California is one of the many states which allows homeowners to build Accessory Dwelling Units (ADUs,) to increase the housing supply and allow homeowners to add new functional spaces to their properties. California also allows homeowners to build Junior ADUs. These aren’t just smaller ADUs; they have different building code criteria than a typical ADU. While the precise rules for how JADUs and ADUs are different and depend on your specific spot in California, we can give you a quick outline on the state rules and which you should consider building.

What are JADUs

Junior ADUs are smaller than your typical ADU. They may be no more than 500 square feet and must be built within the existing walls of the home. They require their own entrance to the home and their own “efficiency” kitchen. An efficiency kitchen is one with the following:

  • A sink
  • A cooking appliance
  • A counter
  • A storage unit
  • No gas or 220v circuits

JADUs also may share a bathroom with the main living space, or they may not.

Unlike ADUs, JADUs can never be sold separately from the main home. They may not require parking. They may not require separate utilities from the rest of the home. If you own a JADU, you are required to either live in the main residence or the JADU. You cannot rent out both spaces.

While these are the general staterules for these small home additions, they are not consistent everywhere. In certain areas of California, JADUs are not allowed. It is up to local municipalities to adopt rules to allow them.

How are JADUs and ADUs Different (in California?)

The comparison between JADUs and ADUs is not always straightforward. This chart should help you understand:

Size Up to 1200 square feet of 50% of existing living space Up to 500 square feet
Location May be added to property Must be within existing walls
Separate Entrance May or may not be required Required
Kitchen Full kitchen required Efficiency kitchen required
Separate Bathroom Required Not required
Separation Often considered a separate unit which may be sold Never considered a separate unit from the main home

Which Should I Build?

When you’re considering which of these home additions to build, there are some questions you should ask yourself:

  • Are JADUs allowed? Not all municipalities allow for JADUs.
  • Can you fit a JADU? It is not legal to build a home extension and fit a JADU. Instead, they are most commonly garage or basement renovations.
  • Can you afford an ADU? It is more expensive to build a full ADU than most JADUs.
  • Would you like to sell or rent? You cannot sell a JADU separate from the rest of the home. You also must live in one space when you own a JADU. In this way, an ADU offers you much more flexibility.

Your ADU builder can help you assess if an ADU or a JADU is right for your property.