How to use SB9
Senate Bill 9 is a 2021 California state law that allows up to 4 homes in most single-family zones, regardless of local zoning. You can use SB9 to split your lot, add a 2nd home to a lot, or both (split lot and have 2 homes on each lot for a total of 4 homes).
Here's how you can build more homes once SB9 takes effect on Jan 1, 2022.
Why use SB9?
Earn money. Even if you don't have the cash to build new homes yourself, you can sell your backyard to a builder or a future homeowner. Take a look at how much empty lots in your neighborhood sell for - it's likely to be hundreds of thousands to over a million dollars.
Do your part to solve California's housing crisis. Maybe you have friends or family members that want a home but can't afford one due to California's high land costs. Homeownership is much more affordable if they're only paying for a new building.
Check if you're eligible:
Property is zoned by the city or county for only 1 home. (if you want to subdivide a multi-family lot, use AB803)
Property is located in an existing urbanized area or urban cluster. See 2010 Census maps and 2020 Census additions. This includes most suburbs.
Not prime farmland or farmland of statewide importance, wetlands, conservation land, habitat for a protected species.
Not on a hazardous waste site, earthquake fault zone, 100-year floodplain or floodway.
Not a historic landmark or in a historic district.
Ellis Act was not used to evict tenants on any buildings on the property within the last 15 years.
If splitting the lot, you need to plan to live in either your existing house or one of the new homes for the next 3 years. This rule does not apply to land owned by community land trusts.
Homestead, a company that finances, designs, builds, & sells homes, has created a map search tool that homeowners can use to check if their lot is SB9 eligible.
Special Conditions
Fire Zones: Cannot use SB9 on land within a very high fire hazard severity zone, unless the development complies with state mitigation requirements.
Rental Housing: SB9 housing cannot demolish or alter housing that currently has a tenant or has previously had a tenant in the last 3 years. You cannot remove more than 25% of the exterior walls of such a building either, even if the rental unit is not altered. Affordable housing or rent controlled buildings on the property also cannot be demolished.
ADUs: If you already have one or more Accessory Dwelling Units on your property, you can still add a house to your lot if you don't split the lot. However, ADUs count towards the maximum number of 2 homes per lot for split lots.
Septic Systems: If your property is not connected to a sewer system, the city or county may require a percolation test before allowing additional homes.
One lot split only: Lots created by a SB9 lot split cannot be further divided. Owners also cannot use SB9 to split adjacent lots.
No AirBNB's: Homes created by SB9 can be sold or rented. However, if rented, the minimum rental is 31 days.
For full details see the bill text and 8/28/21 bill analysis
Submit plans to city. Local regulations may require you to hire an architect. The city is required to approve SB9 projects at the staff level, without having to hold a public hearing.
Sell and/or build. Not interested in managing the construction yourself? You can split the lot and sell the new lot without having to build on it.
Information from Alfred Twu - How to use SB9