Olympia, WA Accessory Structures: Tiny Homes (2026)
Tiny home rules in Olympia, WA, covering tiny houses on wheels (THOWs), park model RVs, and tiny home on foundation builds, determine where they are legal and how they get permitted.
Key Facts
- Adopted appendix
- IRC Appendix Q, Tiny Houses (OMC 16.04.020(A)(2))
- Sprinkler rule
- Section P2904.1.1: protect all areas of a dwelling unit
- Permit exemption ceiling
- Sheds and similar uses, floor area not greater than 200 square feet
- RV definition
- Single chassis, four hundred square feet or less
- RV living ban
- OMC 16.06.020, Section 302.10, with listed exceptions
Summary
In the City of Olympia, Washington, tiny houses are tied to the International Residential Code: OMC 16.04.020(A)(2) adopts Appendix Q, Tiny Houses, along with the radon, solar-ready and dwelling unit sprinkler appendices. Separately, OMC 16.06.020 bars living, sleeping or cooking in a recreational vehicle parked on public or private property, with listed exceptions.
2. International Residential Code Adopted. The current State adopted edition of the International Residential Code (“IRC”), as published by the International Code Council, Inc., as adopted by the State Building Code Council in Chapter 51-51 WAC (excluding Chapter 1, Section R112, Board of Appeals, Chapter 11, and Chapters 25 through 43), except that Chapter 29, Section P2904 is adopted and the following Appendices are hereby adopted: Appendix F Passive Radon Gas Controls Appendix Q, Tiny Houses Appendix T, Solar-Ready Provisions-Detached One-and Two-Family Dwellings, Multiple Single-Family Dwellings (Townhouses)
Full Breakdown
Olympia handles tiny houses through the building code rather than a stand-alone ordinance chapter. OMC 16.04.020(A)(2) adopts the current State adopted edition of the International Residential Code, as adopted in Chapter 51-51 WAC, and names Appendix Q, Tiny Houses, among the appendices adopted. The same list adopts Appendix F Passive Radon Gas Controls, Appendix T Solar-Ready Provisions, Appendix U Dwelling Unit Fire Sprinkler Systems and Appendix V Fire Sprinklers. The appendix text is incorporated by reference and is not reprinted in the OMC.
Sprinklers matter for small dwellings. Amended Section P2904.1.1 requires sprinklers to protect all areas of a dwelling unit, with exceptions that include bathrooms not more than 55 square feet, clothes closets, linen closets and pantries not exceeding 24 square feet, and detached accessory dwelling units with utilities served by an existing single-family residence that does not have an existing sprinkler system. OMC 16.04.040(B)(4) adds Section R313.2, requiring a fully automatic residential fire sprinkler system in all structures subject to the code, per NFPA 13, RCW 18.160 and the approval of the Fire Chief.
Permits and completion follow the ordinary building rules. The Building Official issues a Certificate of Occupancy under amended Section R110.3 after inspection, and OMC 16.04.040(A)(1) exempts only one-story detached accessory structures used as tool and storage sheds, playhouses, and similar uses with a floor area not greater than 200 square feet.
On wheels, OMC 16.04.390(G) defines a recreational vehicle as a structure built on a single chassis, four hundred square feet or less, self-propelled or permanently towable by a light-duty truck, and designed primarily not for use as a permanent dwelling. Under OMC 16.06.020, Section 302.10, no recreational vehicle can be used for living, sleeping or cooking while parked on public or private property. Exceptions cover an RV with a Washington Department of Labor and Industries label in a manufactured/mobile community, a temporary residence meeting OMC 18.04.060(DD), and camping on City right-of-way under OMC 10.16.035.
Violations & Fines
Building Code violations under OMC 16.04.070 are a misdemeanor, with a fine not to exceed $1,000 and/or imprisonment not to exceed ninety days, and each day is a separate offense. Second and later days of a continuing violation are a gross misdemeanor, with a fine not to exceed $5,000. The civil infraction track is Class 3 ($50), Class 2 ($125), then Class 1 ($250). Living in a parked recreational vehicle outside the listed exceptions violates OMC 16.06.020, Section 302.10, and Section 109.3 makes that a civil infraction starting at Class 3 ($50).
Frequently Asked Questions
Does the City of Olympia adopt tiny house standards?
Is a fire sprinkler required in a tiny house in Olympia?
Can I live in an RV or trailer on my lot in the City of Olympia?
Does a small detached building avoid a building permit in Olympia?
Sources & Official References
Other rules in Olympia
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