Accessory Structures in Marin County, CA (2026)
3 county-level rules, plus city-specific rules for 1 city in Marin County, California.
Verified from official government sources
ADU Rules
Marin County Development Code § 22.32.120 sorts accessory dwelling units into a by-right Category 1 (an 800 sq. ft. cap, 4 ft. side/rear setbacks, 18 ft. height) and a permitted Category 2 (up to 1,200 sq. ft.), both processed under Chapter 22.56 in the unincorporated county.
Marin County Accessory Dwelling Unit Standards
Some RestrictionsMarin County Code of Ordinances § 22.32.120
There are two categories of Accessory Dwelling Units, both with different criteria that apply as indicated below. Except as provided under State law, an Accessory Dwelling Unit may not be sold or otherwise conveyed separately from the primary dwelling unit. Category 1-Statewide Exemption Accessory Dwelling Units can be rented only for terms longer than 30 consecutive days. A.Category 1—Statewid...
ADU Owner Occupancy
A Junior Accessory Dwelling Unit in unincorporated Marin County requires the property to be owner-occupied. Marin County Code of Ordinances § 22.32.125(E) states 'the property shall be owner occupied,' with a narrow carve-out only where the owner is a government agency, land trust, or housing organization. The requirement is one of six eligibility conditions a homeowner must meet before converting existing space into a JADU.
Junior ADUs in Marin County Require Owner Occupancy
Some RestrictionsMarin County Code of Ordinances § 22.32.125(E)
A property owner may voluntarily have existing building area recognized as a Junior Accessory Dwelling Unit if it meets all of the following eligibility criteria: ... D.The unit shall be the only junior accessory dwelling unit on the property.E.The property shall be owner occupied, except that owner occupancy is not required if the owner is a government agency, land trust, or housing organization.
Shed & Carport Rules
Marin County Code Section 19.04.060 waives the building permit requirement for small accessory structures, tool sheds, workshops, and horse stalls under three hundred square feet each, on rural parcels of one acre or more, when the structure is also exempt from zoning regulations. Larger or non-qualifying structures still need a standard building permit.
Marin County Shed and Accessory Building Permit Exemption
Light RestrictionsMarin County Code of Ordinances § 19.04.060
Notwithstanding permit exemptions provided by the codes adopted by Section 19.04.010, the following work shall be exempt from obtaining a building permit: In rural areas on parcels of one acre or more, accessory structures used for tool sheds, workshops and horse stalls not exceeding three hundred square feet each and fences over six feet in height may have the obligation to obtain building per...
Accessory Structures by City in Marin County
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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