ADU vs. JADU: What's the Difference in California?

A Junior ADU is capped at 500 square feet and must be created entirely within an existing or proposed single-family home, with an efficiency kitchen and a bathroom it may share with the main house. An ADU can be detached, attached or converted, is commonly allowed up to 1,200 square feet depending on type and jurisdiction, and needs its own full kitchen and bathroom.

Owner occupancy, and what changed in 2026

Owner occupancy has been the significant catch with Junior ADUs. California law has generally required the property owner to live in either the main house or the JADU.

Under AB 1154, effective January 1, 2026, that owner-occupancy requirement is eliminated where the JADU has its own bathroom rather than sharing one with the primary dwelling.

Can you have both?

Many single-family properties in California can have one ADU and one JADU. Whether yours can depends on your jurisdiction and your parcel.

Which one should you build?

A JADU if there is genuinely usable space inside the house and you want the least disruptive route. An ADU if you want separation, a full kitchen and a unit that stands on its own. More on Junior ADUs.

ADU laws and local requirements can change. Information on this page is general and is not a guarantee that a specific project will be approved. Confirm current requirements for the property and jurisdiction before making project or financial decisions.