ADU Laws in California 2025

18 February 2025 Author: Kamal Hyder ( )

California has introduced a series of legislative changes in 2025 that significantly impact Accessory Dwelling Units (ADUs) and Junior Accessory Dwelling Units (JADUs). Over a dozen new housing laws have been enacted, reflecting the state’s ongoing commitment to expanding housing opportunities and streamlining development processes. While some of these laws are specifically focused on ADUs, others are broader housing policies that increasingly intersect with ADU regulations.

This article provides an in-depth analysis of key legislative updates affecting ADU development, including strengthened builder protections, expanded eligibility for two-story ADUs, modifications to transit-oriented development definitions, and revised permit expiration timelines. The legislation also includes provisions related to historic designations, impact fees, and increased enforcement measures against local jurisdictions that fail to comply with state housing mandates.

Each of the new laws plays a crucial role in shaping the regulatory landscape for ADUs. The following sections will explore these legislative updates in detail, outlining their implications for homeowners, developers, and local authorities.

In this article, we will examine the concepts of several SBs (Senate Bills) and ABs (Assembly Bills), which refer to legislative proposals introduced in the Senate and Assembly, respectively. We will explore their key differences, the process they undergo in legislative bodies, and their impact on ADU-related laws. SBs and ABs are designations for bills introduced in different chambers of the legislature. SB is used for bills submitted to the Senate, while AB refers to those introduced in the Assembly (the lower chamber). Both types of bills go through discussions, voting, and become laws after approval by both chambers and the governor's signature.

1. AB 1332 - Streamlining ADU Development with Preapproved Plans

Assembly Bill No.1332 introduces critical reforms to California’s Accessory Dwelling Unit (ADU) approval process, ensuring greater efficiency, consistency, and accessibility. Initially enacted as part of Chapter 759, Statutes of 2023, the bill added Section 65852.27 to the Government Code to expedite the permitting process for ADUs, with its provisions coming into effect on January 1, 2024. However, the legislation imposes additional obligations on local agencies starting January 1, 2025, aimed at accelerating ADU approvals and reducing bureaucratic barriers.

Under AB 1332, all local agencies must establish a preapproval program for ADU plans, requiring them to:

Accept and evaluate pre-approval submissions for ADU plans from any applicant, including homeowners, architects, and developers, following standards outlined in Government Code sections 66314-66342.
Publish pre-approved ADU plans online, along with the contact information of applicants, thereby increasing transparency and promoting the use of standardized designs.
Recognize and post plans pre-approved by other local or state agencies, facilitating a more streamlined and uniform regulatory environment across California.
Charge fees for pre-approval applications, allowing local jurisdictions to offset administrative costs while maintaining efficiency.
Approve or deny applications for detached ADUs within 30 days, provided they rely on pre-approved plans from the current triennial California Building Standards Code rulemaking cycle or an identical plan from a previously approved ADU application.

The primary objective of AB 1332 is to standardize and expedite the ADU approval process, ensuring that homeowners and developers face fewer regulatory hurdles when constructing ADUs. In our previous article, we already discussed about benefits of pre-approved ADU plans and how pre-approved ADU plans can help you save time and money on your accessory dwelling unit project in California. By mandating a statewide framework for pre-approved plans, the bill minimizes inconsistencies in local permitting processes and promotes housing affordability through reduced delays and costs.

A notable aspect of the bill is its recognition of ADU development as a matter of statewide concern, meaning that its provisions apply uniformly to all cities, including charter cities. This approach reflects California’s commitment to solving the housing crisis by encouraging innovative and efficient solutions such as ADUs, which provide affordable, flexible housing options for homeowners, renters, and multigenerational families.

While AB 1332 is designed to simplify ADU approvals, its success depends on effective implementation by local agencies. Some jurisdictions may struggle with limited resources or resistance to adopting a standardized approach, potentially leading to delays in preapproval program rollouts. Additionally, the imposition of pre-approval fees could discourage smaller-scale homeowners from pursuing ADU projects if costs become prohibitive.

However, the bill’s provision allowing cross-jurisdictional recognition of pre-approved plans represents a major step forward in making ADU construction more predictable and accessible. By reducing redundancy in approval processes, this measure ensures that successful ADU designs can be reused efficiently, ultimately accelerating housing production statewide.

