City of San Diego
Development Services Department
A Companion Unit is a detached or attached
accessory structure on a residential lot that
provides living facilities for one or more persons,
independent of the primary dwelling unit, which
includes permanent provisions for living, sleeping,
COMPANION UNIT A. Zoning
1. Permitted as a limited use in residential zones.
2. Permitted as a limited use in multiple dwelling unit residential zones where the maximum allowable density is two units based on the existing lot area.
3. Within the Coastal Overlay Zone, a Coastal Development Permit is required for a companion unit.
1. An attached companion unit shall not
exceed 50 percent of the existing
habitable area of the primary dwelling
unit, up to a maximum of 1,200 square
feet. A detached dwelling unit is
permitted up to a maximum of 1,200
2. Installation of a fire sprinkler system shall not be required for new Companion Units or Junior Units, as defined in the SDMC (and stated per
2016 California Senate Bill 1069 as
Accessory Dwelling Units) that are
1,200 sq. ft. or less in area when
located on the same lot as an existing
non-sprinklered dwelling unit.
1. An existing permitted garage or non-
habitable accessory structure within
setbacks may be converted, subject to
California Building Code.
2. A companion unit may encroach within the side and rear yards as follows:
a. A one story structure, up to a maximum encroachment of 30 feet in length.
b. A second story, if constructed above an existing permitted garage or non-habitable accessory structure.
1. One parking space is required, unless
one of the following conditions is met:
a. Unit is 500 square feet or less.
b. Site is within the Transit Area or
Transit Priority Area.
c. Site is within a historical designated
d. Site is located within a residential
e. Site is located within one block of a
car or bike share station.
2. The conversion or demolition of a garage requires replacement parking, in addition to the one required space. The parking may be placed within setbacks or in a tandem configuration.
1. A companion unit may not be sold or
conveyed separately from the main
2. The owner does not need to live in the
primary dwelling unit nor companion
unit and both can be rented. A
companion unit cannot be used for a
rental term of less than 30 consecutive
3. Only one Companion Unit is allowed
on a premises. A Junior Unit is not
allowed on a site with a Companion
Unit. Guest Quarters and nonhabitable
structures are permitted on
the same premises.