Napa Municipal Code 17.52.015 Accessory dwelling units (ADU).

Each Accessory Dwelling Unit (ADU) shall be subject to the administrative permit requirements, as set forth in Chapter 17.58, and subject to compliance with the standards set forth in this Section 17.52.015. ADUs are exempt from General Plan density requirements and lot coverage percentages.

A.     Construction and Lot Line Setback Standards for ADU:

1.     Bedrooms:. There is a maximum of two bedrooms per ADU.

2.     Maximum floor area: The maximum ADU floor area for attached and detached ADUs is as set forth below:

i.      ADUs attached to an existing dwelling shall not exceed fifty percent (50%) of the existing living area, with a maximum increase in floor area of 1,200 square feet.

ii.      Detached ADUs shall not exceed a total area of 1200 square feet of floor space.

3.     Height: No ADU shall exceed 15 feet in height. However, the Community Development Director may grant an exception for an increase in height up to the limit allowed for the principal dwelling unit.

4.     Side/Rear Yards: Each attached ADU must comply with the setback requirements in the underlying Zoning District for the principal dwelling unit. A setback of no less than five (5) feet from the adjacent interior side lot line, and no less than five (5) feet from the rear lot line shall be required for a detached ADU, including an ADU constructed above a garage. No setback shall be required for an existing garage that is converted to an ADU.

5.     Front and Side Setback: Each ADU must comply with the front setback and side setback requirements that apply to the principal dwelling unit within the underlying Zoning District.

6.     Setback requirement from alley lot lines: An ADU may have a zero foot setback from an alley lot line.

7.     One ADU is permitted per single-family lot. ADUs are not permitted on duplex, triplex, or apartment lots.

8.     Existing Principal Dwelling Unit– A single-family dwelling must exist as the principal dwelling unit on the lot, or it shall be constructed prior to or concurrently with the ADU.

9.     No ADU shall be used for transient occupancy, as defined by Section 17.06.030.

B.     Parking.

1.     Each ADU shall have one parking space per bedroom. For parking purposes, each studio ADU shall be considered a one-bedroom ADU. Parking spaces may be covered or uncovered, provided as tandem parking on an existing driveway, or on a paved surface in a setback or yard area.

2.     Parking requirements shall be waived if the ADU is located: (1) within one-half (1/2) mile of a public transit stop; (2) in a designated historic district; (3) in part of an existing primary residence or an existing accessory structure; (4) in an area requiring on-street parking permits but they are not offered to the ADU occupant; or (5) within one block of a car-sharing pickup/drop-off location.

C.     Conversion of Existing Structure to an Accessory Dwelling Unit.

1.     Upon application, the Director may issue an administrative permit to convert an accessory structure (excluding garages) to an ADU, if the ADU is set back no less than three feet from the adjacent interior side lot line, and no less than three feet from the rear lot line, and (c) the ADU complies with all other requirements of this Section.

2.     Upon application, the Director may issue a use permit to convert a garage to an ADU, if the ADU complies with all other requirements of this Section. No setback shall be required for an existing garage that is converted to an ADU.

3.     When a garage is demolished in conjunction with the construction of an ADU or converted to an ADU, the replacement parking space may be located in any configuration on the same lot as the ADU as a covered, uncovered, or tandem parking space.

4.     Conversion of a non-habitable accessory structure/garage or other living space to an ADU shall meet all building codes for residential occupancy.

D.     Design Guidelines.

1.     Building materials and colors should be compatible with and complement the principal dwelling unit.

2.     Windows and doors which face an adjoining residential property should be designed to mitigate potential impacts on the privacy of neighbors; alternatively, fencing or landscaping may be required to provide screening.

3.     Any ADU that involves work on a historic resource must comply with the requirements of the Historic Preservation Ordinance (See Chapter 15.52, and Section 15.52.070).

E.     Fire Sprinkler Requirements.

1.     ADU’s shall comply with all applicable fire safety provisions of state law, as well as locally adopted building and fire codes under Chapter 15.04.

2.     Under State law, in general, ADU’s shall not be required to be equipped with fire sprinklers unless fire sprinkler installation is required for the primary residence.

F.     Junior Accessory Dwelling Units.

1.     Junior Accessory Dwelling Units (JADUs) means a unit that is no more than 500 square feet in size and is contained entirely within an existing single-family structure.

2.     JADUs shall be limited to one per residential lot zoned for single-family residences with a single-family resident already built on the lot.

3.     Additional parking is not required for a JADU.

4.     JADUs shall meet the following requirements:

i.      Owner-occupancy: The property owner shall reside in either the primary residence or the junior accessory dwelling unit.

ii.      Construction requirements. A JADU shall be constructed within the existing walls of the existing single-family structure, and shall include an existing bedroom within the structure.

iii.     Access: The JADU shall include a separate entrance from the main entrance to the primary residence, with an interior entry to the main living area. A JADU may include a second interior door for sound attenuation.

iv.     Provide an efficiency kitchen, which shall include all of the following:

1.     A sink with a maximum waste line diameter of 1.5 inches.

2.     A cooking facility with appliances that do not require electrical service greater than 120 volts, natural gas, or propane gas.

3.     A food preparation counter and storage cabinets that are of reasonable size in relation to the size of the JADU.

v.     Recordation of a deed restriction, which shall run with the land, shall be filed with the City and include:

1.     A prohibition on the sale of the JADU separate from the sale of the primary residence, including a statement that the deed restriction may be enforced by future purchasers.

2.     A restriction on the size and attributes of the JADU that conforms with this Section. (O2017-007, 3/7/17)

Summary of Napa ADU Codes