2. AB 1893 - Builders Remedy Enforcement Act

Assembly Bill 1893 revises key provisions of the Housing Accountability Act by expanding and clarifying the so-called “builder’s remedy,” which limits a local government’s ability to deny or delay housing projects if its housing element is not state-certified. Specifically, the bill broadens the definition of “housing development project” to include additional types of mixed-use developments and explicitly incorporates farmworker housing. It also updates the criteria for “disapproving” a project to encompass not only outright denials but also administrative maneuvers that improperly prevent housing applications from progressing.

By codifying new definitions and ensuring that qualifying projects meet only objective standards for density, zoning, subdivision, and design review, AB 1893 increases local accountability and streamlines approvals. Although ADUs are typically subject to ministerial permits, homeowners in jurisdictions lacking a compliant housing element may find the builder’s remedy useful if they encounter undue hurdles. Entities such as YIMBY Law maintain records of cities that are noncompliant, providing clarity on where builder’s remedy protections may apply.

3. AB 2533 - ADU Amnesty Expansion

Assembly Bill 2533 expands protections for homeowners with unpermitted Accessory Dwelling Units (ADUs) or Junior Accessory Dwelling Units (JADUs) constructed prior to January 1, 2020. Under this legislation, local agencies are prohibited from denying a permit solely based on building standard violations unless those violations render the structure “substandard” under health and safety criteria. This approach departs from the previous requirement that older units adhere to current building code standards, potentially saving homeowners considerable expense and effort when the unit is otherwise safe.

In practical terms, this means if a homeowner has a converted garage that includes a kitchenette and bathroom but does not meet contemporary building code specifications, the focus will be on ensuring the space meets fundamental health and safety requirements. The bill directs cities and counties to provide a clear checklist detailing the conditions that classify a building as substandard, while also informing property owners that they may hire licensed third-party inspectors on a confidential basis. These measures offer homeowners the opportunity to understand what upgrades or corrections are truly necessary to bring a unit into compliance, rather than being subjected to costly retrofits unrelated to occupant well-being (e.g., reinforcing a roof simply to accommodate future solar panel installations).

Additionally, AB 2533 limits the imposition of impact fees, connection fees, or capacity charges where no new infrastructure is required, further easing the financial burden on property owners. Local agency inspectors must focus on health and safety compliance rather than penalizing homeowners for possessing unpermitted units. If any noncompliance issues are identified, the legislation compels local jurisdictions to approve the permits needed to rectify those issues.

Observers note that amnesty provisions under AB 2533 are particularly beneficial for homeowners who have long wrestled with legalizing units built under outdated codes. By pivoting to health and safety as the key standard, the law makes it possible to legitimize existing living spaces—such as converted garages or similarly repurposed areas—without requiring a full, expensive overhaul. This more nuanced approach to code compliance empowers property owners to expand housing options safely, aligning with California’s goal of increasing housing supply while avoiding burdensome regulatory processes.

4. AB 2553 - Transit ADU Height Expansion

Assembly Bill 2553, introduced by Assemblymember Friedman, modifies the definition of a “major transit stop” under the California Environmental Quality Act (CEQA) and revises certain vehicular traffic-impact-fee requirements. Previously, a major transit stop required bus service intervals of 15 minutes, but AB 2553 extends the acceptable headway to 20 minutes. This change broadens the number of bus routes and stops meeting the definition of “major transit stop,” even in light of post-pandemic service reductions.

From a practical standpoint, this expanded definition enhances eligibility for CEQA exemptions on infill and transit priority area projects—an outcome with significant implications for multifamily and affordable housing, as the bill can also reduce specific traffic-related impact fees. Notably, it has a direct impact on Accessory Dwelling Units (ADUs): single-family homes located within the newly broadened transit zones may now qualify for an 18-foot height limit (rather than the traditional 16 feet), simplifying the construction of two-story ADUs. By lowering fees and recognizing additional transit corridors, AB 2553 aligns with California’s broader objective of encouraging compact development, supporting both homeowners and developers eager to expand housing options near transit.

