To: Board of Supervisors
From: John Kopchik, Director, Conservation and Development
Report Title: Proposed Amendment to the Accessory Dwelling Unit (ADU) Ordinance, Chapter 82-24 of the County Ordinance Code
☒Recommendation of the County Administrator ☐ Recommendation of Board Committee
RECOMMENDATIONS:
1. OPEN the public hearing on Ordinance No. 2025-07, RECEIVE testimony, and CLOSE the public hearing.
2. DETERMINE that the adoption of Ordinance No. 2025-07 is statutorily exempt under CEQA Guidelines Section 15282(h) that exempts the adoption of an ordinance regarding second units.
3. ADOPT Ordinance No. 2025-07 to establish amended regulations and permitting procedures for accessory dwelling units and junior accessory dwelling units.
4. DIRECT the Director of Conservation and Development to file a CEQA Notice of Exemption with the County Clerk.
FISCAL IMPACT:
The costs of preparing this ordinance have been funded by the Department of Conservation and Development’s Land Development Fund. The cost of processing accessory dwelling unit applications will be 100% funded by applicants.
BACKGROUND:
The Board of Supervisors adopted the current Accessory Dwelling Ordinance (Ordinance No. 2023-13), on June 27, 2023. This Ordinance amended the previous 2020 ADU Ordinance. With the adoption of Ordinance No. 2023-13, the County’s ADU Ordinance was consistent with changes in State law related to allowable height limitations as well as allowing the separate sale of an ADU developed by a qualified not profit corporation to a person or family of low or moderate income.
Since adoption of the County’s current ADU ordinance, the state legislature has continued to revise State law related to ADUs. Changes to the State ADU law, commencing with Section 66310 of the California Government Code that became effective on January 1, 2025, are not in the current ADU Ordinance, such as updated references to the Government Code due to the recodification of the State accessory dwelling unit law; increasing the number of allowable accessory dwelling units on lots that include either a single-family or multiple-family dwelling; additional exceptions to replacement parking requirements; removing non-objective standards from permitting requirements; other clarifications in conformance with State law.
The County Planning Commission conducted a public hearing on the proposed Ordinance at its meeting on Wednesday, February 26, 2025. The Commission opened and closed the public hearing with no public testimony, and voted to recommend approval of the proposed Ordinance.
STAFF ANALYSIS:
Below is a summary of revisions that proposed Ordinance 2025-07 would make to the County’s ADU Ordinance. The revisions include the following changes.
• Allow up to eight detached ADUs, not exceeding 800 square-feet in size, on a lot with an existing multiple-family dwelling and not more than the number of existing units on the lot. The current County ADU Ordinance authorizes only two detached ADUs on a lot with a multiple-family dwelling.
• Allow up to two detached ADUs, not exceeding 800 square-feet in size, on a lot with a proposed multiple-family dwelling.
• Not require replacement parking if an uncovered parking space is converted to an ADU.
• Allow one internal conversion ADU and one Junior ADU and one detached ADU on a lot with a proposed or existing single-family dwelling. The current County ADU Ordinance authorizes only one ADU and one Junior ADU on a lot with a single-family dwelling.
• Remove the development standard requiring ADU entrances be subordinate to the primary dwelling unit.
• Not require additional off-street parking to serve an ADU if the ADU permit application is submitted with a permit application for a new single-family or multiple-family dwelling and the ADU or lot qualifies for a parking exception.
• Not require a deed restriction for an ADU, while continuing to require a deed restriction for a Junior ADU to restrict the sale or rental of the Junior ADU in compliance with State ADU law.
General Plan Consistency
The proposed Ordinance is consistent with the 2045 General Plan, in particular, the Housing Element, which includes eight general goals for housing. By facilitating the development of ADUs and JADUs, the proposed Ordinance would specifically promote the following goals:
Goal HE-1: Maintain and improve the quality of the existing housing stock and residential neighborhood in Contra Costa County, including preserve the affordable housing stock.
Goal HE-2: Increase the supply of housing with a priority on the development of affordable housing, including housing affordable to extremely low-income households.
Goal HE-3: Increase the supply of appropriate and supportive housing for the special needs population.
Goal HE-4: Improve housing affordability for both renters and homeowners.
Goal HE-6: Mitigate potential governmental constraints to housing development and affordability.
Goal HE-7: Promote equal opportunity for all residents to reside in the housing of their choice.
In addition to Housing Element Goals, the revised ADU Ordinance is consistent with the following housing policy:
Policy HE-P2.4: Actively promote accessory dwelling unit (ADU) and junior accessory dwelling unit (JADU) construction as a viable means of meeting affordable housing needs by design, particularly in higher resource communities, and those communities identified as RCAAs (racially concentrated areas of affluence) in the central and southern portions of the county.
The revised ADU Ordinance is also consistent with the following housing actions:
Action HE-A2.5: Maintain consistency with ADU state law in the County Ordinance Code. Promote ADU construction in high-resource areas/areas of concentrated affluence. Discuss the option of ADUs with applicants when the call or come in to the planning counter.
Action HE-A2.6: Conduct studies to explore development of new programs or policies to potentially fund or incentivize affordable housing development, including implementation of urban housing development projects (as allowed under SB 9) and creating objective design standards to streamline processing and approval process. Continue updating ADU regulations as needed to remain compliant with state law and implement other community goals.
Zoning Compliance
Proposed Ordinance No. 2025-07 would amend the County ADU Ordinance to be consistent with current State law. The proposed Ordinance allows exceptions to certain development standards of applicable zoning districts, as allowed by State law for the development of ADUs and JADUs. The proposed Ordinance would act in concert with and would not conflict in any manner with the County Zoning Code.
Environmental Review
For purposes of compliance with the California Environmental Quality Act (CEQA) the proposed Ordinance is statutorily exempt under CEQA Guidelines Section 15282(h) that exempts the adoption of an ordinance regarding second units.
CONCLUSION:
Proposed Ordinance No. 2025-07, to amend Chapter 84-24 of the County Ordinance Code, is consistent with the State ADU law, commencing with California Government Code Section 66310, and the County General Plan and Zoning Code. Staff recommends adoption of Ordinance No. 2025-07.
CONSEQUENCE OF NEGATIVE ACTION:
If the recommended actions are not approved, the County’s ADU Ordinance will not be amended to conform with current State law. Pursuant to State ADU law, commencing with California Government Code Section 66310, the County will process applications to establish ADUs, including an increased number of allowable accessory dwelling units on lots that include either a single-family or multiple-family dwelling, additional exceptions to replacement parking requirements, removing non-objective standards from permitting requirements, and not require a deed restriction for an ADU, while continuing to require a deed restriction for a Junior ADU.