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

In unincorporated Riverside County, turning a garage into habitable space generally creates an accessory dwelling unit, governed by Ordinance No. 348, Article XIXj. A key benefit confirmed by the ordinance: "No replacement parking spaces shall be required for conversion of any existing parking spaces, including garages, carports or marked spaces into an ADU" (Sec. 19.807 F.2.d), and the same no-replacement rule applies to interior ADUs and Junior ADUs (Sec. 19.807 F.1.b). An interior ADU created within the existing structure requires no new parking at all. A garage converted to an interior ADU may not exceed 50% of the primary dwelling's floor area (with an 800 sq ft floor and 1,000 sq ft ceiling), and any expansion needed to create egress is capped at 150 square feet (Sec. 19.807 D.1). A JADU conversion is limited to 500 square feet and must remain within the existing one-family dwelling footprint (Sec. 19.807 D.3). California State ADU Law (Gov. Code 66322(a)(3)) prohibits imposing parking standards on ADUs created from an existing primary residence or accessory structure; HCD's May 2025 review specifically directed Riverside County to remove a parking requirement that conflicted with that statute. A garage conversion still requires a building permit to ensure habitability, egress, and fire/life-safety compliance, but is approved ministerially when it meets Gov. Code 66323.