5. AB 2580 - Historic Designation & ADU Compliance

Assembly Bill 2580, introduced by Assemblymember Wicks, expands the annual progress report (APR) requirements under California’s Planning and Zoning Law to include detailed information about new historic designations and their impact on housing projects. Currently, local governments must submit APRs to the Office of Planning and Research (OPR), the Department of Housing and Community Development (HCD), and the local legislative body to demonstrate progress on their general plans, including housing elements.

Under AB 2580, these existing reports must now also:

List all sites newly designated within the past year on the National Register of Historic Places, the California Register of Historical Resources, or a local register of historic places.
Disclose the status of housing development projects proposed for these newly designated sites, including any permit denials specifically related to historic designation.
Provide a more detailed breakdown of reasons for permit denials, bringing greater transparency to the decision-making process.

While historic designation can help preserve cultural and architectural heritage, property owners looking to build Accessory Dwelling Units (ADUs) in such areas often face additional hurdles. Under state law, design guidelines in historic districts must be objective and follow certain criteria, but they still tend to add costs, delays, and frustration for many homeowners. Some have abandoned ADU projects altogether once they realized the complexities of meeting historic preservation requirements—such as specialized materials, mandated architectural reviews, or stringent design standards—that go beyond standard ADU regulations.

The main challenge has been a lack of a single streamlined system for identifying and tracking historic designations across different registries (federal, state, and local). By requiring local governments to include historic designations in their APRs, AB 2580 aims to:

Provide clarity for property owners and developers who need to verify whether a parcel falls within a protected area.
Ensure accountability when a permit is denied based on historic status, enabling stakeholders to see precisely where and why applications face pushback.
Offer a path toward policy improvement by spotlighting patterns of denials or delays, potentially prompting local jurisdictions to refine or simplify their historic review processes for ADUs.

Though this bill does not eliminate historic designation requirements, it encourages transparency in how those requirements are applied, potentially reducing unexpected surprises for homeowners. By capturing and reporting data on where and why ADU permits fail in historic zones, AB 2580 may spur local governments to adopt clearer, more objective standards. Over time, these improvements could lead to a more predictable permitting process—avoiding unnecessary project delays and budget overruns—and help California maintain a delicate balance between expanding housing options and honoring its rich historic heritage.

6. AB 2729 - Permit Expiration Extension Act

Assembly Bill 2729, introduced by Assemblymember Joe Patterson, provides an 18-month extension for the expiration, effectuation, or utilization of housing entitlements issued before January 1, 2024, that would otherwise expire before December 31, 2025. By granting this automatic extension, the law aims to ensure that developers and property owners have additional time to initiate construction or meet other project milestones. If a housing entitlement is involved in litigation, the 18-month period is tolled, preventing the entitlement clock from running out while court proceedings are pending. This measure builds on similar legislative efforts made during the COVID-19 pandemic but applies to a new timeframe, thereby reinforcing California’s commitment to avoiding stalled or canceled housing developments.

While the law is especially relevant for larger housing projects, it can also benefit homeowners who received ADU permits prior to January 1, 2024, and were facing looming expiration deadlines. In such cases, AB 2729 offers extra leeway to begin construction or finalize permit conditions before the approval lapses. Although not a major ADU-focused bill, the extended validity period can still provide much-needed flexibility for property owners who encounter unexpected scheduling or financial hurdles.

By clarifying and standardizing permit extension procedures, AB 2729 also adds to local administrative responsibilities, constituting a state-mandated local program. However, the legislation specifies that no state reimbursement is required, reflecting its broader aim to tackle housing supply challenges on a statewide basis rather than defer them to local jurisdictions. Overall, AB 2729 contributes to the state’s ongoing efforts to streamline the building process, reduce uncertainty for developers and homeowners alike, and maintain momentum in California’s housing market.

7. AB 3057 - JADU CEQA Exemption Act

Assembly Bill 3057 is a succinct yet impactful measure that extends California Environmental Quality Act (CEQA) exemptions to ordinances specifically regulating Junior Accessory Dwelling Units (JADUs). Under existing CEQA provisions, cities and counties adopting ordinances for Accessory Dwelling Units (ADUs) are exempt from extensive environmental review. However, a technical oversight in the statute allowed for the possibility of environmental complaints against local jurisdictions adopting JADU-focused ordinances, despite JADUs typically being treated similarly to ADUs in most regulatory contexts.

