Planning commission approves changes to ADU rules after HCD review; commissioners strip subjective design clause

The Cupertino Planning Commission on July 8 recommended the City Council adopt amendments to municipal code chapters that govern accessory dwelling units (ADUs) to reflect recent state law changes and feedback from the California Department of Housing and Community Development (HCD). Commissioners approved the staff recommendation with one change: striking a clause requiring detached ADUs to "match" certain exterior design elements of the primary dwelling.

John (staff) summarized HCD's review of Cupertino's ADU ordinance. He said HCD sent comments on April 24, 2025 after the city had submitted its ordinance for review and that subsequent state bills adopted after the city's earlier ordinance required additional changes. "HCD, on 04/24/2025, a little over a year after we had submitted the, our new ordinance to them for review, they sent us a letter, summarized our findings, and identified some key areas, where the city could make, needed to make some updates," John said.

Staff described key code changes proposed to comply with state requirements and HCD recommendations, including:

- Classifying duplexes as multifamily uses (multifamily ADU standards apply to duplexes). - Updating state statute citations throughout chapters 19.08 and 19.112 to reflect current Government Code sections. - Modifying multifamily streamlined rules so detached ADUs on multifamily lots are not capped by the prior 1,200-square-foot local limit where state law provides no maximum. - Adding AB 2533-related language limiting local discretion to require correction of nonconforming zoning violations or building standard violations as a condition of permitting certain ADUs (noting exceptions for hazards to public health and safety). - Clarifying that junior ADUs and ADUs may not be used as short-term transient lodging (rentals for fewer than 30 days), consistent with the city's policy to restrict short-term rentals in ADUs.

Commissioners focused on two practical issues: design-objectivity and homeowner burdens. HCD had objected to vague, nonobjective language encouraging ADU design "compatibility." To address that, staff proposed objective criteria for material, roofing and window style in several specific zoning districts that already have defined standards (for example, Eichler-design neighborhoods and some planned developments). After discussion, commissioners moved and approved an amendment to strike subsection I(a) of the proposed structure-design language (the clause that read broadly about matching exterior elements) to avoid rigid, subjective enforcement that could burden applicants whose primary homes date from earlier construction eras.

Commissioners also debated whether policies should distinguish between new multi-unit developments and existing single-family homeowners. Staff emphasized that building and fire codes are separate state- or code-enforced requirements; the safety element and ADU ordinance speak to policy and objective standards, but ministerial and building-code matters are enforced through other channels.

A motion to adopt the staff recommendation with the stated drafting change carried; the Planning Commission record notes Commissioner Fung was absent at the vote. Staff will forward the commission's recommendation and a clean ordinance to the City Council for a public hearing and potential adoption on Sept. 3, 2025.

Public comment included a recurring theme that residents feel state ADU laws change frequently and that HCD review timelines slow local certainty. Jennifer Griffin (resident) urged architectural compatibility limits to protect neighborhood character and voiced frustration with frequent state-level changes.

The Planning Commission's action amends local ADU rules primarily to ensure compliance with HCD comments and current state statutory language; the commission removed a subjective design-matching clause and retained objective standards for specified zoning districts. The item will next be scheduled for City Council consideration on Sept. 3, 2025.