The City of San Jose permits ADUs across most residential zones. Redwood City 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.

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

• Detached ADU: These are new, separate structures built in the backyard, like a backyard cottage.
• Attached ADU: These are located within the existing main residence.
• Conversion ADU: Conversion of uninhabited spaces, including garages, will be allowed for at least one ADU or up to 25% of units in multifamily buildings.
• Junior ADU (JADU): Up to 500 square feet of converted space contained entirely within a single-family home. A JADU may share a bathroom with the existing home.

• Maximum Size:
  
  • Detached: Up to 1,000 sq ft
  • Attached: Up to 850 sq ft OR 50% of the primary dwelling's floor area (whichever is greater, with a maximum cap of 1,000 sq ft)
• Setbacks:
  
  • Minimum 4 ft from side and rear property lines.
• Height Limits:
  
  • Maximum 16 ft for a studio-style unit with a sloped roof. Can be up to 18 ft for other designs.
    
• Parking Requirements:
  
  • Additional parking is not required if the ADU is:
    
    • Located within half a mile of public transit (covers most of the city)
    • A conversion of an existing garage, basement, or other structure.
    • In a Located in an architecturally or historically significant district.

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

• Zoning compliance review: Approval from the Planning Division ensuring the ADU meets local rules for size, setbacks, height, and use.
• Site plan and elevations: A detailed plan showing the entire property, existing structures, and the new ADU, including all dimensions and distances from property lines.
• Architectural drawings: Detailed floor plans and construction drawings illustrating the design and layout of the ADU.
• Structural calculations and engineering: Sealed engineering reports and calculations are required for new construction to verify the structural integrity of the design.
• Title 24 energy documentation: Compliance documents proving the ADU meets California's energy efficiency standards for insulation, windows, and HVAC systems.
• Permit Submission through the City of Redwood City.
  

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

Permit review times vary but are typically between 8 to 16 weeks depending on project complexity and city workload. Projects requiring corrections may take longer. Engaging professionals familiar with Redwood City’s ADU process can help streamline approval.

Most residential zones in Redwood City are eligible for ADUs, including R-1 (Single Family), R-2 (Two Family), and R-3 (multi-family) districts. There are no minimum lot size requirements for ADUs under California state law. Some hillside areas or properties with significant environmental constraints may have additional development requirements.

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