Oakley has adopted section 9.1.1102 Accessory Dwelling Units (ADU), in its Municipal Code


Development Standards. All accessory dwelling units shall comply with the following development standards:

1)    Except as otherwise provided by this section, the accessory dwelling unit satisfies lot size, lot width, lot depth, lot coverage, and other zoning requirements generally applicable to residential development in the zoning district of the primary residence and to residential development generally. Construction of the accessory dwelling unit will not result in total structural lot coverage in excess of forty percent (40%).

2)    The accessory dwelling unit consists of no more than one kitchen, one living room, one dining room, two bedrooms, and one and a half bathrooms. For the purposes of this section a half bathroom includes a toilet, sink, and related plumbing.

3)    An accessory dwelling unit shall not exceed one thousand two hundred (1,200) square feet. If the accessory dwelling unit is an efficiency unit, it conforms to the size limitations for efficiency units provided for in the Uniform Building Code. If the accessory dwelling unit is attached to the main dwelling or created by the internal conversion of an existing single-family dwelling, it does not occupy more than fifty percent (50%) of the habitable floor area of the building, excluding the garage area.

4)    If the applicant proposes to use a private sewage disposal system, water system, or both for the accessor dwelling unit, the system must meet all applicable regulations of the City and Contra Costa County, and the County Health Officer must approve the system. Any such private sewage or water system must be designed by a licensed civil engineer to meet the increased load of the accessory dwelling unit and in accordance with the requirements of the most recent version of the California Plumbing Code. The design of the private sewage disposal or water system must be approved prior to the issuance of any permits for the accessory dwelling unit.

5)    The ADU conforms to the setback requirements of the zoning district applicable to the primary residence. If detached, the ADU is located no closer to structures on adjoining lots than it is to the primary residence and is not closer to the primary residence than permitted by the Uniform Building Code. No setback shall be required for an existing garage that is converted to an ADU, and a setback of no more than five feet from the side or rear lot lines shall be required for an ADU that is constructed above a garage.

6)    The ADU incorporates the same or similar architectural features, building materials, colors, design for trim, windows, roof, roof pitch, and other exterior physical features as the primary residence or compatible dwellings located on adjacent properties. If the primary residence has an identifiable architectural style, the design of the ADU maintains that style. The plans for the ADU comply with the residential design guidelines in effect at the time the application is submitted, particularly the architectural guidelines.

7)    The ADU has a separate entrance not visible from the street front area.

8)    Access by emergency services to both the primary residence and ADU is adequate.

9)    If the ADU is constructed above the primary residence or garage, all windows and doors use techniques to lessen the privacy impacts onto adjacent properties. These techniques may include, but are not limited to, use of obscured glazing, window placement above eye level, windows and doors located toward the existing on-site residence or screening treatments.

10)    The ADU is constructed upon a permanent foundation.

11)    Another dwelling unit exists on the lot or will be constructed on the lot in conjunction with the construction of the  ADU. No more than one ADU may be constructed on any site. An ADU shall not be allowed on a site with more than one unit.

12)    Parking.

a)    One on-site parking space shall be required for each bedroom of the proposed ADU in addition to those required for the primary unit.

b)    The additional parking required may be located in lot setbacks only if the parking is tandem in a driveway. No more than two vehicles may be parked in tandem.

c)    When a garage, carport, or covered parking structure is demolished in conjunction with the construction of an ADU, the replacement spaces may be located in any configuration on the same lot as the ADU, including, but not limited to, as covered spaces, uncovered spaces, or tandem spaces.

d)    On-site parking is not required for an ADU in any of the following instances:

(1)    The ADU is located within one-half mile of public transit.

(2)    The ADU is located within an architecturally and historically significant historic district.

(3)    The ADU is part of the existing primary residence or an existing accessory structure.

(4)    When on-street parking permits are required but not offered to the occupant of the ADU.

(5)    Where there is a car share vehicle located within one block of the ADU.

13)    Frontage improvements per Oakley Ordinance No. 10-01.

14)    The ADU shall not be rented for less than thirty (30) consecutive days at any time.

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