What documents must be included in a California ADU permit application?

A complete California ADU building permit application is essentially a coordinated package of drawings, calculations, and forms that lets the plan checker verify the project meets the building, energy, and zoning codes. Submitting a complete package matters more than almost anything else, because completeness is what starts the statutory review clock and keeps your project out of the incomplete-notice loop.

Core documents nearly every city requires

• Site plan — the property boundary, all existing structures, the proposed ADU location, setbacks to property lines, and the routing of water, sewer, gas, and electric service.
• Architectural plans — floor plan with dimensions, exterior elevations, and building sections.
• Structural plans — foundation and framing details, with engineer-stamped calculations where the scope requires them.
• MEP plans — separate mechanical, electrical, and plumbing sheets, including load calculations, equipment schedules, and DWV layout.
• Title 24 CF1R — the energy compliance certificate, registered with an Energy Code Compliance (ECC) Provider, not just a PDF. See Title 24 Reports.
• Permit application form — the city's intake form, fully completed.
• Owner authorization — required when a contractor, designer, or agent submits on the owner's behalf.

City-specific extras to budget for

Beyond the core set, many jurisdictions ask for additional items depending on site conditions:

• A soils / geotechnical report in hillside areas or where expansive soils are present.
• A landscape or stormwater plan, sometimes tied to lot coverage or drainage requirements.
• A green building / CALGreen compliance form.
• City-specific ADU disclosure or acknowledgment forms.
• A sewer capacity or will-serve letter from the water/sewer district in some areas.

Why completeness is the whole game

Under California law, once you submit, the city has a short window to review the application for completeness and tell you exactly what is missing. A package that passes that completeness check enters plan check immediately and starts the 60-day decision clock. A package missing the Title 24 CF1R, a load calculation, or a coordinated MEP set triggers an incomplete notice — and you restart the intake cycle, losing weeks.

The fastest permits we see are not the ones rushed out the door; they are the ones submitted complete the first time, with MEP and Title 24 already reconciled to each other.

Document checklist before you submit

1. Site plan with setbacks and utility routing
2. Architectural plans (floor plan, elevations, sections)
3. Structural plans and calculations
4. Mechanical, electrical, and plumbing sheets with calculations and schedules
5. Registered Title 24 CF1R for the correct climate zone
6. Completed application form and owner authorization
7. Any city-specific reports or disclosure forms

Requirements and local ordinances vary by jurisdiction — confirm your city's exact submittal checklist before filing. To get the MEP and Title 24 pieces delivered together and pre-coordinated, see our Full MEP Package or place an order.