Island County, WA Accessory Structures: Tiny Homes (2026)
Tiny home rules in Island County, 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
- Governing section
- Island County Code 17.03.040 definitions
- Excluded structures
- RVs, travel trailers, park models, tiny homes on wheels
- Consequence
- Cannot be permitted as a legal ADU
- Alternative cap
- Site-built detached ADU capped at 1,200 sq ft
Summary
Island County's zoning code expressly excludes 'tiny homes on wheels' from qualifying as an accessory dwelling unit. Section 17.03.040's definition of a detached ADU carves out recreational vehicles, travel trailers, park model homes and tiny homes on wheels, so a wheeled tiny home cannot be permitted through the county's ADU process.
Accessory dwelling unit (ADU), Detached means a dwelling unit, situated on the same parcel as a single family dwelling, shares a common access point with the single family dwelling and which cannot be segregated or separately sold, transferred, given, or otherwise conveyed unless the lot is of sufficient size to meet base density and other County Code requirements. Detached ADUs do not include recreational vehicles, travel trailers, park model homes, or tiny homes on wheels. A detached ADU is subject to the requirements and conditions provided in section 17.03.180
Full Breakdown
040, defines a 'detached ADU' as a dwelling unit on the same parcel as a single-family home that shares common access with that home and cannot be sold off separately unless the lot meets base density. I requires every ADU to be established through a building permit as a legal use, a tiny home on wheels cannot use that ADU pathway at all, no matter how it is sited on the lot or how long it stays there. V, rather than as a second permanent dwelling.
I, not a home on a trailer chassis. N, which requires permanent foundations and removal of wheels and towing tongues, underscoring that the code treats wheeled structures differently from permitted dwellings.
Violations & Fines
Placing a tiny home on wheels on a lot and treating it as a permitted ADU is not a legal use under section 17.03.040's detached-ADU definition, so Planning and Community Development can treat it as an unpermitted dwelling and pursue code compliance action, including a requirement to remove the structure or relocate it into a use category the code actually allows, such as a temporary recreational vehicle.
Frequently Asked Questions
Can I put a tiny home on wheels on my property as an ADU in Island County?
What happens if I already have a tiny home on wheels set up as a second dwelling?
Is there any way to legally add a small second home in Island County?
Sources & Official References
Other rules in Island County
Compare Island County to another location·View the Washington accessory structures overview
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