Novato, CA Accessory Structures: ADU Rules (2026)

Section 19.34.030 of the Novato Zoning Ordinance implements California Government Code sections 66310 through 66342 for the City of Novato, Marin County. An ADU is a residential land use not subject to the density requirements of the Novato General Plan. A lot with a primary single-family dwelling gets a maximum of one ADU, and a junior ADU can be added to the same lot. ADUs require only a building permit; if the application is filed with a permit for a new primary dwelling, the ADU decision is deferred until the primary dwelling is acted on.

Attached and detached ADUs share a size cap of 50 percent of the primary dwelling's living area up to 850 or 1,000 square feet, 4-foot side and rear setbacks, and a 3-foot building separation. Attached ADUs top out at 25 feet or the zone limit, whichever is lower, and two stories, with a separate exterior entry and no interior passageway to the primary dwelling. Detached ADUs get 16 feet, or 18 feet within one-half mile walking distance of a major transit stop or high-quality transit corridor.

The statewide default ADU is up to 800 square feet and 16 feet high with 4-foot side and rear setbacks. Conversions within existing walls have no floor area cap, and an existing accessory structure can add up to 150 square feet for ingress and egress. Multi-family lots can convert non-livable space into ADUs up to 25 percent of existing units, and an existing multi-family lot can add up to eight detached ADUs. One off-street parking space is required unless an exemption applies, including a location within one-half mile walking distance of public transit.

Fire sprinklers are not required if the primary dwelling has none, and ADUs under 750 square feet pay no development impact fees. Junior ADUs fall under Section 19.34.031 and are limited to 500 square feet.