Union City City Zoning Code
CHAPTER 18
34 ACCESSORY DWELLING UNITS
§ 18.34.010 Purpose.
The purpose of this chapter is to implement Government Code Sections 66310 through 66342 by allowing the creation of accessory dwelling units (ADUs) and/or junior accessory dwelling units (JADUs) through ministerial review. In the event of any conflict or discrepancy between the ADU and/or JADU standards in this chapter and any other provisions of this title, the standards contained in this chapter shall take precedence.
(Ord. 2025-002, 3/25/2025)
§ 18.34.020 General requirements.
A.
Building Permit Required. All ADUs and/or JADUs, including those that are internal to an existing structure and converted from existing floor area, shall be subject to a building permit.
B.
Permitting Procedure.
1.
Ministerial Review. A permit application for an ADU and/or JADU shall be processed ministerially, without discretionary review or a hearing.
2.
Review Period.
a.
Developed Lot. If there is an existing single-family or multifamily dwelling on a lot, a permit application for an ADU and/or JADU shall either be denied or approved within 60 days of receipt of a complete application.
b.
Undeveloped Lot. If a permit application to create or serve an ADU and/or JADU is submitted with a permit application to create a new single-family or multifamily dwelling on a lot, the City may delay approving or denying the permit application for the ADU and/or JADU until the City approves or denies the permit application to create the new single-family or multifamily dwelling; however, the application to create or serve the ADU and/or JADU shall be considered without discretionary review or hearing. If the applicant requests a delay, the 60-day time period shall be tolled for the period of the delay.
3.
Deemed Approved. If a complete application is not approved or denied within 60 days of receipt of a complete application, the application shall be deemed approved.
4.
Denied Applications. If an application for an ADU and/or JADU is denied within 60 days of receipt of a complete application, the City shall return in writing a full set of comments to the applicant with a list of items that are defective or deficient and a description of how the application can be remedied.
5.
Nonconforming Conditions. No application for a permit to create an ADU and/or JADU shall be denied due to the correction of nonconforming zoning conditions, building code violations, or unpermitted structures that:
C.
Separate Entrance. ADUs and/or JADUs shall provide at least one exterior entrance that is separate from the main entrance of the primary dwelling.
D.
Separate Address. ADUs and/or JADUs shall provide a separate address from the primary dwelling.
(Ord. 2025-002, 3/25/2025)
§ 18.34.030 ADU regulations.
A.
General Plan and Zoning.
1.
Residential Use. ADUs approved in compliance with this chapter shall be considered a residential use that is consistent with the existing general plan and zoning designation for the lot.
2.
Permitted Locations. ADUs are permitted on lots with an existing or proposed single-family or multifamily dwelling in areas zoned to allow single-family or multifamily residential use.
3.
Density. ADUs shall not count toward the maximum density permitted on the lot.
B.
ADU Typology. ADUs shall be either attached to, or located within, the proposed or existing primary dwelling, including attached garages, storage areas or similar uses or an accessory structure or detached from the proposed or existing primary dwelling and located on the same lot as the proposed or existing primary dwelling, including detached garages.
C.
Objective Standards.
1.
Number of ADUs.
a.
Single-Family ADUs.
i.
In addition to a JADU, no more than two ADUs shall be permitted on the same lot that has an existing or proposed single-family dwelling as follows:
(A)
One attached or detached, new construction ADU, or
(B)
One detached, new construction ADU that does not exceed 800 square feet and one ADU that is within the proposed space of a single-family dwelling or existing space of a single-family dwelling or accessory structure and may include an expansion of not more than 150 square feet beyond the same physical dimensions as the existing accessory structure. An expansion beyond the physical dimensions of the existing accessory structure shall be limited to accommodating ingress and egress.
b.
Multifamily ADUs.
i.
Conversion ADUs. A minimum of one ADU and a maximum of 25% of the total number of existing multifamily dwelling units shall be permitted to be converted from existing multifamily 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 the State building standards for dwellings.
ii.
Detached ADUs.
(A)
Existing Multifamily Dwelling. On a lot with an existing multifamily dwelling, not more than eight detached ADUs shall be permitted. The number of ADUs shall not exceed the number of existing multifamily units on the lot.
(B)
Proposed Multifamily Dwelling. On a lot with a proposed multifamily dwelling, not more than two detached ADUS shall be permitted.
2.
Size. The maximum allowable square footage for ADUs shall not exceed the area limitations specified below. For the purposes of this section, the calculation of ADU square footage shall not comprise garages, carports, covered porches/patios, breezeways, and/or other accessory structures.
a.
Existing Floor Area. ADUs converted from existing floor area shall not be subject to any size limitations.
3.
Height.
a.
Existing Floor Area. ADUs converted from existing floor area shall not be subject to height limitations.
b.
New Floor Area.
i.
Attached ADUs. Attached ADUs created from new floor shall not exceed a height of 30 feet or the maximum height permitted in the underlying zoning district. In all cases, ADUs shall not exceed two stories.
ii.
