The City of Campbell permits ADUs across most residential zones. Campbell 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 on site conditions.

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

• Detached ADU: An ADU that is constructed as a separate structure from the primary dwelling unit.
• Attached ADU: An ADU built as an addition to a primary home, including adding a new basement.
• Conversion ADU: Contained within the existing space of a primary dwelling unit, including within its living area, basement, or attached garage.
• Junior ADU (JADU): The floor area of the JADU must not exceed 500 square feet.

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• Maximum Size:
  
  • Detached: Up to 1,200 sq ft
  • Attached: 50% of the existing primary dwelling
    
• Setbacks:
  
  • Minimum 4 ft from side and rear property lines
• Height Limits:
  
  • A detached ADU shall be a maximum of eighteen feet in height
• Parking Requirements:
  
  • Additional parking is not required if the ADU is:
    
    • No parking spaces are required for creation of an ADU or JADU. Existing parking spaces that are removed (in whole or in part) to allow for the creation of an ADU or JADU (e.g., by demolition or conversion of a garage) are not required to be replaced.

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

• Zoning compliance review: Ensure property is in a zone allowing ADUs.
• Site plan and elevations: Show property lines, setbacks, ADU location, and exterior views.
• Architectural drawings: Floor plans, sections, foundation, and roof details.
• Structural calculations and engineering: Compliance with building codes; stamped by a licensed engineer/architect.
• Title 24 energy documentation: Energy compliance report and certificate for insulation, HVAC, lighting, and water heating.
• Permit submission - Apply via the City of Campbell’s online portal with all required documents.
  

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

Permit review times vary but are typically between 1 week to 3-5 months depending on project complexity and completeness of the application. Projects requiring corrections or additional documentation may take longer. Engaging professionals familiar with Campbell’s ADU process can help streamline approval and reduce delays.

Most residential zones are eligible for ADUs in Campbell, including R-1, R-2, and R-M zones. There are no minimum lot size requirements for ADUs in most areas. Some hillside or environmentally sensitive zones may have special restrictions that limit ADU size or location.

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