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

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

• Detached ADU: Converted to a living unit
• Attached ADU: Separate from the main home
• Conversion ADU: A room or rooms within the main home converted to a living unit
• Junior ADU (JADU): Up to 500 sq ft, converted from part of the home, may share a bathroom with the main home

• Maximum Size:
  
  • Detached: Up to 16 ft height for detached ADUs; maximum square footage determined by lot size and city ADU Handbook (often up to 800–1,200 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 (as required by city standards)
• Height Limits:
  
  • Typically 16 ft for detached ADUs
• 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 Milpitas, the following approvals are typically required:

• Zoning Compliance Review: Confirm the property is in compliance with Milpitas’ local zoning laws and California state ADU requirements
• Site Plan and Elevations: Include detailed plans that illustrate the proposed ADU's layout, setbacks (minimum 4 feet from side and rear), and elevations
• Architectural Drawings: Submit complete architectural plans explaining the design, size (up to 1,200 sq ft), and construction of the ADU
• Structural Calculations and Engineering: Provide 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 to the City of Milpitas Planning Department for review and approval
  

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

Permit times are usually about 60 days 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 Milpitas's ADU process can help make approval easier.

Accessory dwelling units shall be a permitted use in any district where residential uses are permitted. In Milpitas, ADUs are generally allowed up to 1,200 sq. ft., with a minimum of 800 sq. ft., a maximum height of 16 feet, and must be at least one story. Minimum setbacks are 4 feet from side and rear property lines. State law requires a minimum living area of 150 sq. ft. for an ADU.

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