Closing a Legislative Loophole

Before AB 3057, the code’s wording inadvertently left a gap: while ADU ordinances were explicitly CEQA exempt, JADU ordinances did not receive the same unambiguous protection. In theory, a party could have filed a CEQA challenge whenever a city or county attempted to adopt or revise an ordinance allowing JADUs—an outcome legislators considered inconsistent with broader state housing goals. By explicitly confirming JADU ordinances as CEQA exempt, AB 3057 removes this potential legal snag, ensuring local governments can move forward without the threat of time-consuming environmental review or litigation.

Practical Implications

For homeowners and policymakers alike, the bill’s brevity belies its importance:

Streamlined Adoption of JADU Ordinances: Cities and counties can now adopt or update JADU ordinances without fear of CEQA-related delays, thus speeding up the path to legalizing or newly creating JADUs.
Reducing Administrative Hurdles: Because JADUs are typically small-scale conversions (like an extra unit carved out of an existing single-family residence), the potential for significant environmental impact is minimal—aligning logically with the bill’s exemption status.
Consistency with ADUs: By placing JADU ordinances on par with ADU ordinances in terms of CEQA treatment, AB 3057 removes confusion and helps ensure uniform application of state housing policies across different dwelling unit types.

Although the bill itself comprises only a few lines, its core takeaway is clear: the state intends to treat JADU ordinances much like ADU ordinances by exempting them from CEQA review. This amendment reflects California’s ongoing commitment to fostering incremental infill housing solutions—such as JADUs—without subjecting local authorities or homeowners to unnecessary procedural hurdles.

8. SB 937 - ADU Impact Fee Reform

Senate Bill 937, introduced by Senator Scott Wiener, refines the collection and timing of impact fees under the Mitigation Fee Act. These changes respond to a common challenge in housing development: some localities require substantial upfront fees—often in the millions—for large projects, forcing developers to borrow large sums at the outset and accrue interest over multi-year construction timelines. This practice can inflate overall project costs, hinder new housing starts, and delay the creation of much-needed units.

Key Provisions and Rationale

- Delayed Impact Fee Collection:

Under SB 937, local governments are prohibited from charging impact fees until the certificate of occupancy is issued or—if no certificate is required—the final inspection is completed.
This shift alleviates the burden of hefty upfront fees, allowing developers to defer payment until the project is ready for occupancy.

- Financial Relief for Developers:

By removing the requirement to pay impact fees at the start of construction, the bill reduces the interest costs that developers—or homeowners—might otherwise face when taking out loans to cover these fees early in the project cycle.
Lower overall carrying costs can, in turn, encourage more housing production, particularly in regions struggling to meet demand.

- Performance Guarantees Remain an Option:

SB 937 continues to allow local authorities to protect themselves against nonpayment. Developers can post a performance bond or provide a letter of credit to ensure the fees will be paid upon completion.

Benefits for ADUs—Especially Larger Units

While SB 937 primarily targets large housing developments, it also extends benefits to certain Accessory Dwelling Units (ADUs). ADUs over 750 square feet frequently incur impact fees; under this bill, those fees no longer need to be paid upfront. Instead:

Delayed Payment: Homeowners can pay fees at the final inspection, allowing them to manage their finances more flexibly and avoid withdrawing or borrowing funds prematurely.
Reduced Financing Costs: Homeowners using a HELOC or other loan products can delay the loan draw, reducing interest expenses over the project’s timeline.

This alignment with California’s broader housing agenda creates a more predictable and affordable pathway for expanding housing stock, be it through larger ADUs in single-family zones or significant new multifamily developments. Overall, SB 937 represents a major stride in making housing construction more cost-effective and streamlined, marking a win for both developers and homeowners looking to add units to the state’s tight housing market.

9. SB 450 - SB 9 Implementation Refinement

Senate Bill 450, introduced by Senator Toni Atkins, refines and reinforces the provisions of SB 9—the state law that grants homeowners the right to split their single-family residential lots and develop additional housing units. While SB 9 was envisioned to accelerate housing creation, certain local governments have sought to slow or block projects through stringent zoning and approval processes. SB 450 aims to close these loopholes, ensuring that SB 9 functions consistently across California.

