1

Streamlined legal framework and oversight

SB 477, which went into effect in March 2024, consolidated previously scattered ADU regulations into a more coherent framework under sections 66310-66342. The 2025 handbook reflects this reorganization, providing clearer guidance on these consolidated regulations. Additionally, new legislation has expanded the HCD’s role, granting them comprehensive authority to enforce all state ADU Laws as of January 1, 2024—a significant shift from their previous advisory capacity.

2

Clarifying state-mandated ADUs (66323 Units)

One of the most important aspects of the new handbook is its clarification of “66323 Units”—state-mandated ADUs and junior accessory dwelling units (JADUs) that must be approved ministerially and are exempt from many local development standards. State law now defines four distinct categories of these units: :

• JADUs within single-family homes (and ADUs converted from the space of a single-family home or accessory structure)

• Detached ADUs on single-family lots (up to 800 square feet)

• ADUs converted from non-living spaces in multi-family buildings

• Detached ADUs on multi-family lots

These units receive special treatment under the law: local agencies cannot impose typical zoning requirements like lot coverage or front setbacks, though standard building safety standards still apply.

3

Expanded multi-family development options

SB 1211 significantly expands opportunities for multi-family ADU development. Property owners can now build up to eight detached ADUs on lots with existing multi-family dwellings, provided the number doesn’t exceed the total number of existing units. The bill also introduces a clear definition of “livable space” and eliminates the requirement to replace uncovered, off-street parking spaces demolished during ADU construction.

4

Path to compliance for older units

AB 2533, effective January 1, 2025, creates a pragmatic approach to unpermitted ADUs and JADUs constructed before January 1, 2020. The law now prohibits local agencies from denying permits for these units based on building standard violations, provided the structure isn’t substandard. This creates a clear pathway for bringing existing units into compliance while ensuring safety standards are met.

5

Streamlined approval processes

State law continues to require agencies to process ADU applications within 60 days, and the new handbook reflects additional streamlining measures. These include simultaneous review requirements for demolition and construction permits for garage conversions, and a new mandate for agencies to implement pre-approved ADU plans by January 1, 2025. The handbook provides comprehensive guidance on these ministerial review processes, helping both agencies and applicants navigate the requirements more effectively.

6

Expanded owner rights and flexibility

Changes to state government and civil code have permanently eliminated owner-occupancy requirements for ADUs. Additionally, the law now allows local agencies to adopt ordinances permitting ADUs to be sold separately from the primary residence through condominium conversion. This marks a significant shift in property rights, potentially allowing ADU owners to create separate, saleable real estate assets where local jurisdictions permit it. The law has also strengthened protections against restrictive HOA policies, explicitly voiding CC&Rs that limit ADU development and preventing HOA influence in local agency approval processes.

7

Changes to impact fees and financial considerations

The 2025 handbook outlines important legislative provisions regarding fees and costs. State law continues to prohibit impact fees for ADUs under 750 square feet while requiring proportional fees for larger units. New provisions extend these protections to previously unpermitted ADUs built before January 1, 2020, reducing barriers to bringing these units into compliance.

8

Integration with existing housing laws

The 2025 handbook offers improved clarity on how ADU regulations interact with Senate Bill 9 (SB 9), specifically noting that local agencies aren’t required to allow more than four units on a single lot. This clarification helps property owners and developers better understand their options when considering both ADU and SB 9 development strategies.

Looking forward