If you’ve been searching for a home, downsizing, or looking for a rental in Massachusetts, you may have noticed the rising housing prices, which continue to climb.
In 2024, the average price of a single-family home in Massachusetts reached a record $615,000, making it tough for first-time buyers and middle-income families. Rental prices in cities like Boston, Newton, Cambridge, and Springfield are similarly high, with fierce competition and limited availability.
Homeowners across the Commonwealth are seeking creative ways to maximize their property’s potential amid limited inventory, high mortgage rates, and soaring rents – without moving or buying a second home.
Enter the Accessory Dwelling Unit or ADU.
Whether you’re considering an ADU for a loved one, for extra income, or simply to make better use of your land, you’re not alone. Thousands of homeowners across the state are exploring this option, too.
But let’s be honest – many Massachusetts homeowners also have real hesitations:
Is it expensive to build?
What if my town doesn’t allow it?
Will the process be overwhelming or buried in red tape?
In this post, we’ll show you why ADUs are becoming one of the fastest-growing housing trends in the Commonwealth – and how they might be the perfect fit for your home and your plans.
Massachusetts Housing Crisis in 2025 – The Problem
Housing in Massachusetts IS expensive, and several key factors contribute to this reality:
- Wages lag behind home prices
- Zoning restrictions hinder the construction of affordable units
- New construction struggles to meet population growth and demand
- Not In My Backyard (NIMBY) opposition often delays multifamily or mixed-income projects
As a result, the state estimates a need for over 200,000 new homes by 2035 to address a significant housing shortfall.
The good news is that solutions are on the table. The Affordable Homes Act, for example, aims to make it easier for communities to expand housing through smart growth, zoning updates, and more flexible housing types.
Why ADUs are a smart housing solution
Compared to building a brand-new house (or even buying one), ADUs are far more cost-effective. They use land you already own, and if you choose to convert a basement, garage, or attic, you can avoid many of the costs of new construction.
The benefits extend beyond budget. ADUs are perfect for multigenerational living, allowing aging parents or adult children to stay close while maintaining independence. They can also generate rental income through long-term or short-term leases.
By using existing lots, ADUs increase housing efficiency without promoting urban sprawl. Their small size also means less environmental impact, mainly when constructed with energy-efficient materials.
Massachusetts Policy Changes Supporting ADUs
ADUs are no longer just a niche housing option. Thanks to updated statewide housing laws, they’re now central to the state’s push for more flexible, affordable housing.
So, what is the new housing law in Massachusetts?
In 2024, the state passed the Affordable Homes Act, one of the most ambitious housing reforms in Massachusetts. One of the cornerstone features of the law is its support for ADUs as a practical solution to the state’s housing crisis.
Here’s what changed:
- Homeowners in Massachusetts can now build one ADU by right in single-family zones without needing a zoning board hearing or special permit, as long as they meet standard requirements.
- Municipalities can’t ban ADUs outright, although they can regulate details like design, square footage, and property setbacks.
- Most towns have removed owner-occupancy requirements, making it easier for investors and multi-homeowners to participate.
- Many cities are streamlining the ADU permitting process to reduce red tape and make it more accessible for homeowners.
How does the Affordable Housing Act work?
At its core, the Massachusetts Affordable Housing Act was designed to:
- Simplify local zoning
- Encourage cities and towns to build more diverse housing types (like ADUs)
- Create incentives for innovative, incremental development
- Increase housing supply without massive new infrastructure
It aims to solve the housing crisis by promoting missing middle housing, including duplexes, small apartments, and ADUs, especially in areas already zoned for single-family homes.
What towns in Massachusetts allow accessory dwelling units?
Thanks to the state’s new rules, ADUs are legal throughout Massachusetts, and some towns are leading the charge regarding local implementation and support.
Here are a few standout examples:
Boston, MA
Offers design templates and technical assistance to homeowners navigating ADU planning. Their program also prioritizes income-eligible homeowners and older adults.
Salem
Streamlined its process to include fast-track permitting and waived certain fees to encourage ADU adoption.
Amherst, Arlington, Brookline, Newton
These towns have updated zoning bylaws to allow ADUs with minimal restrictions. Many now permit detached, attached, and interior conversion units without extensive reviews.
The Impact of ADUs on Communities
As more Massachusetts towns adopt ADU-friendly zoning under the Affordable Homes Act, we’re beginning to see their broader impact for individual homeowners and entire neighborhoods.
On one hand, Massachusetts accessory dwelling units have the potential to bring housing where it’s most needed. On the other hand, thoughtful planning is crucial to ensure ADUs truly serve the community and avoid unintended side effects.
Community Advantages of ADUs
ADUs in Massachusetts support affordable housing goals while preserving neighborhood character. They can increase housing supply through “soft density” without the impact of large complexes or subdivisions.
Here’s how ADUs are already making a positive difference:
- Affordable housing options in high-cost areas like Newton or Brookline, where multi-family housing is rare
- Helps seniors age in place, allowing them to live close to family instead of entering assisted living
- Diversifies housing types in traditionally single-family zones, promoting equity and accessibility
- Encourages walkable, livable neighborhoods by integrating new homes into existing infrastructure
By building granny flats or in-law units in Massachusetts, homeowners are helping towns grow smarter, not bigger. And in a state where land is limited and home prices are high, that’s no small feat.
But what are the downsides of ADUs?
ADUs aren’t without critics, and it’s crucial to consider concerns early so towns and homeowners can plan proactively.
Here are a few commonly raised issues:
- Parking and traffic strain, especially in neighborhoods already tight on space
- The risk of over-commercialization, such as turning properties into short-term rentals instead of long-term housing
- Some ADUs being built to luxury standards, pricing out the very populations they were meant to serve
- Poor design or lack of local oversight can lead to ADUs that feel out of place or disrupt neighborhood cohesion.
ADUs in urban planning: The big picture
From a planning standpoint, ADUs are one of the few tools that allow communities to increase housing without altering the landscape dramatically.
That’s why cities are using them to:
- Reuse underutilized land, like oversized backyards or basements
- Promote transit-oriented development in neighborhoods near commuter rails and bus lines
- Achieve gentle growth without the tension that often comes with high-density housing
In short, ADUs are a chance to make the most of what’s already there. And with support from the Affordable Homes Act in Massachusetts, towns now have the policy backing to do just that.
If you’re unfamiliar with the basics of ADUs, check out our complete guide to accessory dwelling units in Massachusetts to learn more about what they are, how they work, and whether your home might qualify.
What does this mean for homeowners like you?
Simply put, you no longer need to buy a new lot or take on a second mortgage to accommodate aging parents, grown children, or changing financial needs. Whether in a city like Boston or a suburban town like Arlington, an accessory dwelling unit in Massachusetts can offer a personalized, cost-effective solution that adapts as your life changes.
If you’re thinking about building a granny flat in Massachusetts, ask yourself:
- Do I have underused space on my property? (Like a backyard, garage, or basement?)
- Could I benefit from passive income to offset my mortgage or boost retirement savings?
- Would an in-law unit help me support aging parents or young adult children?
- Do I plan to stay in my home long-term and want it to work harder for me?
If you answered yes to even one of those, building an ADU in Massachusetts might be a smart next move.
Thinking about building an ADU on your property?
Schedule a free consultation with our local experts and find out what’s possible for your home. From planning and permits to cost and design, we’re here to help you take the next step, without the guesswork.