State law permits ADUs up to 1,200 sqft for detached units. 10,000–20,000+ sqft in equestrian-zoned neighborhoods. Standard residential lots range from 6,000–10,000 sqft. No minimum lot size required by state law to build an ADU.
Up to 16 feet for single-story detached ADUs. Up to 25 feet for two-story ADUs per state law (AB 1332) in qualifying residential zones.
4-foot minimum from rear and side property lines for new detached ADUs. Conversions of existing structures (barns, guest houses, garages) are exempt from setback requirements. Properties within the Los Rios Historic District may require additional design review for street-facing facades.
One parking space per ADU may be required. Exempt if within 0.5 miles of the San Juan Capistrano Metrolink station, within one block of a car-share vehicle, or if the ADU is a conversion of existing space.
No owner-occupancy requirement for ADUs (made permanent by AB 976 in 2025).
Estimated cost $275K–$425K. Permit fees $6K–$14K. Impact fees: Waived under 750 sqft.
San Juan Capistrano is one of Orange County's most distinctive cities, anchored by the historic Mission San Juan Capistrano — the birthplace of Orange County — and the surrounding Los Rios Historic District, the oldest continuously occupied residential neighborhood in California. The city's rural-residential character sets it apart from the master-planned communities to the north, with equestrian-zoned neighborhoods featuring generous lots of 10,000 to 20,000+ square feet along streets like Paseo Adelanto and Calle Arroyo. The annual Return of the Swallows celebration draws visitors each March, and the Capistrano Depot anchors a walkable downtown with independent restaurants and galleries. San Juan Capistrano sits along the Metrolink Orange County Line, providing commuter rail access to Irvine, Laguna Niguel, and Los Angeles. Major employers in the surrounding area include the Capistrano Unified School District, St. Margaret's Episcopal School, and the equestrian and agricultural industries that define the local economy.