Detached ADU for an ADU in Orange County: what does state law allow?

Up to 1,200 sq ft. At least 800 sq ft is always allowed.

Height for an ADU in Orange County: what does state law allow?

16 ft; 18 ft within half a mile of transit, plus 2 ft for a roof that matches the home.

4 ft from the side and back of the property.

None needed within half a mile of transit, or for a conversion.

No impact fees up to 750 sq ft. No school fees up to 500 sq ft.

The city must decide within 60 days of a complete application.

Orange County

What state law allows on any property in Orange County, and which cities ADUCheck covers in full. Updated November 6, 2026.

State rules apply now. City rules for Irvine, Anaheim, Santa Ana and Huntington Beach come first. Enter an address to see which rules apply to it.

Every city must allow at least this much. A city can allow more, never less. State rules current to November 6, 2026.

Detached ADU
Up to 1,200 sq ft. At least 800 sq ft is always allowed.
Height
16 ft; 18 ft within half a mile of transit, plus 2 ft for a roof that matches the home.
Setbacks
4 ft from the side and back of the property.
Parking
None needed within half a mile of transit, or for a conversion.
Fees
No impact fees up to 750 sq ft. No school fees up to 500 sq ft.
Timeline
The city must decide within 60 days of a complete application.

35 cities get the state rules today.