State law permits ADUs up to 1,200 sqft for detached units. 6,000–8,000 sqft typical residential lots in Tustin proper. North Tustin unincorporated areas feature significantly larger parcels, often 10,000–20,000+ 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 AB 1332 provisions in qualifying residential zones.
4-foot minimum from rear and side property lines for new detached ADUs. Conversions of existing structures are exempt from setback requirements.
One parking space per ADU may be required. Exempt if within 0.5 miles of public transit, 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 $250K–$400K. Permit fees $5K–$12K. Impact fees: Waived under 750 sqft.
Tustin is a centrally located Orange County city with over 115,000 residents, offering a compelling mix of older character neighborhoods and modern master-planned communities. Old Town Tustin features tree-lined streets with mid-century homes on generous lots, while the Tustin Legacy development — built on the former Marine Corps Air Station — brings newer housing, retail at The District, and open space. The city sits at the geographic heart of Orange County with direct access to the I-5 and SR-55 freeways, placing residents minutes from Irvine's massive employment base. Major employers like Blizzard Entertainment are headquartered nearby, and the diverse local economy spans tech, healthcare, and retail sectors.