Mill Valley · Building on your lot

Building on your lot in Mill Valley

Mill Valley sets its own fence permit limits, accessory-structure limits and home-business rules. Fence limits depend on whether the fence sits in an exterior or interior yard setback.

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Key points

Fence height: City rule: without a permit, fences are limited to 7 ft in interior setbacks or outside setbacks, 4 ft in exterior yard setbacks.
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.
Home businesses: City rule: home businesses in residential districts need a business license and may employ no one except for domestic purposes.

Each rule below is marked Mill Valley code or CA state law and links to the section it comes from (checked October 2026). General information, not legal advice.

Fences and walls

Mill Valley code What Mill Valley's code adds
Height anywhere on the lot	Up to 7 feet high without a fence permit. Applies: Entirely on private property, outside the required setbacks or in the interior yard setbacks. Taller fences need a fence permit. § 20.60.065 · code text Fencing located entirely on a private property outside the required setbacks or within the required interior yard setbacks and not exceeding seven feet in height
Front yard height	Up to 4 feet high without a fence permit. Applies: In the required exterior yard setbacks. Taller fences need a fence permit. § 20.60.065 · code text within the required exterior yard setbacks and not exceeding four feet in height
Permit	A fence permit is needed in public rights-of-way, or above 4 feet in exterior setbacks or 7 feet elsewhere. § 20.60.065 · code text Fencing located within public right-of-ways or which exceeds the four-foot and seven-foot height limits require a fence permit from the Planning and Building Department.

Sheds, garages and other accessory structures

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.

Running a business from home

Mill Valley code What Mill Valley's code adds
Employees	No employees except those needed for domestic purposes. § 20.60.250 · code text No persons are employed other than that necessary for domestic purposes.
Permit	A business license is required. Applies: Home occupations in residential districts. § 20.60.250 · code text Home occupations are permitted in residential districts with a business license (See Chapter 5.08, Business Licenses) if they meet the following standards:
Businesses not allowed	Clinics, barber shops and cosmetology establishments (the list is not complete) § 20.60.250 · code text Prohibited home occupations shall include, but are not limited to, clinics, barber shops and cosmetology establishments.

Lot splits under SB 9

Mill Valley code What Mill Valley's code adds
How the lot may be divided	New lots must be about equal; neither may be smaller than 40% of the original lot area. Applies: Urban lot split. § 21.29.040 · code text Each newly created lot shall be approximately equal in lot area provided that one parcel shall not be smaller than 40% of the lot area of the original parcel proposed for subdivision.
Minimum new lot size	Each new lot must be at least 1,200 square feet. Applies: Each newly created lot. § 21.29.040 · code text In no instance shall a new parcel be less than 1,200 square feet in lot area.
Standards	An urban lot split must create exactly 2 parcels. Applies: Urban lot split parcel map. § 21.29.040 · code text The parcel map to subdivide an existing parcel shall result in two parcels. No more than 2 dwelling units. Applies: Each newly created lot. § 21.29.040 · code text Newly created lots shall include no more than two dwelling units as defined in Government Code Section 66411.7(j)(2). No setback required. Applies: Existing structures. § 21.29.040 · code text No setback shall be required for an existing structure. A 25-foot-wide panhandle or a 16-foot access easement. Applies: New lots without direct frontage on a public or private road. § 21.29.040 · code text A 25-foot-wide panhandle (for a flag lot) or a 16-foot ingress/egress easement shall be provided for all newly created lots that do not have direct frontage on a public or private road. A fire access road at least 20 feet clear width, able to carry 45,000 pounds. Applies: New units more than 150 feet from a city right-of-way, on an urban lot split. § 21.29.040 · code text All new dwelling units located more than 150 feet from a City right-of-way must be accessible through a path of travel that is accessible for emergency service vehicles by way of an approved fire apparatus access road at least 20 feet in clear width with an approved driving surface capable of supporting the imposed load of fire apparatus weighing at least 45,000 pounds. Driveways must be at least 16 feet wide. Applies: Driveways to new buildings on an urban lot split. § 21.29.040 · code text Driveways that provide access to new buildings shall have a minimum width of 16 feet with an approved driving surface capable of supporting the imposed load of a fire apparatus weighing at least 45,000 pounds. Driveway grade 18% or less, cross slope of 8%, inside curve radius at least 27 feet. Applies: Driveways on an urban lot split. § 21.29.040 · code text Driveways shall have grades of 18% or less, cross slope of eight percent, and a horizontal inside radius of curvature no less than 27 feet. Standards are waived if they would block 2 units on either new parcel or force units below state minimum size. Applies: Urban lot split objective standards. § 21.29.040 · code text Notwithstanding the foregoing, the following standards shall be waived if they have the effect of physically precluding the development of two dwelling units on either of the resulting parcels or that would result in dwelling units with less than the minimum allowable square footage permitted by state law.

