Santa Cruz County, CA Accessory Structures: Garage Conversions (2026)

Converting an existing garage to living space in unincorporated Santa Cruz County is most commonly done as a "conversion ADU" under County Code Section 13.10.681, consistent with California ADU law (Gov. Code 66310+). The County's ADU/JADU Development Standards specify a 150 sq ft minimum for a conversion ADU; conversion ADUs are formed within the existing footprint and the County materials note a 500 sq ft figure for the conversion category, with up to 150 sq ft of new construction allowed for required ingress/egress. A key benefit is that no new parking is required for a conversion ADU, and under state law converting a garage does not by itself trigger replacement parking in most areas, although certain designated Coastal Zone areas (Live Oak, Seacliff/Aptos/La Selva, Davenport/Swanton, and Opal Cliff Drive segment) do require replacement parking when existing spaces are demolished or converted. Only legally constructed structures are eligible for conversion. The converted unit must include permanent cooking facilities and a full bathroom, and a detached unit needs a separate exterior entrance. Fire sprinklers are not required for the ADU if they are not required in the primary residence. Conversions in the Coastal Zone may be subject to additional building-permit review. Septic systems may need to be upgraded to serve the new dwelling. Building, electrical, and plumbing permits are required to make the converted space code-compliant habitable space.