San Jacinto, CA Accessory Structures: ADU Rules (2026)

Section 17.405.060 of the San Jacinto Municipal Code implements California ADU law through two classes. Class 1 ADUs are approved under Government Code Section 66323. They include one ADU and one JADU converted within a single-family dwelling or, for the ADU, within the existing space of an accessory structure plus up to 150 additional square feet for ingress and egress. They also include one new detached ADU of 800 square feet of livable space or smaller with side and rear setbacks of at least four feet. A lot with an existing multi-family dwelling can take up to eight detached ADUs, and a lot with a proposed multi-family dwelling no more than two. Class 2 ADUs are approved under Government Code Sections 66314 through 66322 and carry the extra standards in Subsection G.

Processing runs on fixed clocks. The City has 15 business days to tell an applicant whether the application is complete, and a missed deadline means the application is deemed complete. The 60-day approval clock then runs, and an application not acted on within 60 days is deemed approved unless the applicant asked for a delay. A denial must list every defective item. Appeals go in writing to the City Clerk, and the Planning Commission decides within 60 business days. The processing fee is set in the Master Fee Schedule.

A detached ADU is capped at 16 feet, or 18 feet within one-half mile walking distance of a major transit stop or high quality transit corridor, with up to two more feet to match the roof pitch of the primary dwelling. An attached ADU is capped at 25 feet or the zone height limit, whichever is lower, and at two stories. Class 2 ADUs use four-foot side and rear setbacks and 25-foot front setbacks, but no percent-based size limit, FAR, front setback, lot coverage limit or open-space requirement can force an ADU below 800 square feet. Open space cannot fall below 50%, and one off-street space is required per ADU or bedroom, whichever is less, with listed exceptions.