State law permits ADUs up to 1,200 sqft for detached units. 5,000–7,000 sqft for standard residential neighborhoods. Premium neighborhoods like Floral Park, Morrison Park, and Park Santiago offer lots up to 10,000+ sqft. No minimum lot size required by state law to build an ADU.
Up to 16 feet for detached ADUs. Up to 25 feet for attached ADUs 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.
No additional parking required if within 0.5 miles of public transit — which covers a significant portion of Santa Ana due to OCTA bus route density. Otherwise, one space per ADU may be required.
No owner-occupancy requirement for ADUs (made permanent by AB 976 in 2025).
Estimated cost $225K–$375K. Permit fees Contact city for current schedule. Impact fees: Waived under 750 sqft.
Santa Ana is the county seat of Orange County and its most urban city, with approximately 310,000 residents packed into 27 square miles. As the administrative hub of OC — home to the Orange County Superior Court, federal courthouse, and county government offices — Santa Ana has a massive daytime workforce. Roughly 55% of households are renters, making it the strongest rental market in the county by volume. The city has emerged as one of the most ADU-friendly jurisdictions in Orange County, offering expedited same-day counter processing for compliant applications and a pre-approved ADU plans program that dramatically reduces permitting timelines. For investors, Santa Ana represents the most affordable entry point for ADU construction in Orange County while delivering reliable rental income.