Rialto, CA Accessory Structures: Garage Conversions (2026)

Under Cal. Gov. Code §65852.2 (state ADU law, as amended by SB 9 / AB 68 / AB 681 / AB 671), Rialto must ministerially approve the conversion of an existing attached or detached garage into an ADU on a single-family or multifamily lot, with no requirement to replace lost parking. Rialto Municipal Code Title 18 includes local ADU standards that must conform to state law; where local rules conflict with state ADU law, state law controls. A garage conversion that is NOT being processed as an ADU (e.g., expanding the primary dwelling) still requires a building permit under the California Building Code adopted in RMC Title 15, must meet light/ventilation/egress/insulation/smoke-and-CO-alarm requirements, and must comply with zoning setbacks and lot-coverage limits in Chapter 18.06. Removing a required covered parking space outside the ADU pathway can trigger off-street parking replacement under Rialto's parking standards. All conversions need plan check, structural review, and a final inspection from Rialto Building & Safety.