ADU Construction in Brea

Brea is an affluent, family-friendly community of approximately 48,000 residents in north Orange County, with a median household income of $131,000. Known for its excellent schools (Brea-Olinda Unified School District), well-maintained neighborhoods, and the Brea Mall — one of the region's premier shopping destinations — Brea offers a high quality of life that attracts long-term residents. The city sits along the 57 freeway corridor near the Birch Hills Golf Course and Carbon Canyon Regional Park, providing quick access to both Orange County and Inland Empire employment centers. Brea has proactively embraced ADU development by offering a pre-approved ADU plans program that streamlines permitting and reduces costs for homeowners.

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 18 feet for detached ADUs per 2025 regulatory updates. Up to 25 feet for attached ADUs in some 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

6,000–8,000 sqft for standard residential neighborhoods. Some hillside and estate properties offer larger 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

Brea offers a pre-approved ADU plans program — selecting from pre-approved designs significantly streamlines the permitting process and can reduce plan check timelines to 30 days. Fee schedule was updated in July 2025 — contact the Community Development Department for current rates.

How to permit your ADU in Brea

Explore pre-approved plans

Before commissioning custom designs, review Brea's pre-approved ADU plans program. These designs have already been reviewed for code compliance, reducing your plan check timeline to approximately 30 days and eliminating common revision cycles.

Design your ADU (or adapt pre-approved)

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

Submit to Community Development

Submit your complete plan set to the Community Development Department at 1 Civic Center Circle. Include structural engineering, Title 24 energy compliance, and any required soils reports for hillside properties.

Plan check review

Pre-approved plans target a 30-day turnaround. Custom designs follow standard review — state law mandates a 60-day maximum for compliant ADU applications. Fee schedule updated July 2025 — confirm current fees at submission.

Build & inspect

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

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.

City of Brea Community Development Department — Planning Division, 1 Civic Center Circle • Fees: Contact city for current fee schedule (updated July 2025). Call (714) 990-7600 or visit 1 Civic Center Circle for the latest rate sheet. • Timeline: 4–8 weeks for custom plans (60-day state maximum). Approximately 30 days for pre-approved plans.