California’s housing landscape is set to undergo significant changes in 2025, thanks to a series of new laws aimed at increasing housing supply and affordability. These laws particularly focus on Accessory Dwelling Units (ADUs) and multifamily housing, offering exciting opportunities for homeowners and developers alike.
As an architect who’s spent countless hours helping families create additional living spaces, I’m genuinely excited to share how California’s new ADU laws for 2025 could transform your property’s potential. Let me break this down in a way that matters to you, sharing some real stories from my experience.
Major Changes to California ADU Laws in 2025
AB 2533: Amnesty for Unpermitted ADUs
One of the most impactful new laws is AB 2533, which provides a path to legalization for existing unpermitted ADUs. This law aims to bring these units into compliance without excessive costs or bureaucratic hurdles. Just earlier this year, I met with Sarah, a homeowner in Los Angeles who had converted her garage into a living space for her aging mother years ago. Like many others, she was afraid to come forward about her unpermitted unit. The new AB 2533 is designed exactly for situations like hers.
Here’s what this means for you:
- Instead of requiring expensive upgrades to meet current building codes, cities will now focus on basic safety standards
- You can get a confidential inspection without fear of being reported
- Most fees will be waived if your existing infrastructure is adequate
SB 1211: Expanding ADU Options for Multifamily Properties
SB 1211 significantly expands the potential for ADUs on multifamily properties. Starting January 2025, property owners can build one detached ADU per existing unit, up to a maximum of eight ADUs. I recently worked with a family in Pomona who owned an R-2000 lot and dreamed of creating more housing for passive rental income. We utilized SB 330 to increase density and build a 3-building complex. With the new SB 1211 taking effect next year, they can add up another 8 ADUs per existing unit.
Here’s SB 1211 in a nutshell:
- One detached ADU per existing unit (up to 8 ADUs)
- Additional converted units from common spaces
- More flexible parking solutions
If you have an R2, R3, R4, or interested about Multifamily development and ADUs, read this complete guide for SB 1211.
Impact Fee Relief: SB 937
Perhaps one of the most significant new ADU laws comes from SB 937, which transforms how impact fees are handled. This law addresses one of the biggest hurdles my clients face – the timing of impact fees.
Previously, homeowners building ADUs over 750 square feet had to pay substantial impact fees upfront. These fees range significantly between jurisdictions, with Los Angeles reporting a multifamily development fee of $12,000 per unit, while Fremont reports $75,000 according to UC Berkeley’s Terner Center. Additionally, while the magnitude of development fees varies nationwide, the six jurisdictions with the highest recorded fees are all in California.
Now, impact fees for ADUs over 750 square feet will be collected at the final inspection or when the certificate of occupancy is issued, rather than upfront before construction begins. This change is intended to improve cash flow for homeowners during the construction process.
Key Changes with SB 937
New Fee Collection Timeline:
- Impact fees now collected at final inspection or certificate of occupancy
- Previously required upfront payment before construction
- Applies to ADUs over 750 square feet
- Reduces initial capital requirements
Financial Benefits
- Reduces borrowing costs and interest payments
- Allows more efficient use of construction funds
- Improves cash flow management
- Particularly beneficial for HELOC financing
Example of Impact Fees in Sonoma
For a family in Sonoma, building an 840-square-foot ADU, this means delaying payment of approximately $5,856 in impact fees until project completion, significantly improving cash flow during construction.
SB 937 is a game-changer for ADU financing. If you’ve been putting off your ADU dreams due to budget concerns, now is the time to reconsider. Let’s discuss your project and see how these new rules can make your ADU a reality sooner than you think. Contact us today to get started!
SB 1077: Simplifying Coastal Zone ADU Development
The California Coastal Commission (CCC) and local coastal authorities have historically made it challenging to build ADUs in coastal zones. SB 1077 aims to create a more transparent and consistent process while protecting coastal resources.
Key Improvements:
- Standardized Process: Clear, uniform guidelines will be established, ensuring consistent standards for ADU approvals across different coastal regions.
- Focus on Urban Development: The law prioritizes ADU construction within existing developed coastal areas, particularly supporting interior conversions.
- Environmental Safeguards: While simplifying the process, SB 1077 maintains existing protections for coastal access and sensitive zones.
If you’ve been hesitant to pursue an ADU in a coastal zone due to the perceived complexities, SB 1077 empowers you to:
- Navigate the approval process with ease: Clear guidelines mean fewer surprises and a more straightforward path to approval.
- Reduce waiting times: The streamlined process translates to faster turnaround times, so you can start enjoying your ADU sooner.
- Expect predictable outcomes: Standardized regulations minimize uncertainty, giving you greater peace of mind.
