SB-9 Explained: From Single Family to 4 Plex

Oct 7, 2021 | ADU, Building

I am sure that you have heard one way or another about the new senate bill 9 which will take effect January 2022.

With that, I am also sure you are not clear on what the bill really means and how it could affect your property, so let me try to make some sense into it.

Keep in mind that we are all learning on the go with this new law.

This is all general information based on our reading, consulting with professionals and understanding, so you should not treat it like legal advice for your specific situation, as we all know by now each city will understand it differently and it will be a learning curve for all, same as it was and still is with ADU’s.

If you want to start by reading the actual bill: SB-9 Housing Development


What Is SB9 Law?

California’s newest housing bill which will take effect January 2022 makes it easier for homeowners of single-family dwellings to build more housing and, under certain conditions, split their lots into two lots.

In some cases, if you can combine both parts of the law, you can split a lot into 2 lots and build 2 units on each – for a total of 4 units.


SB9 Has Two Important Parts


1. Urban lots zoned for one single-family home that can now build a second home:

The first section of SB 9 is about building two residential units on many lots where you used to only be able to build one unit. The legislative counsel says that in the first section “would require a proposed housing development containing no more than 2 residential units within a single-family residential zone to be considered ministerially, without discretionary review or hearing, if the proposed housing development meets certain requirements”.

SB 9 offers a ministerial, non-discretionary permitting process, which means the planning staff can issue it without it going to the planning commission. You don’t need to go through processes that drag a lot of housing projects through various reviews and public notice. It’s supposed to be as easy as the ADU permits if you’re eligible.

Like the ADU laws, you mostly use the existing local code unless it would pre-empt you from building up to 800 sqf with a 4 ft side and rear yard setback.

For example, you would follow the local guidelines for yard requirements and height requirements, unless those rules would prevent the construction of two 800 sqf units on the lot.

The local jurisdiction can also require up to 1 parking space per unit unless the unit is located within half a mile of major transit, high quality bus service, or within a block of a car share.

If you’re replacing an existing non-conforming structure, you can generally maintain the existing footprint.


2. Urban lots larger than 2400 sqf that can now be split into two lots

The second section of SB 9 is about splitting lots into 2 lots.

There are many restrictions covered later in the article, but if your lot is eligible then you can get a ministerially approved, non-discretionary permit to split your lot into two lots. And you can sell those lots separately! The lots must be a roughly 50/50 split (you can go up to 40/60 split).

The lots both need to have access to the public right of way (i.e., you need to access the street), so if your lot is a deep lot that can only be divided to front and back lots, it potentially means an easement will be placed on the front lot that will allow access to the back lot (flag lot)

Neither lot can be smaller than 1,200 sq. ft.

You cannot split a lot that has already been split with SB9 – no infinite splits!

And you cannot split a lot adjacent to a lot you already split (or somebody you’re working with has already split) so individuals won’t be able to split adjacent lots with SB9.


Criteria To Qualify For SB9


SB9 second unit

  • Urban lot (as designated in the census).
  • Single Family Zone.
  • No historic district or on a historic registry of property.
  • No HOA that has practically prohibited the use of SB9.
  • Affordable housing, under a covenant, rent control, or long-term tenants (3 years) lots can’t demolish or alter too much of existing building.
  • You can’t have used the Elis Act in the past 15 years to evict a tenant.
  • City can block your option If you have a lot with fire, flooding or seismic risk with a preponderance of evidence on the record.
  • 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.


SB9 lot split

All the above with addition of:

  • Owner occupancy – you must sign an affidavit that says you plan to live in one of the units on those lots for the next 3 years.
  • The resulting lots sizes need to be bigger than 1,200 sqf EACH.
  • Both lots needs to have access to the public right of way (access the street).
  • You cannot split a lot that has already been split with SB9 – no infinite splits!
  • You cannot split adjacent lots.


Single Family To 4 Plex (Or More)

If you can combine both sections of the bill, you can take a lot zoned for one single family residence, split it into two lots, and build two homes on each lot for a total of FOUR homes.

Accessory dwelling units and Junior accessory dwelling units count toward the unit total so no city will be required to allow more than 2 units per lot (or 4 units after a lot split.)

Note: a city or county CAN choose to allow for ADUs and JADUs on top of the SB9 law, but it is not required.


Cities And Counties Must Abide By This New Law

Under SB 9, local government officials may only deny a development application if they find that the proposed project would have a “specific, adverse impact” on “public health and safety or the physical environment” and there are no feasible and satisfactory mitigation options.


ADU Or An SB9 Regular Dwelling Unit?

Some will benefit from using ADU rules and others will benefit from using regular dwelling unit rules. The answer to this question really depends on your project goals, your jurisdiction’s rules, and property situation.

For example, if you want to build a two-story home but your jurisdiction doesn’t allow ADUs to be greater than 16 feet in height, you might want to build a regular dwelling unit instead.

On the other hand, if you are in an HOA that has prohibited the use of SB9 to make additional dwellings, your only choice is to build an ADU or JADU (using AB670).

The rules about each of these units are very different and can vary tremendously from one jurisdiction to the next. You should really work with a professional to get answers about your specific project.