Washington amends state building code to permit scissor stairs in multifamily buildings, effective 11 June 2026

Washington state - acting at the state level through its legislature - has amended its building code to permit scissor stairs in multifamily residential buildings. House Bill 2228 was signed by Governor Bob Ferguson and took effect 11 June 2026 as Chapter 4 of the 2026 Laws, making Washington the first state in the United States to allow scissor stairs in multifamily construction^[1].

What the bill changes

Under the existing Washington State Building Code (WAC 51-50), multifamily buildings above three stories must meet the two-stairway egress requirement drawn from the International Building Code. HB 2228 does not itself rewrite that requirement. Instead, it directs the State Building Code Council (SBCC) to convene a technical advisory group to recommend amendments to the state building code that would allow scissor stairs to count toward the minimum two-stairway requirement for certain multifamily residential buildings^[1].

The bill defines scissor stairs as:

• Two interlocking stairways with two separate exits
• Separately enclosed and divided by fire-resistance-rated assemblies
• Each providing a distinct means of egress

The advisory group's recommendations must address public health, safety, and welfare, as well as construction cost, and must be submitted in time for incorporation into the 2027 state building code update. The provision in HB 2228 expires 1 January 2031.

Affected trades and occupancies

The amendment applies to buildings with more than two dwelling units in which residents live permanently - R-2 occupancy in IBC terms. Architects, structural engineers, fire protection engineers, and general contractors working on mid-rise multifamily projects in Washington are the primary trades affected. The key technical parameters the advisory group must resolve include minimum separation between stair doorways and the fire-resistance rating of the dividing wall assembly - parameters for which New York City's existing scissor stair code provides a working reference.

Research cited in support of the reform suggests scissor stairs can reduce total construction costs by 6% to 13% per building, even after accounting for additional fire-protection requirements. Proponents argue the design is particularly useful on narrow urban infill lots, where placing two conventional stairwells at opposite ends of a floor plate can make development infeasible.

Implementation timeline

The law's effective date of 11 June 2026 does not itself permit scissor stair construction to begin. Final implementation depends on the SBCC's rulemaking process, which is expected to extend into 2027; Sightline Institute has noted that the SBCC's code update cycle - nominally the 2027 update - is in practice expected to conclude closer to 2030. Permits already filed under the current code are governed by the code in effect at the time of application; the authority having jurisdiction determines applicability in ambiguous cases.

Dallas has allowed scissor stairs in buildings up to 75 feet since 2017, and Chicago has proposed amendments permitting them up to 150 feet, but no other state had adopted a statewide provision before Washington.

Designers and developers should monitor the SBCC's technical advisory group proceedings for draft amendment language and the formal comment period that will precede adoption into WAC 51-50.