SB 450 responds directly to tactics some municipalities have used to circumvent or delay SB 9 implementation—such as imposing restrictive design standards or slow-moving permit procedures. By strengthening deadlines and limiting the conditions under which local agencies can deny or complicate SB 9 applications, the law streamlines lot splits and the development of additional housing units. This underscores California’s broader commitment to rapidly expanding its housing supply—including opportunities for homeowners to create smaller, attainable homes on single-family lots, ultimately contributing to the state’s long-term affordability and housing security goals.

10. SB 477 - ADU Code Reorganization

Senate Bill 477 implements nonsubstantive reorganizations of the statutes governing Accessory Dwelling Units (ADUs) and Junior Accessory Dwelling Units (JADUs). Existing law already allows for the creation of ADUs and JADUs under either local ordinances or ministerial approvals when no local ordinance is in place. Although SB 477 does not alter core policy requirements—such as unit size, setbacks, or parking standards—it re-chapters and consolidates these provisions to make them easier to locate and reference within the California Government Code.

Overall, SB 477 underscores California’s ongoing commitment to simplifying regulations for accessory dwelling units. While it does not introduce new rules, its re-chaptering provisions help to keep ADU and JADU statutes clear, organized, and readily usable, preventing unnecessary confusion or administrative delay as the state continues to promote small-scale housing solutions.

11. SB 1037 - Housing Law Enforcement Act

Senate Bill 1037 grants the California Attorney General (AG) and the Department of Housing and Community Development (HCD) the authority to impose substantial fines on cities and counties that violate state housing laws, including those related to Accessory Dwelling Units (ADUs). While the law primarily addresses larger compliance issues such as housing element updates and ministerial approvals for housing projects, it carries significant implications for ADU permit approvals, where local agencies sometimes fail to meet state-mandated timelines.

Key Provisions

- Steep Monthly Fines

Local jurisdictions found in violation of state housing requirements may face civil penalties ranging from $10,000 to $50,000 per month per violation.
Penalties escalate if a court finds the jurisdiction’s noncompliance is arbitrary, capricious, without evidentiary support, or procedurally unfair.

- Enforcement by Attorney General or HCD

Attorney General’s Role: The AG, often prompted by HCD, can initiate legal action against noncompliant cities or counties.
Court-Ordered Compliance: If a jurisdiction persists in blocking or delaying housing projects, the court can increase financial penalties and force expedited adherence to state mandates.

- Local Benefit of Fines

Penalty revenues are deposited into the Building Homes and Jobs Trust Fund, earmarked exclusively for affordable housing development within the offending jurisdiction.
If a local agency refuses to pay, the court may order the California State Controller to intercept local funds and direct them to the trust fund for affordable housing.

- Applies Statewide

The legislation specifies that these enforcement powers address a matter of statewide concern, preventing charter cities or counties from opting out or watering down state housing laws.

Impact on ADUs

Under existing law, cities must ministerially approve ADU permits—often within 60 days—provided all objective standards are met. However, certain jurisdictions have imposed unlawful roadblocks or prolonged processing times, effectively discouraging or denying ADU construction:

Financial Deterrent to Noncompliance: With SB 1037, local agencies that ignore statutory deadlines or impose unwarranted restrictions on ADUs could incur fines of up to $50,000 per unit per month.
Reinvestment in Local Affordable Housing: The penalty payments go into an affordable housing fund for use within the same jurisdiction—incentivizing compliance rather than simply penalizing the locality.

By creating a powerful financial incentive to follow state housing requirements, SB 1037 aims to curb jurisdictions that historically slow down or reject ADU applications. Homeowners seeking to build an ADU—and facing unjustified permitting delays—stand to benefit from heightened state oversight.

Why This Matters

Discourages Local Obstruction: Some municipalities have attempted to circumvent state law by setting up restrictive ADU policies or extended review processes. SB 1037 closes these loopholes with significant fines.
Speeds Up ADU Permits: The potential for monthly penalties provides a clear motivation for local staff to process ADU applications in a timely manner.
Promotes Housing Production: With fewer administrative hurdles, more ADUs can be added to the state’s housing stock, supporting California’s broader effort to mitigate housing shortages.

