SB9 Most Accurate 2023 Update: Everything You Must Know

Sep 23, 2023 | ADU, Garage Conversions

Starting January 1, 2022, California SB-9 Housing Development might have became just as important as the ADU law that allows homeowners to build additional homes in their backyards.

When this law went into effect, two important things happened to single-family zoned parcels.

First, lot splits are permitted: lots that are currently zoned as Single-Family Residences can be subdivided into two parcels or lots. This act also permits duplex residences, which means you can convert or construct two units on each lot. SB9 states that a local municipality must approve lot splits and duplex construction (or the combination) ministerially, meaning that now it gets easier to approve these projects without prolonged review or hearings.

Through SB9, the State intends to increase the viability of middle-income housing by increasing density while protecting renters and historic properties.

SB9 Consists of Two Important Parts

1. Building a Second Home on Urban Lots Zoned for Single-Family Homes

The initial part of SB9 focuses on allowing the construction of two residential units on lots where only one was previously allowed. This section of SB9 aims to streamline the approval process, meaning that if certain requirements are met, a proposed housing development with a maximum of two units within a single-family residential zone will be approved without needing a discretionary review or hearing. This process is referred to as ministerial, indicating that the planning staff can grant the permit without involving the planning commission. This approach eliminates the need for extensive reviews and public notices that often slow down housing projects.

The process is intended to be similar to the straightforward process for Accessory Dwelling Units (ADUs) if the criteria are met. In most cases, existing local building codes will apply, unless they prevent the construction of two 800-square-foot units with a 4-foot side and rear yard setback. For instance, local guidelines for yard and height requirements will be followed, unless they prevent the construction of the two 800-square-foot units. Parking requirements are flexible but can include up to 1 parking space per unit, unless the unit is within a half-mile of significant transit options, high-quality bus services, or close to a car-sharing program. For replacing an existing non-conforming structure, the original footprint can generally be maintained.

Qualifications for SB9 Second Home Eligibility

For a property to be considered eligible under SB9 for a second home, it must meet these specific criteria:

  1. The property should not be in a historically designated zone and should avoid high-risk areas like fire-prone zones, floodplains, or earthquake fault zones.
  2. The existing property on the parcel must not have any form of rent or price control in place.
  3. The property cannot currently have a tenant living there in the past three years, nor can it have been subject to an Elis Act eviction within the last 15 years.
  4. Affordable housing, under a covenant, rent control, or long-term tenants (3 years) lots can’t demolish or alter too much of existing building.
  5. Assembling a neighboring parcel or collaborating with a neighbor to split an adjacent lot is not allowed.
  6. No HOA that has practically prohibited the use of SB9.
  7. Parcels must be situated in urban areas.
  8. Only rental agreements with durations exceeding 30 days are permitted; short-term and vacation rentals are prohibited.
  9. The property owner must commit to residing on the property for three years.
  10. When counting how many units there are on a lot, ADUs and JADUs count toward the total units. So, if you already have an ADU or JADU, then you are already at the limit for that lot.

2. Splitting Larger Urban Lots into Two

The second part of SB9 pertains to dividing lots into two separate lots. While specific limitations are detailed later in the article, eligible lots can be divided into two through a ministerially approved, non-discretionary permit. These two lots can also be sold separately. The division needs to be a split of approx. 40/60. Both resulting lots must have direct access to a public right-of-way (i.e., a street), which means that if your lot can only be divided into front and back sections due to depth, an easement might be established on the front lot to provide access to the back lot (flag lot). Neither of the divided lots can be smaller than 1,200 square feet. It’s not possible to split a lot that has already been divided with SB9 – multiple splits aren’t allowed. Additionally, a lot adjacent to a lot that has been split (or a lot belonging to someone collaborating with you) cannot be split using SB9, preventing continuous adjacent splits by different individuals.

Qualifications for SB9 Lot Split Eligibility

For a property to be considered eligible under SB9 for a lot split, it needs to meet al the second home qualification and the additional specific criteria:

  1. The resulting lots sizes need to be bigger than 1,200 sqf EACH.
  2. Both lots need to have access to the public right of way (access the street).
  3. You cannot split a lot that has already been split with SB9 – no infinite splits!
  4. You cannot split adjacent lots.

From a Single Family to 4 Plex

By combining both sections of the bill, you have the opportunity to take a piece of land zoned for a single-family home, divide it into two lots, and construct two homes on each lot, resulting in a total of FOUR homes.

The count of units includes both accessory dwelling units (ADUs) and junior accessory dwelling units (JADUs), which means no city is obligated to permit more than 2 units per lot (or 4 units after a lot split).

Note: A city or county has the option to allow ADUs and JADUs in addition to the SB9 law, but this is not mandatory.

