Committee advances multiplex appendix to let standardized 3‑story, 3–6‑unit buildings under IRC with added egress and EV rules

The BFRW voted Feb. 13 to forward a draft multiplex appendix for the International Residential Code that would let municipalities (statewide adoption) permit 3‑story multiplexes of three to six dwelling units built per modified IRC rules.

Staff said the appendix implements RCW 19.27.800 and establishes a clear scope: multiplex buildings are limited to three stories above grade plane (with at most one basement) and a maximum total floor area of 8,000 square feet. "Multiplex buildings are subject to all of the following conditions," Dustin said, summarizing the scoping language, including limits on common use areas and egress path protections.

Fire‑protection and egress requirements add IBC‑style clarity: 1‑hour separations between dwelling units, NFPA 13R sprinkler systems for multiplexes where required, corridor protections (minimum 36‑inch width, half‑hour rated), maximum 125‑ft travel distance, protected interior exit stairs and exterior egress balconies. Figures included in the draft illustrate acceptable interior/exterior stair and corridor configurations.

The appendix also carries EV‑ready infrastructure requirements where on‑site parking is provided: 20% of spaces must be EV‑ready (rounded up), minimum 40‑amp branch circuits, and allowance for automatic load management systems to allocate charging capacity. Staff and members clarified that accessible parking with EV infrastructure may count toward overall EV requirements.

Committee members discussed whether grade‑plane language should allow multiple basement levels on steep lots; the committee agreed to limit multiplexes to three stories above grade plane with no more than one basement to avoid creating configurations that require IBC treatment.

The modified appendix was moved forward to the full council by motion and will be considered during the CR102 public‑comment process.