"Accessory Dwelling Unit" ("_ADU_") shall mean an attached or detached residential dwelling unit that provides complete independent living facilities for one or more persons and is located on a lot with a proposed or existing dwelling. It shall include permanent provision for living sleeping, eating, cooking, and sanitation on the same parcel as the single-family dwelling is or will be situated. It also includes an efficiency unit and manufactured homes (as defined in Section 18007 of the Health and Safety Code).

"Junior Accessory Dwelling Unit" ("JADU") shall mean a unit that is no more than five hundred square feet in size and contained entirely within a single-family structure. A JADU may include separate sanitation facilities or may share sanitation facilities with the existing structure. 3. "Internal Accessory Dwelling Unit" ("Internal _ADU_") means an _ADU_ that is contained within the existing space of a single-family residence or accessory structure, has independent exterior access, and does not add any floor area to an existing structure, and is over five hundred square feet in size. An Internal _ADU_ may have internal access to the primary dwelling.

"Attached Accessory Dwelling Unit" ("Attached _ADU_") means an _ADU_ that shares a common wall with the primary dwelling unit on the lot, either by being constructed as a physical expansion (i.e., addition) of the primary dwelling unit, conversion of an existing garage attached to the primary dwelling, or installation of a new basement underneath an existing primary dwelling unit.

"Detached Accessory Dwelling Unit" ("Detached _ADU_") means an _ADU_ that is constructed as a separate structure from the primary dwelling unit on the lot or is created by the conversion (full or partial) of an existing detached accessory building into an accessory dwelling unit.

"Accessory Structure" means a structure that is accessory and incidental to a dwelling located on the same lot.

"Nonconforming zoning condition" means a physical improvement on a property that does not conform with current zoning standards.

A high-quality transit corridor with fixed route bus service with service intervals no longer than fifteen minutes during peak commute hours.

The intersection of two or more major bus routes with a frequency of service interval of fifteen minutes or less during the morning and afternoon peak commute periods.

"Objective Development standards" means standards that involve no personal or subjective judgment by a public official and are uniformly verifiable by reference to an external and uniform benchmark or criterion available and knowable by both the development applicant or proponent and the public official prior to submittal. (See Objective Development Standards table for accessory dwelling in Section B of this Chapter).

"Passageway" means a pathway that is unobstructed clear to the sky and extends from a street to one entrance of the _ADU_.

"Public transit" means a location, including, but not limited to, a bus stop or train station, where the public may access buses, trains, subways, and other forms of transportation that charge set fares, run on fixed routes, and are available to the public.

"Tandem parking" means that two or more automobiles are parked on a driveway or in any other location on a lot, lined up behind one another.

Administration. This section provides for the establishment and reasonable regulation of _ADUs_ and JADUs in order to encourage housing opportunities for all segments of the population while ensuring the public health safety and welfare of the town.

Application and fee. Applications for an _ADU_ shall be processed ministerially and shall be accompanied by the appropriate fee. _ADU_ shall be permitted through issuance of a building permit.

_ADUs_ are permitted in single and multi-family zoned lots, and JADUs are permitted in single-family zoned lots.

Director of community development or designee as review authority and review process. Building permit applications for _ADUs_ shall be acted upon by the director of community development or designee ministerially without discretionary review or a public hearing. The building permit application shall be approved or denied in writing within sixty days from receipt of a completed application and if not acted upon within that timeline the application shall be deemed approved. The director of community development or designee shall approve the application if the application meets all the requirements and standards of this Chapter. The director of community development or designee shall deny the application if he or she determines that the application does not meet all of such requirements. The community development director or designee's denial shall include a full set of comments to the applicant with a list of defective or deficient items and a description of how the application can be remedied by the applicant. If the applicant requests a delay, the sixty-day time period shall be tolled for the period of the delay. A courtesy notice shall be provided to owners of property within one hundred feet of the subject property, as set forth on equalized county tax assessment rolls, at least ten days prior to a decision by the director.

