What is an ADU?
An Accessory Dwelling Unit (ADU) is a self-contained residential unit built on the same property as a single-family or multi-family home. Often called granny flats, in-law units, or backyard cottages, ADUs can be detached, attached, or converted from existing structures like garages or basements.
In California, ADUs are a key strategy in addressing the housing shortage—and the state has passed laws to make permitting easier. But even with streamlined processes, submitting the right documents is essential for fast approval.
✅ Benefits of Building a Permitted ADU
- Getting the right permits for your ADU may take time—but the benefits far outweigh the hassle:
Increased Property Value: Permitted ADUs boost resale potential and equity.
Rental Income: Legally rent out your ADU and generate passive income.
Legal Peace of Mind: Avoid penalties, red tags, or forced demolition.
Utility Access: Permitted ADUs are eligible for water, sewer, and electrical connections.
Access to Financing: Permitted ADUs qualify for construction loans and refinance options.
📄 What Documents Do You Need to Submit for an ADU Permit in California?
Each city has specific submittal guidelines, but most jurisdictions across California require the following core documents for an ADU permit application:
1. Site Plan
Shows property boundaries, existing structures, and where the ADU will be placed.
Must include setbacks, lot dimensions, and utility locations.
2. Floor Plans
Detailed layout of the ADU interior.
Must include room dimensions, window/door placements, and labels (e.g., kitchen, bedroom, bathroom).
3. Elevation Drawings
Front, side, and rear views of the ADU with height and roof pitch details.
Helps planning departments ensure the ADU meets local design and height regulations.
4. Foundation Plan
Engineering specifications for the ADU foundation (slab, raised, etc.).
Required especially for detached or new-construction ADUs.
5. Roof Plan
Details roofing materials, slope, and drainage.
Critical in fire zones or areas with architectural review boards.
6. Title 24 Energy Calculations
Required for energy efficiency compliance under California’s Building Energy Efficiency Standards.
Typically prepared by a certified energy consultant.
7. Structural Calculations (If Applicable)
Required if your ADU includes new framing, second stories, or modifications to load-bearing structures.
8. Utility Plans
Plumbing, electrical, and mechanical layouts.
Includes service panel upgrades, meter locations, water/sewer tie-ins.
9. Landscaping & Grading Plan (If Required)
Some cities request landscape plans to ensure stormwater compliance and site drainage.
10. Permit Application Form
Standard city-provided application with owner information, contractor details, and project scope.
- Soil Report – Required in areas with expansive soil or slope.
Survey Report – Helpful for verifying property lines and avoiding boundary disputes.
Photographs of Existing Site – Sometimes requested during initial plan review.
🏙️ City-Specific Variations
Different jurisdictions may have additional or slightly different requirements:
San Francisco often requires neighborhood notifications for certain ADU types.
San Jose offers pre-approved ADU plans to streamline documentation.
Los Angeles requires separate LADWP (water/power) coordination.
Always check your city’s official planning or building department for the most current checklist.
