// Placentia

ADU Construction in Placentia

Growing rental demand driven by Cal State Fullerton proximity, top-rated Placentia-Yorba Linda Unified schools attracting families, historic downtown revitalization increasing neighborhood appeal, and practical lot sizes with a straightforward city permitting process.

Placentia — branded as "A Pleasant Place to Live" — is a well-established city of approximately 52,000 residents in north-central Orange County. The city features a mix of mid-century neighborhoods with mature tree canopy and newer developments, all served by the highly rated Placentia-Yorba Linda Unified School District. Placentia's historic downtown along Santa Fe Avenue is undergoing a revitalization that includes new dining, retail, and mixed-use development, bringing renewed energy to the city center. The proximity to Cal State Fullerton (CSUF) — located just across the border in Fullerton — creates consistent demand for rental housing from students, faculty, and university staff. Residential lots typically range from 5,000 to 7,000 sqft, providing practical space for ADU construction. The city's central north OC location offers convenient access to the 57 and 91 freeways.

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 single-story detached ADUs. Up to 25 feet for two-story ADUs per state law (AB 1332) in qualifying residential zones.
Parking
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.
Lot Size
5,000–7,000 sqft typical residential lots. Some older neighborhoods near downtown have slightly smaller parcels. 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
Properties near the downtown revitalization area may benefit from increased property values as new retail, dining, and mixed-use projects are completed. ADUs under 750 sqft are exempt from impact fees.

How to permit your ADU in Placentia

01

Verify lot & zoning

Confirm your property's zoning designation and lot dimensions on the city's zoning map. Most single-family residential zones in Placentia allow ADUs by right. Check for any easements, utility locations, or planned infrastructure improvements in your area.

02

Design your ADU

Create architectural plans including site plan, floor plan, elevations, structural, mechanical, electrical, and plumbing. Placentia's established neighborhoods feature a mix of ranch-style and mid-century homes — design your ADU to complement the existing streetscape. Include Title 24 energy compliance.

03

Submit to Community Development

Submit your complete plan set to the Community Development Department. Include Title 24 documentation and any required soils reports. Pay plan check fees at submission.

04

Plan check review

The city reviews plans for compliance with building codes and ADU regulations. State law mandates a 60-day maximum review period for compliant ADU applications.

05

Build & inspect

Once permitted, begin construction with your licensed contractor. Schedule required inspections at each milestone — foundation, framing, rough MEP, insulation, and final.

06

Final inspection & occupancy

Request final inspection from the Building Division. Once passed, receive your Certificate of Occupancy. Your ADU is now legal to rent or occupy — and Placentia's rental market is ready for new inventory.

City of Placentia Community Development Department • Fees: $5,000–$10,000 total (plan check, building permit, school fees). Impact fees waived for ADUs under 750 sqft. • Timeline: 4–8 weeks for plan check. 60-day maximum review required by state law.

Get your Placentia ADU estimate