
Can You Build an ADU in Orange County? The 2026 Rules, Costs, and Which Cities Make It Easy
Yes, you can build an ADU on most single-family lots in Orange County. State law requires every OC city to approve a qualifying ADU ministerially within 60 days, allows up to 1,200 sq ft detached, and waives impact fees under 750 sq ft. Coastal lots may also need a Coastal Development Permit, which adds time.



