Washington State Residential Code: Stairs & Guards

Washington runs its own Washington State Residential Code (WSRC) — WAC 51-51 — on its own state-run adoption cycle rather than a straight IRC pass-through. The current edition is based on the 2021 IRC, effective 15 March 2024, with Washington amendments layered on top (the state is best known for going beyond the IRC on energy efficiency).

For a house stair, the figures follow the IRC baseline — 7¾ in max riser, 10 in min tread, 6 ft 8 in headroom, 36 in min width, 34–38 in handrails, 36 in guards, the 30 in guard trigger and the 4 in sphere. No Washington-specific stair or guard amendment is confirmed here. See the US stair & guard rules for the shared figures, and confirm against the current WSRC text for any local amendments.