Accessory Dwelling Units (ADUs)
Now Allowed By Right in Massachusetts
Photo Credit: AdobeStock_145314013
Draft ADU Regulations Now Available! Review through January 10, 2025
The Massachusetts Executive Office of Housing and Livable Communities (EOHLC) has released draft regulations to provide clarity on the administration of the new ADU law.
EOHLC will open an official public comment period from December 20, 2024 to January 10, 2025. EOHLC intends to issue final regulations by the effective date of the ADU law, February 2, 2025.
Find out more information at www.mass.gov/adu.
ADUs are an important tool in addressing local housing needs – they provide smaller, more affordable housing choices.
In August 2024, Massachusetts passed the Affordable Homes Act, which, among other things, legalized Accessory Dwelling Units (ADUs) by right in the entire state.
This legislation will go into effect on February 2, 2025.
ADUs can support intergenerational living, residents with caregiver needs, young people, aging residents, and so many more.
Questions? Please contact:
Gwendolyn Hellen-Sands
Regional Housing Planner II
[email protected]
Alexis Smith
Principal Regional Housing and Land Use Planner
[email protected]
What Does the New State Law Say?
The law establishes limits on how ADUs can be regulated, including requiring by-right approval for the first ADU on a property; prohibiting occupancy requirements; and limiting parking requirements. The law does allow communities to regulate whether ADUs are used as short-term rentals (vacation homes).
The ADU law goes into effect after February 2, 2025, and zoning provisions that are inconsistent with MGL c. 40A Section 3 may be unenforceable after this date. An application for an ADU in a single-family zoning district that is consistent with MGL 40A definition and requirements should be accepted and acted on consistent with state statute. Municipalities are encouraged to review their zoning and identify provisions that are not consistent with the law. (Source: EOHLC ADU FAQs: Accessory Dwelling Units (ADUs) - FAQs | Mass.gov)
What Does This Mean for Cities and Towns?
The newly passed state legislation requires that all cities and towns allow ADUs by-right in single-family residential zoning districts.
What are ADUs?
Accessory Dwelling Units (ADUs) are small homes inside or attached to a single-family home or in a detached structure, such as a garage or carriage house. Sometimes known as granny flats, in-law apartments, or secondary dwelling units, they include a kitchen, bath, usually at least one bedroom and a separate entrance.
Why Does Greater Boston Need More ADUs?
Housing is unaffordable and in short supply across Greater Boston, and we are particularly lacking in smaller housing choices.
ADUs are a low-impact way to diversify housing options in all communities, provide more affordable homes for young families or older adults, and help current homeowners with additional income through rent. Accessory homes are so unobtrusive that they usually can’t be seen from the street. ADUs can:
Provide Less Expensive Housing Choices
- Cost less than a new single-family home on a separate lot, thus provide options for low- and moderate-income residents
- Help seniors stay in their community and “age in place” by renting out their ADU or downsizing and living in it themselves
- Provide a smaller housing option to meet the growing needs of empty nesters, smaller families, and young adults
Note: ADUs offer lower-cost rental options, often serving as naturally occurring affordable housing (NOAH). ADUs are not subsidized affordable housing, which is restricted for the exclusive use of lower income households. It is possible to apply deed restrictions to ADUs to create more affordable housing.
Provide Homeowners with More Options to:
- Downsize while staying on their property and live in the ADU
- House a caretaker on their property
- House their children or parents
- Generate supplemental income (from renting the ADU) to help homeowners afford to stay in their primary home
Have a Low Impact on the Environment and Neighborhood
- More compact, infill development promotes more walkable, compact neighborhoods and reduces development pressures on open space
- Minimal construction impacts due to scale of ADUs
- Leverages existing infrastructure, saving municipal funds potentially
- Gentle density designed and maintained by homeowners
Increasing Affordable Housing through ADUs
Greater Boston needs more housing generally, but deed-restricted Affordable Housing is even more critical as the number of cost-burdened renters is staggeringly high (over 50% of renters pay more than 30% of their income on housing). Cities, towns, and nonprofits are all finding ways to leverage ADUs to increase the share of Affordable Housing in communities.
Salem, MA | Photo Credit: AdobeStock_880938010
Best Practice: Salem
The City of Salem allows affordable accessory dwelling units by right. The City achieves this through ensuring that ADUs are allowed by right, but they are required to be rented at or below 70% of the fair market rent limit.
Homeowners in Salem who have an ADU on their property and are renting it at or below the 70% rate are eligible for a tax incentive that exempts the value of the ADU from their property taxes. This incentive encourages the creation and rental of affordable ADUs throughout the city. Note that aspects of the City’s ADU policy may need to be amended to be consistent with the state law.
Learn more about Salem's ADU policies:
Facts about Accessory Dwelling Units (ADUs) | salemma
Photo Credit: AdobeStock_145314013
Research: Opportunities for Nonprofits
A study published in September of 2024 by Haewon Wa with support from the Joint Center for Housing Studies at Harvard University and Neighborworks America explored the role that non-profits can play in the creation of affordable accessory dwelling units.
The study focuses on four case study programs that supported ADU creation in various states and for diverse resident populations. Non-profits were found to be helpful in two main areas of ADU creation: supporting homeowners to construct new or renovate existing ADUs on their property and advocating for policies that allow informal ADUs to be formalized.
Access the Study: Nonprofit Accessory Dwelling Unit (ADU) Programs as Affordable Housing Strategies
Resources for Municipalities
Several cities and towns in the MAPC region have existing ADU ordinances or bylaws that may need to be amended to be consistent with the new state law. Others may not have any existing ADU regulations but will want to create them to better administer the new law. MAPC is working on updated guidance to help communities amend or create new bylaws/ordinances. Existing ADU resources and examples from other MA communities that may be helpful are linked below.
More comprehensive guidance is forthcoming!
Tips for Implementing Accessory Dwelling Units (ADUs) Legislation in Your Community Webinar
On December 9, 2024, MAPC hosted a virtual opportunity for communities to learn tips for implementing the new Accessory Dwelling Units (ADU) State Law.
This webinar highlighted two examples of local ADU regulatory updates in response to changes in state law, provided by:
- Erin Wortman, Stoneham Director of Planning and Community Development
- Kristina Johnson, Hudson Director of Planning and Community Development
MAPC also shared best practices and considerations for crafting strong local ADU regulations.
ADUs Research, Trends, and Opportunities
How Nonprofits Are Using Accessory Dwelling Units as an Affordable Housing Strategy
(Harvard Joint Center for Housing Studies, 2024)
ADUs: Lessons for Massachusetts from Around the Country
(Harvard Joint Center for Housing Studies, 2023)
Overcoming Barriers to Bringing ADU Development to Scale
(Enterprise, 2020)
State of Zoning for Accessory Dwelling Units
(Pioneer Institute, 2018)
ADUs in the News
Governor Maura Healey Signs Most Ambitious Legislation to Address Housing Costs in State History
August 6, 2024 | Source: Mass.gov
ADUs ‘by Right’ Are Now the Law in Massachusetts; Gov. Healey Signs AARP Backed Housing Bill
August 6, 2024 | Source: AARP
Massachusetts now has a 'historic' $5.2 billion housing law on the books. But how far will it go?
August 6, 2024 | Source: The Boston Globe
New ADU Tools May Unlock Affordable Housing in Your Backyard
September 26, 2024 | Source: American Planning Association Planning Magazine
Homeowner and Property Owner Resources
Building an ADU
(Building an ADU)
Frequently Asked Questions (FAQs)
Coming soon!