Council moves multiplex‑housing appendix into rulemaking; allows small three‑story up to six units under modified IRC rules

The council voted Feb. 20 to move a new multiplex-housing appendix into the CR‑102 public‑rulemaking process after a high‑level review of scope and technical provisions.

Roger Haringa summarized the draft produced under RCW direction to permit multiplex buildings—defined in the appendix as three to six dwelling units consolidated into a single structure of common walls and floors—to be constructed under a modified residential code. The draft sets an overall floor-area cap of 8,000 square feet, allows one basement plus three stories above grade plane, and adds definitions and provisions absent from the IRC, such as shared corridors, egress paths, EV‑ready parking requirements for shared on‑site parking, and fire‑resistance and smoke/draft control measures.

The appendix requires automatic sprinklers (NFPA 13R residential systems for multiplex) and clarifies corridor fire-resistance, exit widths, 125‑foot travel distances and allowable exterior/interior stairs. It also limits corridor charging risks (no plug-in charging in corridors) and requires EV‑ready infrastructure where shared parking is provided. Council member Patrick Hanks and others praised the tag’s collaborative process and its aim to align residential energy and EV requirements.

Staff noted an editorial fix on the accessible parking/EV table (table 105.3) could be handled in-house by embedding the intended wording into section 105.3 and that the appendix will be posted to the tag page and the upcoming council meeting page before CR‑102 filing.

Next steps: Council authorized staff to make the editorial change and advance the multiplex appendix into the CR‑102 process; the appendix will be open to public comment during rulemaking.