San Diego has taken another significant step toward addressing California’s housing shortage. The City Council recently approved a comprehensive package of 25 reforms to its Accessory Dwelling Unit (ADU) and Junior Accessory Dwelling Unit (JADU) regulations.
The updates are designed to align local ordinances with state law, while refining the City’s ADU Home Density Bonus Program to reflect community concerns around infrastructure, fire safety, and parking. The reforms are the result of months of public hearings and City Council discussions, culminating in a balanced approach to housing expansion that prioritizes both safety and affordability.
“These reforms are the result of thoughtful input from community members and the City Council to evaluate the ADU program and make meaningful changes,” said City Planning Director Heidi Vonblum. “Our goal is to ensure public safety and allow for development at scale with the surrounding neighborhood while continuing to create affordable homes for San Diegans of all incomes, particularly in the City’s high-resource areas.”
Understanding ADUs and JADUs
Accessory Dwelling Units, often referred to as “granny flats” or “in-law suites”, are independent housing units located on the same lot as a primary residence. Junior Accessory Dwelling Units are smaller, self-contained living spaces (no more than 500 square feet) created within an existing single-family home. Both ADUs and JADUs have become vital tools in California’s efforts to increase housing supply, particularly in urban areas where vacant land is scarce.
Under California law, cities must allow ADUs in most residential zones. The state’s overarching framework, outlined in Government Code §§ 65852.2 and 65852.22, was designed to streamline ADU permitting, reduce barriers to construction, and encourage affordability through smaller-scale housing options. San Diego’s latest reforms build upon these state laws, adding local measures to ensure that ADU development complements neighborhood safety, accessibility, and character.
Overview of the 2025 Reform Package
The City Council’s new ADU package reflects two overarching priorities: implementing mandatory state law updates and strengthening San Diego’s ADU Home Density Bonus Program. The latter program, initially introduced to encourage the creation of affordable housing units, allows property owners to build additional ADUs beyond standard zoning limits in exchange for providing affordable units.
The reforms also address key community concerns raised during public hearings held by the Planning Commission on May 1 and the Land Use and Housing Committee on May 15. The result is a balanced set of regulations that aim to expand affordable housing options while maintaining safety, infrastructure stability, and compatibility with surrounding neighborhoods. These changes will take effect 30 days after final passage for areas outside the Coastal Zone, while implementation within the Coastal Zone awaits certification from the California Coastal Commission, expected in 2026.
Key State-Law-Driven Changes to ADU and JADU Regulations
There are three primary areas where changes will be made to San Diego’s ADU and JADU regulations:
1. Fire Safety Setbacks
One of the most significant updates to San Diego’s ADU regulations focuses on fire safety. The City now requires a minimum four-foot side and rear setback for Accessory Dwelling Units built in areas designated as High or Very High Fire Hazard Severity Zones. This setback is designed to create “defensible space”—a critical buffer that helps protect homes from the rapid spread of wildfire and provides firefighters with safe access during emergencies.
The regulation also empowers the City’s Fire Code Official to require greater setbacks when necessary to ensure compliance with the California Fire Code. This case-by-case discretion acknowledges that certain topographical features or vegetation conditions may demand more substantial spacing to achieve true fire safety compliance.
By aligning local building requirements with statewide fire safety standards, San Diego is ensuring that ADU expansion does not come at the expense of public safety. For homeowners and developers, this means that early site assessments and consultation with fire officials are now an essential step in the permitting process. The rule underscores the City’s commitment to balancing density with responsible risk mitigation, particularly in hillside neighborhoods and communities bordering wildland areas.
2. Number of Units Allowed on Single-Family Lots
San Diego has clarified one of the most common points of confusion in ADU development: how many units are allowed on a single-family lot. Under the updated rules, a property owner may now build up to three distinct secondary units on a lot with an existing or proposed single-family home: one Junior Accessory Dwelling Unit (JADU) within the main structure, one converted ADU (such as a garage or basement conversion), and one detached ADU.
This clarification aligns San Diego’s local ordinance with state housing law and provides homeowners with a clear framework for increasing housing capacity without triggering the complexities of multifamily zoning. The change also promotes “gentle density,” encouraging incremental growth that adds affordable housing options while preserving the character and livability of established neighborhoods.
By clearly defining the number and type of allowable units, the City reduces permitting uncertainty for homeowners and small-scale developers. The result is a more predictable process that supports California’s broader housing goals while maintaining community trust in local planning standards.
3. Separate Sale or Conveyance of ADUs
Perhaps the most groundbreaking reform in this package is the implementation of Assembly Bill 1033, which authorizes the subdivision of ADUs into separate condominium units that may be sold independently from the primary residence. This reform introduces a new layer of housing flexibility, transforming ADUs from purely rental opportunities into pathways for homeownership.
For example, a homeowner could legally subdivide their property and sell the ADU as an affordable condominium to a first-time buyer or family member. This could help moderate-income households enter the housing market while allowing property owners to build equity or reinvest in their properties.
However, this opportunity comes with important legal considerations. Subdividing an ADU into a condo unit typically requires compliance with the Subdivision Map Act, creation of a homeowners association (HOA), and execution of shared maintenance and utility agreements. Financing may also become more complex, as lenders will need to evaluate the property’s new legal structure and HOA governance documents.
For these reasons, property owners should consult a real estate attorney before pursuing an ADU subdivision. Legal guidance is essential to ensure compliance with state subdivision laws, draft equitable maintenance agreements, and navigate the title, tax, and financing implications of selling a newly created condo unit.
