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

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

• Detached ADU: The unit is separated from the primary structure.
• Attached ADU: The unit is attached to the primary structure.
• Conversion ADU: Space on the lot of the primary residence that is converted into an independent living unit.
• Junior ADU (JADU): is a small unit (500 square feet or less in size) created from a portion of a single-family dwelling.

• Maximum Size:
  
  • Detached: Up to 850 sq ft
  • Attached: Up to 50% of the floor area of an existing or proposed primary dwelling unit
• Setbacks:
  
  • Minimum 4 ft from side and rear property lines
• Height Limits:
  
  • Typically, 16 ft, up to 25 ft depending on location and unit type
• Parking Requirements:
  
  • Additional parking is not required if the ADU is:
    
    • located within one-half mile walking distance of public transit
    • located within an architecturally and historically significant historic district
    • on-street parking permits are required but not offered to the occupant of the ADU
    • there is an established car share vehicle stop located within one block of the ADU.

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

• Zoning compliance review
• Site plan showing lot lines, existing and proposed structures, and setbacks
• Architectural drawings, including floor plans, elevations, and roof plan
• Structural calculations and engineering, including mechanical, plumbing, and electrical plans
• Title 24 energy documentation
• Permit submission through the City of Antioch’s online portal
  

Homeowners should also review Antioch’s current fee schedule, utility connection requirements, fire code compliance, and consider using pre-approved ADU plans to streamline the permitting process.

Permit review times vary but are typically between 6 to 12 weeks depending on project complexity and city workload. Projects requiring corrections or additional review may take longer. Utilizing pre-approved ADU plans and engaging professionals familiar with Antioch’s ADU process can help streamline approval.

Most residential zones in Antioch are eligible for ADUs, including single-family and multi-family zones. There are no minimum lot sizes for ADUs in most areas of Antioch. Some hillside, environmentally sensitive, or historic zones may have special restrictions or additional review requirements.

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