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Statewide ADU FrameworkCalifornia ADU Intelligence
California ADU Rules
California has one of the country's most developed statewide ADU frameworks. State law establishes important protections for ADU development while cities and counties continue to administer permits and local development standards.
Guide Last Reviewed
August 2026
At a Glance
What to know about ADUs in California.
These are the major statewide points to understand before drilling into city, county, and property requirements.
01
Statewide ADU laws apply across California
02
Local jurisdictions administer permitting
03
Attached, detached, and conversion ADUs are recognized
04
Ministerial approval is a major part of the state framework
Important
Local requirements still matter.
Local zoning, building, fire, utility, coastal, historic, and site-specific requirements may still affect what can be built on an individual property.
Local Coverage
Local California guides are coming.
We're building city and county guides to complement this statewide information.
Before Choosing a Plan
Start with the property, not just the floor plan.
The plan works best when it follows the real-world conditions of the building site.
01
Understand the State
Start with the broader California ADU framework and the statewide rules that may apply.
02
Research the Locality
Check the city or county rules that may add requirements, limits, or approvals.
03
Verify the Property
Review zoning, setbacks, utilities, septic, access, and other property-specific conditions.
04
Choose the Plan
Use what you learned to narrow down the ADU plans that make sense for the site.
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Tell us about your property, goals, available space, and must-have features. We'll help narrow the plans worth considering.
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1
State guidance is the starting point.
2
Local regulations can change the project.
3
Property-specific verification still matters.
4
Plan compatibility should never be assumed.
Explore Plans
ADU plans to start exploring.
These are general designs to explore. They are not being represented as approved, compliant, or compatible with every property in California.
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Where this information comes from.
We prioritize official state and government sources when building ADU rule guides.
Primary Source
California Department of Housing and Community Development
Visit Official SourceReviewed August 2026
Before You Build
Verify current requirements.
Best ADU Plans provides general educational information, not legal, zoning, engineering, permitting, or architectural advice.
Requirements may differ by city, county, zoning district, property, and project. Always verify current requirements before purchasing, permitting, or building an ADU.
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