A Well-Informed Start to 2025: BBK’s Guidance for New Laws in California – Housing Part Two

In part two of the Housing New Laws series, Best Best & Krieger LLP (BBK) attorneys provide key analyses of new housing legislation in 2025 addressing governing urban lot splits and two unit projects, accessory dwelling units (ADUs), and new extensions to certain housing development permits and approvals. Below are key takeaways and analyses of SB 450, SB 477, SB 1211, AB 2533, AB 2117 and AB 2729.

Urban Lot Splits and Two Unit Projects

SB 450

Since January 1, 2022, SB 9 has required cities to allow any lot in a single-family residential zone to be: (1) split, roughly into halves, with resulting lots as small as 1,200 sf (termed an “urban lot split”); and (2) developed with a second primary dwelling unit. SB 9 allowed cities to impose objective zoning, subdivision, and design standards on SB 9 projects, subject to some limitations.

SB 450 significantly reduces the scope of local authority to regulate SB 9 projects. Most notably, under SB 450 cities: 

• May no longer impose standards on second primary dwelling unit projects “that do not apply uniformly to development within the underlying zone” … that is unless the SB 9-specific standards “are more permissive.”
• May only impose standards on urban lot splits that are “related to the design or to improvements of a parcel.”
• Must approve or deny a “completed application” for an urban lot split or second primary dwelling unit project within 60 days. (Failure to act results in the application being deemed approved.)
• Must provide detailed comments with any denial of an urban lot split or second primary dwelling unit application.
• May no longer deny an application for an urban lot split or second primary dwelling due to specific adverse impacts to the “physical environment” (now only adverse impacts on “public health and safety” are a valid basis for denying an SB 9 application).

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Accessory Dwelling Units

SB 477

SB 477’s purpose was to make state law governing ADUs and junior ADUs (JADUs) easier to read and navigate. It did so by relocating numerous Government Code sections into a new chapter and, within that chapter, dividing key regulations into smaller sections by topic area. The state ADU law is now located in Government Code Sections 66310-66342.

SB 1211

Before SB 1211, state law prohibited cities from requiring off-street parking spaces to be replaced when a garage, carport, or covered parking structure is demolished with the construction of, or conversion to, an ADU. SB 1211 amended this prohibition to also bar cities from requiring replacement parking when an uncovered parking space is demolished for or replaced with an ADU. 

For some time, state law has required cities to ministerially approve qualifying building permit applications for ADUs within portions of existing multifamily dwelling structures that are not used as livable space. The term “livable space” was not defined by state ADU law. SB 1211 changed this by adding a new definition stating “‘livable space’ means a space in a dwelling intended for human habitation, including living, sleeping, eating, cooking, or sanitation.” 

SB 1211 also increased the number of detached ADUs that lots with an existing multifamily dwelling can have. Previously, lots with an existing or proposed multifamily dwelling could have up to two detached ADUs. Following SB 1211, lots with an existing multifamily dwelling can have up to eight detached ADUs or as many detached ADUs as there are primary dwelling units on the lot, whichever is less. SB 1211 did not alter the number of ADUs that lots with proposed multifamily dwellings can have — they remain limited to two detached ADUs.

AB 2533

Subject to limited exceptions, existing state law prohibits cities from denying a permit to legalize an unpermitted ADU that was constructed before January 1, 2018, if the denial is based on the ADU not complying with applicable building, state or local ADU standards. One exception allowed cities to deny a permit to legalize if they make a written finding that correcting the violation is necessary to protect the health and safety of the public or the occupants of the structure. 

AB 2533 altered this landscape by: (1) expanding its applicability to JADUs; (2) changing the construction cutoff date from January 1, 2018, to January 1, 2020; (3) replacing the above exception with a requirement that cities find correcting the violation necessary to comply with the standards specified in Health and Safety Code Section 17920.3 (Substandard Buildings); (4) mandating new public-notification requirements about limits on local regulation, substandard-building criteria, and pre-application inspection by a private contractor; and (5) addressing the scope of city inspections and remedial actions.

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Development Permit Extensions

AB 2117

AB 2117 provides that the period of time before a development permit or project approval expires shall not include the period of time during which any legal action or proceeding involving the approval or conditional approval is or was pending. This extension of time applies to development permits or project approvals but specifically excludes building permits, excavation and grading permits, demolition permits, and other nondiscretionary permits that are required or issued after the entitlement process has been completed. As a result, from the time an action challenging development approvals is commenced until the action is fully resolved, the time to act on the applicable development approvals will be tolled.

AB 2729

AB 2729 provides an 18-month extension to all “housing entitlements” that were in effect on January 1, 2024, and were set to expire prior to December 31, 2025. The bill defines housing entitlements broadly to include discretionary approvals of housing development projects; ministerial approvals that are a prerequisite for obtaining a building permit (i.e., an SB 35 ministerial approval); any requirement to submit an application for a building permit within a specific time after the effective date of a housing entitlement; approved subdivision maps for a housing development project, including tentative subdivision maps, vesting tentative maps or parcel maps and any other vested right associated with the above approvals. SB 35 specifically excludes statutory development agreements, tentative maps that were already extended for a minimum of 24 months pursuant to Government Code Section 66452.6 on or after January 1, 2024, and preliminary applications for housing development projects as defined in Section 65941.1. A “housing development” is defined as a residential development or a mixed-use development in which at least two-thirds of the square footage of the development is designated for residential use. The extension provided is tolled during any time that the housing entitlement is the subject of a legal challenge.

Disclaimer: BBK Legal Alerts are not intended as legal advice. Additional facts, facts specific to your situation, or future developments may affect subjects contained herein. Seek the advice of an attorney before acting or relying upon any information herein.