Approved existing _ADUs_ remain valid. Any secondary dwelling unit legally established with an approved conditional use permit prior to July 1, 2003, and in continued existence shall be deemed a legal, conforming dwelling unit. Secondary dwelling units established by any such conditional use permit shall continue to comply with all conditions of original permit approval, and with building code for secondary dwelling units in effect at the time of permit approval. The town shall not require the correction of any nonconforming zoning condition as a condition of approval for an _ADU_

Unpermitted _ADUs_ and JADUs. Any permit for an unpermitted _ADU_ or JADU that was constructed before January 1, 2020, shall not be denied due to the _ADU_ or JADU's violation of building standards or its noncompliance with this Chapter unless it is deemed substandard pursuant to Section 11720.3 of the Health and Safety Code.

Prior to Submission, Prior to submission of an _ADU_ or JADU application, the director of community development or designee shall inform homeowners that they may obtain a confidential third-party code inspection from a licensed contractor to determine the unit's existing condition or potential scope of building improvements before submitting an application for a permit. The total area of floor space shall not exceed eight hundred fifty sq. ft. when there is only one bedroom, on a lot smaller than ten thousand sq. ft.

A homeowner applying for a permit for a previously unpermitted _ADU_ or JADU constructed before January 1, 2020, shall not be required to pay impact fees or connection or capacity charges except when utility infrastructure is required to comply with Section 1790.3 of the Health and Safety Code and when such a fee is authorized by Chapter 16-52.100(C)(19).

Upon receiving an application to permit a previously unpermitted _ADU_ or JADU constructed before January 1, 2020, an inspector from the local agency may inspect the unit for compliance with health and safety standards and provide recommendations to comply with the standards necessary to obtain a permit. If the inspector finds noncompliance with health and safety standards, the Town shall not penalize an application for having an unpermitted _ADU_ or JADU and shall approve necessary permits to correct noncompliance with health and safety standards.

Expiration. _ADU_ permits issued in compliance with this section shall expire and become null and void eighteen months after building permit issuance unless a certificate of occupancy has been issued by the building division or extension of the existing building have been granted through the building division.

Periodic update. The director shall maintain a record of all legal _ADUs_ and all legal secondary dwelling units and shall review and update the record every two years.

Violations considered an infraction. Violations of this section shall be punished as infractions or by administrative citation, in the discretion of the director and shall be subject to the provisions of section 16-56.030 (violations and penalties) and/or Chapter 31 (enforcement of code).

Administrative Review. If the _ADU_ meets the objective design standards outlined in section B of this Chapter, the decision of the director granting or denying an _ADU_ permit is a ministerial decision as required by state law, and not subject to a public hearing.

Structures beyond _ADU_ or JADU. Any proposed exterior improvement or structures beyond the proposed _ADU_ or JADU shall comply with the standards under TMC 16-52.020. Ministerial review is only applicable for the structure of the _ADU_.

Roof Decks. Roof Decks shall not be permitted under the _ADU_ ministerial review process. Roof Decks are subject to the standards outlined under TMC 16-52.020.

Density. Pursuant to California Government Code Section 66319, no _ADU_ approved under these provisions shall be considered in calculating the density of the lot allowed by the land use designation contained in the land use element of the Tiburon General Plan, and _ADUs_ are deemed a residential use that is consistent with the existing general plan and zoning for the lot.

