The City of Sunnyvale permits ADUs across most residential zones. Sunnyvale 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.

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

• Detached ADU: A new, freestanding unit that is separate from the primary home; can be located in the backyard or elsewhere on the lot.
• Attached ADU: A new unit built as an addition to the primary home, sharing at least one wall with it; allowed only on single-family properties.
• Conversion ADU: Created by converting existing space within a main dwelling or accessory structure, such as a garage, basement, or attic. 
• Junior ADU (JADU): Up to 500 sq. ft., located entirely within the existing primary dwelling, with a separate entrance and an efficiency kitchen; owner occupancy is required.

• Maximum Size:
  
  • Detached: Up to 800 sq ft for ministerial (streamlined) approval; larger ADUs (up to 1,000 sq ft or more) may be allowed depending on lot and zoning. 
  • Attached: Up to 50% of the primary dwelling’s floor area, not exceeding 1,000 sq ft. 
• Setbacks:
  
  • Minimum 4 ft from side and rear property lines.
• Height Limits:
  
  • Detached: Up to 16 ft (standard); up to 18 ft if located near transit corridors or above a garage. 
  • Attached: Up to 25 ft or the same height as the primary dwelling, whichever is lower.
• Parking Requirements:
  
  • Additional parking is not required if the ADU is:
    
    • Located within half a mile of public transit
    • Converted from an existing structure (such as a garage or basement)
    • Within a historic district or in areas with on-street parking permits exempting ADUs

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

• Zoning compliance review
• Site plan and elevations showing property layout, setbacks, and building design
• Architectural drawings including floor plans, sections, and elevations
• Structural calculations and engineering for foundations, framing, and roof systems
• Title 24 energy documentation demonstrating compliance with California Energy Code
• Fire Department review if required (especially for attached or larger ADUs)
  

Homeowners should also review Sunnyvale’s current fee schedule, utility connection requirements, and fire code compliance to ensure the project meets all city and state standards.

Permit review times vary but are typically between 6 to 12 weeks depending on project complexity and city workload. Projects requiring corrections or additional plan checks may take longer. Engaging professionals familiar with Sunnyvale’s ADU process can help streamline approval.

Most residential zones are eligible for ADUs, including R-1, R-2, and R-M zones. There are no minimum lot sizes for ADUs in most areas of Sunnyvale. Some hillside or environmentally sensitive zones may have special restrictions or additional design requirements.

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