Detached ADUs. Detached ADUs created from new floor area, on a lot with an existing or proposed single family or multifamily dwelling unit, shall not exceed a height of 16 feet, or a height of 18 feet if either of the following conditions are met:
(A)
Transit Proximity. The lot on which the ADU will be created is within one-half mile walking distance of a major transit stop or a high-quality transit corridor, as those terms are defined in Public Resources Code Section 21155. An additional height of two feet, for a maximum height of 20 feet, shall be allowed to accommodate a roof pitch on the ADU that is aligned with the roof pitch of the primary dwelling unit.
(B)
Multifamily, Multistory Structure. The lot on which the ADU will be created consists of an existing or proposed multifamily, multistory dwelling.
4.
Setbacks.
a.
Existing Floor Area. ADUs located within an existing living area or an existing accessory structure, or ADUs that replace an existing structure and are in the same location and to the same dimensions as the structure being replaced, shall not be subject to setbacks.
b.
New Floor Area. ADUs created from new floor area are subject to the following setbacks:
5.
Parking. ADUs shall not be subject to the City's minimum parking requirements. Additionally, replacement parking shall not be required when a garage, carport, covered parking structure, or uncovered parking space is demolished in conjunction with the construction of an ADU or converted to an ADU. A demolition permit for a detached garage to be replaced with an ADU shall be reviewed and issued concurrently with the ADU permit application.
6.
Historic Resources. An ADU that involves exterior modifications to structures listed in the California Register of Historical Resources shall be designed and constructed in conformance with the objective standards for preservation provided in the Secretary of the Interior's Standards for the Treatment of Historic Properties.
D.
Building Code Requirements. ADUs must comply with the City's building code requirements for detached dwellings. However, constructing an ADU does not constitute a Group R occupancy change under Section 310 of the California Building Code (Title 24), unless the Building Official issues a written finding, supported by substantial evidence, that the construction poses a specific, adverse impact on public health and safety. This provision shall not prevent the City from changing the occupancy code for space converted from uninhabitable or non-residential use to residential use.
E.
Fire Sprinklers. ADUs shall not be required to provide fire sprinklers if fire sprinklers are not required for the primary residence. The construction of an ADU shall not trigger a requirement for fire sprinklers to be installed in the existing primary dwelling.
F.
Impact Fees. ADUs that are 750 square feet or larger shall be subject to all applicable impact fees. Impact fees shall be charged proportionally in relation to the square footage of the primary dwelling unit. As ascribed in Government Code Section 66324, as the same may be amended from time to time, and reprinted here for reference, "impact fee" means:
A "fee" as defined in subdivision (b) of [Government Code] Section 66000, expect that it also includes fees specified in [Government Code] Section 66477. "Impact fee" does not include any connection fee or capacity charge charged by a local agency, special district, or water corporation.
G.
Passageway. No passageway shall be required in conjunction with the construction of an ADU. As ascribed in Government Code Section 66313, as the same may be amended from time to time, and reprinted here for reference, "passageway" means:
A pathway that is unobstructed clear to the sky and extends from a street to one entrance of the ADU.
H.
Separate Sale. Except as permitted by Government Code Section 66341, as the same may be amended from time to time, ADUs shall not be sold or conveyed separately from the primary dwelling.
I.
Sewage. ADUs using a private sewage disposal system shall obtain approval by the local health officer.
J.
Short-Term Rental Limitation. ADUs shall not be rented for a term of less than 30 days.
K.
Utility Connection. ADUs constructed within the proposed space of a primary dwelling or existing space of a primary dwelling unit or accessory structure shall not be required to install a new or separate utility connection directly between the ADU and the utility or impose a related connection fee or capacity charge, unless the ADU was constructed with a new single-family dwelling, or upon separate conveyance of the ADU pursuant to Government Code Section 66341.
(Ord. 2025-002, 3/25/2025)
§ 18.34.040 JADU regulations.
A.
Permitted Locations. JADUs shall be permitted in single-family residential zones.
B.
Number of JADUs. In addition to any ADUs, no more than one JADU shall be permitted per residential lot zoned for single-family residences with a single-family residence built, or proposed to be built, on the lot.
C.
Size. JADUs shall be limited to a maximum size of 500 square feet in floor area.
D.
Owner Occupancy. JADUs shall be subject to owner-occupancy either in the remaining portion of the single-family residence or the newly created JADU. Owner occupancy shall not be required if the owner is another governmental agency, land trust, or housing organization.
E.
Deed Restriction. A recordation of a deed restriction, which shall run with the land, shall be filed with the City. The deed restriction shall include:
1.
A prohibition of the sale of the JADU separate from the sale of the single-family residence, including a statement that the deed restriction may be enforced against future purchasers; and
F.
Interior Entry. In addition to a separate exterior entrance, JADUs that do not comprise a bathroom shall include an interior entry to the main living area of the single-family residence.
H.
Parking. No parking spaces (additional or replacement) shall be required as a condition of permitting a JADU, even when the JADU is converted from an attached garage.
(Ord. 2025-002, 3/25/2025)