The City of San Anselmo permits ADUs across most residential zones. San Anselmo 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.

San Anselmo 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 (e.g., master bedroom, attached garage, storage area, or similar use, or an accessory structure) on the lot of the primary residence that is converted into an independent living unit.
• Junior ADU (JADU): are small living units (up to 500 square feet) created out of a space within an existing single-family dwelling or an attached garage.

• Maximum Size:
  
  • Detached: Up to 850 sq ft
  • Attached: Up to 50% of the primary dwelling’s floor area, not exceeding 1,200 sq ft
• Setbacks:
  
  • A setback of no more than four 4 feet from the side and rear lot lines
• Height Limits:
  
  • The maximum height is 16 feet for a detached ADU
  • The maximum height is 25 feet Attached ADU
• Parking Requirements:
  
  • Additional parking is not required if the ADU is:
    
    • Located within one-half (1/2) mile walking distance of a public transit stop
    • Located within an historic district, as may be designated by the Town Council from time to time
    • The ADU is part of the proposed or existing primary residence or an accessory structure
    • When on-street parking permits are required but not offered to the occupant of the ADU

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

• Zoning compliance review: Ensure your property complies with local zoning regulations, including setbacks, height limits, and allowable uses.
• Site plan and elevations: Provide a site plan showing the location of the ADU relative to property lines and existing structures.
• Architectural drawings: Submit a complete set of architectural plans, including floor plans, sections, details, framing plans, and foundation plans.
• Structural calculations and engineering: Provide structural calculations and a soils report, when requested by the Building Department.
• Title 24 energy documentation: Provide floor plans with dimensions, orientation of the building and average ceiling height.
  

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

Permit review times vary but are typically between 30 Days depending on project complexity and city workload. Projects requiring corrections may take longer. Engaging professionals familiar with San Anselmo’s ADU process can help streamline approval.

Most residential zones are eligible for ADUs, including R-1, R-2, and R-3 zones. There are no minimum lot sizes for ADUs in San Anselmo. Some multifamily or commercial zones may have special restrictions or additional requirements for ADUs.

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