sb9 california planning

What do California’s SB9 and SB10 legislations mean for homeowners?


You’ve most likely heard about the recent passing of California's SB-9 and SB-10 housing legislation. These bills aim to boost California’s housing supply, play a part in fighting the Affordable Housing Crisis, and assist in limiting California’s greenhouse gas emissions.

While that all sounds great.

What do SB9 and SB10 actually mean for you and your single-family property?

First, let's clarify a few terms:

Parcel/lot = plot of land, in this context, one that’s ‘single-family’ zoned
Local government / agency = City or County
Unit = form of housing or single room that meets the requirements for separate living quarters

Essentially, Under SB9, you could split your current lot into two separate lots - should you meet the new set of requirements; or, If your property is located in an ‘urban infill site’ or ‘transit-rich’ area, SB10 gives local government a rezoning option, which allows up to 10 units on that same parcel.

So, let's break down what that means:


There are a number of new requirements that current single-family lots must meet in order to take advantage of the bill.
  • each new lot is required to be at least 1,200 square feet and approximately equal in size (60/40 split at most)
  • the lot split does not require the demolition or alteration of any rent-controlled housing, or housing that has been occupied by a tent in the last 3 years
  • the lot split does not require the demolition of more than 25% of the existing exterior structural walls
  • the parcel is not located within a historic district or property included on the State Historic Resources Inventory
  • local government may require a setback of up to four feet from the side and rear lot lines
The team at Sonderpods can help you understand if your property meets these requirements.

SB9 would preempt city zoning and apply to most residential neighborhoods across the state. However, cities still retain some input into the size and design of the new construction, and certain neighborhoods, like historic districts, are protected under the legislation.

It’s important to note that the bill requires a signed affidavit from the homeowner, stating their intention to occupy one of the units as their principal residence for a minimum of 3 years.


Let’s start out by defining exactly what is a “Transit rich area” and an “Urban infill site”.

To be considered a Transit-rich area, your lot must be within one-half mile of a major transit stop. A major transit stop means a site containing either an existing rail or bus rapid transit station.

The bill specifies the stop must:
  • have an average service interval of no more than 15 minutes during the three peak hours between 6 a.m. to 10 a.m., and the three peak hours between 3 p.m. and 7 p.m., on Monday through Friday.
  • have an average service interval of no more than 20 minutes during the hours of 6 a.m. to 10 p.m., inclusive, on Monday through Friday.
  • have average intervals of no more than 30 minutes during the hours of 8 a.m. to 10 p.m., inclusive, on Saturday and Sunday.
As for an ‘Urban infill site’, your lot must meet the following requirements:
  • The lot must be located within a city boundary which includes some portion of either an urbanized area or urban cluster, as defined by the United Census Bureau
  • at least 75 percent of the perimeter of the site adjoins parcels that are developed with urban uses
  • at least two-thirds of the square footage of the development needs to be designated for residential use
  • fire hazard mitigation measures must be in place if the parcel is located within a very high fire hazard severity zone, as determined by the Department of Forestry and Fire Protection
Click here, and we can help you find out if your property meets these requirements.

In layman's terms, SB10 gives cities the opportunity to rezone a single-family parcel, and classify it as a ‘multi-family' parcel. This provides the owner the opportunity to build up to 10 housing units, as well as an additional 2 Accessory dwelling units (ADUs), and 2 junior ADUs on that land parcel. The ADU and JADU do not count towards the 10 units specified in the bill.

Whereas SB9 creates another option for homeowners – you can choose to add up to 3 units on your property (with the addition of an ADU and a Junior ADU per existing ADU laws) or you can choose to add a second residential unit on your single-family property and split the lot, then add an additional 2 units on the new lot. Creating a total of 4 units, across 2 lots, on what once was a single-family parcel.

Local agencies could also allow more than 2 units per lot, but we will have to wait and see how the different local agencies implement SB9 once it is effective next year!

Together, both bills aim to create extra housing units closer to high-value jobs. In turn, reducing commute times, increasing population density, and providing more affordable housing options across California.

If you want help understanding what SB9 or SB10 mean for you, and whether you can build on your single family parcel, get in touch with the Sonderpods team today!

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