The City of Alameda permits ADUs across most residential zones. Alameda follows both state and local ADU laws, allowing most single-family homes to build one detached ADU and one Junior ADU (JADU) per lot. Multi-family properties may be eligible for multiple ADUs, depending onsite conditions.

Alameda aligns with California’s broader ADU legislation but has its own requirements for height, setbacks, and design review.

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• Detached ADU: Separate building from the main residence
• Attached ADU: Added onto the main home
• Conversion ADU: Converts some of a current house or accessory structure (e.g., garage) into an ADU
• Junior ADU (JADU): Up to 500 sq ft, converted from part of the home, may share a bathroom with the main home

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• Maximum Size:
  
  • Detached: Up to 1,200 sq ft
  • Attached: Up to 50% of primary dwelling, max 1,200 sq ft
• Setbacks:
  
  • Minimum 4-foot setbacks from the rear and side property lines
• Height Limits:
  
  • Typically 16 ft unless
• Parking Requirements:
  
  • Additional parking is not required if the ADU is:
    
    • Conversion ADU or Junior ADU (entirely within the existing primary residence or accessory structure)
    • Located within ½ mile of public transit
    • Situated within a historic district
    • Within one block of a car-share service

To build an ADU in Alameda, the following approvals are typically required:

• Zoning Compliance Review: Confirm the property is in compliance with the local zoning laws.
• Site Plan and Elevations: Include detailed plans that illustrate the proposed ADU's layout and elevations.
• Architectural Drawings: Submit complete architectural plans explaining the design and construction.
• Structural Calculations and Engineering: Add engineering reports explaining the structural stability of the ADU.
• Title 24 Energy Documentation: Include documentation proving the property complies with California's energy efficiency code.
• Permit Submission: All necessary documents should be submitted via City of Alameda's online portal, SJPermits.org.
  

Homeowners should also review Alameda’s current fee schedule, utility connection requirements, and fire code compliance.

Permit times are usually 6 to 12 weeks depending on complexity of the project and workload in a specific city. Some simple projects can be speeded up, whereas those with corrections or requiring additional information may take a little longer. Having experts who know Alameda's ADU process can make approval easy.

All but a few areas in Alameda qualify for ADUs, such as R-1 (single-family), R-2 (two-family), and R-M (multi-family) zoning. There are no lot size requirements for ADUs in most of Alameda. Special restrictions may apply to some hillside or environmentally sensitive areas.

For the most current and complete information, refer directly to the City of Alameda.