139.9K
Population
37,621
Parcels
Orange
County
What You Can Build in Orange
Under California state law, most residential properties in Orange are eligible for significant development beyond their current use. Here's what the law allows:
Accessory Dwelling Unit (ADU)
California law (AB 68, AB 881, SB 897) allows homeowners in Orange to build an ADU up to 1,200 sq ft on most single-family and multi-family lots. No minimum lot size required. ADUs can be detached, attached, or converted from existing space (garage, basement).
Junior ADU (JADU)
In addition to an ADU, Orange homeowners can build a JADU of up to 500 sq ft within the existing footprint of the primary home. Owner occupancy required for either the JADU or primary unit.
SB 9 Duplex + Lot Split
Single-family homeowners in Orange can split their lot into two parcels and build a duplex on each — up to 4 units total. Lot must be in a single-family zone, not in a historic district, and each resulting parcel must be at least 1,200 sq ft (40% of original lot).
SB 1211 — Multiple ADUs
Effective 2025, SB 1211 allows up to 8 detached ADUs on multi-family properties in Orange, plus additional ADUs from garage/carport conversions. Single-family lots can have an ADU + JADU.
AB 1033 — ADU Condo Conversion
If Orange has opted in, homeowners can convert ADUs into separately sellable condominiums. This allows ADUs to be sold independently from the primary home, creating new homeownership opportunities.
Frequently Asked Questions
Can I build an ADU in Orange?
Yes. Under California state law, most residential properties in Orange are eligible for at least one ADU up to 1,200 sq ft, regardless of local zoning restrictions. The state has preempted local ordinances that unreasonably restrict ADU development.
How much does it cost to build an ADU in Orange?
ADU construction costs in Orange County typically range from $150,000 to $400,000+ depending on size, finishes, and site conditions. Prefab/factory-built ADUs can reduce costs to $100,000-$250,000. Garage conversions are generally the most affordable option at $50,000-$150,000.
Can I split my lot under SB 9 in Orange?
If your property is in a single-family zone, not in a historic district, and meets minimum size requirements, you can split your lot into two parcels under SB 9. Each resulting parcel must be at least 1,200 sq ft. You can then build up to two units on each parcel.
Do I need a permit to build an ADU in Orange?
Yes, you need a building permit from the City of Orange. However, cities are required to approve ADU applications ministerially (without discretionary review) within 60 days if the project meets state standards. Impact fees are waived for ADUs under 750 sq ft.