Committee approves ‘smart‑stair’ housing bill with safety amendments to allow five‑story single‑stair apartments in larger jurisdictions

The House Transportation, Housing and Local Government Committee voted 12‑1 to advance House Bill 12‑73 after adopting a suite of safety and design amendments that sponsors said were negotiated with fire chiefs and building officials.

The bill would allow single‑stair, four‑ to five‑story multifamily residential buildings in Colorado jurisdictions with sufficient fire‑service capacity and other protections: sprinklers and modern alarm systems, defined fire ratings for stair enclosures and corridors, minimum stair width tied to floor plate size (a 48‑inch minimum with proportional increases up to 54 inches for larger floors), limits on units per floor, and prohibitions on storage in corridors. Sponsors described the proposal as a measured way to create “missing‑middle” housing suited to small infill lots.

“Smart stair design also allows for greater flexibility to provide multiple bedroom units, which is critical to provide more options for multi‑generational families,” Representative Woodrow, a co‑sponsor, said in committee. He and co‑sponsor Representative Basenicker said the bill is intended to expand infill, reduce land costs and create family‑sized apartments that are difficult to deliver under the current two‑stair code model.

Supporters including architects and housing advocates pointed to experience in other U.S. cities and an empirical report from the Pew Charitable Trusts that found modern single‑stair, mid‑rise buildings showed safety records comparable to other multifamily building types when required sprinklers, alarms and other protections were in place. “Our new research fills this gap,” Siva Radnanski of Pew told the committee, summarizing the 2024 Pew analysis the bill’s proponents cited.

Fire professionals and some building officials testified with caution or opposition earlier in the hearing, urging that any change be tightly tied to modern life‑safety requirements. Colorado Professional Firefighters and local fire marshals asked the committee to require specific protections. Sponsors responded with several pro‑safety amendments in committee — including required non‑combustible or mass‑timber construction types in certain drafts, mandatory sprinklers and smoke control, stair‑width scaling with floor area, and a requirement that jurisdictions adopting the code provide notice to local fire organizations.

Supporters said the approach unlocks small‑lot infill development that is economically infeasible under current two‑stair requirements and allows more three‑ and four‑bedroom units to be built near transit. Several city mayors and chambers of commerce testified they support the change as a tool to expand the housing supply. The committee adopted sponsor amendments and forwarded the bill to the Committee of the Whole by roll call vote, 12‑1.

What’s next: House Bill 12‑73, as amended, will be scheduled for floor debate. Sponsors and affected jurisdictions will continue to refine implementing details; advocates and public safety officials said they expect more iterative adjustments as code language evolves.