Download the pdf: Accessory Dwelling Unit (ADU) Ordinance

SECOND DWELLING UNITS

(a.k.a – Accessory Dwelling Units & Junior Accessory Dwelling Units)
Napa County Code permits a second dwelling unit in a number of zoning districts provided certain criteria have been met.

WHAT IS A SECOND UNIT?
A second unit is a complete, independent living facility for one or more persons, including permanent provisions for living, sleeping, eating, cooking and sanitation on the same parcel on which the primary unit is situated. (Section 18.08.550)
The California Legislature calls these types of units Accessory Dwelling Units (ADU) and Junior Accessory Dwelling Units (JADU).

CAN I BUILD ONE ON MY PROPERTY?
A second dwelling unit is permitted on a legal lot, provided certain criteria are met, in the following zoning districts:
(1) AW (Agricultural Watershed);
(2) RC (Residential Country);
(3) RS (Residential Single); and
(4) PD (Planned Development) only on legal lots containing a single family dwelling
(If your parcel is in the Milliken-Sarco-Tulocay (MST) Groundwater Deficient Area, a second dwelling unit may not be permitted.
Call the Planning, Building, and Environmental Services for further information).

HOW MANY SECOND UNITS CAN BE BUILT?
Only one second unit is allowed per legal lot.

ARE THERE DIFFERENT TYPES OF SECOND UNITS?
Yes, there are four types of second units as follows:
(1) Detached – Unit is not connected to the primary dwelling unit but may be attached to other detached accessory structures
(2) Attached – Unit is connected as an addition to the primary dwelling unit and may include conversion of existing floor area within the primary dwelling unit
(3) Interior – Unit is limited to conversion of existing floor area within the primary dwelling unit or legally constructed accessory structure
(4) Junior Accessory Dwelling Unit (JADU) – Limited to 500 sq. ft. and cannot have full kitchen and includes conversion of a bedroom within existing single family residence and may share bathroom facilities.

Download the pdf: Accessory Dwelling Unit (ADU) Ordinance