California ADU Zoning and Lot Size Requirements

We all know now for a fact that all single-family homes can have two ADUs - one ADU and one JADU. Now, obviously, the laws for JADU's are very specific, it has to be under 500 square feet, it has to be attached either to your house or to your ADU. Now, when we talk about multi-families, you can build up to two multi-families but there are some restrictions. If you have a duplex, a triplex, a fourplex, a five plex, six-plex, or seven plex you can build one ADU. If you have eight units and above, you can build two ADUs.

Now the big question is, “Can ADUs exceed the general zoning densities?” The answer is, yes. Some people have, for example, a single-family home with a 7,500-square foot lot size and they can only build one unit. You can still build an ADU and one JADU, it doesn't matter what your zoning says.

Lot Size requirements:

• Scenario #1: “My lot is too small, can I still build an ADU?

The answer is, yes. No law allows cities to say that a lot is too small. You can always build an ADU even if your lot size is 2,000 square feet or 3,000 square feet.

• Scenario #2: “I want to build a huge ADU.”

The answer is no. Cities can deem the maximum sizes of ADUs. The maximum size of ADUs for cities that don't have ordinances is 1,200 square feet and also 50% of the lot. So you can’t build over 50% of your lot, that's the main thing you should know. 

California Statewide Exemption 

Let’s also talk about the statewide exemption. This is the perfect ADU for everyone. So, it has to be under 800 square feet, it has to have four feet from rear and side and if you build 800 square feet and four feet for rear and side setbacks then there's no lock coverage, there's no floor size ratio and there's no minimum lot size so that is the California statewide exemption for ADUs. Anyone who wants to build 800-square feet can do it.