What Homeowners Should Watch For

60-Day Deadline: If your ADU application stalls beyond 60 days without a clear explanation, SB 1037 may serve as added leverage—the state could intervene if there’s a pattern of local noncompliance.
Uncertain Direct Enforcement: While individual homeowners cannot directly impose penalties, they can report systemic violations to HCD, which may prompt AG enforcement.
Local Government Adaptations: Expect cities to update policies to avoid fines, potentially streamlining ADU permitting and reducing delays.

Overall, SB 1037 places real financial consequences on jurisdictions that undermine state housing goals. By intensifying enforcement and funneling penalty funds into local affordable housing, the legislation provides a powerful tool to ensure consistent application of California’s pro-housing laws—especially as they pertain to ADUs.

12. SB 1077 - Coastal ADU Permit Reform

Senate Bill 1077, authored by Senator Blakespear, aims to clarify and simplify the permitting process for Accessory Dwelling Units (ADUs) and Junior Accessory Dwelling Units (JADUs) in California’s coastal zone. While the final version of the bill was somewhat narrowed during the legislative process, proponents emphasize that it still represents a major step forward for homeowners seeking to create smaller-scale housing units in areas governed by the California Coastal Commission (CCC).

Under existing law, each region along the coast has a Local Coastal Program (LCP), approved by the CCC, that sets localized rules to protect coastal resources and public access. These LCPs vary greatly: some are straightforward about ADU approvals, while others apply complex or opaque regulations that inhibit even interior conversions or small infill additions. Critics have noted that, in practice, this can discourage homeowners from constructing ADUs, despite there being little or no environmental impact when modifying an existing residence.

Key Provisions of SB 1077

- Coastal Commission & HCD Coordination

By July 1, 2026, the CCC, working with the Department of Housing and Community Development (HCD), must develop guidance for local governments on integrating ADU-friendly policies into their LCPs.
This joint effort ensures environmental priorities remain intact while streamlining approvals for ADUs and JADUs.

- Public Input & Transparency

The CCC will hold at least one public workshop to solicit feedback on its draft guidance. Homeowners, environmental advocates, and other stakeholders can weigh in on how best to balance housing creation with coastal protection.
The final guidance document will be publicly posted, helping ensure local agencies, homeowners, and the broader public have a clear reference for ADU regulations in the coastal zone.

- Local Coastal Program Amendments

Once the guidance is finalized, LCPs will be expected to update their rules accordingly.
If an LCP adopts the recommended approach, homeowners may experience a more predictable, faster path to ADU approval—particularly for modest projects like garage conversions or interior remodels that do not affect coastal access or sensitive habitats.

Some advocates highlight that coastal zone boundaries include a broad range of urban and suburban neighborhoods, not just the beachfront. Areas like Venice Beach (Los Angeles) or Solana Beach are already densely populated, often featuring large parking lots and existing structures. Converting a spare bedroom or garage into an ADU in such locales is unlikely to diminish public beach access or degrade the environment, yet has historically triggered extra regulatory hurdles.

By mandating a standardized approach to ADUs in the coastal zone, SB 1077 can alleviate confusion and encourage sensible infill where infrastructure already exists. Proponents underscore that these reforms will help local homeowners add living space without facing an overly complex coastal development permit process. Still, observers note the bill’s initial goals were somewhat watered down during negotiations, underscoring the balancing act between protecting coastal resources and addressing the state’s housing crisis.

Although the legislation itself is concise, the context is extensive:

Public Workshops: Stakeholders will have an opportunity to advocate for clear, objective criteria that seamlessly distinguish between minor conversions and more impactful new construction.
Local Enforcement: LCPs have historically diverged widely. SB 1077’s mandate for statewide guidance aims to standardize approvals and provide long-term clarity for both local agencies and homeowners.

Overall, SB 1077 represents a commonsense step toward ensuring that coastal communities can expand housing supply via ADUs and JADUs, while still upholding the California Coastal Commission’s overarching goal—preserving the coastline for public enjoyment and ecological sustainability.

13. SB 1123 - ADU Density Incentive

Senate Bill 1123, introduced by Senator Caballero, builds upon the foundation established by a previous law—SB 684—aimed at creating more “starter homes” by streamlining small developments of 10 or fewer units under specific conditions. SB 1123 clarifies that ADUs and JADUs do not count toward the 10-unit threshold, effectively granting developers an “ADU bonus.” This change is especially significant for small-scale residential projects, as it allows them to include accessory units without losing eligibility for the ministerial approval process designed for developments under 10 units. As a result, homeowners and developers can now integrate ADUs more easily into new “starter home” communities, potentially increasing the overall housing supply in California.

