3 county-level rules, plus city-specific rules for 1 city in Marin County, California.
Verified from official government sources
Marin County Code §22.32.120 regulates ADUs in unincorporated areas. Detached and conversion ADUs under 800 square feet receive ministerial by-right approval. ADUs are allowed in single-family, multifamily, and mixed-use zones. The county currently extends its ADU permit fee waiver through December 31, 2026.
Sheds in unincorporated Marin County must meet county zoning setbacks. Under the California Building Code, a permit is generally required for accessory structures over 120 square feet; agricultural buildings on ag-zoned land have broader allowances.
Converting a garage to living space in unincorporated Marin County requires a county building permit and zoning review for egress, light/ventilation and parking; creating a separate unit is processed as an ADU under state law.
1 cities in Marin County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
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Marin County Ordinance Hub →