| Objective Development Standards Table | | --- | | | Attached _ADU_ ¹ | Detached _ADU_ | Internal Conversion _ADU_ | | --- | --- | --- | --- | | Minimum Floor Area | 150 square feet | | Maximum Floor Area | | | Over 500 square feet, under 1,000 square feet. | | | One Bedroom or Less | 850 square feet ² | | | More than One Bedroom | 1,000 square feet ³ | | Lot Coverage Maximum | None | | Setbacks | (Minimum) | | | | Front | A front setback must yield to the extent necessary to enable the construction of an 800 square foot _ADU_ with four-foot side- and rear-yard setbacks. | None ⁴ | | | Side | 4 feet | | | Rear | 4 feet | | Maximum Height | 25 feet | 16 feet ^5,6 | N/A | | Parking | 1 space ^7,8 | None | | Separate independent entrance required | Yes | | Separate sanitary facility required | Yes | | Kitchen required | Yes | | 1\. The total floor area of an attached _ADU_ may not exceed 50% of an existing primary dwelling, notwithstanding the guaranteed allowance. 2\. For lots greater than 10,000 sq. ft, the total floor space shall not exceed 1,000 sq. ft. 3\. The total floor area of an attached _ADU_ may not exceed 50% of an existing primary dwelling, notwithstanding the guaranteed allowance. 4\. No Setback shall be required for an existing living area or accessory structure, or a structure constructed in the same location and to the same dimensions as an existing structure that is converted to an Accessory Dwelling Unit or to a portion of an Accessory Dwelling Unit, and a setback of no more than four feet from the side and rear lot lines shall be required for an accessory dwelling unit that is not converted from an existing structure or a new structure constructed in the same location and to the same dimensions as an existing structure. 5\. A detached accessory dwelling unit on a lot with an existing single-family residence, one half of a mile walking distance away from a major transit stop (as defined in Section 21155 of the Public Resources Code) shall not exceed a max height of eighteen feet. A local agency shall also allow an additional two feet in height to accommodate a roof pitch on the accessory dwelling unit that is aligned with the roof pitch of the primary dwelling unit. 6\. A lot with an existing or proposed multifamily, multistory dwelling unit shall not exceed a max height of eighteen feet. 7\. One off-street parking space per accessory dwelling unit shall be required, unless parking exceptions as set forth in this section (16-52.100(C)(7)) apply. 8\. When a garage, carport, or covered parking structure is demolished in conjunction with the construction of an accessory dwelling unit or converted to an accessory dwelling unit, those off-street parking spaces need not be replaced. If desired, parking may be provided as tandem parking on a driveway. |

Guaranteed Allowance. Maximum floor area, floor area ratio, and open space standards shall not prohibit an _ADU_ with at least an eight hundred square feet of floor area, a height not to exceed the limits established by Section 16-52.100(B)(7) of this Chapter, and four-foot side and rear yard setbacks.

Size. The total floor area of an attached or detached _ADU_ shall be as follows:

The total area of floor space shall not exceed eight hundred fifty sq. ft. when there is only one bedroom, on a lot smaller than ten thousand sq. ft.

The total area of floor space shall not exceed one thousand sq. ft. when there is more than one bedroom.

For lots greater than ten thousand sq. ft, the total floor space shall not exceed one thousand sq. ft.

For _ADUs_ which exceed the maximum size of one thousand square feet, a Site Plan and Architectural Review will be required as well as a building permit, if approved. As part of this review, the _ADU_ shall comply with all regulations set forth within the land use designation.

Exterior Access. _ADUs_ shall have independent exterior access separate from the primary dwelling.

Setback. Minimum setbacks of attached and detached _ADUs_ shall be:

A front setback must yield to the extent necessary to enable the construction of an eight hundred square foot _ADU_ with four-foot side- and rear-yard setbacks.

A lot with an existing single-family residence, one half of a mile walking distance away from a major transit stop (as defined in Section 21155 of the Public Resources Code), may have a detached _ADU_ up to a max height of eighteen feet. A local agency shall also allow an additional two feet in height to accommodate a roof pitch on the _ADU_ that is aligned with the roof pitch of the primary dwelling unit.

A lot with an existing or proposed multifamily, multistory dwelling unit shall not exceed a max height of eighteen feet.

Any attached _ADU_ shall not exceed twenty-five feet. This clause shall not require a local agency to allow an _ADU_ to exceed two stories.

Parking. One off-street parking space per _ADU_ shall be required, unless the parking exceptions in Section 16-52.100(C)(7) of this Chapter apply.

Parking exceptions. No parking shall be required of an _ADU_ in any of the following instances:

The _ADU_ is located within one half of a mile walking distance of public transit, as measured along path of travel.

When a permit application for an _ADU_ is submitted with a permit application to create a new single-family dwelling or a new multifamily dwelling on the same lot, provided that the _ADU_ or the parcel satisfies any other criteria listed in this subdivision.

When the existing floor area is converted to an accessory structure. This includes the conversion of an existing garage or carport.

Projections into setbacks. The ordinary projection of sills, bay windows, cornices, architectural features, entry roofs and eaves may extend beyond the wall of the _ADU_ and into the front, side and rear setbacks; provided, however, that none shall project into a minimum setback more than three feet.

Lighting. Lighting shall be shielded and/or directed such that it does not produce glare visible from off-site or illuminate adjacent or nearby property.