Major Changes to the ADU Home Density Bonus Program
In addition, there are a few key changes to the ADU Home Density Bonus Program that may impact real estate in the area:
Applicability Limits in Low-Density Zones
The City has redefined where the ADU Home Density Bonus Program can be applied. Under the new regulations, the program is now prohibited in San Diego’s lowest-density residential zones, including RS-1-1, RS-1-2, RS-1-3, RS-1-4, RS-1-8, RS-1-9, RS-1-10, and RS-1-11. These zones primarily encompass single-family neighborhoods characterized by larger lots and limited infrastructure capacity.
Exceptions are available in “high-resource” areas, which are locations identified by the state as offering strong access to schools, jobs, and services. These exceptions are made provided the lots are outside open spaces and parks. The amendments also establish a maximum total unit count tied to lot size, ensuring that any increase in density remains proportionate to the available land.
This zoning clarification helps prevent overdevelopment and addresses public concerns about parking congestion, traffic flow, and strain on local utilities. It also creates a fairer distribution of ADU incentives by prioritizing areas where infrastructure and public resources can accommodate additional residents.
Fire Safety and Evacuation Requirements
The revised program also strengthens fire safety standards for projects in high-risk areas. Properties located in High or Very High Fire Hazard Severity Zones must now be situated on an improved public street with at least two evacuation routes. This rule is intended to enhance emergency preparedness by ensuring residents have multiple ways to exit their neighborhoods during a wildfire or other crisis.
By integrating evacuation planning into the ADU permitting process, San Diego is taking a proactive stance on disaster readiness. This change reflects a broader effort across California to harmonize housing growth with climate resilience, which is a particularly urgent concern as wildfires become more frequent and severe.
Parking Requirements
In a notable policy adjustment, the City has reinstated certain parking requirements for ADUs built under the Density Bonus Program. Specifically, one off-street parking space must now be provided for each affordable or bonus ADU located outside of designated Transit Priority Areas.
This requirement addresses the practical realities faced by residents in suburban and semi-rural areas where public transit access is limited. By ensuring adequate off-street parking, the City seeks to minimize street congestion and maintain neighborhood functionality, while still incentivizing ADU development near transit hubs where fewer cars are needed. The policy strikes a measured balance between promoting housing accessibility and protecting the quality of life in lower-density communities.
Community Enhancement Fee
A new Community Enhancement Fee will apply to affordable and bonus ADUs under 750 square feet. The revenue generated from this fee will fund essential infrastructure projects that directly benefit local communities, such as improvements to parks, libraries, fire stations, and pedestrian and cycling networks.
This fee-based approach helps offset the localized impact of increased density, particularly in “communities of concern” where infrastructure may already be strained. For developers and homeowners, the fee adds a modest cost to ADU construction but ensures that the benefits of development are shared citywide. It also signals San Diego’s commitment to linking new housing growth with public investment in community amenities.
Sustainable Development Clarification
Finally, the reforms provide greater clarity on how walking distance to major transit stops is measured for Density Bonus eligibility. To qualify as a pedestrian path of travel, the route must now include a continuous sidewalk. This clarification ensures that projects claiming proximity to public transit genuinely promote safe, walkable access.
This change might seem technical, but it reinforces the City’s broader sustainability goals: encouraging true transit-oriented development and improving accessibility for all residents, including those with disabilities. It also aligns local ADU policy with California’s long-term vision for reducing car dependency and promoting greener, more connected urban design.
Together, these updates to the ADU Home Density Bonus Program demonstrate San Diego’s nuanced approach to housing reform: incentivizing growth where appropriate while safeguarding safety, infrastructure, and community livability.
Impact on San Diego Homeowners and Developers
The new reforms bring both opportunities and responsibilities for property owners and developers. For homeowners, the clarified rules create new pathways to build income-generating rental units, provide housing for extended family, or sell newly subdivided ADU condominiums. For developers, the amendments provide clearer density parameters and reinforce the need for compliance with fire safety and infrastructure standards.
While the City continues to support ADU expansion, the updated requirements mean developers must take a more strategic approach to site selection, design, and permitting. Consulting with land use professionals and attorneys is now essential to ensure projects comply with both local zoning codes and evolving state mandates.
Timing and Implementation
The adopted reforms will become effective 30 days after final passage for properties located outside the Coastal Zone. However, for projects within the Coastal Zone (which includes many neighborhoods west of Interstate 5), implementation awaits certification by the California Coastal Commission. That certification is anticipated in 2026, meaning homeowners in those areas should monitor timelines closely before filing ADU permit applications.
How Peterson Law, LLP Can Help
At Peterson Law, LLP, we help San Diego homeowners and developers navigate the evolving landscape of ADU regulations. Our firm represents clients in disputes about property zoning, permit eligibility, density bonus compliance, condominium conversion, and title documentation. With extensive experience in local real estate law, we can help you navigate disputes and litigation that arise as these regulations change.
Building a Safer, Smarter, and More Accessible San Diego
San Diego’s new ADU reforms represent a forward-thinking approach to housing growth: one that recognizes the need for affordability, sustainability, and public safety. By refining the ADU program and clarifying density, fire, and infrastructure requirements, the City has created a clearer roadmap for responsible housing development. For homeowners and developers alike, these updates offer new opportunities to expand housing options while enhancing the livability of San Diego’s neighborhoods.
As implementation begins, working with experienced real estate attorneys who understand the intersection of local regulation and state housing policy will be critical. With proper guidance, property owners can take full advantage of San Diego’s evolving ADU landscape and contribute to the city’s vision of a more inclusive and sustainable housing future.
