Marin County, CA Accessory Structures: Shed & Carport Rules (2026)

Section 19.04.060 of the Marin County Code exempts specific rural accessory structures from the building permit requirement that otherwise applies under the codes adopted in Section 19.04.010. To qualify, the parcel must be at least one acre in a rural area, and each individual accessory structure, whether a tool shed, workshop, or horse stall, must not exceed three hundred square feet. The same section also allows waiver of the building-permit obligation for fences taller than six feet. In every case, the exemption from a building permit is conditioned on the structure or fence also being exempt from zoning regulations; a structure that triggers zoning review, such as one exceeding a district's accessory-structure standards or falling within a setback, still needs the permit regardless of its size.

Because the exemption only removes the building permit, not zoning compliance, property owners on smaller in-town parcels, or those building sheds over three hundred square feet, must still apply through the Building and Safety Division under the codes adopted in Section 19.04.010, pay the applicable fee from the Master Fee and Service Schedule under Section 19.04.032, and meet the accessory-structure use, height, and setback standards of the Marin County Development Code. An exempt shed built without a permit that is later found to be unsafe or in violation of use limits remains subject to abatement as a substandard structure under Section 19.04.027.