Legalising single stairways in small or mid-rise multifamily buildings could facilitate more housing in Massachusetts — and do so safely, according to a new report from The Pew Charitable Trusts.

Introduced by Massachusetts State Representative Meghan Kilcoyne of Clinton, House Bill 1542 would establish a special commission to determine if single-stair multifamily residential buildings up to six stories should be legalized in the state. The bill has yet to pass.

Massachusetts is just one of many states introducing similar legislation: In 2025, Colorado, Maine, Montana, New Hampshire and Texas passed laws allowing the housing type.

The Pew Charitable Trusts says reforms like these could lower construction costs and provide more housing options while maintaining fire safety.

Pew’s original research found building single-stairway multifamily buildings to be 6% to 13% less expensive than dual-stairway structures of similar size. Benefits of single-stairway styles also include the ability to build dense housing on small or irregularly-shaped lots, common throughout Massachusetts.

The study also found no increased risk to fire safety for single-staircase buildings. In fact, Pew found modern apartment buildings built since 2000 to be much safer than 93% of American homes that are not modern multifamily housing.

“Massachusetts has a real chance to make it easier and more affordable to build the kind of homes people need,” Alex Horowitz, director of Pew’s housing policy initiative, told Boston Agent Magazine. “Allowing safe single-stairway apartment buildings would help cities and towns add more housing near jobs and transit while improving fire safety by adding modern apartments, the safest housing type.”

“Until recently, Seattle and New York City were the only U.S. cities to allow four-to-six-story apartment buildings with only one stairway — even though they are legal in much of the world,” said Chase Hatchett, Pew’s principal associate of housing policy. “This move to reform building codes is part of broader bipartisan efforts to increase housing supply and improve affordability. Allowing the construction of single-stairway buildings enables the development of much-needed multifamily housing, particularly in cities where vacant land is scarce and expensive.”