San Dimas City Zoning Code
CHAPTER 18
38 ACCESSORY DWELLING UNITS
§ 18.38.010 Purpose.
A.
The provisions of this chapter are intended to set forth standards, in accordance with state law, for the creation or conversion of at least one accessory dwelling unit (ADU) per lot zoned single-family or multifamily use. An ADU/JADU is an accessory use and does not count toward the allowable density.
B.
The California State Legislature has identified that the need exists for new housing to shelter California's population. Creating the opportunity to provide accessory dwelling units on existing residential property addresses this need and would provide additional housing options within the community.
(Ord. 979 § 2, 1993; Ord. 1251 § 1, 2017; Ord. 1281, 2020; Ord. 1321, 3/11/2025)
§ 18.38.015 Definitions.
For the purpose of this chapter, words and terms used in this chapter shall have the meaning respectively ascribed to them set forth in Chapter 18.08 of this title.
(Ord. 1281, 2020; Ord. 1321, 3/11/2025)
§ 18.38.020 Permitted uses.
A.
A maximum of one accessory dwelling unit, either attached or detached, and one junior accessory dwelling unit shall be permitted in zoning districts where single-family residential uses are allowed or on multiple family zoned properties which have been improved with a single-family dwelling.
B.
Accessory Dwelling Units within Existing or Proposed Multifamily Structures. Multiple accessory dwelling units are allowable within the portions of existing or proposed dwelling structures that are not used as livable space, including, but not limited to, storage rooms, boiler rooms, passageways, attics, basements, or garages, if each unit complies with state building standards for dwellings. At least one accessory dwelling unit shall be allowed within an existing or proposed multifamily structure, and up to a maximum of twenty-five percent of the existing proposed multifamily dwelling units may be allowed in zoning districts where multifamily dwelling residential uses are permitted.
C.
Detached Accessory Dwelling Units with Existing or Proposed Multifamily Structures. Not more than two accessory dwelling units that are located on a lot that has an existing or proposed multifamily dwelling, but are detached from the multifamily dwelling shall be allowed in zoning districts where multifamily dwelling residential uses are allowed. Such units are subject to a height limit of sixteen feet and minimum four-foot rear yard and side yard setbacks.
(Ord. 979 § 2, 1993; Ord. 1135 § 1, 2003; Ord. 1251 § 1, 2017; Ord. 1281, 2020; Ord. 1321, 3/11/2025)
§ 18.38.030 General provisions.
The following provisions shall apply to all accessory dwelling units:
A.
Accessory dwelling units shall be permitted in any zone where single-family or multifamily dwelling residential uses are allowed or as part of any proposed residential development.
B.
Accessory dwelling units may be rented. If rented, the rental term shall not be for less than thirty days.
C.
Any legally permitted structure, or a structure constructed in the same location and to the same dimensions as a legally permitted structure, which is to be converted to an accessory dwelling unit may be converted without any additional setbacks.
D.
(Reserved)
E.
Accessory dwelling units may not be sold separately from the main residence, unless the accessory dwelling unit or the primary dwelling was built or developed by a qualified nonprofit corporation, then the ADU can be sold or conveyed separately from the primary residence to a qualified buyer consist with Government Code Section 66341(a) through (e).
F.
No certificate of occupancy shall be issued for an accessory dwelling unit constructed concurrently with a primary dwelling unit. The primary dwelling unit shall be completed and have first obtained a certificate of occupancy prior to issuance of a certificate of occupancy for the accessory dwelling unit.
G.
Any unpermitted ADU or JADU may be permitted if they were constructed before January 1, 2020. This does not apply if the local agency makes a finding that "correcting the violation is necessary to protect the health and safety of the public or occupants of the structure" (Government Code § 66332, subdivision (b)) or to a building that is deemed substandard pursuant to Health and Safety Code Section 17920.3 (Government Code § 66332, subdivision (c)).
(Ord. 979 § 2, 1993; Ord. 1135 § 2, 2003; Ord. 1251 § 1, 2017; Ord. 1281, 2020; Ord. 1321, 3/11/2025)
§ 18.38.040 Development standards.
The following property development standards shall apply to all accessory dwelling units:
A.
Floor Area. The following floor area standards for accessory dwelling units apply:
1.
Attached accessory dwelling units shall not exceed fifty percent of the existing primary dwelling or either eight hundred fifty square feet for a studio or one-bedroom unit or one thousand square feet for a multi-bedroom unit, whichever is less, provided, however, that these floor area requirements shall not preclude an accessory dwelling unit of at least eight hundred square feet from being constructed.
2.
