Washington Tiny House Standards Under State Building Code

Washington adopts IRC Appendix Q for tiny houses on permanent foundations of 400 square feet or less through chapter 51-51 WAC, providing relaxed ceiling-height and loft standards. RCW 35.21.686 defines a tiny house and a tiny house with wheels as dwellings built to the state building code, and it authorizes cities to regulate tiny house communities. It also bars a city from adopting an ordinance that prevents entry or requires removal of a tiny house with wheels used as a primary residence in manufactured or mobile-home communities. Zoning and density rules otherwise still apply.

Local rules that exclude a tiny house with wheels used as a primary residence in a manufactured or mobile-home community are limited by RCW 35.21.686.