All skylights shall be bronzed or tinted, and no lights shall be placed in or directed up into the wells.

The _ADU_ shall comply with the following architectural compatibility standards when the proposed new unit exceeds eight hundred square feet.

Color and Materials. The color and materials of the _ADU_ shall match the primary unit. Match shall mean to correspond with the primary unit in terms of color, texture, material and design, to a degree that a reasonable person would consider the replacement indistinguishable from the original when viewed at a standard viewing distance of six feet under normal lighting conditions.

Historic Structures. No demolition of a historic building (Local, State, or Federal Listing) is allowed as part of the construction of an _ADU_.

Trees with a circumference exceeding sixty inches, measured twenty-four inches above the ground level, oak trees, including coast live oak, blue oak, California black oak, interior live oak, canyon live oak, Engelmann oak or valley oak tree, or dedicated trees, which are removed to build an _ADU_, must be replaced with trees of equivalent size and species. All other trees shall continue to be governed by Chapter 15A of the Tiburon Municipal Code.

Creek. The _ADU_ shall be located at least ten feet from the top of any creek bank that exists on the lot of the proposed _ADU_. The top of creek bank shall be defined by a licensed civil engineer.

Fire Sprinklers. Fire sprinklers are not required in an _ADU_ if they are not required of the primary dwelling unit. Fire safety equipment such as smoke detectors may be required.

Fire District Regulations. The _ADU_ shall comply with all applicable Fire District regulations, subject to provisions and limitations set forth in Government Code Section 65852.2.

Sanitary Service. Adequate sanitary service capacity for the additional increment of effluent resulting from the _ADU_ shall be available. If the lot is connected to the public sewer system, the applicant shall submit a letter from the appropriate sanitary district to that effect. If the lot is not connected to the public sewer system, the applicant shall submit a letter from the County of Marin Environmental Health Department confirming that the individual or alternative sewage disposal system serving the lot has adequate capacity to accommodate the proposed _ADU_.

Separate Utility Connection. New and separate utility connections shall be required directly between the _ADU_ and the utility. Consistent with Government Code section 66013, the connection may be subject to a connection fee or capacity charge that shall be proportionate to the burden of the proposed _ADU_, based upon either its square feet or the number of its drainage fixture unit (DFU) values, as defined in the Uniform Plumbing Code adopted and published by the International Association of Plumbing and Mechanical Officials, upon the water or sewer system. This fee or charge shall not exceed the reasonable cost of providing this service.

Exception. An _ADU_ or JADU described in Government Code shall not require the applicant to install a new or separate utility connection directly between the _ADU_ and the utility or impose a related connection fee or capacity charge, unless the _ADU_ was constructed with a new single-family dwelling.

Premises identification. Any town-assigned street address number for the _ADU_ shall be plainly visible and legible from the street fronting the property as required by the applicable building code.

Rental and Sale. The _ADU_ may be rented separate from the primary unit but may not be rented for a period of less than thirty consecutive days or used as a vacation rental. The _ADU_ may not be sold separately from the primary unit unless the conditions in Section 66341 of the Government Code are met.

Kitchen. The _ADU_ shall have a permanent full kitchen with a sink, refrigerator, and stove/oven. Only one kitchen is allowed per _ADU_.

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| Objective Development Standards Table | | --- | | | JADU | | --- | --- | | Minimum Floor Area | 150 square feet | | Maximum Floor Area | 500 square feet ¹ | | Lot Coverage Maximum | N/A | | Setbacks | (Minimum) | | | | Front | N/A | | | Side | N/A | | | Rear | N/A | | Maximum Height | N/A | | Parking | None | | Separate independent entrance required? | Yes | | Interior access allowed? | Yes | | Separate sanitary facility required | No ² | | Kitchen required | Yes ³ | | 1\. The junior accessory dwelling unit may include an expansion of not more than one hundred fifty square feet beyond the physical dimensions as the existing accessory structure. The expansion shall be limited to accommodating ingress and egress. 2\. If a JADU unit does not include a separate bathroom, the JADU unit must include both a separate entrance from the main entrance to the structure, and an interior entry to the main living area. 3\. The junior accessory dwelling unit shall have a permanent efficiency kitchen as defined in D (3). Only one kitchen is allowed per junior accessory dwelling unit. |

Maximum Size. JADUs shall be no greater than five hundred square feet in size and contained entirely within a single-family residence. The JADU may include an expansion of not more than one hundred fifty square feet beyond the physical dimensions as the existing accessory structure. The expansion shall be limited to accommodating ingress and egress.

