SBCC advances multiplex‑housing appendix to CR‑102; sets area and egress limits

The State Building Code Council on Feb. 20 approved moving a new multiplex‑housing appendix into the CR‑102 rulemaking process, clearing the proposed text for public comment with a staff‑directed editorial change to the EV parking language.

The appendix, developed under RCW 19.27.800, is intended to allow three‑story multiplex buildings (three to six dwelling units consolidated in a single structure) to be designed under the International Residential Code (IRC) with targeted modifications where the residential code lacks apartment‑style provisions. Key features adopted for CR‑102 consideration include a maximum total floor area of 8,000 square feet, allowance for one basement, a requirement for automatic sprinkler systems (NFPA 13R permitted for multiplex), defined corridor and means‑of‑egress provisions, fire‑resistance assemblies at defined locations, and EV‑ready shared parking criteria when on‑site parking is provided.

Roger Haringa summarized the document’s approach: “Multiplex buildings shall be permitted to be constructed in accordance with the IRC as modified by appendix **,” he said. The appendix adds definitions (for circulation paths, exit passageways, load‑management EV systems), prescriptive corridor and stair dimensions (36‑inch minimum corridor width; 125‑foot travel distance limit), and simplified structural triggers (professional engineering required when in higher seismic design categories).

Council discussion centered on clarification of corridor protections, accessible parking/EV‑ready spaces, and the decision to limit the appendix to relatively small, prescriptive buildings so that more complex projects would still be designed under the full building code. Council members also suggested editorial changes to improve clarity; staff agreed to remove Table 105.3 and fold its intent into §105.3 wording to avoid confusion about EV‑ready accessible spaces.

Motion and outcome: Roger moved to release the multiplex appendix into the CR‑102 process and permit staff to implement the editorial change; the motion was seconded and passed unanimously. Staff said the revised document will be posted to the TAG page and the upcoming council meeting materials for broader review prior to rule filing.

What happens next: Staff will post the updated appendix and supporting figures to the SBCC website and proceed with CR‑102 preparation for the public comment period; proposed editorial changes will also be visible to stakeholders during CR‑102.