State rules create the framework. Local review applies it.
California treats accessory dwelling units and junior accessory dwelling units as important housing options. State law shapes what local agencies must allow, while the city or county reviews the actual parcel, plans, construction details, utilities, fire access, and applicable building standards.
Because laws and local procedures change, use this page as an educational planning guide—not as a substitute for current advice from the authority having jurisdiction or licensed professionals.
Check the property before choosing a design.
Confirm the jurisdiction and parcel constraints first; they determine which size, type and placement can become a permit-ready plan.
- Confirm the responsible city or county and the parcel’s zoning.
- Review lot conditions, existing buildings, easements, access, and utilities.
- Verify allowable unit type, floor area, height, setbacks, and placement.
- Ask about parking, fire access, coastal, historic, environmental, or utility constraints.
- Confirm fees, submittal documents, plan review steps, and inspections.
Move from feasibility to a permit-ready conversation.
Define the use, test the parcel, assemble the required expertise and confirm the current submittal path with the local agency.
Family housing, long-term rental, guest space, or downsizing.
Measure the site and verify local rules before committing to a layout.
Engage qualified design, engineering, energy, and construction professionals as needed.
Submit through the local agency and respond to plan-review comments.
Use current, official information.
Start with California HCD’s March 2026 handbook, then confirm current forms, interpretations and property details with the responsible city or county.
California ADU questions
These answers explain the statewide starting point; the city or county must confirm the parcel-specific result.
Are ADUs allowed in California?+
California law requires cities and counties to provide a pathway for qualifying ADUs and JADUs, but property conditions and local procedures still determine what can be approved.
Do California ADUs need permits?+
Yes. Planning or zoning review, building permits, utilities, fire access, energy rules, and other property-specific requirements may apply.
Where should I verify the latest rules?+
Start with the current California HCD ADU Handbook, then confirm the parcel and application requirements with the city or county that has jurisdiction.