ADU vs JADU: Which Backyard Unit Should You Build?

A JADU (junior accessory dwelling unit) and an ADU sound similar but are legally different products. Choosing the right one can save you tens of thousands of dollars — or unlock far more rent.

What a JADU is

A JADU is up to 500 sq ft, must be created within the walls of an existing single-family home (often a converted bedroom), and can share a bathroom with the main house. It needs only an efficiency kitchen. Because you're not adding new structure, it's the cheapest unit you can build — frequently $40,000–$90,000.

What a full ADU is

A full ADU can be detached, attached or a garage conversion, up to 1,200 sq ft in many jurisdictions, with its own full kitchen and bathroom. It costs more but rents for more and adds more resale value.

The owner-occupancy catch

In most states you can rent out a full ADU without living on-site. A JADU almost always still requires the owner to occupy either the main home or the JADU — so if your goal is a pure rental or you don't live there, a full ADU is usually the better fit.

• Tightest budget, you live on-site: build a JADU.
• Want maximum rent or a pure rental: build a full ADU.
• Have an underused garage: a garage conversion splits the difference.