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

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

• Detached ADU: Separate from the main home (may be site-built or prefab/modular - see below)
• Attached ADU: A new structure sharing at least one wall with main home
• Conversion ADU: Converted existing space in the main home or on the property
• Junior ADU (JADU): Up to 500 square feet with at least an efficiency kitchen

• Maximum Size:
  
  • Detached: 1,200 square feet max
  • Attached: 50% of the living area of the primary dwelling unit or 1,200 square feet, whichever is less
• Setbacks:
  
  • Minimum 4-ft setbacks from the rear and side property lines
• Height Limits:
  
  • Attached: 25 ft max
  • Detached: 16 ft
• Parking Requirements:
  
  • Additional parking is not required if the ADU is:
    
    • The ADU is within 0.5-mile walking distance of public transit
    • The ADU is within an architecturally and historically significant historic district 
    • The ADU is part of the existing primary unit or an existing accessory structure
    • On-street parking permits are required but not offered to the occupant of the ADU
    • There is a car share vehicle located within one block of the ADU

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

• Zoning Compliance Review: If your ADU is over 800 square feet, you must first apply for zoning compliance review with the Planning Division before submitting a building permit application to the Building Division
• 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
  

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

Permit times are usually 4-6 weeks depending on the complexity of the project and workload in the city. Some simple projects can be expedited, whereas those with corrections or requiring additional information may take longer. Having experts familiar with Vallejo's ADU process can help make approval easier.

Accessory dwelling units (ADUs) are permitted within Vallejo in areas where residential uses are established. Development standards are enforced for attached or converted ADUs. Submissions need to be made to the Planning Division together with the necessary fees.

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