ADU Rules: Antioch vs Brentwood
How do adu rules rules compare between Antioch, CA and Brentwood, CA?
Antioch and Brentwood have similar restriction levels.
Antioch, CA
Contra Costa County
Antioch implements California state ADU law through Antioch Municipal Code Section 9-5.3805, allowing one ADU plus one JADU on single-family lots with a four-foot side and rear setback, a 16-foot height limit for detached ADUs, and ministerial 60-day approval.
View full Antioch rules →Brentwood, CA
Contra Costa County
Brentwood must allow Accessory Dwelling Units on any single-family lot under California Government Code Section 65852.2, as expanded by AB 68, AB 881, and SB 13. Detached ADUs up to 800 sq ft with 4-foot setbacks are ministerial approvals processed within 60 days. AB 1033 now allows selling an ADU separately from the primary home.
View full Brentwood rules →Key Facts Comparison
| Fact | Antioch | Brentwood |
|---|---|---|
| Code section | AMC § 9-5.3805 (Accessory Dwelling Units) | - |
| State law | Gov. Code § 65852.2 / §§ 66310-66342 | - |
| ADUs allowed per single-family lot | 1 ADU + 1 JADU | - |
| Detached ADU max size | 1,200 sq ft | - |
| Attached ADU max size | 50% of primary dwelling or 1,200 sq ft, whichever is less | - |
| JADU max size | 500 sq ft (inside existing single-family residence) | - |
| Side/rear setback (new detached) | 4 ft minimum | - |
| Detached ADU max height | 16 ft (18-20 ft near transit) | - |
| Attached ADU max height | 25 ft | - |
| Parking | Up to 1 space per bedroom; waived near transit, JADUs, conversions | - |
| Owner occupancy | Not required for ADUs permitted on/after Jan 1, 2020; required for JADUs | - |
| Permit review clock | 60 days (ministerial) | - |
| - | - |
Highlighted rows indicate differences between cities.
Antioch FAQ
Do I need to live in my Antioch ADU as the owner?
No. Under California state law and Antioch Municipal Code Section 9-5.3805, ADUs permitted on or after January 1, 2020 are not subject to owner-occupancy. JADUs remain subject to owner-occupancy of either the primary dwelling or the JADU.
How tall can a detached ADU be in Antioch?
A detached ADU on a single-family or multifamily lot may be up to 16 feet tall by right. If the lot is within one-half mile walking distance of a major transit stop or high-quality transit corridor, the ADU may be up to 18 feet, with up to two additional feet (20 feet total) allowed to match the roof pitch of the primary dwelling.
What setbacks apply to a new detached ADU in Antioch?
Antioch requires a minimum four-foot setback from the rear and interior side property lines for a new-construction ADU on a single-family lot, matching California's statewide minimum under Government Code Section 65852.2.
Does Antioch require parking for ADUs?
Required parking may not exceed one space per bedroom. Parking is fully exempt when the ADU is located within one-half mile walking distance of public transit, when the ADU is created within an existing structure (such as a garage conversion), for JADUs, in historic districts, and where on-street permits are required.
Brentwood FAQ
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