ADU Builder Massachusetts
A Practical Guide by MBA Builders
“Adding a second unit on your property can increase your home’s value by up to 30%.” – Freddie Mac, 2020 Study on ADUs
Homeowners across Massachusetts are starting to realize the real potential of building an ADU – and not just for the extra space. Whether it’s to house aging parents, create a private home office, or earn passive rental income, Accessory Dwelling Units (ADUs) are becoming a smart and flexible solution to limited housing options and changing family needs.
In fact, the state of Massachusetts has recognized this growing demand – and as of August 2024, passed legislation to support more ADU development across all municipalities, making it easier than ever to add livable space and meet the evolving needs of families and communities.
But figuring out how to design, plan, and build one? That’s where we come in.
At MBA Builders, we’re not just your average contractor. We’ve built a whole system around helping homeowners through complex, high-investment home projects – and we’ve seen firsthand how confusing the ADU process can be.
If you’re considering an ADU in Massachusetts, here’s what you need to know – and how working with a specialized ADU builder like MBA Builders can make all the difference.
Key Summary
- ADUs (Accessory Dwelling Units) are small, independent living units on the same lot as a primary residence.
- An experienced ADU builder helps with zoning, design plans, permitting, and construction.
- MBA Builders offers a clear, multi-phase approach: preconstruction planning and detailed build execution.
- ADUs can be attached, detached, or interior conversions – and are legal “by right” (meaning no zoning approval process required) in all MA municipalities as of August 2024.
- The right planning upfront leads to fewer surprises and a budget you can trust.
What Is an ADU?
An ADU, or Accessory Dwelling Unit, is a secondary housing unit built on the same property as a main home. It can be detached (like a backyard cottage), attached (like an in-law suite), or even part of the main home (like a finished basement apartment with a separate entrance).
People build ADUs for all kinds of reasons:
- Housing for parents or adult children
- Rental income
- Guest space or Airbnb
- On-site caregiver quarters
- Home offices with privacy – or space to give teens their own zone (and get them out of your hair… but not too far)
These units can be up to 900 square feet – or half the size of the primary home, whichever is smaller – under Massachusetts’ new statewide ADU law (effective August 2024). While zoning is now streamlined across the state, local factors like site reviews, environmental restrictions, grading, or setback requirements can still vary.
That’s why it’s helpful to work with a local ADU builder who understands the nuances and can guide you through the process.
Why Hire an ADU Builder?
Working with a dedicated ADU builder means you’re not starting from scratch – and you’re not taking on a full-time job trying to understand zoning, design, and construction.
Preconstruction Planning
Every project starts with a call to our office. Our client coordinator listens carefully and figures out if an ADU makes sense for your goals. If it does, you’ll meet with our design team who’ll then visit your property, talk through your vision, and make sure everything aligns with local zoning laws.
From there, we create a Preconstruction Agreement – which covers site assessments, design planning, budget forecasting, and all the details needed to move forward. You’ll walk away from this phase with a complete project roadmap, including:
- Architectural plans
- Finish selections
- Detailed specs
- A budget you can count on
The Build
Once your ADU plan is approved and finalized, we move into the build phase. This is where our construction team takes over and executes every detail – from utilities and framing to interior finishes – based on the plans we developed together.
Unlike small contractors who jump straight into building, we invest in planning first. That’s why when we give you a construction estimate, we’re typically within 10% accuracy – while smaller builders can miss the mark by a mile.
Legalizing an ADU in Massachusetts
Zoning for ADUs in Massachusetts just got easier – but the details still matter.
Thanks to statewide legislation passed in August 2024, building an ADU is now allowed by right in every Massachusetts municipality – meaning no zoning approval process in most cases. Owner occupancy can’t be required, and square footage limits are now standardized across the state: up to 900 square feet or half the size of the primary home, whichever is smaller.
But while the big hurdles have been cleared, local nuances remain. Some towns attempt to complicate the process with building height caps, design restrictions, or costly site prep requirements like drainage and grading. While many of these may be considered “unreasonable” under the new law, towns are still figuring out how to interpret and apply it.
That’s where we come in. With experience across Greater Boston, our team knows how to navigate these evolving requirements and spot the potential red flags before you commit. If you’re thinking about building an ADU, we’ll help you assess feasibility, avoid surprises, and move forward with confidence.
What You Get When You Work With MBA
Clients tell us the same thing over and over: “We had no idea how much work this involved – thank God we had you.”
When you work with MBA Builders on your ADU project, here’s what you get:
- A clear process that starts with planning
- A full team: client care, design consultants, project managers, and craftsmen
- A final project that reflects your goals, timeline, and budget
- Guidance on zoning, permitting, and inspections
- A company that communicates and documents everything clearly
Next Steps
Thinking about building with us? Start by getting to know MBA Builders – we’re a full-service team that handles everything from planning to permits to construction. Learn more about us, explore our process, and take a look at our work to see what we’ve done for homeowners across Massachusetts. From home design services to full ADU builds, we’re here to make it simple. Have questions?
You can also check out our services to see the range of ways we can support your project.
Frequently Asked Questions
What is an ADU?
An ADU, or Accessory Dwelling Unit, is a self-contained living space located on the same lot as a single-family home. It usually includes a kitchen, bathroom, and separate entrance.
Are ADUs legal in Massachusetts?
Yes – as of August 2024, ADUs are legal by right in all Massachusetts municipalities. That means most previous zoning hurdles (like owner-occupancy requirements or discretionary approvals) have been removed. However, interpretation of the new regulations can still vary by city or town. Some localities may introduce design guidelines, height restrictions, or site prep requirements. That’s why working with an experienced local builder is key to navigating the process smoothly.
How much does it cost to build an ADU in Massachusetts?
The cost to build an ADU in Massachusetts typically ranges depending on size, finishes, and location. Planning costs are separate for full specs and plans.
What’s the difference between an ADU and a guest house?
A guest house is often just extra space without a full kitchen or bathroom. An ADU is a fully independent living space – more like a small home – and can legally be rented out in some towns.
How long does it take to build an ADU?
The full process – from planning to permitting to construction – can vary, but timelines have gotten much faster. Thanks to updated state regulations (as of August 2024), most ADUs no longer require lengthy zoning board approvals, which significantly speeds things up. The biggest factors now are your town’s permitting turnaround for building, plumbing, and electrical – and how quickly you make design and material decisions.