ADU Rules: El Cerrito vs Martinez
How do adu rules rules compare between El Cerrito, CA and Martinez, CA?
El Cerrito has fewer restrictions than Martinez.
El Cerrito, CA
Contra Costa County
Contra Costa County allows one ADU and one JADU on any residential lot by ministerial permit, consistent with AB 68/AB 881 and Gov. Code 65852.2. Detached ADUs up to 800 sq ft with 4-foot setbacks are permitted as of right, with 60-day review, no impact fees under 750 sq ft, and no replacement parking required near transit.
View full El Cerrito rules →Martinez, CA
Contra Costa County
Martinez complies with California Gov Code §65852.2 (statewide ADU law). One ADU and one JADU (up to 500 sq ft) are permitted per single-family lot. Detached ADUs up to 1,200 sq ft; attached up to 1,000 sq ft or 50% of primary home. 4-ft rear/side setbacks for new detached ADUs. ADUs under 750 sq ft exempt from impact fees. ADUs cannot be used as STRs per city's STR prohibition.
View full Martinez rules →Key Facts Comparison
| Fact | El Cerrito | Martinez |
|---|---|---|
| Units allowed | 1 ADU + 1 JADU per lot | - |
| Max detached ADU size | 800 sq ft ministerial; up to 1,200 sq ft | - |
| Setbacks | 4 ft side/rear (state minimum) | 4 ft rear and interior side (new detached ADU) |
| Processing time | 60 days ministerial | - |
| Short-term rental | Prohibited for ADUs (<30 days) | - |
| Max Size (Detached) | - | 1,200 sq ft |
| Max Size (Attached) | - | 1,000 sq ft or 50% of primary home |
| STR Use | - | Prohibited — city bans all STRs |
Highlighted rows indicate differences between cities.
El Cerrito FAQ
Do I need to provide a parking space for my new ADU?
No, if your property is within half a mile of public transit, in a historic district, or the ADU is a conversion of an existing garage. Otherwise one space is required, which can be in a driveway tandem.
Can I rent my ADU on Airbnb?
No. State law allows counties to prohibit ADU rentals under 30 days, and Contra Costa prohibits short-term rentals of ADUs.
Martinez FAQ
Can I build an ADU on my property in Martinez?
Martinez complies with California Gov Code §65852.2 (statewide ADU law). One ADU and one JADU (up to 500 sq ft) are permitted per single-family lot. Detached ADUs up to 1,200 sq ft; attached up to 1,000 sq ft or 50% of primary home. 4-ft rear/side setbacks for new detached ADUs. ADUs under 750...
What are the size limits for an accessory dwelling unit in Martinez?
Max Size (Detached): 1,200 sq ft. Max Size (Attached): 1,000 sq ft or 50% of primary home. Setbacks: 4 ft rear and interior side (new detached ADU). STR Use: Prohibited — city bans all STRs.
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