Current code requirements stipulate that apartment buildings that are four to six stories must have two stairwells with a hallway connecting the stairwells on every floor, forcing building designers to put individual apartments on either side of the corridor.

The resulting dual-loaded corridor buildings tend to limit the size of apartments and put windows on one side, blocking natural sunlight and cross-ventilation. They also cost more to build than multifamily buildings with a centrally located stairwell that serves as a fire exit, a common practice in Europe.

London now permits apartment buildings as high as 10 stories with single stairwells, also known as vertical shared access buildings. In the U.S., only Seattle, New York City and Honolulu permit single-stair multifamily buildings of up to six stories, with specific regulations regarding floor area and the number of units per floor.

Nithya Raman, an L.A. council member representing the 4th District who has proposed the code reform, described current requirements for two stairwells as a relic of early 20th century planning concerns that now are standing in the way of construction of affordable apartment buildings with larger family-sized units.

Housing advocate group California YIMBY supports the single-stair code reform. “While the requirement for two stairwells was originally adopted for fire safety, developments over the past two or three decades have made such requirements obsolete,” according to a message from YIMBY group.

“Modern buildings across the U.S. and Europe have fire safety ratings that greatly exceed buildings with two staircases, even though they only have one staircase,” the group said.

According to California YIMBY, the building code requirement for two stairwells is an “anachronism” that has “become a hindrance to housing variety and affordability.”

Because of the additional floor area required to accommodate an extra stairwell, dual-loaded corridor buildings can only be built on larger lots, which effectively blocks the construction of family-sized apartments on smaller or oddly-shaped lots.

AB 835 was unanimously passed by both chambers of the state legislature in 2023 and signed into law by Gov. Gavin Newsom on Oct. 7, 2023.

Raman’s motion asks for reports on the feasibility of single-stair multifamily buildings from L.A.’s Department of Building and Safety and the city’s Fire Department, as well as the American Institute of Architects. The motion also directs the Planning Department to report back on existing and proposed regulations in cities where single-stair buildings are being allowed.

Before the pandemic, multifamily developers typically built smaller units in a tight market to command the highest rent per square foot. The widespread adoption of hybrid or remote work patterns during the pandemic has increased the demand for apartment units with larger footprints.