You can just add 1 primary unit + 1 ADU without splitting the lot, per SB-9

[Felicia Nitu]

Under SB-9, you’re allowed to add 1 primary unit and 1 ADU on a single-family lot without needing to split the lot. That means you can develop 2 full units on the same parcel. No subdivision paperwork required!

A two-unit development simply means having 2 homes on one lot. This can be done in a few flexible ways:

– Keep your existing home and add a new single-family dwelling plus an ADU or JADU
– Or build a duplex and add 2 detached ADUs on the same property

This setup not only adds much-needed housing, but it also puts more function and value into the same property, all while keeping ownership simple.


Why This Matters for Agents and Investors
For real estate agents, this opens the door to new inventory strategies. Helping clients buy or sell properties with hidden development potential. For investors, it’s a chance to multiply income streams, especially in high-demand neighborhoods, without dealing with the cost or complexity of lot subdivision. SB-9 two-unit development is a clear, streamlined way to increase property value and create more housing, all on the same lot.