5 rules for unincorporated Mendocino County, California.
Verified from official government sources
Unincorporated Mendocino County allows ADUs and Junior ADUs consistent with California state law. Detached and attached ADUs are capped at 1,200 square feet and JADUs at 500 square feet. Inland ADUs are approved ministerially; coastal-zone ADUs are regulated by Chapter 20.458 and generally require a Coastal Development Permit.
Unincorporated Mendocino County exempts one-story detached accessory structures of 120 square feet or less from a building permit, though zoning still applies. Small detached accessory buildings 15 feet or less at the ridge and 500 square feet or less may use a reduced 5-foot setback under the County's yard regulations (Section 20.152.015).
Converting a garage into living space in unincorporated Mendocino County requires a building permit and zoning compliance. Converting a garage into an ADU is permitted under the County's ADU rules (state-law-based), and a converted-garage ADU is one of the streamlined ministerial options. Coastal-zone conversions may also require a Coastal Development Permit.
Carports are treated as accessory structures in unincorporated Mendocino County. They must meet the zoning district's setback, height and lot-coverage standards; small detached accessory structures of 120 square feet or less are exempt from a building permit, but most carports exceed that and require one. Coastal-zone carports may require a Coastal Development Permit.
Unincorporated Mendocino County has no separate tiny-home ordinance. A permanent tiny house on a foundation is regulated as a dwelling or as an Accessory Dwelling Unit under the County's ADU rules (detached ADUs up to 1,200 square feet). Tiny homes on wheels are treated as recreational vehicles and generally cannot be used as permanent residences.
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