The Case for Single
Housing & Urban Policy The Case for Single-Stair Multifamily While many advocates have focused on zoning reform, one change could unlock even more new housing: legalizing single-stair multifamily .
Nov. 17, 2025 By Joe Tedino Colorado made a bold housing move earlier this year: To encourage higher-density development and enhance the quality of life for apartment dwellers, the state enacted a law in May allowing multifamily buildings of up to five stories to be built with a single staircase instead of the two previously required for municipalities with populations exceeding 100,000 ...
Exit Strategy
Single-stair designs also unlock economically feasible multifamily development on small infill lots. On such sites, two interior stairwells and a corridor would take up so much of the allowable floor plate that multifamily buildings are rendered infeasible unless adjacent lots are acquired.
Single-stair designs also unlock economically feasible multifamily development on small infill lots. On such sites, two interior stairwells and a corridor would take up so much of the allowable floor plate that multifamily buildings are rendered infeasible unless adjacent lots are acquired.
States Advance Single
New single-stair buildings would be built with the same types of modern technologies and standards that have improved multifamily fire safety. This suggests that allowing single-stair buildings would improve not only housing supply but also fire safety.
Single-stair building code reforms are spreading as states and cities seek more small multifamily housing while maintaining fire safety.
Red Rocks Rising
The Single-Stair Challenge In the United States, building codes require two staircases for buildings exceeding three stories, a mandate intended to enhance safety by providing multiple escape routes in an emergency. However, in practice, this often results in unnecessary redundancy—one stair sits largely unused while taking up valuable buildable area. For smaller infill lots, this ...
Prevailing building codes that require two separate stairwells in multifamily buildings taller than three stories are stymieing development of affordable housing, according to some design and construction professionals. The two-stairwell rule forces developers to allot more square footage to stairs , which removes space for living areas.
The Single
Allowing single-stair buildings gives developers the flexibility to create more human-centered spaces with desirable open space that residents can utilize. European and Asian cities offer many examples of single-stair mid-rise buildings clustered around shared courtyards and open spaces.
Allowing more single-stair buildings in the US will positively affect quality of life, public health, infill flexibility, family-friendly units, costs, and even climate adaptation.