Bellingham, WA Accessory Structures: Tiny Homes (2026)
Tiny home rules in Bellingham, 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
- Adopting section
- BMC 17.10.020, § 118, item 2
- Standard adopted
- 2021 IRC Appendix Q
- State baseline
- IRC required; Appendix Q optional
- Minimum fine
- $100 civil infraction
Summary
Bellingham's building code locally adopts IRC Appendix Q, the tiny-house construction standard, giving builders a legal path to permit compliant tiny homes as accessory structures.
SECTION 118: INTERNATIONAL RESIDENTIAL CODE TECHNICAL AMENDMENTS. The 2021 Edition of the International Residential Code, as adopted by BMC 17.10.010 is amended as follows: 1. Appendix F "Radon control methods" is adopted. 2. Appendix Q "Tiny houses" is adopted. 3. Appendix U "Dwelling unit fire sprinkler system" is adopted.
Official source re-checked September 8, 2026: no newer edition of the code had been published (publisher’s edition: current through Ordinance 2026-06-015, passed June 1, 2026).
Full Breakdown
BMC 17.10.020 amends the state-adopted International Residential Code with Bellingham's own list of optional appendices, and Section 118, item 2 specifically adopts Appendix Q, "Tiny houses." Washington's base building code (RCW 19.27) doesn't require cities to opt in to Appendix Q, so Bellingham's adoption is a genuine local choice that gives tiny homes, with their reduced ceiling heights, loft egress rules and smaller floor-area minimums, a legal path to a building permit instead of being unpermittable under standard IRC dimensional rules. The same amendment adopts Appendix U (fire sprinklers) and Appendix T (solar-ready provisions).
Violations & Fines
Building a tiny house that doesn't meet Appendix Q, or building without a permit, is subject to civil infraction fines up to $2,050 per violation ($100 minimum) under Construction Administrative Code § 114.4.
Frequently Asked Questions
Does Washington state law require cities to allow tiny houses?
Can I put a tiny house on wheels in my backyard as an accessory structure?
Sources & Official References
Other rules in Bellingham
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