floor area of the principal dwelling or 900 square feet, whichever is smaller;
- Meet municipal restrictions, including, but not limited to, additional size restrictions and restrictions or prohibitions on short-term rental.
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What are the benefits of ADUs?
Property owner benefits:
- Provide an additional rental income for property owners, which can help offset maintenance and repair costs
- Low-cost housing opportunity for adult children and other relatives to remain in their community
- Provides long-term options for seniors – either as an opportunity for caregivers to live close by or to downsize while remaining in their community
Renter benefits:
- Add affordable rental units to the housing stock to meet the needs of smaller households
- Long-term residents can stay in the neighborhood they love and know (work in)
Benefits to Massachusetts:
- Increases much-needed affordable and diverse housing opportunities
- Provides accessible housing to seniors or persons with medical needs or disabilities and their care givers
- Compact growth makes use of our existing land use, structures and infrastructure, which can be more sustainable and far more economical than building a single-family home on a new lot
- ADUs are smaller and utilize less water and electricity, making them a more sustainable housing option