Susan Gittelman
Like most states, Massachusetts requires two stairways in multifamily dwellings of more than three stories. But according to a 2024 Boston Indicators report, allowing 4- to 6-story dwellings to have a single stairway could result in 130,000 new homes being built in Greater Boston.
Single-stair buildings are less expensive to build and more efficient. According to Joshua Brandt, the owner of Boston-based construction management and development firm Stack + Co, a two-stairwell building typically maxes out at 82 percent of the structure being used for housing, while the number rises to 92 percent for a one-stairway structure.
This higher efficiency means being able to create more units out of the same building envelope and larger family-sized units – a rarity in the market – without additional cost.
The Boston Indicators report also finds that adding a second stairwell typically adds between $200,000 and $500,000 in construction costs for Boston projects on 3,000 to 5,000 square-foot parcels which are the right size for so-called missing middle housing – small-to-medium size multifamily housing. So why aren’t we doing it?
Rule Predates Modern Alarms, Sprinklers
Safety has long been the rationale for the two-stairway requirement. But a February 2025 Pew study found New York City and Seattle, two cities that allow 4- to 6-story, single-stair buildings, have fire death rates that are comparable to other cities. It also found that the lack of a second stairway didn’t play a role in any of the four deaths those cities experienced in single-stair buildings over 12 years. Current code requirements were established before buildings had modern sprinkler systems and fire alarms.
And overall safety considerations are not what drives the market, given that single-family homes are the predominant building type in most communities.
“The fact is that on a per capita basis, single-family homes have much higher death rates from emergency events than single- or double-stair buildings,” said Sam Naylor, an architect and associate at Utile who worked on the Boston Indicators study.
The Healey administration estimates that Massachusetts needs to build 222,000 housing units over the next decade to meet demand. As is usually the case with crises of this magnitude, there isn’t a silver bullet solution.
“Most of the debate has centered around zoning reforms like setbacks and building height,” Naylor said. But building codes also matter, and this is the building code reform that would have the biggest impact.”
Amid surging construction materials costs, rising interest rates and banks pulling back from construction lending after events such as the Silicon Valley Bank collapse, Boston housing starts have cratered in the last two years, falling from 4,400 in 2023 to 2,100, and they may well drop more.
“It’s like a needle in a haystack to find projects that pencil out right now,” Brandt said. “Development costs have gone up even more than rents. Relatively speaking, single stair is the low-hanging fruit in terms of unsticking projects and making them viable.”
Road to Legalization Is Long
For decades, housing policy decisions have been made in a vacuum, based on making projects safer, more affordable or more sustainable without considering the trade-offs associated with each. The result is the dramatic shortage we face today.
Creating a sufficient supply of housing that is safe, affordable and sustainable will require paying more attention to these trade-offs, such as when a perceived increase in safety adds significant costs that make projects infeasible and exacerbates the shortage.
A bill to create a group to study the single stair issue has been reported favorably out of the Massachusetts Legislature’s Joint Committee on Housing and its prospects for passage during the current session appear to be good.
But the $250,000 to fund the study has been stripped out of the bill, and even if the study gets funded it could be years before it is completed; its recommendations make their way to the Board of Building Regulations and Standards, which adopts and periodically updates the state building code; and reforms are enacted.
Perhaps a better route would be for a jurisdiction like Cambridge that has demonstrated an appetite for bold housing reforms – such as approving multifamily housing developments up to four stories by right – to adopt a provision similar to the ones in New York and Seattle that allow single stair in 4- to 6-story multi-family dwellings. As it did in other states, lowering the cost of housing development without compromising safety would likely encourage other Massachusetts jurisdictions to follow suit.
Massachusetts doesn’t have the luxury of time to address its housing crisis. High costs are driving residents out of the state and exacting a severe human and economic price. Changing that will require an “all of the above” approach that prioritizes housing development, and changing the building code to allow more single-stair multifamily dwellings must be part of that strategy.
Susan Gittelman is executive director of B’nai B’rith Housing, a nonprofit affordable housing developer currently working in Boston, MetroWest and the North Shore.