RV and boat parking

Mill Valley code What Mill Valley's code adds
Parking on the street	Not allowed unless attached to a motor vehicle. Applies: Trailers on a public street; emergency repairs are an exception. § 10.04.200 · code text It is unlawful for any person, firm or corporation, to park a trailer upon any public street in the City of Mill Valley unless such trailer is at all times attached to a motor vehicle.

Solar panels and EV chargers

Mill Valley code What Mill Valley's code adds
EV charger permit	Expedited nondiscretionary permit; complete applications meeting checklist and health and safety rules are approved administratively within 1 to 3 days. Applies: Electric vehicle charging stations. Design Review is not required. § 14.50.060 · code text Anyone seeking to install an electric vehicle charging station at any site within the City may apply to the Building Official for an expedited nondiscretionary building permit.
Solar permit process	Expedited nondiscretionary permit, approved administratively when complete and meeting the checklist and all health and safety rules; no Design Review. Applies: Small rooftop solar systems. § 14.52.060 · code text Anyone seeking to install a small rooftop solar energy system within the City may apply to the Building Official for an expedited nondiscretionary building permit.
Review time	1 to 3 business days. Applies: Small rooftop solar systems meeting all health and safety requirements, with no specific adverse impact on public health or safety. § 14.52.060 · code text the Building Official shall administratively approve the application within one to three business days.

Tree removal

Mill Valley code What Mill Valley's code adds
Permit to remove	The Director of Building and Planning may issue an emergency removal permit; the tree must be removed within 7 days. Applies: A heritage tree that poses an immediate threat to people or property. § 20.67.080 · code text If a heritage tree poses an immediate threat to the safety of persons or property, the Director of Building and Planning may issue an emergency tree removal permit

Pets, chickens and bees

Mill Valley code What Mill Valley's code adds
Chickens	At most 12 mature poultry; no crowing roosters, quacking ducks, geese, guinea fowl or peafowl. Applies: Any premises in the city. § 6.12.120 · code text More than 12 mature poultry or six mature rabbits;
Coop setback	At least 40 feet. Applies: Rabbits or poultry, from any dwelling on an adjacent property. § 6.12.120 · code text Any rabbits or poultry within 40 feet of any dwelling on adjacent property;
Large animals	No bulls, cows, calves, heifers, goats, sheep or swine. Applies: Any premises in the city. § 6.12.130 · code text It is hereby declared a nuisance and it shall be unlawful to keep or permit to be kept upon any premises in the City, any bull, cow, calf, heifer, goat, sheep or swine.

Who this affects

HomeownersContractorsDesigners

Frequently asked questions

How tall can a fence be in Mill Valley?

City rule: without a permit, fences are limited to 7 ft in interior setbacks or outside setbacks, 4 ft in exterior yard setbacks.

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.

Can I run a business from my home in Mill Valley?

City rule: home businesses in residential districts need a business license and may employ no one except for domestic purposes.

Can I split my lot under SB 9 in Mill Valley?

Mill Valley's code: New lots must be about equal; neither may be smaller than 40% of the original lot area. (Urban lot split.) (§ 21.29.040); Each new lot must be at least 1,200 square feet. (Each newly created lot.) (§ 21.29.040).

Can I park an RV or boat at my home in Mill Valley?

Mill Valley's code: Not allowed unless attached to a motor vehicle. (Trailers on a public street; emergency repairs are an exception.) (§ 10.04.200).

Do I need a permit for solar panels or an EV charger in Mill Valley?

Mill Valley's code: Expedited nondiscretionary permit; complete applications meeting checklist and health and safety rules are approved administratively within 1 to 3 days. (Electric vehicle charging stations. Design Review is not required.) (§ 14.50.060); Expedited nondiscretionary permit, approved administratively when complete and meeting the checklist and all health and safety rules; no Design Review. (Small rooftop solar systems.) (§ 14.52.060).

Do I need a permit to remove a tree in Mill Valley?

Mill Valley's code: The Director of Building and Planning may issue an emergency removal permit; the tree must be removed within 7 days. (A heritage tree that poses an immediate threat to people or property.) (§ 20.67.080).

Can I keep chickens or bees at my home in Mill Valley?

Mill Valley's code: At most 12 mature poultry; no crowing roosters, quacking ducks, geese, guinea fowl or peafowl. (Any premises in the city.) (§ 6.12.120); At least 40 feet. (Rabbits or poultry, from any dwelling on an adjacent property.) (§ 6.12.120).

General information, not legal advice.

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