Implementation of SB9 by Different Jurisdictions

The way each jurisdiction (city/county) adopts SB9 can either enable or hinder its application. Some cities, such as Sunnyvale, are strongly supportive of SB9 and have incorporated it directly into their regulations. Conversely, numerous cities are less favorable towards SB9 and have devised innovative methods to obstruct its execution. There are even talks of certain cities combining SB9 with Accessory Dwelling Units (ADUs) to allow the construction of more than four units on a single lot.

In several of the most restrictive cities, unique laws have been introduced that create substantial barriers to building SB9 units on private properties. These regulations might entail mandates like erecting hedges along property lines or enforcing the creation of gardens on the premises. In some cases, there are efforts to designate the entire city as a historic district.

Beyond standard enforcement limitations, jurisdictions have developed innovative approaches to obstruct the implementation of SB9 within their cities or counties. Given the substantial number of cities opposing SB9, there’s a likelihood that your jurisdiction may have adopted one of these tactics to make the construction process as challenging as possible. Here are a few strategies that jurisdictions are employing to impede the effectiveness of this new law:

Varied Zoning Laws

While the SB9 unit and primary home should adhere to the same zoning laws, certain jurisdictions have distinct zoning regulations exclusively for the SB9 (secondary) unit. Consequently, the unit constructed under SB9 might be subjected to dissimilar square footage requirements, setback specifications, floor area ratios, and more, compared to the primary home. For instance, your primary residence could be permitted to reach a height of 24 feet, whereas the SB9 secondary unit might be limited to 16 feet under these obstruction tactics.

Excessive Affordability Demands

While cities can enforce inclusionary ordinances, some jurisdictions have established separate inclusionary ordinances specifically for SB9 units, differing from the rest of the city. This issue arises when certain cities demand affordability for every home, extending the requirement to SB9 units as well. This becomes burdensome when primary homes are not required to be affordable, only the secondary SB9 units.

Overly Stringent Objective Standards

Although the SB9 law permits objective zoning standards, certain jurisdictions overextend this concept by imposing challenging and almost impractical objective requirements. For instance, they may demand that your SB9 unit matches the designs of both neighboring houses, a concept referred to as design matching. If the city enforces design matching solely for SB9 units and not for the entire area, building an SB9 unit becomes nearly impossible due to the variations in neighboring house heights and roof types.

Exclusion of Lots Based on Zoning Eligibility

A potent method utilized by cities to delay SB9 is through upzoning. Upzoning laws allow cities to regain some control by excluding lots from SB9 eligibility based on their zoning status. Here’s how it works: If your lot is zoned for a single-family home and meets SB9’s fundamental criteria, you can construct a secondary unit. However, if your lot is zoned for multiple units (Multifamily) that can be separately conveyed, it no longer qualifies for SB9. This is because SB9 is exclusively intended for single-family residential plots. Sunnyvale consider such situations eligible. The outcome hinges on how your city manages upzoning.

The manner in which your jurisdiction chooses to implement SB9 will significantly influence the feasibility of establishing an SB9 unit on your property.

Why is SB9 important?

Why is SB9 Important?

SB9 could help fix California’s housing shortage by making more homes in single-family neighborhoods and giving more people a chance to own a home. But it only works if it’s put into action the right way. It’s still too early to say if SB9 is working or not. Not many people have used the law yet, maybe because planning departments are busy, interest rates are going up, prices are rising, and construction is getting disrupted.

But it’s also not too soon to think about how to make SB9 even better and help homeowners build more homes on their land. Just because there haven’t been many applications for SB9 projects doesn’t mean people aren’t interested. Lots of people are inquiring with us about SB9, but it takes time and resources to start a project, especially when building an extra home on the property could also be done. Maybe there’s more that local and state governments can do to make SB9 work better.

2021 analysis by the Terner Center estimated that over 700,000 new homes would be newly feasible to build using SB9.

Terner Center for Housing Innovation at UC Berkeley’s study suggested policymakers should make California’s new housing laws work better and offered a few suggestions:

  1. Make clearer rules for SB9 homes. SB9 could be better if there were clearer rules about what can be built where. This is one reason why ADUs have become popular in California – there were clear rules that helped them grow. SB9 could get better with new rules too, like allowing bigger homes and limiting extra costs when turning a single-family home into a duplex.
  2. Also, the rule that says the owner must live there might be stopping some people. Policymakers could think about changing this rule to encourage more people to use SB9, while still protecting against problems.
  3. California’s Department of Housing and Community Development could help cities use SB9 to meet their housing goals. They could let cities that are using SB9 a lot to plan for more growth and set bigger goals. This would make cities work harder to teach people about SB9 and use it well.
  4. Cities can also make better rules for SB9. Even without new state laws, cities can do things to help SB9 work better. They can lower fees and make it clear how to use SB9. They can also think about making more types of housing, not just duplexes, in neighborhoods that don’t have many homes. Some cities are already trying this, like Berkeley and Sacramento. This would help SB9 reach its goals.
  5. Make it easier for people to own homes. SB9 could make more homes that people can afford to buy. But there are still problems that make it hard to build these homes. Lawmakers should look at rules that make building homes more expensive and harder. They could change these rules so that building small homes to sell is easier and cheaper. They should think about special rules for small home projects like SB9. This would help more people become homeowners.