Detached accessory dwelling units shall not exceed eight hundred fifty square feet for a studio or one-bedroom unit or one thousand square feet for a multi-bedroom unit.
3.
Junior accessory dwelling units shall not exceed five hundred square feet.
4.
All newly constructed accessory dwelling units and junior accessory dwelling units have a minimum size of one hundred fifty square feet, the size of an efficiency unit as defined in Section 17958.1 of the California Health and Safety Code.
B.
Lot Coverage. The lot coverage of the underlying zone shall apply provided, however, that these lot coverage limitations shall not preclude an accessory dwelling unit of at least eight hundred square feet from being constructed.
C.
Minimum Yard Areas. The following minimum yard requirements apply.
1.
Front Yards. The provisions of the applicable underlying zoning designation of the subject property shall apply. Accessory dwelling units that are eight hundred square feet or less may be located within the front yard setback area of the underlying zoning designation, if there is no other area on the parcel that can accommodate the accessory dwelling unit, as determined by the director of community development, provided that the front yard setback shall not be less than four feet.
2.
Rear Yards. The minimum rear yard shall be four feet.
3.
Side Yards. The minimum side yard shall be four feet.
D.
Nonconforming Residential Structures. Any nonconforming zoning conditions on the subject property shall not require correction for the purposes of adding either an accessory dwelling unit or junior accessory dwelling unit.
E.
Building Height. The following maximum height requirements shall apply for all accessory dwelling units:
1.
Sixteen feet for a detached accessory dwelling unit on a lot with an existing or proposed single-family or multifamily dwelling unit.
2.
Eighteen feet for a detached accessory dwelling unit on a lot with an existing or proposed single-family or multifamily dwelling unit that is within one-half of one-mile walking distance of a major transit stop or a high-quality transit corridor, as those terms are defined in Section 21155 of the Public Resources Code. An additional two feet in height is permitted, solely, to accommodate a roof pitch on the accessory dwelling unit that is aligned with the roof pitch of the primary dwelling unit.
3.
Eighteen feet for a detached accessory dwelling unit on a lot with an existing or proposed multifamily, multistory dwelling.
4.
Twenty-five feet or the height limitation in the underlying zone designation of the subject parcel shall apply, whichever is lower, for an accessory dwelling unit that is attached to a primary dwelling.
5.
Accessory dwelling units shall not exceed two stories.
F.
Building Separation. The minimum separation for a detached accessory dwelling unit from the primary dwelling unit shall be six feet, provided, however, that this minimum separation requirement shall not preclude an accessory dwelling unit of at least eight hundred square feet from being constructed.
G.
Parking. No additional parking shall be required for an accessory dwelling unit.
H.
Design Standards. The following design standards shall apply to all accessory dwelling units:
1.
All accessory dwelling units shall be designed to architecturally match the existing or proposed residence located on the same property.
2.
The entrance to an attached accessory dwelling unit shall be on a separate elevation from the main entrance of the residence. Entry to an accessory dwelling unit or junior accessory dwelling unit shall not be on the elevation of the residence or garage which is parallel to the street; however, the entrance requirements in this subsection shall not preclude the development of an eight hundred square foot or less accessory dwelling unit, per Government Code Section 66323, subdivision (a)(1) through (4).
3.
A detached accessory dwelling unit shall have no exterior entrances on elevations where the distance to a side property line is less than fifteen feet; however, the entrance requirements in this subsection shall not preclude the development of an eight hundred square foot or less accessory dwelling unit, per Government Code Section 66323, subdivision (a)(1) through (4), from being constructed.
4.
An accessory dwelling unit with less than a five-foot side or rear setback shall only have clerestory windows which are a minimum six feet above the floor on those sides.
5.
All exterior lighting shall be shielded in a way so that no light spills onto adjacent properties.
6.
All accessory dwelling units must have a minimum of one hundred square feet of usable open space on the subject property, provided, however, that the usable open space requirement shall not preclude an accessory dwelling unit of at least eight hundred square feet, that is sixteen feet in height with four-foot side and rear yard setbacks. Such open space may be fenced off to provide a separate yard for the accessory dwelling unit or be located within a yard shared with the main residence.
I.
Garage Conversions. Garage conversions shall be allowed subject to the following provisions:
1.
No additional setback shall be provided for an existing garage which is converted to an accessory dwelling unit. A setback of no more than four feet from side and/or rear lot lines shall be allowed for an accessory dwelling unit constructed above a garage.
2.
The garage door shall be removed. The new façade shall match the primary residence in regards to materials, colors and architectural elements.
J.
Interior Amenities. The following interior amenity standards shall apply for all accessory dwelling units:
1.
