
A photo of Denver taken from a drone in March 2020. (Courtesy Guerilla Capturing)
Denver is poised to go beyond a state mandated minimum when it allows single-stair residential buildings.
The proposed measure going before the City Council would allow the buildings to use Type III construction, in addition to the Type I, II and IV construction standards that a new state law specifies must be allowed.
The standards refer to the combustibility of a building’s structural elements.
“Type III is what most would think of as typical wood-frame apartment buildings — two-by-four-type construction for walls and maybe trusses or engineered wood joists for floors and roofs, things like that,” Eric Browning, the city’s chief building official, told council members earlier this month.
Browning said he and Cory Debaere, the Denver Fire Department’s division chief of fire prevention, discussed whether to allow Type III “for quite some time.”
“We evaluated the risk, or the lack thereof, and ultimately decided to come forward with the recommendation that Type III can and should be allowed because of the other redundancies in life safety features that are associated with these buildings,” Browning said.
House Bill 1273, which Gov. Jared Polis signed into law in May, requires cities with more than 100,000 people to allow for a single stairway in apartment buildings of up to five stories, with a maximum of four units to a floor.
Currently, those buildings must have at least two stairways.
The goal of the change is to make it easier to add density in urban areas with high housing costs. Buildings with one stairway generally require less land than buildings with two stairways and thus are cheaper to build.
But buildings with one stairway also inherently come with additional risk to residents, given that a fire blocking the stairway could trap those on the upper floors. That’s why the two-stairway requirement became standard in the first place in the mid-1900s.
In a nod to the fire safety concerns, the state measure passed this year requires affected municipalities to coordinate with fire officials regarding design of the single-stair structures it mandates be legal in larger municipalities.
Browning said Denver’s proposed measure to allow single-stair buildings was “in research and development for well over a year,” even before the state law passed.
Denver’s proposed measure requires single-stair buildings to be fully protected by sprinklers and have wide stairs allowing for simultaneous use. Smaller details include limitations on the locations of electrical outlets — none in the stairway, to reduce the chance of a fire starting there.
Debaere noted that the five-story height restriction allows the fire department to reach the upper floors with its ladders.
“There will be opportunities for stairwells to be blocked, and like anything else we’ll work around that,” he said.
A final vote is expected Nov. 24 on the measure, which is sponsored by Councilmembers Amanda Sandoval, Sarah Parady, Paul Kashmann and Darrell Watson.
Single-stair buildings are already allowed in some capacity in cities including New York, Seattle and Honolulu, according to city staff.

A photo of Denver taken from a drone in March 2020. (Courtesy Guerilla Capturing)
Denver is poised to go beyond a state mandated minimum when it allows single-stair residential buildings.
The proposed measure going before the City Council would allow the buildings to use Type III construction, in addition to the Type I, II and IV construction standards that a new state law specifies must be allowed.
The standards refer to the combustibility of a building’s structural elements.
“Type III is what most would think of as typical wood-frame apartment buildings — two-by-four-type construction for walls and maybe trusses or engineered wood joists for floors and roofs, things like that,” Eric Browning, the city’s chief building official, told council members earlier this month.
Browning said he and Cory Debaere, the Denver Fire Department’s division chief of fire prevention, discussed whether to allow Type III “for quite some time.”
“We evaluated the risk, or the lack thereof, and ultimately decided to come forward with the recommendation that Type III can and should be allowed because of the other redundancies in life safety features that are associated with these buildings,” Browning said.
House Bill 1273, which Gov. Jared Polis signed into law in May, requires cities with more than 100,000 people to allow for a single stairway in apartment buildings of up to five stories, with a maximum of four units to a floor.
Currently, those buildings must have at least two stairways.
The goal of the change is to make it easier to add density in urban areas with high housing costs. Buildings with one stairway generally require less land than buildings with two stairways and thus are cheaper to build.
But buildings with one stairway also inherently come with additional risk to residents, given that a fire blocking the stairway could trap those on the upper floors. That’s why the two-stairway requirement became standard in the first place in the mid-1900s.
In a nod to the fire safety concerns, the state measure passed this year requires affected municipalities to coordinate with fire officials regarding design of the single-stair structures it mandates be legal in larger municipalities.
Browning said Denver’s proposed measure to allow single-stair buildings was “in research and development for well over a year,” even before the state law passed.
Denver’s proposed measure requires single-stair buildings to be fully protected by sprinklers and have wide stairs allowing for simultaneous use. Smaller details include limitations on the locations of electrical outlets — none in the stairway, to reduce the chance of a fire starting there.
Debaere noted that the five-story height restriction allows the fire department to reach the upper floors with its ladders.
“There will be opportunities for stairwells to be blocked, and like anything else we’ll work around that,” he said.
A final vote is expected Nov. 24 on the measure, which is sponsored by Councilmembers Amanda Sandoval, Sarah Parady, Paul Kashmann and Darrell Watson.
Single-stair buildings are already allowed in some capacity in cities including New York, Seattle and Honolulu, according to city staff.