Wash. Rev. Code § 35A.21.430
A code city shall not prohibit transitional housing or permanent supportive housing in any zones in which residential dwelling units or hotels are allowed. Effective September 30, 2021, a code city shall not prohibit indoor emergency shelters and indoor emergency housing in any zones in which hotels are allowed, except in such cities that have adopted an ordinance authorizing indoor emergency shelters and indoor emergency housing in a majority of zones within a one-mile proximity to transit. Reasonable occupancy, spacing, and intensity of use requirements may be imposed by ordinance on permanent supportive housing, transitional housing, indoor emergency housing, and indoor emergency shelters to protect public health and safety. Any such requirements on occupancy, spacing, and intensity of use may not prevent the siting of a sufficient number of permanent supportive housing, transitional housing, indoor emergency housing, or indoor emergency shelters necessary to accommodate each code city's projected need for such housing and shelter under RCW 36.70A.070(2)(a)(ii).
RCW 35A.21.430