Mendocino County, CA Accessory Structures: Tiny Homes (2026)

Mendocino County does not publish a dedicated tiny-home ordinance, so tiny dwellings are regulated through existing building and zoning rules. A tiny house built on a permanent foundation is treated as a single-family dwelling or, where it is a second unit on a parcel with an existing home, as an Accessory Dwelling Unit under California law and the County's ADU provisions; detached ADUs may be up to 1,200 square feet, and a Junior ADU is limited to 500 square feet within an existing residence. A site-built or factory-built permanent tiny home must meet the California Building Code (or applicable manufactured-housing standards) and obtain a building permit. A 'tiny home on wheels' is generally classified as a recreational vehicle or park trailer rather than a permanent dwelling, and like other RVs it cannot lawfully be used for permanent occupancy on a residential lot outside of approved RV parks or other permitted situations. The County's parks and camping rules (Title 14, Chapter 14.28) separately restrict where camping and trailer use are allowed. In the unincorporated Coastal Zone, placing a new dwelling unit, including a tiny-home ADU, typically requires a Coastal Development Permit under the Coastal Zoning Code. Because no tiny-home-specific code exists, applicants should work with Planning & Building Services to confirm whether the unit is reviewed as a dwelling, ADU, manufactured home or RV.