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

Trinity County does not have a separate garage-conversion ordinance; turning a garage into habitable space is handled through the accessory dwelling unit rules in Zoning Code Chapter 17.95 (Public Review Draft, April 2026), which implement California ADU law (Gov Code 66310-66342). The ADU definition in Section 17.95.020 expressly includes a 'repurposed existing space' residential unit, so an existing garage or accessory structure may be converted into a complete independent dwelling with provisions for living, sleeping, eating, cooking, and sanitation. Under Section 17.95.030(D), a demolition permit for a detached garage that is to be replaced with an ADU is reviewed together with the ADU application and issued at the same time. The parking standards in Section 17.95.040(E) exempt conversions from extra parking when the ADU is part of the existing primary residence or an existing accessory structure, among other exemptions; this tracks state law that bars the county from requiring replacement of off-street spaces lost when a garage or covered parking is converted to an ADU. Converted units must still meet building, fire-safe, and life-safety codes, connect to approved water and an approved sewer or on-site septic system through Environmental Health, and stay within the 1,200-square-foot ADU size cap. A garage conversion that creates a junior ADU within the walls of the home must also comply with the JADU provisions of state ADU law.