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Mill Valley · Building on your lot

Sheds, garages and other accessory structures in Mill Valley

City rule: accessory structures are limited to 15 ft, 500 sq ft each, and 3 per lot, not counting pools and required garages.

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Key points

  • Accessory structures: City rule: accessory structures are limited to 15 ft, 500 sq ft each, and 3 per lot, not counting pools and required garages.

Each rule below links to the section of the Mill Valley Municipal Code it was read from, with the code text one click away (checked October 2026). General information, not legal advice.

What Mill Valley's code says

Mill Valley code What Mill Valley's code adds
Maximum height
  • No more than 15 feet high.
    § 20.60.075 · code text
    the height of an accessory structure or building, as measured in accordance with the provisions of Section 20.08.050 of the Mill Valley Municipal Code, shall not exceed 15 feet
  • No more than 30 feet for the whole structure.
    Applies: A garage or carport needed to meet parking requirements.
    § 20.60.075 · code text
    The overall height of the entire structure, as measured in accordance with the provisions of Section 20.08.050 of the Mill Valley Municipal Code, shall not exceed 30 feet.
  • No more than 25 feet, measured from the parking deck's finished floor.
    Applies: A garage or carport needed to meet parking requirements.
    § 20.60.075 · code text
    The height of the structure, as measured vertically from the finished floor elevation of the parking deck, but otherwise in accordance with the provisions of Section 20.08.050 of the Mill Valley Municipal Code, shall not exceed 25 feet.
Size or lot coverage
  • No more than 500 square feet of enclosed floor area per structure.
    Applies: Each accessory structure, measured from the outside walls; swimming pools do not count.
    § 20.60.075 · code text
    The maximum gross floor area of an individual accessory structure, excluding swimming pools, shall be limited to 500 square feet of enclosed space as measured from the exterior walls of the proposed structure
  • No more than 3 accessory structures per property.
    Applies: Below-grade pools, and carports and garages needed to meet parking requirements, do not count.
    § 20.60.075 · code text
    No more than three accessory structures are permitted on any property excluding below grade swimming pools, and carports and garages which are necessary to satisfy applicable parking requirements for the specific zoning on the property.
Distance from the house
  • At least 6 feet from the main building or any other structure.
    Applies: Accessory structures, except below-grade swimming pools.
    § 20.60.075 · code text
    A minimum separation of six feet must be maintained between an accessory structure, excluding below grade swimming pools, and the main building or any another structure on the property.

Who this affects

HomeownersContractorsDesigners

Frequently asked questions

How big can a shed or accessory building be in Mill Valley?

City rule: accessory structures are limited to 15 ft, 500 sq ft each, and 3 per lot, not counting pools and required garages.

General information, not legal advice.

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Mill Valley Municipal Code — full text