18.23.060 Development Standards | Larkspur Municipal Code

18.23.060 Development Standards.

An ADU and JADU shall comply with the following development standards except that the City shall not apply any development standards in this section that would preclude the development of one (1) accessory dwelling unit of at least eight hundred (800) square feet with four (4) foot rear and side setbacks and a maximum height to be constructed in compliance with subsection (G) of this section, as required by state law (Cal. Gov’t Code Section 65852.2(c)(2)(C)).

1. A parcel with a single-family residential use may have one attached accessory dwelling unit, one detached accessory dwelling unit, and one junior accessory dwelling unit.

2. A parcel with a multifamily use may have:

a. At least one (1) and up to a maximum of twenty-five (25) percent of the existing multifamily dwelling units within the portions of existing multifamily dwelling structures that are not used as livable space, including, but not limited to, storage rooms, boiler rooms, passageways, attics, basements, laundry rooms or garages, if each unit complies with state building standards for dwellings. When the twenty-five (25) percent limit results in a fraction of a unit, the total number of accessory dwelling units that may be added shall be determined by rounding the fraction up to the next whole number.

b. No more than two (2) attached or detached accessory dwelling units per site that has an existing or proposed multifamily dwelling, that are subject to height limits established in subsection (G) of this section, and four (4) foot rear and side yard setbacks.

B. Location of Accessory Dwelling Unit. The accessory dwelling unit may be within, attached to, or detached from the primary dwelling unit, duplex, or multifamily residence. Accessory dwelling units may be created through the conversion of a garage, carport, covered parking structure, storage area or accessory structure.

C. Access. An ADU or JADU shall have separate, independent exterior access.

D. Kitchen Facility and Bathroom. An accessory dwelling unit shall have a kitchen and bathroom separate from the primary dwelling unit that meets minimum requirements of the building regulations in Larkspur Municipal Code Title 15. A junior accessory dwelling unit shall have at least an efficiency kitchen, which shall include a cooking facility with at least countertop appliances and a food preparation counter and storage cabinets that are of reasonable size in relation to the size of the junior accessory dwelling unit. A junior accessory dwelling unit may include separate sanitation facilities or may share sanitation facilities with the existing structure.

E. Setbacks. No front setback shall be applied that would preclude the development of an 800 sq. ft. ADU with at least four (4) foot side and rear setbacks. A minimum setback of four (4) feet from the side and rear lot lines shall be required for an ADU, except as follows:

1. When an existing residence has nonconforming setbacks, the conversion of space to an interior accessory dwelling unit shall not require additional setbacks, except as required for fire and safety.

2. An existing legal accessory structure, with nonconforming setbacks, is converted to an accessory dwelling unit or to a portion of an accessory dwelling unit.

3. An ADU that is converted from an existing structure with nonconforming setbacks or a new structure constructed in the same location and to the same dimensions as an existing structure.

F. Floor Area Limits. The accessory dwelling unit shall have a minimum floor area of one hundred fifty (150) square feet (required to accommodate an efficiency unit per Cal. Health and Safety Code Section 17958.1), and a maximum floor area of eight hundred fifty (850) square feet in size for studio and one bedroom units. A two (2) bedroom unit shall have a maximum floor area of one thousand (1,000) square feet. For units of three (3) or more bedrooms, the maximum floor area shall be either one thousand two hundred (1,200) square feet or fifty (50) percent of the floor area of the existing primary dwelling, whichever is less. An ADU converted from an existing accessory structure is not bound by these requirements.

G. Height Limits. All new accessory dwelling units (ADUs) shall be subject to the height limits detailed below:

1. A height of sixteen (16) feet for a detached accessory dwelling unit on a lot with an existing or proposed single-family or multifamily dwelling unit.

2. A height of eighteen (18) feet for a detached accessory dwelling unit on a lot with an existing or proposed single-family or multifamily dwelling unit that is within one-half (1/2) mile walking distance of a major transit stop of high-quality transit corridor, as defined in Cal. Pub. Res. Code Section 21155.

a. An additional two (2) feet in height shall be allowed so long as the additional height is to accommodate a roof pitch for the ADU which is aligned with the roof pitch of the primary dwelling unit.

3. A height of eighteen (18) feet for a detached accessory dwelling unit on a lot with an existing or proposed multifamily, multistory dwelling.

4. A height of twenty-five (25) feet for an ADU which is attached to a primary dwelling. This subsection shall not authorize an ADU of greater than two (2) stories.

1. Unless otherwise specified in subsection (H)(2) of this section:

a. One (1) additional off-street parking space is required for each attached or detached accessory dwelling unit.

b. No additional off-street parking is required for the primary residence, except as specified under subsection (H)(4) of this section.

c. Parking Space Dimensions. All required interior and exterior parking space dimensions shall be pursuant to Larkspur Municipal Code Section 18.56.150(A)(11), a minimum of nine (9) feet wide by eighteen (18) feet long for nonconfined stall, and a minimum twelve (12) feet wide by eighteen (18) feet long for confined stall.

2. Parking Exemptions. Off-street parking is not required for a junior accessory dwelling unit. Off-street parking is not required for an accessory dwelling unit in the following instances:

a. The accessory dwelling unit is located within one-half (1/2) mile walking distance of a public transit stop;

b. The accessory dwelling unit is located within an architecturally and historically significant historic district;

c. In an area requiring on-street parking, permits are required but not offered to the occupant of the accessory dwelling unit;

d. When the accessory dwelling unit is located within one (1) block of a car sharing pick-up/drop-off location;

e. The accessory dwelling unit is built within the legally existing primary residence or a legally existing accessory structure.

f. Attached or detached accessory dwelling units which are no more than eight hundred (800) square feet in floor area, no more than sixteen (16) feet in height, and at least four (4) foot side and rear yard setbacks.

g. When a permit application for an accessory dwelling unit 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 accessory dwelling unit or the parcel satisfies any other criteria contained in this chapter.

