Portland city officials have approved building codes that allow for the construction of single-staircase multifamily buildings up to four stories, but a requirement inserted at the insistence of fire authorities may make the code unworkable, according to interviews with multifamily experts.

Housing advocates have long championed the potential for single-staircase buildings to provide apartment and condo units in dense urban areas such as Portland.

“It lets you put multifamily buildings on smaller lots,” said Michael Andersen, director of cities and towns for the Sightline Institute, a Seattle-based nonprofit.

On Nov. 4, Portland Permitting & Development issued new code guidance allowing for single-staircase buildings as tall as four stories, in consistency with the updated 2025 Oregon Structural Specialty Code, which took effect Oct. 1.

The prior code allowed single-staircase buildings as tall as three stories, but a fourth story adds more density and, potentially, revenue-generating units, making more projects financially feasible.

The new rules allow for up to 4,000 square feet of total building footprint, with up to four units per floor, for a total of 16 units.

But some outside experts and designers are concerned that a condition meant to provide firefighters with a second point of access to an engulfed building will render plans impossible to construct.

The requirement calls for an unobstructed street width of 26 feet, not including shoulders or parking, and no overhead utility or power lines that would be within 10 feet of an aerial fire ladder extended from the street to a building’s roof.

That could prove a challenge on Portland’s narrow streets, according to interviewees.

“If they enforce this as written and don’t provide alternatives, it makes it almost impossible to find a site to build four-story, single-staircase buildings,” said Iain MacKenzie, a multifamily designer at TVA Architects and a noted local commentator on design and public policy.

Portland’s streets typically have little more than 20 feet of clear width after parked cars and shoulders are taken into account, MacKenzie said.

“All the other conditions (code officials) put on there are totally reasonable and workable,” he said. “But this one thing is a deal-breaker, and it’s not something you can solve by design — it just makes most sites unbuildable.”

A fire official defended the requirement, saying it’s necessary to preserve two access points for firefighters.

“The fact of the matter is a single stair is already a concession to the construction and development industry to maximize livable space on maybe a constrained lot,” said Tom Walsh, assistant fire marshal for Portland Fire & Rescue. “This is already a concession. This is us working with the industry to come up with innovative solutions, but we’ve got to maintain firefighter and occupant safety for fire code.”

The requirement is an “an extrapolation of the existing code language,” Walsh said.

The fire concerns are real — no one wants to go back to the days when entire cities burned down. But housing advocates argue buildings are much more fire resistant than they used to be.

“We required sprinklers, which have been extremely effective at fire prevention, along with modern cladding, fire separation and all the rest,” Andersen said.

The single-staircase discussion filtered down from the International Code Council after several cities approved taller single-staircase buildings. Cities such as New York City, Seattle and Honolulu allow six-story single-staircase buildings, something Andersen said he’d like to see in Oregon.

“We don’t want the only way to add apartments to a block to be to completely transform it,” Andersen said. “We want there to be attractive, family-sized housing sprinkled through neighborhoods.”

A double-staircase design tends to force architects into a design with a long corridor, with a staircase on each side, resulting in units that have windows facing only one direction, MacKenzie said. Think of a hotel.

Housing advocates say single-staircase buildings result in more corner units, and more multiple-bedroom units.

“The single stair is the international standard,” said MacKenzie, who hails from Scotland.

Designers of some smaller projects have found solutions to fire access. Two projects designed by QUAD Architects on Southeast Division Street have no aerial access because of power lines and other obstructions, but they were allowed to build with a large roof hatch and a ship ladder. However, both of those projects are only three stories.

The hatch-and-ladder design requires a fairly flat roof, so firefighters can walk atop it, said Armin Quilici, co-founder and partner of QUAD Architects. The hatch-and-ladder solution, he said, was “pretty simple to do.”

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