Colorado HB25-1273: Unlocking the Potential of Single-Stair Multifamily Buildings
In May 2025, Colorado passed House Bill 25-1273, which allows single-stair multifamily buildings under specific conditions. This change supports higher density housing on small lots while keeping building size and cost more manageable.
What HB25-1273 Allows
HB25-1273 permits single-stair buildings, also known as point access blocks, in buildings meeting specific safety and size criteria:
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Maximum 5 stories above grade
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Maximum 20 dwelling units per building
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Minimum 40-inch stair width
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Non-combustible materials required (Types I, II, or IIIA)
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All egress paths must meet fire code requirements
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Local fire department must approve all plans
The bill applies to cities with over 100,000 people. These cities must adopt the policy by December 1, 2027.
What Are Point Access Blocks?
Single-stair buildings are also called point access blocks in international housing policy. They are common in many European cities.
These buildings are compact and efficient. They typically use one central stair and short corridors to reach all units.
Until now, U.S. building codes required two exits in most multifamily buildings. This made single-stair designs very rare.
Impacts on Design and Development
Single-stair buildings reduce construction area. They eliminate the need for a second stair and long double-loaded corridors.
This approach allows more usable floor area per building. It supports greater financial feasibility for small and mid-sized developments.
They work especially well on narrow or irregular infill sites, where typical building layouts don’t fit well.
They also result in smaller building mass, which better matches existing neighborhood scale and aesthetics.
Fire Safety Considerations
HB25-1273 keeps safety a priority. It requires non-combustible construction and local fire authority review of all projects.
The 40-inch stair width ensures safe egress. It allows space for residents and emergency personnel in case of fire.
All egress components must follow national life safety codes. No corners are cut in life safety protections.
Benefits for Missing Middle and Affordable Housing
This bill promotes “missing middle” housing types, like stacked flats and walk-up apartments. These types fit well in walkable areas.
Developers can add more units per site without increasing building height or mass. That helps preserve neighborhood character.
Lower construction costs help support naturally affordable housing without subsidies. This benefits renters and buyers priced out of the market.
EVstudio’s Experience with Single-Stair Buildings
EVstudio has deep experience designing compact, efficient multifamily housing. We understand the unique design strategies that single-stair buildings require.
Our integrated services include Architecture, Structural, MEP, Civil, and Surveying. We streamline every phase of project delivery.
We work directly with fire departments and building officials. Our team helps developers meet both safety and zoning goals quickly.
Whether on a tight infill lot or a challenging site, our team delivers creative, code-compliant housing solutions.
Learn More
Contact EVstudio to explore how HB25-1273 can help make your next multifamily project simpler, smarter, and more profitable.
