California, Statewide
California ADU Permit: do you likely need a permit?
California state law creates important ADU protections, but homeowners still need local ministerial review, building permits, and site-specific compliance.
What the official sources say
California HCD's ADU materials describe ADUs as secondary dwelling units with independent living facilities, including detached, attached, and repurposed existing-space units such as garage conversions. HCD's updated ADU Handbook summarizes State ADU Law, while local agencies still apply objective standards, building code, utilities, and local application processes.
Likely permit path
- Local ADU/JADU application and building permit through the city or county with jurisdiction.
- Plan set, site plan, and trade permits for electrical, plumbing, mechanical, solar/energy, or utility work where applicable.
- Local checks for coastal, fire, historic, septic, utility, and owner-occupancy/JADU issues.
Watch-outs
- Statewide rules do not remove the need for local permit submission and code compliance.
- Unpermitted ADUs built before January 1, 2020 have special state-law provisions, but health and safety corrections may still be required.
- Local coastal, fire hazard, septic, utility, and historic conditions can add steps.
Documents to gather
- Jurisdiction, parcel details, site plan, floor plan, unit type, and intended use.
- Existing-space conversion notes, utility scope, energy-code details, and photos.
- Any unpermitted-work history and prior permit records.
Questions to ask before applying
- Is this an ADU, JADU, attached ADU, detached ADU, garage conversion, or non-rental habitable-space conversion?
- What zoning district, overlays, coastal/historic/flood/fire conditions, HOA limits, or deed restrictions apply to the property?
- Will the unit include independent living, sleeping, cooking, and sanitation facilities?
- What building, zoning, trade, utility, addressing, parking, inspection, and certificate-of-occupancy steps apply before occupancy or rental use?
Official sources
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PermitCheckup provides informational permit-readiness guidance based on public sources. It is not legal, architectural, engineering, or contractor advice. Always confirm your project with the authority having jurisdiction before beginning work.