Issue 4: Accessory Structure Standards
An ADU is one type of accessory structure – other types include garages, carports, sheds, gazebos, and other similar structures. The Zoning Code defines an accessory structure as “a detached structure, the use of which is subordinate and incidental to and customarily associated with, the main structure or the principal use of the site and which is located on the same site as the main structure or principal use.” State law requires local agencies to allow an existing accessory structure to be converted into or replaced with an ADU. Local agencies must allow the conversion or replacement of accessory structures located anywhere on a lot, including within required yards.
In the single-family zoning districts (R-1, R-R, and R-MT), the Zoning Code currently allows accessory structures within 3 feet of a rear and side property line. The maximum height is 18 feet within required yards and 35 feet outside of yards. In multifamily zoning districts, setback and height standards for accessory structures are the same as for main buildings.
The Zoning Code also currently allows for a guest house on a residential lot, defined as accessory living quarters without kitchen or cooking facilities. A guesthouse must comply with accessory structure standards and is limited to maximum floor area of 600 square feet. Either a guesthouse or an ADU is permitted on a parcel, but not both.
Recommendation:
City staff recommends updating existing accessory structure standards given that any accessory structure may be converted to an ADU under state law, and to reflect the increased intensity that the City must allow on residential lots under state ADU law.
Recommended accessory structure standards are shown in Table 3. Figure 2 illustrates these standards on an example 20,000 square-foot R-1 lot.
Table 3: Recommended Accessory Structure Standards
Zoning District
R-1, R-R, R-MT R-M, R-H, R-VH
Setbacks (min)
Front and Street Side Same as primary dwelling
Rear and Interior Side 3 ft. for structures less than 10 ft. in height and 120 sq. ft. in size.
Same as primary dwelling for all other structures. [1]
Height (max)
Structure complies with
district yards
18 ft. on lots less than 10,000 sq. ft.
25 ft. on lots 10,000 – 20,000 sq. ft.
35 ft. on lots more than 20,000 sq. ft.
Same as primary structure,
subject to design review [2]
Structure does not comply
with district yards 10 ft.
Site Coverage (max) 50% for all impervious surfaces on lot Floor Area
Structure complies with
district yards
100% of primary dwelling
floor area [3] No maximum, subject to
Structure does not comply design review [2]
with district yards 120 sq. ft.
Number of structures per lot
(max)
Habitable structures 2 structures [4] No maximum, subject to Non design review [2] -habitable structures No maximum
Distance Between Structures
Structures less than 16 ft. As required by building code Structures 16 ft. or more 10 ft. plus 1 ft. for every 2 ft. of height above 16 ft. of lowest structure Notes:
[1] No minimum setbacks for landscaping features such as planter boxes and open trellises, and children’s play equipment, movable dog houses, and similar movable objects.
[2] On R-M, R-H and R-VH lots occupied by a single-family dwelling, accessory structure standards for height, floor area, and maximum number are the same as in the R-1 zoning district. [3] On lots larger than 20,000 square feet, the Community Development Director may allow a floor area up to 4,000 square feet regardless of primary dwelling size upon finding that the character of the accessory structure remains incidental to the primary dwelling on the lot.
[4] Includes ADUs.
Figure 2: Allowed Accessory Structures on R-1 Lot (20,000 sq. ft.) In addition to the above standards, staff also recommends requiring kitchen facilities in all new habitable detached accessory structures with bathrooms. As such, these structures would be considered an ADU and would be included in the City’s annual reports to the state on new unit production. Proposed new rules for habitable buildings in both in single-family and multifamily residential zoning districts are as follows:
• An accessory building with habitable space must either 1) contain a bathroom and kitchen facility and comply with the City’s accessory dwelling unit (ADU) requirements; or 2) contain no plumbing connections or fixtures. • New guest homes without kitchen facilities are not allowed. • An accessory building without plumbing connections or fixtures is allowed on a property in addition to an ADU.
NEXT STEPS
Based on direction received from the Planning Commission, staff and consultants will prepare draft Zoning Code amendments for Planning Commission review. The amendments will include additional details beyond the recommendations contained in this report. The Planning Commission will hold a future public hearing to make a recommendation to the City Council on the amendments. Following Planning Commission recommendation, the City Council will hold a public hearing to consider adoption of the amendments.