- Build responsibly: Environmental protections remain in place, ensuring your ADU project aligns with sustainable practices.
If you’re considering an ADU in a coastal zone, SB 1077 offers a more streamlined path forward. Let’s discuss your project and explore how these changes can benefit you.
Additional Key Legislation in California 2025
While the major ADU laws like AB 2333, SB 1211, and SB 937 have garnered significant attention, several other pieces of legislation are poised to make a substantial impact on California’s housing landscape in 2025. These laws address specific aspects of ADU development, further streamlining processes, expanding opportunities, and ensuring compliance:
AB 3057: Making JADU Development Easier
Junior Accessory Dwelling Units (JADUs) offer an affordable way to create additional housing within your existing home. As an architect who frequently works with families in Los Angeles, I’ve seen how JADUs can provide perfect solutions for multigenerational living or rental income opportunities.
Key Changes Under AB 3057
- CEQA Exemption
- Removes environmental review requirements for JADU ordinances
- Eliminates potential legal challenges based on environmental concerns
- Streamlines the city’s process for adopting JADU regulations
What Makes JADUs Different
- Created within existing home’s living space (usually up to 500 sq ft)
- Can share bathroom with main home
- Must have efficiency kitchen
- Requires separate entrance from main home
How AB 3057 Might Help You
This year, I worked with a family in Eagle Rock who wanted to convert their rarely-used home office into a JADU for their daughter returning from college but permitting has been tricky and time-consuming. Next year under AB 3057, you won’t face the previous environmental review hurdles that could have delayed the project or added unnecessary costs for your JADU>
Historic Properties and ADUs: AB 2580
As someone who frequently works with historic properties in Los Angeles, I’m particularly excited about AB 2580. This law creates clearer guidelines for ADUs in historic zones while maintaining neighborhood character. It requires cities to:
- Provide objective standards for historic preservation
- Track historic designations affecting ADUs
- Report denials of ADU permits in historic zones
Enforcement with Teeth: SB 1037
This law introduces significant fines ($10,000-$50,000 per unit per month) for cities that obstruct housing development, including ADU projects. The best part? These fines go directly into local affordable housing funds.
SB 477: ADU Code Organization
- This law reorganizes and clarifies existing ADU laws, consolidating them into a more user-friendly and accessible format.
- Impact: Simplifies the process of understanding and navigating ADU regulations for homeowners, developers, and local agencies.
SB 1123: Starter Home Development
- This law clarifies that ADUs do not count toward the 10-unit density limit in starter home developments.
- Impact: Encourages the inclusion of ADUs in new housing projects, increasing housing density and affordability in these developments.
AB 2553: Transit-Oriented Development
- This law expands the definition of a “major transit stop” to include areas with 20-minute transit headways (instead of the previous 15-minute requirement).
- Impact: Allows more properties near transit to qualify for relaxed ADU size and parking standards, promoting housing options in transit-rich areas.
AB 2580: Historic Property Rules
- This law establishes clearer guidelines for ADU development in historic districts, balancing preservation concerns with the need for additional housing.
- Impact: Provides more clarity and predictability for ADU projects in historic zones, while ensuring that local agencies track and report ADU permit denials.
AB 2023: Enhanced Enforcement
- This law strengthens the enforcement powers of the California Department of Housing and Community Development (HCD).
- Impact: Ensures that local agencies consistently apply and enforce state ADU laws, preventing unnecessary barriers to ADU development.
AB 1893: Builder’s Remedy
- This law allows developers to bypass certain local zoning restrictions if a city or county is not meeting its housing element requirements.
- Impact: Provides a powerful tool to incentivize housing production, including ADUs, and hold local governments accountable for meeting housing needs.
SB 450: SB 9 Integration
- This law addresses inconsistencies between existing laws, particularly in relation to SB 9 (which allows lot splits and duplexes).
- Impact: Facilitates increased housing density in single-family zones while ensuring compatibility with ADU development.
SB 1037: Enforcement Mechanisms
- This law introduces significant fines ($10,000-$50,000 per unit per month) for cities that obstruct housing development, including ADU projects. These fines are directed into local affordable housing funds.
- Impact: Provides a strong financial incentive for local governments to follow state housing laws and approve ADU projects in a timely manner.
Looking Ahead: California ADU Development in 2025
These new California ADU laws represent unprecedented opportunities for homeowners and developers. Whether you’re legalizing an existing unit or adding a new ADU to your property, 2025 brings exciting possibilities under these reformed regulations.
Let’s chat about your ADU project over coffee! If you’re in the Los Angeles area, I’d love to meet and discuss how these new California ADU laws could benefit your specific situation. Not local? We offer virtual consultations to review your plans and possibilities. Schedule your complementary architect consultation today.
