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

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

• Detached ADU: A fully independent unit located in the backyard, separate from the main house
• Attached ADU: A unit connected to the primary home
• Conversion ADU: An ADU created by converting existing spaces within the primary dwelling or accessory structures, such as garages or basements.
• Junior ADU (JADU): 500 square feet

• Maximum Size:
  
  • Detached: Up to 1,000 sq ft
  • Attached: 50 percent of the square footage of the existing single-family dwelling
• Setbacks:
  
  • Minimum 4 ft from side and rear property lines
• Height Limits:
  
  • 16 feet, measured to the highest point of roof
• Parking Requirements:
  
  • Additional parking is not required if the ADU is:
    
    • ½ mile walking distance from transit
    • A primary residence or accessory structure
    • On street parking is required but not offered to inhabitant of the ADU
    • A car share vehicle is located within one block

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

• Zoning compliance review: Ensure the property is zoned to permit ADU.
• Site plan and elevations: Provide detailed drawings showing the ADU's location and design.
• Architectural drawings: Submit comprehensive plans that outline the structure and layout.
• Structural calculations and engineering: Include calculations and engineering details to demonstrate compliance with safety standards.
• Title 24 energy documentation: Provide energy compliance documentation as per California's Title 24 standards.
• Permit submission: Submit all required materials through Brentwood's Electronic Submittal Portal

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

Permit review times in Brentwood vary but are typically between 4 to 8 weeks depending on project complexity and city workload. Projects with unique designs, required variances, or needing corrections may take longer. Engaging professionals familiar with Brentwood’s ADU process can help streamline approval.

Most residential zones in Brentwood are eligible for ADUs, including single-family and multi-family residential districts. There are generally no minimum lot sizes for ADUs, though some lots may have specific development standards. Certain environmentally sensitive or hillside areas may have special setback or design restrictions.

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