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For years, in-law apartments have been discouraged in Greater Boston. The housing shortage is changing that

Wesley Williams, Jr., who has converted the basement of his home in Mattapan into a one-bedroom rental unit, showed the bedroom and its two closets.Pat Greenhouse/Globe Staff

Wesley Williams Jr. can’t help but get a little excited when he shows off the apartment he built in his Mattapan basement. Sure, the sparkly quartz countertops in the kitchen cost extra. So did the heated floor in the bathroom. But he wanted it to be nice.

The 73-year-old retiree is among the first homeowners in Boston to complete a legally permitted rental unit in a single-family home. Often called in-law apartments or granny flats, these sorts of units have grown in popularity elsewhere in the country but have long been severely restricted in most Boston-area cities and towns.

But now, as the region wrestles with a deep housing shortage, more municipalities are mulling so-called accessory dwelling units as one way to add housing without drastically altering the feel of neighborhoods.


This spring, both Arlington and Salem passed measures to allow such units. Framingham and Barnstable, among others, are considering doing so, as well. Boston is expanding a similar 2019 program, and some candidates in the city’s mayor’s race are calling for even more permissive rules to encourage them.

Rules vary around the state, but in order to be eligible for rental, the units must generally be separate parts of an owner-occupied property, with their own kitchens and bathrooms. Supporters say they are good tools to help older people and those on fixed incomes stay in their homes by converting unused space into income-producing property, while providing relatively low-cost rental stock.

Private entrance to the new apartment.Pat Greenhouse/Globe Staff

Another goal of Boston’s program is to bring unpermitted units into compliance and to ensure they meet safety standards.

While there are some single-unit houses in the city that were eligible previously for conversion into multifamily homes, many homeowners have also carved out smaller units for family members or even tried to create rental spaces off the books.

ADUs are an opportunity, said Boston City Councilor Andrea Campbell, “to be more creative and to think outside the box” about affordable housing. One of two mayoral candidates — along with City Councilor Michelle Wu — to propose expanding Boston’s program, Campbell suggested some homeowners might even want to create a “tiny house” on their land — something not currently. allowed.


“For me it’s asking, ‘How do we make it easier for residents and homeowners who want to help the city of Boston address the affordability crisis?’” she said.

A 2018 study by the free-market Pioneer Institute found that only 37 of 100 municipalities surrounding Boston allowed ADUs for rental to anyone other than a homeowner’s family or caregiver. And in many of those cities and towns, the rules were so strict that few people were building them.

Wesley Williams Jr. converted his Mattapan basement into a one-bedroom apartment. The full bath has a high-tech mirror. Pat Greenhouse/Globe Staff

Even with more permissive zoning, ADUs won’t come close to solving the region’s housing crunch on their own. They are usually small, which doesn’t help larger households in need of shelter. And only a portion of homeowners will have the interest or capability to undertake what can be a complex project. But a thoughtful approach could house thousands of people across the region, the Pioneer Institute suggested.

Every little bit helps relieve pressure on the housing market, said Salem Mayor Kim Driscoll, long a proponent of accessory units. She said her city’s new rules represent a willingness to try new things to make Salem more accessible.

“That is core to our values: accepting and welcoming all,” Driscoll said. “And housing is keeping people out. It’s a big, tall gate.”


It also represents the impact of a recent change in state law that makes it easier for cities and towns to change their zoning. The Housing Choice Act, signed by Governor Charlie Baker in January, lowered the threshold to approve many zoning votes from a two-thirds majority to 50 percent plus one.

And so this spring, when the Salem City Council voted 7 to 4 to approve ADUs, that was enough to pass. The measure had failed in previous years with the same level of support. Now the city allows the units with relatively simple permitting, when they are priced at affordable rates — this year set at about $1,350 per month for a one-bedroom.

The living-dining area in Wesley Williams Jr.'s converted basement.Pat Greenhouse/Globe Staff

There’s still opposition, usually focused on the normal impacts of increased density: parking, traffic, and worries that packing in more residents might change the character of neighborhoods dominated by single-family homes.

But the change in state law has lowered the temperature somewhat in what can be difficult conversations about zoning, said Jennifer Raitt, Arlington’s director of planning and community development. Town Meeting representatives approved the change there by a vote of 189 to 48 after two days of discussion, including several unsuccessful attempts to change or scale back the program.

“I think we’ll start to see more changes proposed and moving forward,” Raitt said.

Boston updated its zoning code in 2019 to allow ADUs (they’re known as “additional” dwelling units in Boston) in existing structures. And it is in the midst of a pilot program in Dorchester, Jamaica Plain, Mattapan, and Roslindale to examine whether they should be allowed in outlying structures such as garages or carriage houses. So far, there are about 50 homes being retrofitted with additional units in the city, and about 50 more awaiting approvals.


The city is trying to design a user-friendly program, said Taylor Cain, director of Boston’s Housing Innovation Lab. A key question, she said, is “How do we create a process that is really easy for folks to navigate, to minimize barriers to entry?”

That approach struck Williams, the Mattapan homeowner, almost immediately as he began preparing his basement to be used as a rental unit. He started dreaming about bringing to his neighborhood the kind of quality and finish that he sees in neighborhoods like the South End, where he lived as a young child.

The entrance to the Mattapan ADU apartment at right. Pat Greenhouse/Globe Staff

“This place should be a model of what Boston’s about,” Williams said. “We’re Mattapan, we’re out of downtown, but we’re making our statement.”

He couldn’t help but get a little nervous when city inspectors showed up.

But the process was smooth. City regulators guided him through it. When his ideas ran up against building codes, inspectors helped him figure out ways to build within the rules. And the city gave Williams a $30,000 loan for what added up to a roughly $125,000 project. He hopes to have the basement apartment ready for occupancy within a few weeks, at about $1,000 a month — well below affordability guidelines.


“The most important thing . . . was that the city cared,” Williams said. “The city wasn’t blowing smoke. The city was making a contribution to the neighborhood, which wasn’t the case when I was growing up.”

Andy Rosen can be reached at andrew.rosen@globe.com.