Issaquah, WA Accessory Structures: Tiny Homes (2026)

IMC 16.04.020 adopts the 2021 Edition of the International Residential Code, excluding Chapter 1 (Scope and Administration), Chapter 11 and Chapters 25 through 43, and adds five appendices by name: AF Radon Control Methods, AQ Tiny Houses, T Solar-Ready Provisions, U Dwelling Unit Fire Sprinkler Systems and V Fire Sprinklers. Administration comes from the Construction Administrative Code adopted in IMC 16.04.010, not from IRC Chapter 1.

Section 101.4.2.1 of that administrative code explains why the appendix matters. Provisions in the IRC appendices do not apply unless specifically referenced in the adopting ordinance, and an appendix affecting single-family or multifamily residential buildings is not effective until approved by the State Building Code Council under RCW 19.27.060(1)(a). Exception 2 then states that IRC Appendix F, Appendix Q (Tiny Houses) and Appendix U are included in adoption.

The IRC applies, under section 101.4.2, to detached one- and two-family dwellings and townhouses not more than three stories above grade plane with a separate means of egress, and to their accessory structures not more than three stories above grade plane.

The permit process is the ordinary one. Section 105.1 requires an owner or authorized agent who intends to construct a building or structure to apply to the Building Official and obtain the required permit first. Section 105.2 exempts one-story detached accessory structures only when they are tool and storage sheds, tree-supported play structures, playhouses and similar uses with a floor area not exceeding 200 square feet that are located in accordance with all land use regulations. Section 105.5 makes every permit expire 2 years from issuance. No Land Use Code section in the exported file uses the words tiny house or tiny home, so zoning placement follows the general district and accessory structure standards.