How Many ADUs Were Approved in Massachusetts in 2025?

By Buz Artiano, BuildX | February 2026

When Massachusetts passed the Affordable Homes Act in February 2025, we started keeping track of the numbers. After 14 years of building homes in Massachusetts and serving on a Conservation Commission, we understand and we can explain to you how the changes in the laws and codes will directly affect you and your build.

If you're trying to decide whether or not to move forward with your ADU, you probably want to know if there are a lot of other people doing the same thing and is it a good idea. There are a lot of people building ADUs, which tells you that the permit process is working and builders have figured out how to make it all work for people who want to build.

At BuildX, we've been part of this wave since it all started. We build ADUs exclusively in Massachusetts, and we've watched the approval numbers go up every month. Here's what the numbers say and what it means for your ADU project.

How Many ADUs Have Been Built Since the Law Passed?

Lieutenant Governor Kim Driscoll said that Massachusetts has had 880 permits filed and over 550 ADUs built since the Affordable Homes Act made ADUs a right statewide in February 2025.

Those numbers come from official state tracking data, but keep in mind that the data is based on a survey of Massachusetts towns, and not every town responded, so there is some missing data there. Based on our conversations with people we know in the industry, the real number of completed ADUs is probably around 800.

We've also heard that there have been over 1,000 permits pulled since February 2nd. Since there's a gap between getting permits and finishing an ADU, it seems like that number will go up quite a bit once all those projects are finished.

How Does Massachusetts Compare to California?

California is the benchmark for ADUs because they have had the laws allowing them for a lot longer than Massachusetts. But even though our laws passed more recently, Massachusetts is currently building at about 25% of California's rate.

California permitted about 800 ADUs per year in 2014. They permitted more than 30,000 in 2024. Today, about one fourth of all building permits that are issued are for ADUs in California.

Massachusetts has a population of about 7 million, California's is closer to 40 million. Using California's numbers as a standard, analysts say that Massachusetts could eventually be building 3,000 to 5,000 ADUs per year once the market matures a bit.

That doesn't happen overnight though. California took almost 10 years to get to those numbers. But the early Massachusetts data tells us that people are really responding to the freedom the new laws give them.

Why Are the Early Numbers Encouraging?

The state ADU law only became effective in February 2025, which means we're looking at less than a year of data. A lot of the ADUs that they are counting as "completed" could have already been started or at least permitted before the law passed and then they were just able to move faster through the process once by-right permitting became available.

And it's showing no signs of slowing down either. Over 170 communities in Massachusetts have been permitting ADUs. They're spread out all over Massachusetts, which tells you that the law is working all over the state, and not just in some of the more progressive towns.

For homeowners thinking about building an ADU, all this is important because it means the permit process is working. Building departments have figured out how to review ADU applications under the new rules, and builders like us have adapted to them as well.

What Do These Numbers Mean for Your Project?

The approval numbers tell you three things worth knowing as you are thinking about your own ADU project.

The permit process works. Towns across Massachusetts are approving ADUs left and right under the new Affordable Homes Act. What that means for you is that you won't be fighting against a system with no history of approvals.

Builders have experience. With hundreds of ADUs built statewide, experienced builders have worked through the permitting, utility, and construction processes many many times. That experience is valuable to you and it makes sure you don't run into surprises on your project.

The market is still early. Compared to California, Massachusetts is just getting started. If you build now, you're among the early adopters taking advantage of regulation that were designed to encourage ADU construction.

Does This Data Apply to Every Homeowner?

Not necessarily. The survey numbers we've seen don't tell you whether your specific property qualifies for an ADU or what issues might come up based on site conditions and other things. Some towns have been better about implementing the new law than others. Properties with septic systems, wetland buffers, or unusual lot layouts can still bring up issues that we aren't able to predict.

If you're trying to figure out whether an ADU is possible on your lot, the number of approvals in the state are a good sign, but they're not a guarantee or substitute for a site-specific evaluation. The thing that really matters most is your property's individual characteristics and your town's current waiting time on permits.

Is the State Data Complete?

We want to be clear that the numbers are not bullet proof. The state survey didn't hear back from every municipality or town, so the actual numbers are higher than reported. The Lieutenant Governor's office has told us that they're only tracking building permits, not any other information about who's living in these ADUs or how they're being used or built.

It's also too early to compare Massachusetts to California's market directly since they've got a ten year head start on us. We have data from all of California's permitting over the last decade, but Massachusetts has only had a few months under the new law. The early numbers are promising, but we won't see the full picture for years.

If you want to understand how the ADU approval process works in your specific town, we can help you evaluate whether your property qualifies and what the permit timeline looks like.

Ready to Be Part of the Numbers?

Massachusetts homeowners are adding ADUs a lot faster than we expected. Over 550 completed units and nearly 900 permits in the first six months demonstrates that the by-right framework is really showing results all over the state.

Want to learn more about how ADU permitting works in Massachusetts? Explore our ADU planning resources to understand the timeline, costs, and requirements before you start.

If you're ready to explore whether your property can support an ADU, schedule a free consultation with BuildX. We'll review your lot, explain what's possible under your town's rules, and give you a clear picture of timeline and cost before you commit to anything.