Accessory Dwelling Units (ADUs) are secondary dwelling units that provide complete independent living facilities for one or more persons on the same lot as a primary dwelling unit. Previously, this type of dwelling unit has been defined by state law first as “granny flats” and then as second dwelling units. In 2004, consistent with state requirements at the time, the City Council adopted Ordinance No. 163 to establish regulations governing the permissible locations and development standards for second dwelling units. The Ordinance allowed second dwelling units by right, similar to single-family dwelling units, and established regulations governing the development of these units.
In 2016, the State of California enacted Senate Bill (SB) 1069 and Assembly Bill (AB) 2299 to encourage and facilitate the development of ADUs in residential zoning districts. These bills amended state law to require the ministerial approval of ADUs within a single-family residential zone, while further limiting the regulations and standards that local agencies can impose on these uses and structures. The provisions of the City’s previously adopted Ordinance No. 163 addressing second dwelling units did not conform to the new provisions in state law and became null and void as of January 1, 2017, the effective date of the bills.
On November 28, 2017, the City Council adopted Ordinance No. 321, which established regulations and procedures for the development of ADUs within the City.
In 2019, the state enacted six statutes pertaining to the permitting and regulation of ADUs, including: Senate Bill 13 and Assembly Bills 68, 587, 670, 671, and 881. (SB 13, AB 68, and AB 881 amended some of the same provisions and overlapped, so only certain sections in each became law.) These statutes created further limitations on the ability of local jurisdictions to impose regulatory requirements on ADUs. The City Council adopted Ordinance No. 364 in February 2021 to update development standards applicable to ADUs, including setbacks, lot coverage, maximum height, building separation, minimum and maximum sizes, required parking, design standards, and separate utility requirements. The regulations also required conformance with the standards of the City's Fire Hazard Overlay District for properties located within the overlay district and disallowed the development of ADUs in the Sleepy Hollow and Canon Lane (south of Carbon Canyon Road) communities due to public safety concerns. Consistent with state law, the regulations also identified types of ADUs exempt from most development standards and allowed the development of ADUs on properties developed with multi-family residential structures.
In February 2024, the City Council adopted Ordinance No. 406, which clarified and updated provisions in multiple chapters of Title 16 (Development Code) of the Chino Hills Municipal Code. As part of these updates, the City eliminated the requirement for property owners to record a restrictive covenant (deed restriction) for ADUs. This update addressed a change in state law that limited the applicability of such restrictive covenants and challenges experienced by staff and applicants in implementing the restrictive covenant requirement. In March 2024, the state enacted urgency legislation, Senate Bill No. 477, which reorganized the various accessory dwelling unit provisions into a more cohesive and organized chapter of the Government Code and made other non-substantive changes, along with other changes not directly related to ADUs.
Towards the end of the 2023-2024 legislative session, the state enacted additional statutes updating the provisions governing the permitting and regulation of ADUs, most significantly in three bills that became effective on January 1, 2025. Assembly Bill No. 2533 broadened restrictions on local agencies denying permits to legalize an unpermitted ADU existing prior to January 1, 2020. Assembly Bill No. 3057 expanded the existing California Environmental Quality Act exemption for ADU ordinances to explicitly include ordinances establishing regulations for junior accessory dwelling units. Lastly, Senate Bill No. 1211 increases the permissible number of ADUs on properties developed with multi-family dwelling units from two to eight, prohibits local agencies from requiring the replacement of uncovered parking spaces lost during the development of an ADU, and clarifies the applicability of objective design and development standards to ADUs meeting the criteria specified in Government Code Section 66323 (including ADUs developed within an existing structure, detached ADUs with a floor area of 800 square feet or less, and ADUs on multi-family properties).
Planning Commission Review
At the December 3, 2024, Planning Commission meeting, staff presented to the Planning Commission (Commission) the proposed updates to the City’s ADU regulations (Municipal Code Amendment No. MCA-0003-2024). The Commission discussed the following considerations with staff:
- The potential effect of allowing the development of up to eight (8) accessory dwelling units on properties developed with multi-family housing on parking and landscaping;
- The legalization of unpermitted ADUs in the City as required by state law;
- The lack of any feedback from neighbors of ADU development expressing either concern or appreciation;
- The absence of state or local requirements to enforce the use of ADUs as a dwelling unit as opposed to non-living spaces (e.g. personal offices or recreation areas);
- The use of ADUs as a buffer to the City’s Regional Housing Needs Assessment (RHNA) allocation and the degree to which ADU development has matched the projection in the Housing Element;
- The potential for state law to allow the conversion of a multi-family project’s recreation areas into ADUs; and
- That staff has not received any reports of property owners experiencing insurance coverage challenges after developing an ADU.
The Commission opened the public hearing, but there were no public comments on this matter. The Commission asked staff to continue monitoring and to provide updates and additional information regarding ADU development in the City on an ongoing basis. The Commission adopted a resolution recommending that the City Council approve Municipal Code Amendment No. MCA-0003-2024 to update the City’s ADU regulations.
Proposed Municipal Code Amendment
To address the changes in state law pertaining to the regulation and permitting of ADUs and Junior ADUs, and to incorporate experience gained by staff during the implementation of the City’s current regulations, the attached draft ordinance would update and clarify the City’s ADU regulations. The more substantive changes to the current regulations include:
- Increasing the number of detached ADUs permissible on a property developed with an existing multi-family dwelling unit from two to eight, pursuant to Senate Bill No. 1211;
- Clarifying the applicability of objective design and development standards to specific types of ADUs meeting the criteria specified in Government Code Section 66323, pursuant to Senate Bill No. 1211;
- Increasing the maximum height from 16 feet to 18 feet for a detached ADU and allowing an ADU that is attached to the primary dwelling to match the height of the existing primary dwelling or to a maximum height of 25 feet, whichever is greater;
- Clarifying the standards applicable to a detached two-story ADU;
- Requiring interior entry to the main dwelling, in addition to exterior access, for a Junior ADU that shares a sanitation facility with the primary dwelling;
- Clarifying and updating the objective design standards, including prohibiting entrances and stairways serving a second story ADU from being located on street-facing elevations, requiring connections and space for a clothes washer and dryer, and requiring a roof overhang of at least 12 inches; and
- Updating the separate utility requirement to exclude sewer service, as residents have expressed concern regarding potentially significant costs associated with its installation and the Public Works Department has determined that the installation of the separate sewer connections has the potential to weaken the City’s sewer infrastructure and impair the quality of the City’s street network.
Upon adoption by the City Council, the City will submit the ordinance updating the City’s ADU regulations to the California Department of Housing and Community Development (HCD), which will evaluate the ordinance’s conformance with state law. If any nonconformities are identified, the City will have 30 days following notification of such nonconformities to provide a written response to HCD’s findings. Staff had intended to submit a draft of the ordinance to HCD for review prior to its consideration by the City Council to minimize the potential for further updates to be required after its adoption, but HCD advised staff that it is not currently performing courtesy reviews of draft ordinances and that the ordinance must be submitted after adoption. While staff has worked with the City Attorney to prepare these updates in conformance with the latest statutes, it may be necessary to prepare a subsequent ordinance to address any comments resulting from HCD’s review of the ordinance.
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