Wisconsin bill would allow single-stair apartment buildings, raising potential housing and safety implications for Milwaukee

A building-code change under consideration in Madison could reshape small and mid-sized apartment construction

Legislation introduced in the Wisconsin Legislature in December 2025 would authorize certain multifamily buildings of up to six stories to be served by a single stairway, a departure from the two-stair standard embedded in many U.S. building codes. The proposal is paired with the creation of a “multifamily housing innovation council,” indicating an intent to both permit a new building form and monitor implementation.

The Senate version of the measure was introduced on Dec. 12, 2025, and referred to the Senate Committee on Insurance, Housing, Rural Issues and Forestry. A companion Assembly bill was introduced on Dec. 17, 2025 and referred to the Assembly Committee on Housing and Real Estate. A public hearing for the Assembly bill is scheduled for Jan. 21, 2026.

Why stairway requirements matter for housing feasibility

In most jurisdictions that rely on the International Building Code framework, residential buildings above three stories generally require two means of egress. Supporters of single-stair allowances argue that the second stair and associated corridor space can force larger building footprints, complicating projects on narrow or irregular urban lots and increasing construction costs. National research has estimated that single-stair designs can reduce construction costs in the range of roughly 6% to 13% compared with comparable dual-stair layouts, with the largest feasibility impacts often tied to infill sites and midrise “missing middle” apartment types.

Milwaukee has been actively debating how to add housing options within established neighborhoods. In July 2025, the Milwaukee Common Council approved the city’s updated Housing Element as part of the Comprehensive Plan, reflecting policy focus on expanding housing choice and neighborhood-scale options. While the city’s plan largely addresses land use and zoning, stairway rules are governed by building codes—meaning state-level action could influence what is financially and physically possible even where zoning already allows multifamily housing.

Safety standards and the core dispute

Single-stair proposals typically center on modern fire-safety requirements: automatic sprinklers, fire-rated and enclosed stairwells, fire-rated assemblies between units, and self-closing doors. Research examining modern small single-stair apartment buildings has reported no higher fire-death rates in jurisdictions where they are permitted under defined conditions. At the same time, segments of the fire-safety community have expressed concern that having only one interior stair can create vulnerabilities if smoke or fire compromises that route, potentially increasing reliance on rescues from windows or balconies and affecting firefighter operations.

The policy question is whether modern suppression and compartmentation features are sufficient to offset the loss of redundancy provided by a second stair—particularly in taller, denser buildings.

What would change for Milwaukee if a Wisconsin bill becomes law

• Infill development potential: Narrow-lot and small-footprint apartment buildings could become more viable in built-out areas where assembling larger parcels is difficult.

• Design flexibility: Single-stair floor plans can reduce the need for long double-loaded corridors, potentially enabling more corner units and different unit layouts within the same envelope.

• Regulatory coordination: City zoning reforms and state building-code changes would need to align; allowing a building type in zoning does not ensure it can be built under egress rules.

• Implementation scrutiny: The proposed innovation council suggests lawmakers anticipate ongoing technical debate about building limits, safety features, and oversight.

As of Jan. 20, 2026, the Wisconsin proposal remains at the committee stage. The Jan. 21 Assembly hearing is the next scheduled milestone, with potential impacts for Milwaukee hinging on final bill language, subsequent code updates, and how local development patterns respond.