In addition to excluding accessory units from the 10-unit count, SB 1123 refines various zoning and density provisions. For instance, the bill broadens eligibility to lots zoned for both multifamily and single-family uses—provided those single-family lots are vacant and no larger than 1.5 acres—and permits newly created parcels of at least 1,200 square feet in single-family zones. It also lowers the required density for projects built on parcels not listed in a jurisdiction’s housing element to at least 66% of the maximum allowable density (down from 100%), further encouraging moderate-scale development.

Meanwhile, SB 1123 expands acceptable ownership structures—adding tenancy in common arrangements to the existing options of fee simple or community trust ownership—and clarifies that these properties need not meet certain frontage requirements. By streamlining these rules and setting a clear date of July 1, 2025, for implementation, the legislation underscores that these changes address a matter of statewide concern and apply uniformly across all jurisdictions, including charter cities.

Though the bill makes several technical adjustments, the primary takeaway for ADUs remains its policy of exempting them from the 10-unit cap. By removing this constraint, SB 1123 paves the way for small, starter home developments to incorporate ADUs more readily. Observers anticipate that this clarification will lead to a visible uptick in ADU construction—either as standalone units or as conversions of existing spaces—in smaller housing projects, thereby advancing California’s overarching goal of increasing accessible and diverse housing options.

14. SB 1211 - Multifamily ADU Expansion

Senate Bill 1211 significantly expands how many Accessory Dwelling Units (ADUs) can be added to existing multifamily dwellings, establishing that property owners can build one detached ADU per existing residential unit, up to a cap of eight. Previously, owners of multifamily properties could only build two detached ADUs regardless of how many existing units they had. Starting in January 2025, a duplex can have two detached ADUs, a triplex can have three, and so on, until hitting the eight-ADU limit. By contrast, newly proposed (i.e., not yet existing) multifamily developments remain restricted to a maximum of two detached ADUs.

This law also clarifies that property owners may continue to convert interior space (such as storage rooms or other non-livable areas) to ADUs in addition to constructing detached units. SB 1211 defines “livable space” to include any interior area meant for living, sleeping, eating, cooking, or sanitation. For an eight-unit property, for instance, it may be possible (on paper) to build eight detached ADUs and also convert certain interior spaces into two additional ADUs—potentially yielding ten total ADUs. However, most multifamily sites will remain constrained by setback, design, and lot size limitations, so the actual number of feasible units will typically be lower.

Beyond the multifamily provisions, SB 1211 also applies a parking flexibility update: local agencies cannot require replacement parking if an uncovered parking space is demolished or converted to create an ADU. Previously, replacement-parking exemptions were limited to garages or carports. Additionally, the bill reaffirms that local governments cannot impose any unauthorized or excessive objective development standards on ADUs that meet state criteria.

Overall, SB 1211 pushes the concept of ADUs beyond traditional single-family backyards and into the realm of multifamily expansion. While these new allowances may only apply to a select number of properties able to accommodate multiple detached structures, they signal a broadening shift in California’s housing policies—particularly in urban areas where intensifying existing lots can produce much-needed homes. This evolution parallels certain local programs, such as those seen in San Diego, where additional ADUs can be built by providing affordable units or meeting other criteria. The result is that ADUs, once viewed primarily as “granny flats,” are poised to become a major force in reshaping multifamily housing developments and potentially increasing density in appropriate locations without lengthy discretionary approvals.

15. Conclusion

The information provided here is intended solely for general informational purposes and does not substitute the counsel of a qualified attorney for any specific construction or legal matter. It is strongly recommended to seek professional legal advice tailored to individual circumstances.

Links to the original laws and related notes are included for those who wish to review the statutory language firsthand. By consulting reliable sources and engaging experts, property owners can help ensure they remain compliant with evolving ADU regulations and make informed decisions about their housing projects.

We are happy to share our experience and opinions, and we are always glad to discuss your ADU project with you. For a free consultation, please sign up for a complimentary appointment.

California ADU Laws 2025: Key Legislative Updates and Changes

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