Siskiyou County, CA Accessory Structures: Garage Conversions (2026)

Siskiyou County does not publish a stand-alone garage-conversion ordinance. A habitable conversion of an attached or detached garage into independent living space is regulated as an Accessory Dwelling Unit under the county's Second Unit Housing provisions in Zoning Code Section 10-6.1515, which the 2025 Zoning Code Audit confirms the county administers in accordance with State law. Under California Government Code Section 66323 (the renumbered successor to former Section 65852.2), a code-compliant ADU created within the existing footprint of a structure such as a garage must be approved ministerially. State law also prohibits the county from requiring replacement off-street parking when a garage, carport, or covered parking structure is demolished or converted in conjunction with an ADU, and SB 1211 (effective January 1, 2025) extended that protection to uncovered spaces. A Junior ADU up to 500 square feet may be created within the walls of an existing single-family dwelling, including an attached garage, but a detached garage is converted as a regular ADU rather than a JADU. All conversions still require building permits and must satisfy Title 24 energy, egress, smoke-alarm, and fire-separation standards, and on rural parcels Environmental Health must confirm septic and well capacity for the added unit.