Members of the Denver City Council approved an ordinance on Monday that adds provisions allowing five-story single-stair buildings into Denver’s building and fire code amendments. 

The ordinance also makes additional revisions to support building projects by extending expiration timeframes, easing barriers to adaptive reuse, simplifying neighbor notification options, and coordinating cross-departmental requirements.

Additionally, the approval aligns the city with the new state law.

During the 2025 legislative session, the Colorado General Assembly approved HB25-1273 to allow up to five-story apartment/condominium buildings to be served by a single access/exit stair starting in late 2027. 

The ordinance aims to provide greater flexibility, unlock more opportunities to build on small lots, and offer more affordable housing options.

Single-stair buildings are less complicated to design, use less space and have lower construction costs.

By eliminating the second staircase and long corridors, more usable living space is created and makes such buildings more financially feasible for small lots.

The single-stair buildings provisions will allow new multifamily residential, apartment, or condo-type buildings to be constructed up to five stories, or four stories with an occupied rooftop deck, with a single access and exit stair for that building,” said Eric Browning, the city’s chief building official, at a committee meeting on the ordinance earlier this month. “There are a number of criteria that are relevant to the design and construction for these buildings to ensure that minimum levels are life safety of life safety are maintained with the allowance for just a single stair to be provided.”

New multi-family residential buildings up to five stories, or four stories with an occupied roof deck, may be designed and built with a single access/exit stair, subject to specific building and fire code criteria that largely match state law.

Under the new criteria, builders could build up to 6,000 square feet per story and up to four units per story, and would be required to have all units fully protected by sprinklers.

Additionally, stars would need to be wide to accommodate simultaneous use.

City officials estimate that there are close to 39,000 parcels that could support the single-stair building configuration, both built-out and vacant. 

The city of Denver builds a lot more apartments than single-family homes, but the average apartment building is over 50 units, and one of the reasons is the building code,” Sean Jurnick, an architect with SAR Architects. “The single stair code will unlock apartments that are smaller scale, 10 to 20 units that’ll be able to be built on lots in urban areas where housing is in most demand, and unlock small lots in the city that currently aren’t being developed.”

The new ordinance will take effect Dec. 31, 2025.