From banished to beloved: Triple-decker's Somerville.

Making room for more Bostonians! Somerville's embrace of triple-deckers, like these on Highland Avenue, paves the way for a denser, more vibrant city with diverse housing options.

Triple-deckers stand as a fundamental element of Somerville's architectural landscape. Stretching from Winter Hill to Davis Square, these three-story, three-unit residences seamlessly intermingle with charming two-family homes and traditional single-family houses throughout the area.

However, despite their pervasive presence, a perplexing reality has remained obscured: the construction of new triple-deckers has been prohibited in the city and much of Greater Boston for decades due to widespread bans on their development. Prompted by a state law designed to tackle Massachusetts' housing crisis, Somerville has recently eliminated crucial restrictions on triple-deckers. Officials anticipate that these changes will pave the way for the construction of these beloved structures once again.

Certainly, according to housing advocates, the recent decision by the Somerville City Council marks a historic move, making it the inaugural city in the region to completely legalize Boston's renowned stacked housing style. This distinctive housing type characterizes dense neighborhoods throughout the inner ring of suburbs in the region.

Expressing his enthusiasm, Matthew McLaughlin, a Somerville city councilor who spearheaded the initiative, stated, "I love triple-deckers. We're not only permitting more housing, but also reinstating the construction of a historical and culturally significant structure."

The exact number of new triple-deckers that will emerge under the revised rules remains uncertain, but the vote signifies a significant juncture for the region. The area has grappled with a complex relationship with these structures since they were prohibited in most cities and towns during the early 1900s, coinciding with the anti-immigrant movement.

Somerville's modifications align with a nationwide trend, where cities and states are increasingly inclined to promote more moderate-density housing by easing zoning regulations.

The updated regulations are quite clear-cut: Any three-unit structure is now permitted throughout the entire city without the need for special approval from city zoning boards, and certain previous constraints that posed challenges to their construction have been eliminated.

While triple-deckers were technically re-legalized during a zoning overhaul in 2019, property owners were restricted to building a triple-decker only if it was adjacent to an existing one, and one of its three units had to be income-restricted. At the time, some city councilors, particularly those emphasizing the importance of affordability, supported these restrictions, as noted by McLaughlin.

However, since the adoption of that rule, only three individuals secured permits to construct one of these structures, and all three eventually withdrew from their respective projects. Councilors attribute the recent change to the state's MBTA communities law, which mandates that cities and towns zone for additional housing near transit. Unlike suburbs like Newton and Milton, which have faced heated debates over how to comply with the law, Somerville, being an already densely populated city, encountered relatively minimal controversy surrounding its decision.

The law's end-of-year deadline for submitting new zoning to the state served as the extra push that Somerville needed to get the new rules across the finish line, according to officials. City Councilor Ben Ewen-Campen expressed, "We thought this approach just made sense. These new rules essentially just legitimize what Somerville already looks like." Some councilors anticipate that property owners might leverage the regulations to add a third unit to existing two-family buildings.

From Past to Present: A Time Capsule in Albion Street's Triple-Deckers 

Not everyone endorsed the modification. During recent City Council meetings, some residents expressed concerns that the structures might encroach on open space in the city or exacerbate overcrowding in already densely populated neighborhoods. Critics, in particular, were troubled by the council's elimination of the affordability requirement.

Somerville, once a working-class city, has evolved into one of the most expensive places to reside in Massachusetts, with a median rent of $2,500 for a one-bedroom apartment, according to Zillow. Certain residents feared that permitting buildings without any affordable units could exacerbate the issue, as developers might exclusively construct at high price points.

In contrast, proponents of the change anticipate that any new units, regardless of their price, will contribute to bolstering the city's housing supply and mitigating the surge in costs. "We certainly heard what some folks were saying, but we tried the affordability requirement, and they weren't getting built," remarked Ewen-Campen. "This was the best way to give the city a shot at building some triple-deckers again."

Somerville's new regulations could be seen as something of an experiment, assessing whether these structures can be revived as symbols of affordability, as they were in the late 1800s and early 1900s. During that period, triple-deckers were abundantly constructed across the region, offering a unique opportunity for working-class families. The buildings, being relatively dense and cost-effective to build, were often purchased by families—frequently immigrants—as multigenerational homes or to rent out other units for additional income.

A sight of a triple-decker along Clarendon Avenue in Somerville.

Eventually, in 1912, state lawmakers enacted the Tenement Act—a local option rule aimed at prohibiting structures with roots in the anti-immigrant movement—and numerous cities and towns swiftly adopted it. In the subsequent decades, particularly during the 1960s and 1970s, municipalities tightened their zoning regulations, progressively adding layers that made building triple-deckers all but impossible, as noted by Jeff Byrnes, a member of the pro-housing group Somerville YIMBY (Yes In My Backyard).

Despite these challenges, these structures have endured. In many neighborhoods, they represent what housing advocates refer to as the last "naturally occurring affordable housing," offering rents below market rates without government subsidies.

It's likely that the new three-story structures won't be as affordable as their older counterparts, Byrnes explained, due to soaring construction costs and high market rents. However, the units may still be more budget-friendly than single-family homes and certain newly constructed apartments and condominiums.

"The idea is that we're hoping to see more of these structures that so many people love," Byrnes emphasized. "They're not going to be naturally affordable anymore, but it is going to mean more homes across the city, even if it is a modest number.”