Longstanding building codes are hindering new housing construction in Boston, according to a report released Thursday.
The codes, some written a century ago, were designed to protect residents in case of a fire but are no longer necessary in all cases, the report states.
It was issued by Boston Indicators, the Harvard Joint Center for Housing Studies and the design firm Utile and focuses on the requirement that residential buildings with 12 or more units or that are taller than three stories include two separate stairways.
Increasing the exemption to six-story buildings would allow more than 130,000 new housing units to be built in the region while maintaining the same level of, or even improving, fire safety, the researchers said.
“The proposal to expand single-stair buildings … does raise legitimate questions about safety, and I don’t want to sweep those under the carpet,” Chris Herbert, managing director of the Joint Center for Housing Studies, said when the report was released Thursday.
“And we recognize that in attempting to solve the wicked problem of affordability, we may also raise questions about whether or not we’re compromising safety,” he continued. “What we hope this report is, is to raise from the design perspective what is possible.”
The researchers also want to start a conversation about building code changes.
The first Boston building codes
Boston began regulating residential building exits and entry in the 19th century and officially began requiring two independent exit routes in residential buildings above two stories in 1901.
The current version of the building code, adopted in 2017, requires buildings with more than three stories to have two staircases. Single-stair buildings, known as “point access blocks” because they have one entry point and a central lobby can have a maximum of four units per floor, for a total maximum of 12 units per building.
However, few 12-unit buildings are built because construction and land costs render them financially infeasible.
“Land values in this area are extremely expensive, and it’s very difficult to outbid the rich single-family home consolidation or commercial uses if all you have is 12 units to give,” Ian Hatch, partner at Fulcrum Land and Infrastructure, said.
Similarly, because buildings with two staircases are more expensive to construct, developers must design them to be very large with many units in order to make them financially feasible. By design, they typically involve long hallways with apartments or condos on either side, which limits the size of each unit and leaves all but corner units with only one exterior wall for windows.
Developable land shrinking in Boston
As the amount of developable land in the region shrinks, parcels where these buildings fit, or groups of parcels that can be combined into one site, have become few and far between.
Of the multifamily housing built in the last 20 years, 75% of units were in buildings with 50 or more units, according to the report, while only 15% of units were in buildings with 10 to 50. Before 1940, 90% of residential buildings constructed had fewer than 50 units. Today, that number is about 35%.
The researchers recommended raising the threshold for requiring multiple staircases to six stories, the point after which buildings are considered “high-rise” because fire ladder trucks can no longer reach the upper floors. Keeping current requirements the same for a six-story building would double the number of units that could be built on a smaller property to 24 rather than 12.
Based on the number of available parcels in Greater Boston ranging from 3,000 to 15,000 square feet, the sizes where the researchers considered single-stair buildings to be viable, they estimated that this change could allow the construction of more than 130,000 new housing units within a 15-minute walk of a public transit station.
“Even if a fraction of those got permitted, I think it would make a meaningful impact on our housing goals, our production and the vibrancy of our cities,” said Sam Naylor, an associate at Utile.
Fire safety options have improved
Technological developments since the building code was first implemented mean two staircases are no longer necessary for safety, according to the report. The proposed changes would leave in place other fire safety requirements, including sprinkler systems and emergency escape or rescue openings.
In addition, the researchers explained that because of the design of single-stair buildings, the occupants of each unit would have to travel a much shorter distance and there would be fewer people using the stairs than the average in a two-staircase building. They argued that this would make the design overall safer than previous requirements.
Naylor compared concerns he had heard about removing the second staircase requirement to removing one wing of an airplane. However, he said it was more similar to switching to a helicopter.
“Single-stair buildings are more nimble,” he said. “It’s just a different analogy altogether.”
Other countries allow single-stair buildings
The United States is one of a few countries in the world to limit single-stair buildings to three stories, along with South Africa, Uganda and Saudi Arabia. Countries comparable to the U.S. by climate, economy and urban development tend to allow up to six to nine stories, while some, like Switzerland and South Korea, have no limit at all.
At the same time, the United States is tied for the highest fire death rate among high-income countries, according to the report. Of fire deaths that occur in homes, 99% are in buildings without sprinklers, and fires in hallways and stairwells are very rare, which the researchers said indicates that having additional means of egress is not a significant factor in improving safety.
“We’ve advanced substantially from 1890,“ Eduardo Mendoza, Livable Communities Initiative policy director, said. “We have sprinkler systems that completely change casualties and deaths in apartment buildings. Even our furniture is fire-rated now.”
“When you speak with a building code official or fire engineer … in good faith, there’s always common ground where they may meet you,” he added.
New York City, Seattle and Honolulu allow single-stairway buildings up to six stories, and California, Oregon and Washington will begin allowing single-stairway construction by 2026. Nine other states are considering similar changes.
In addition to unlocking the construction of more much-needed housing, the researchers said single-stair buildings have quality-of-life benefits. By not requiring a long, often dark hallway with units on either side, buildings can have more airflow and natural light, and neighbors can mingle more frequently on their way in and out.
The change would also allow for greater variety and creativity in the design of new buildings that better fit the existing urban fabric of the neighborhoods where they are built.
“I’ve never been in a corridor that I loved, and I’ve never had a long conversation with a neighbor in a carpeted, long corridor,” Naylor said. “In contrast, I have lived and stayed in places with beautiful, single-stair entry moments.”
To read the full report visit bostonindicators.org.