Washer/dryer hookups shall be provided within the accessory dwelling unit. For junior accessory dwelling units, the hookups may be provided within a shared common space within the main residence.
K.
JADU Separate Entrance/Interior Access.
1.
A JADU shall include a separate entrance from the main entrance to the proposed or existing single-family residence.
2.
A JADU that does include a separate bathroom within the JADU and shares bathroom facilities with the main residence shall include an interior entry to the main living area.
L.
Equestrian/Agricultural Property. Notwithstanding any other provisions of this chapter, accessory dwelling units shall be located in such a manner so as not to conflict with the equestrian setback standards of adjoining properties, as set forth in Chapter 18.28 and 18.112 of the San Dimas Municipal Code, to the extent physically feasible. In the event locating an accessory dwelling unit on a parcel in compliance with the setbacks required by this subsection is not physically feasible, this subsection shall not be construed to prohibit the construction of an accessory dwelling unit as described in California Government Code Section 66323(a)(1) through (4).
M.
Hillside Property. The grading standards of the underlying zoning designation shall apply.
N.
Fire Sprinklers. Accessory dwelling units shall not be required to provide fire sprinklers if they are not required for the primary residence.
O.
Solar Requirements. Newly constructed ADUs are subject to the California Energy Code requirement (excluding manufactured homes) to provide solar systems if the unit(s) is a newly constructed, detached ADU (see Title 24, Section 150.1 for exemptions). Per the California Energy Commission (CEC), the solar systems can be installed on the ADU or on the primary dwelling unit. ADUs that are constructed within existing space, or as an addition to existing homes, including detached additions where an existing detached building is converted from non-residential to residential space, are not subject to the California Energy Code requirement to provide solar systems.
P.
Utility Connections.
1.
Accessory dwelling units shall not be considered new residential uses for the purposes of calculating city and county connection fees or capacity charges for utilities, including water and sewer service, unless the accessory dwelling unit was constructed in conjunction with a new single-family residence.
2.
For a junior accessory dwelling unit or an accessory dwelling unit located within the existing residence, a new or separate utility meter shall not be required and a related connection or capacity fee may not be charged, unless the accessory dwelling unit has been constructed with a new single-family dwelling.
3.
When the accessory dwelling unit is attached or detached, a new or separate utility meter may be required. Any connection fee or capacity charge shall be proportionate to the burden of the proposed accessory dwelling unit based upon either its size or the number of plumbing fixtures for a water or sewer system.
4.
All new accessory dwelling units within urban service areas shall connect to public wastewater systems. Outside urban service areas, sanitation facilities, plumbing, and water supply for the accessory dwelling unit, including any septic or waterless toilet systems used, shall comply with all applicable County Health Department requirements for sewage disposal and water supply.
Q.
ADU Accessory Structures. These structures are subject to the same four-foot setback requirements as the ADU and shall count towards lot coverage. Any other accessory structure not listed in this subsection shall comply with the development standards of the underlying zone.
1.
An attached or detached ADU may include an attached covered patio and/or porch, which, if provided, shall be integrated into the design of the ADU and shall not exceed a total combined area of one hundred square feet in size.
2.
An attached or detached ADU may include an attached two-car garage, which, if provided, shall be integrated into the design of the ADU and shall not exceed five hundred twenty-nine square feet in size, with a minimum interior area of ten feet by twenty feet per vehicle.
3.
An attached ADU located on the second floor, or a detached two-story ADU may include a deck(s), which, if provided, shall be integrated into the design of the ADU and shall not exceed a total combined area of forty square feet in size. The deck shall not extend past the footprint of the existing building nor encroach into the required four-foot setback.
(Ord. 979 § 2, 1993; Ord. 1135 §§ 3—5, 2003; Ord. 1156 §§ 1, 2, 2006; Ord. 1251 § 1, 2017; Ord. 1281, 2020; Ord. 1321, 3/11/2025)
§ 18.38.050 Plan review.
The city shall approve or deny the building permit application for an accessory dwelling unit within sixty days from the date the completed application is received if there is an existing single-family or multifamily dwelling on the lot. If a permit application to create an ADU is submitted with a permit application to create a new single-family dwelling on the parcel, the city may delay in acting on the permit application for the ADU until the city acts on the permit application to create the new single-family dwelling. If the city denies an application for an ADU or JADU, the city shall, within the time period described, return in writing a full set of comments to the applicants with a list of items that are defective or deficient and a description of how the application can be remedied by the applicant.
(Ord. 979 § 2, 1993; Ord. 1135 § 6, 2003; Ord. 1251 § 1, 2017; Ord. 1281, 2020; Ord. 1321, 3/11/2025)
