Suisun City has adopted City Code 18.30.170 – Accessory Dwelling Units.

The following regulations shall apply to all accessory dwelling units in a residential zoning district:

A. Ministerial Consideration.

  1. New Construction. If the director of development services receives an application to construct an accessorydwelling unit (by either adding on to an existing structure, or constructing a new detached structure), and the proposal meets all of the requirements of this Code, then within 120 days of receipt of a complete application for the accessory dwelling unit, the director of development services shall ministerially approve the application without a hearing.
  2. No Expansion. If the applicant will not be adding floor area, and instead has submitted a complete application for an accessory dwelling unit entirely within the existing space of a single-family residence or accessory structure, then the director shall, without a hearing, ministerially approve a complete application for a building permit to create an accessory dwelling unit if all of the following apply:

a. The unit is contained entirely within the existing space of a single-family residence or accessorystructure (without adding floor area to the existing residence or accessory structure).

b. The unit is on a lot zoned R-M (medium-density residential), RH1 or RH2 (high-density residential).

c. There will be only one accessory dwelling unit on the lot.

d. The unit has independent exterior access from the existing residence.

e. The side and rear setbacks are sufficient for fire safety as determined by the fire marshal.

f. Fire sprinklers are provided to the same extent that they are required for the primary residence.

B. An accessory dwelling unit may be established on any residentially zoned parcel, which permits single-family dwellings containing an existing single-family dwelling.

C. Accessory dwelling units shall not exceed the allowable density for the lot upon which the accessory dwellingunit is located.

D. Accessory dwelling units are a residential use that shall be consistent with the existing general plan and zoning designation for the lot.

E. An applicant must be both an owner and the current resident of the property for which an accessory dwellingunit is proposed.

F. The accessory dwelling unit can either be attached to and designed to be located within the living area of the existing dwelling or detached from and no less than ten feet from the existing single family dwelling, and such unit shall be architecturally integrated into the existing building design.

G. The proposed increase in gross floor area of an attached or detached accessory dwelling unit shall not exceed 50 percent of the existing living area up to a maximum of 1,200 square feet.

H. Detached accessory dwelling units shall be located no closer than five feet from any side or rear property lines.

I. As part of any such building permit application, the applicant shall submit a copy of the deed to the property including a full and complete set of any conditions, covenants and restrictions.

J. Connection Fees. A local agency is prohibited from requiring a new or separate utility connection for an accessory dwelling unit if contained within the existing space of a single-family residence or accessory structure (in accordance with Government Code Section 65852.2(f)).

K. Parking.

a. Maximum of one space per unit or one space per bedroom. Tandem parking on an existing driveway is allowed, which may be within setback areas.

b. No additional parking for accessory dwelling units can be required when:

i. An accessory dwelling unit is located:

  1. Within one-half mile of public transit;
  2. Within an architecturally and historically significant historic district;
  3. Within an existing primary residence or an existing accessory structure;

ii. On-street parking permits are required but not offered to the occupant of the accessory dwelling unit; or

iii. There is a car share vehicle located within one block of the accessory dwelling unit.