Find Your City's ADU Rules

California state law sets the floor for accessory dwelling units, but every city layers its own zoning, setback, parking, and plan-check requirements on top. What you can build in one city may not be permitted a mile away.

Below are city-by-city guides covering how many ADUs you can build, size and height limits, setback requirements, parking rules, and the local plan-check process. Each guide is written for homeowners, not planners.

Size and Separation
  • Maximum size: 1,200 sq ft (detached or attached, or 50% of the size of the main dwelling)
  • Side/rear setbacks: 4 feet 
  • Two story: Yes, for both attached and detached ADUs
  • Building separation: 6 feet
Additional Requirements
  • Soils Report: Possibly, especially in areas with grading or on hillsides
  • Building Verification Survey: Yes
  • Coastal permit (in some areas): N/A
  • Stormwater Mitigation: Yes

Common ADU Permit Questions

Do I need a permit to build an ADU in California?

Yes. Every ADU requires a building permit, and most cities also require planning or zoning review before plans are approved. Converting existing space, such as a garage, still requires permits.

How long does ADU plan check take?

Under California law, cities must approve or deny a complete ADU application within 60 days. In practice, the full process, including corrections and resubmittals, commonly runs 4 to 12 weeks depending on the city and the completeness of your plans.

Can my city deny my ADU?

A city cannot deny an ADU that meets state and local standards. Denials are typically the result of plans that exceed size limits, violate setbacks, or are missing required documentation. Meeting the standards in your city guide is the fastest path to approval.

Does my city's rules override state ADU law?

No. State law sets minimum rights that cities cannot take away, but cities may adopt their own standards within that framework. That is why size limits, parking requirements, and design rules differ from city to city.

Nashville
ADU Gallery
Parking for Alhambra ADU

Have Additional Questions?

Visit our comprehensive FAQ page for more information.