Choosing Between an ADU or an SB9

While Additional Dwelling Units (ADUs) have been established for some time now, legislation is still clarifying the details of SB9. Apart from the legal aspects, let’s delve into the actual differences between these two options.

ADUs are compact secondary units constructed on the land of a single-family home. At first glance, this might seem like SB9. However, the key distinction lies in size regulations. ADUs adhere to strict size limits, making them notably smaller than SB9 units. Additionally, ADUs are subject to zoning regulations and rent control laws distinct from SB9 units. Furthermore, they cannot be sold as independent units.

The most significant contrast arises from the fact that many cities lean against SB9, often putting up obstacles to prevent SB9 unit development. On the other hand, they are generally more amenable to the establishment of ADUs. ADUs have gained popularity in various Californian cities as they offer a means to address the housing crisis by providing affordable housing without causing significant disruption to neighborhoods due to their smaller size and restriction against short-term rentals. Therefore, if time is of the essence, opting for an ADU might be a more viable route, as SB9 endeavors could encounter numerous challenges.

However, in cities that support SB9, there are potential advantages to building more sizeable units. This includes the option to split a lot and sell it to a developer or develop it yourself. Nonetheless, this avenue is only feasible if your city is among the few that are not impeding SB9 initiatives.

What Comes Next?

When SB9 was passed in 2021, many saw it as a big step in housing and a way to bring new homes into well-resourced neighborhoods while also addressing the limits of single-family zoning. But making big changes in policies often needs more than just one time – it needs a longer effort. So far, in 2023 not many people have used SB 9, which suggests that the law could be improved. For SB9 to really work like it’s supposed to, lawmakers need to watch what it does and think about changing it, as it’s important to make sure SB9 is set up for success.

Hire A Professional To Help You Navigate Through SB9

At Levi Design Build, we specialize in assisting property owners with understanding the advantages and disadvantages of SB9 compared to an ADU based on their needs and property circumstances.

Unlike some other firms, we keep the design phase team separate from the build phase team, allowing you maximum control over your project and finances. This approach ensures that you have the flexibility to review and manage the budgeting process with confidence.

Our commitment is to provide you with exceptional service throughout your project, we offer a personalized approach to design, planning, project management, and consultation, tailoring our services to meet your specific needs and preferences.

You can trust us to be your trustworthy partner in your SB9 or ADU project and deliver the highest level of service.


  • What are the key provisions of California SB-9 Housing Development?
    Starting January 1, 2022, California SB-9 Housing Development allows for lot splits and duplex construction in single-family zoned parcels. It streamlines the approval process, making it easier to build additional units in these areas.
  • What does the first part of SB9 entail?
    The initial part of SB9 focuses on allowing the construction of two residential units on lots where only one was previously allowed. This process, referred to as ministerial, streamlines the approval without the need for a discretionary review or hearing.
  • What are the qualifications for SB9 second home eligibility?
    To be eligible for a second home under SB9, a property must meet specific criteria, including no historical designation, no rent control, and the property owner residing on the property for three years, among other requirements.
  • What does the second part of SB9 involve?
    The second part of SB9 allows for the division of lots into two separate lots, with certain conditions and size requirements. These divided lots must have access to a public right-of-way and cannot be smaller than 1,200 square feet each.
  • What are some strategies that jurisdictions use to impede SB9 implementation?
    Some jurisdictions have introduced strategies to hinder SB9 implementation, including varied zoning laws, excessive affordability demands, overly stringent objective standards, and the exclusion of lots based on zoning eligibility.
  • Why is SB9 important?
    SB9 is crucial because it aims to address California’s housing shortage by making it easier to build more homes in single-family neighborhoods, potentially providing more people with the opportunity to own a home. Its success depends on effective implementation.
  • What suggestions have been made to improve SB9 implementation?
    Suggestions for improving SB9 implementation include making clearer rules, reconsidering the owner-residency requirement, and encouraging cities to set bigger goals for housing growth.
  • How does SB9 differ from Additional Dwelling Units (ADUs)?
    SB9 allows for larger units and lot splits, while ADUs are smaller secondary units with different zoning regulations. The ease of implementation may vary by location, with some cities favoring ADUs over SB9.
  • What comes next for SB9?
    SB9 is still evolving, and its effectiveness will depend on ongoing changes and improvements. Policymakers are considering adjustments to make SB9 more successful in addressing California’s housing needs.
  • Should I hire a professional for SB9 or ADU projects?
    It’s advisable to consider hiring a professional, like Levi Design Build, to navigate through SB9 or ADU projects. They can provide expertise in understanding the best approach based on your specific needs and property circumstances.