Location. No more than one JADU is permitted on a residential lot within an existing single-family structure. No setbacks apply to internal/JADUs.

Kitchen. The JADU shall have a permanent efficiency kitchen with a sink, cooking facility with appliances that do not require electrical service greater than one hundred twenty volts, and a food preparation area that is of reasonable size in relation to the size of the unit. Only one kitchen is allowed per JADU.

Sanitation facilities. A JADU may include separate sanitation facilities or may share sanitation facilities with the existing structure. If a JADU unit does not include a separate bathroom, the JADU unit must include a separate entrance from the main entrance to the structure, with an interior entry to the main living area.

Owner Occupancy. One of the dwelling units on the site (either the primary unit or the JADU) shall be owner-occupied. For purposes of this standard, "owner" is defined as a person or entity with a majority (i.e., fifty-one percent or greater) interest in the property. Property owned in joint tenancy shall be considered a single ownership for any party named. Property owned in tenancy in common shall be considered a single ownership for the party named, unless shares are specified, in which case ownership requires a majority interest. Owner occupancy shall not be required if the owner of the JADU is another governmental agency, land trust, or housing organization.

Prohibition on sale. JADUs shall not be sold separately. A prohibition on the sale of the JADU separate from the sale of the single-family residence, including a statement that the deed restriction may be enforced against future purchasers.

Rental. The JADU may be rented separate from the primary unit but may not be rented for a period of less than thirty consecutive days or used as a vacation rental. The JADU may not be sold separately from the primary unit.

Fire Sprinklers. Fire sprinklers are not required in a JADU if they are not required of the primary dwelling unit. Fire safety equipment such as smoke detectors may be required.

Ministerial Approval. Notwithstanding Sections 16-52.100(B) and 16-52.100(C) above, inclusive, the Town shall ministerially approve an application for a building permit within a residential or mixed-use zone to create any of the following:

One _ADU_ and one JADU per lot with a proposed or existing single-family dwelling if all of the following apply:

The _ADU_ or JADU unit is within the proposed space of a single-family dwelling or existing space of a single-family dwelling or accessory structure and may include an expansion of not more than one hundred fifty square feet beyond the same physical dimensions as the existing accessory structure. An expansion beyond the physical dimensions of the existing accessory structure shall be limited to accommodating ingress and egress.

The JADU complies with the requirements of Government Code section 66333 through 66339 as they may be amended.

One detached, new construction, _ADU_ that does not exceed four-foot side and rear yard setbacks for a lot with a proposed or existing single-family dwelling. The _ADU_ may be combined with a JADU described in subsection (a) of this section. An _ADU_ permitted under this subsection is subject to the following conditions

Multifamily Dwelling _ADUs_. Multiple _ADUs_ within the portions of existing multifamily dwellings structures that are not used as livable space, including, but not limited to, storage rooms, boiler rooms, passageways, attics, basements, or garages, if each unit complies with state building standards for dwellings.

One _ADU_ within an existing multifamily dwelling shall be allowed and up to twnety-five percent of the existing multifamily dwelling units.

On a lot with an existing multifamily dwelling, not more than eight _ADUs_ that are detached from that multifamily dwelling and are subject to a height not to exceed the height limitations in Section 16-52.100(C)(5) of this Chapter and four-foot rear yard and side setbacks, provided, however, the number of detached _ADUs_ shall not exceed the number of existing units on the lot.

(Ord. No. 519 N.S., § 3(Exh. A), 3-17-2010; Ord. No. 541 N.S., § 2(X), 8-15-2012; Ord. No. 568 N.S., § 2(C), 2-1-2017; Ord. No. 587 N.S., §§ 2, 3(Exh. A), 2-19-2020; Ord. No. 594 N.S., § 3, 2-16-2022; Ord. No. 603 N.S, §§ 2, 3, 6-7-2023; Ord. No. 608 N.S. , §§ 2, 3, 2-5-2025)