ADU Construction in Santa Ana

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.

Zoning & requirements

Setbacks

4-foot minimum from rear and side property lines for new detached ADUs. Conversions of existing structures are exempt from setback requirements.

Height

Up to 16 feet for detached ADUs. Up to 25 feet for attached ADUs in qualifying residential zones.

Parking

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.

Lot Size

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.

Owner Occupancy

No owner-occupancy requirement for ADUs (made permanent by AB 976 in 2025).

Additional Notes

Santa Ana offers a pre-approved ADU plans program — selecting from pre-approved designs significantly reduces plan check time. Expedited same-day counter processing is available for compliant applications that use standard designs and meet all requirements. Due to OCTA's extensive bus network, many Santa Ana properties qualify for the transit parking exemption.

How to permit your ADU in Santa Ana

Check for pre-approved plans

Before designing from scratch, check the city's pre-approved ADU plans catalog. Using a pre-approved design can reduce your permitting timeline from weeks to days and eliminate plan check review entirely for qualifying applications.

Design your ADU (or select pre-approved)

If using custom plans, create architectural drawings including site plan, floor plan, elevations, structural, and MEP. If using pre-approved plans, prepare site-specific adaptations showing your lot layout, utility connections, and setback compliance.

Submit to Planning and Building

Submit your plans to the Planning and Building Department. For compliant applications using pre-approved or straightforward designs, expedited same-day counter review may be available. Email planning@santa-ana.org for questions.

Plan check review

Custom designs undergo standard plan check review. State law mandates a 60-day maximum. Pre-approved plans may receive expedited processing — as little as one day at the counter for fully compliant applications.

Build & inspect

Once permitted, begin construction with your licensed contractor. Schedule required inspections at each milestone. Call (714) 667-2738 for inspection scheduling.

Final inspection & occupancy

Request final inspection. Once passed, receive your Certificate of Occupancy. Your ADU is now legal to rent or occupy in Orange County's strongest rental market.

City of Santa Ana Planning and Building Department • Fees: Contact city for current fee schedule. Santa Ana periodically updates fees — call (714) 667-2738 or email planning@santa-ana.org for the latest schedule. • Timeline: Same-day to 60 days depending on application type. Pre-approved plans with compliant applications may receive same-day counter approval. Custom designs follow standard 60-day state-mandated timeline.