3. Location of Required Parking. Parking required for the accessory dwelling unit may be located in a garage, carport, uncovered or tandem space on a driveway so long as the proposed accessory dwelling unit parking area does not eliminate required parking for the primary residence or multifamily structure and required guest parking for the primary residence or multifamily structure:

a. Required parking may be located within the required front yard setback, street side setback, and rear yard setback areas.

b. A parking structure (e.g., carport, garage, or parking deck) shall comply with required setbacks for both primary and accessory structures.

4. Replacement Parking. When an existing garage, carport, or covered parking structure is demolished or converted in conjunction with the construction of an accessory dwelling unit or junior accessory dwelling unit, no replacement parking is required.

5. Substantial Remodels of Primary Dwelling. Substantial remodels to an existing primary dwelling, unless such remodel is solely for the construction of an accessory dwelling unit or junior accessory dwelling unit and does not involve any other changes, may require additional parking for the primary dwelling as applicable, subject to Larkspur Municipal Code Section 18.56.030(B).

I. Architectural Standards. ADUs shall be designed to comply with the following standards:

1. Materials and Colors. All external construction shall be constructed of the same or similar exterior materials, finishes, and family of colors as the primary dwelling unit on site.

2. Exterior Lighting. Exterior lighting shall be shielded and/or directed so that it does not glare off site or illuminate onto adjacent and nearby property.

3. Privacy. Windows shall be located offset from neighbors’ windows to maximize privacy and to avoid line of sight to windows of abutting properties. Clerestory windows, obscured glass, and other techniques may be used to avoid line of sight. All second story windows facing adjacent properties and located thirty (30) feet or less from the property line shall have a sill height of at least six (6) feet above finished floor or composed of obscured glass unless this requirement makes it infeasible to meet building code regulations for egress.

J. Building Code. Accessory dwelling units shall comply with all applicable requirements of the adopted California building codes and Larkspur Municipal Code Title 15.

K. Permanent Foundation. A permanent foundation shall be required for an ADU and JADU.

L. Short Term Rental Prohibited. Any rental of an ADU or JADU shall be for a term longer than thirty (30) days.

M. Separate Sale Prohibited. Except as provided in Larkspur Municipal Code Section 18.23.080, an ADU or JADU shall not be sold or otherwise conveyed separate from the primary residence (including creation of a stock cooperative or similar common interest ownership arrangement), but may be rented.

N. Fire Sprinklers. Fire sprinklers and other fire safety measures are not required in the ADU if they are not required in the primary dwelling unit. The construction of an accessory dwelling unit shall not trigger a requirement for fire sprinklers to be installed in an existing primary or multifamily dwelling.

O. Street Address Required. Street addresses shall be assigned to all accessory dwelling units to assist in emergency response.

P. Business License Required. If the accessory dwelling unit is rented, the property owner shall comply with Larkspur Municipal Code Chapter 5.04, Business Licenses and Regulations.

Q. Deed Restriction. Prior to issuance of a building permit for an ADU or JADU, a deed restriction, approved by the Community Development Director or such other head of the permitting department at the City, or their designee, shall be recorded with the Marin County Recorder’s office. Said deed restriction shall run with the land and shall be binding upon any successor in ownership of the property. The deed restriction shall include the prohibition on the sale of the accessory dwelling unit or junior accessory dwelling unit separate from the sale of the single-family residence, except as allowed in Larkspur Municipal Code Section 18.23.080, and restrictions that ensure continued compliance with a restriction on the size and attributes of the ADU or JADU.

R. Fire and Life Protection. For purposes of any fire or life protection ordinance or regulation, a junior accessory dwelling unit shall not be considered a separate or new dwelling unit. The City shall apply any ordinance or regulation relating to fire and life protection requirements that applies uniformly to all single-family residences within the zone regardless of whether the single-family residence includes a junior accessory dwelling unit or not.

S. Termination of Use. To encourage the retention of affordable housing and rental housing units in the City, any modification of the ADU or JADU or termination of use shall require the issuance of a building permit and be subject to the then-applicable zoning and building codes. For example, if the kitchen, bathroom, and/or sleeping facilities of the accessory dwelling unit are removed and the structure no longer qualifies as an accessory dwelling unit or junior accessory dwelling unit, the structure may be required to provide additional off-street parking or comply with floor area, lot coverage or other development requirements.

T. Historic Preservation. Applications to construct accessory dwelling units on properties that are designated as historic resources by the City, the state of California, or by the National Register of Historic Places shall show substantial compliance with the guidelines of the Secretary of the Interior for development on such properties.

U. Owner Occupancy for Junior Accessory Dwelling Units. The City shall require owner-occupancy of the single-family residence in which a junior accessory dwelling unit will be permitted as required by Cal. Gov’t Code Section 65852.22(A)(2). The owner may reside in either the remaining portion of the structure or the newly created junior accessory dwelling unit. Owner-occupancy shall not be required if the owner is another governmental agency, land trust, or housing organization.

V. Passageways. No passageway shall be required in conjunction with the construction of an accessory dwelling unit. (Ord. 1066 § 6 (Exh. A), 2023; Ord. 1062 § 14, 2022; Ord. 1045 § 2, 2020; Ord. 1044 § 3, 2020; Ord. 1038 § 1 (part), 2019; Ord. 1030 § 2(12), 2018; Ord. 1012 § 5, 2016; Ord. 953 § 1(28), 2007; Ord. 921 § 4, 2003. Formerly 18.21.040, 18.23.040)