Understanding SB 9

California continues to look for ways to address the housing shortage, and one of the most significant changes in recent years is Senate Bill 9 (SB 9). This law allows homeowners to split certain residential lots and build additional housing units, creating new opportunities for property owners to increase housing density and property value.

For homeowners exploring ADUs in Southern California, SB 9 can open the door to even more development potential.When combined with strategies like custom ADU design across Southern California or garage conversions that transform existing space into rental units, SB 9 can open the door to even greater development potential. SB 9 may allow homeowners to significantly expand the number of housing units on their property.

Understanding how SB 9 works can help homeowners and investors determine whether their property could support additional housing while maximizing long-term value.

What Is SB 9?

SB 9 is a California law that allows qualifying homeowners to split a single-family residential lot into two separate parcels and build additional housing units on each lot. The law was designed to encourage small-scale housing development in areas that were previously limited to only one home per lot.

Before SB 9, many neighborhoods were restricted to single-family homes. Now, homeowners may have the opportunity to create duplexes or small multi-unit developments where only one home previously existed.

For property owners already researching ADU zoning Southern California and ADU laws Southern California, SB 9 offers an additional development strategy that can increase housing flexibility and investment potential.

What SB 9 Allows Homeowners to Do

SB 9 provides two primary development options for eligible properties.

Duplex Development

Under SB 9, homeowners may build a duplex on a single-family lot, meaning two residential units can exist where only one was previously allowed.

This could include:

• Converting a single home into two units
• Building a second unit on the same lot
• Constructing a duplex structure

This option allows homeowners to increase housing density without needing to split the lot.

Urban Lot Splits

B 9 also allows homeowners to divide a qualifying property into two separate lots.

Once the property is split, each lot may be able to accommodate up to two residential units, depending on local regulations.

This means a property that once had one house could potentially support up to four homes after a lot split and new construction.

For homeowners considering building an ADU, SB 9 lot splits can create opportunities for small-scale development that significantly increases property value.

SB 9 vs. ADUs: Understanding the Difference

Although SB 9 and ADUs both increase housing opportunities, they function in different ways.

ADUs allow homeowners to add additional living units to an existing property, such as detached backyard homes or junior ADUs or garage conversions within an existing residence.

SB 9, on the other hand, allows property owners to split their lot into separate parcels, potentially enabling each new lot to have its own residential development.

Many homeowners explore combining these strategies. For example, a lot split could allow for new homes on each parcel while also providing opportunities for pre-designed additions.

Working with an experienced ADU contractor can help homeowners evaluate which approach best fits their property and investment goals.

Key Requirements for SB 9 Projects

Although SB 9 allows greater development potential, certain requirements must still be met.

Some common requirements include:

• The property must be located in a single-family residential zone
• Each new lot created must generally be at least 1,200 square feet
• Lot splits are typically limited to two parcels
• Historic properties and certain protected housing types may not qualify
• Local regulations such as setbacks and height limits may still apply

Because these regulations can vary by city, homeowners often begin by researching local zoning guidelines before planning a project. You can find additional information in our ADU Resource Center.

How SB 9 Can Increase Property Value

For homeowners looking to maximize the value of their property, SB 9 can provide several advantages.

By allowing additional housing units or lot splits, SB 9 may help homeowners:

• Increase property value
• Generate rental income
• Create additional housing for family members
• Sell newly created lots or homes
• Develop small multi-unit properties

When strategically planned,  homeowners may be able to unlock significant value from underutilized land.

Planning an SB 9 or ADU Development

Every property is unique, and the feasibility of an SB 9 project depends on factors such as lot size, zoning regulations, and existing structures.

Homeowners considering development often begin by evaluating:

• Lot size and layout
• Local zoning regulations
• Utility access
• Construction costs
• Potential rental income

Working with a knowledgeable ADU builder can help determine whether a property may qualify for SB 9 development or additional ADU opportunities.

Start Exploring Your Property’s Potential

As California continues to address housing demand, laws like SB 9 are giving homeowners more flexibility to develop their properties in ways that were not previously possible.

Whether you're researching ADU costs Southern California, considering an ADU or JADU, or exploring how SB 9 might allow additional housing units on your property, thoughtful planning can help maximize both property value and long-term income potential.

Our team helps homeowners evaluate their property so they can design housing solutions that maximize both functionality and return on investment.