Single stairs do not put residents at risk

New urbanists have typically focused on code changes that impact the outside of buildings, their density and use, and the way they address the public realm. But sometimes, inside-the-building codes have a major impact on how buildings are expressed on the outside—and thus, the form of the city.

Such is the care with stairwell requirements. They are partly responsible for the dull, generic streetscapes created by new mid-rise multifamily buildings from coast to coast. Most building codes require two staircases. Double-stair buildings have corridors in the middle and most apartments have windows on only one side. They create large, long facades on a block that may suck the vibrancy out of streetscapes. Single-stair buildings (often with elevators by the stairwell), by contrast, can be constructed on smaller lots, with apartments that get light on two or three sides and mid-block open space. “Single-stair’s efficiency and flexibility contribute to dense, walkable, and fine-grained neighborhoods and cities,” explains CNU Mid-Atlantic chapter. Cities required two stairwells for fire safety, but modern fire safety advancements and new building materials make the requirements superfluous. 

Now, a new Pew study confirms that single-stair buildings are no riskier than double-stair buildings. “A first-ever analysis of fire death rates in modern four-to-six-story buildings with only one stairway shows that allowing these buildings to have only one staircase does not put residents at greater risk: Single-stairway buildings as tall as six stories are at least as safe as other types of housing. And allowing the construction of such buildings could provide much-needed housing, including homes for people with modest incomes.”

The US has a shortage of 4-7 million homes, Pew notes, and eliminating this requirement could allow for new development to bridge the gap. Single-stairwell buildings can be built at a small-to-medium size in walkable neighborhoods. Single-stairwell buildings can fit onto small, irregularly shaped infill lots, contributing to missing middle housing.

“Current U.S. building codes in all but three major cities (New York City, Seattle, and Honolulu) stipulate that apartment buildings four to six stories must have two stairways. However, model codes written by the National Fire Protection Association (NFPA) allow small apartment buildings up to four stories tall to be served by a single stairway; Vermont, Georgia, and Puerto Rico have adopted the NFPA rules,” Pew explains. Seattle allows buildings up to six stories with a single staircase.

Earlier this week, I reported that the CNU Mid-Atlantic chapter is sponsoring a design competition for single-stair buildings in Baltimore, which is one of many jurisdictions that is proposing to allow mid-rise, one-stairwell buildings.