-WA State Law: Dwelling that may be built on wheels; is no larger than 400 sf, not including lofts; includes permanent provisions for living, sleeping, eating, cooking and sanitation; and is built to Washington State Building Code including IRC Appendix Q as amended by WA State. See Section 5: https://app.leg.wa.gov/billsummary?BillNumber=5383&Year=2019
[“Tiny house” and “tiny house with wheels” means a dwelling to be used as permanent housing with permanent provisions for living, sleeping, eating, cooking, and sanitation built in accordance with the state building code.]
–A tiny house is designed, engineered, stamped/approved as permitted housing, built to RV or travel trailer standards.
-There are many other TH options out there such as: ADU, A-frame, bus conversion, cabin, full-time RV living, van, yurt; attic, basement and garage conversions, and backyard cottages.
-Most people define a tiny house on wheels as constructed with conventional building methods. The most popular is built on a flatbed trailer.