Junior ADUs: a private unit inside the home you have.

A junior accessory dwelling unit is created within the walls of an existing single-family home. It can be up to 500 square feet, must have its own exterior entrance and needs at least an efficiency kitchen.

Because a JADU uses space that already exists, it often avoids new foundations and roofs entirely. It can share a bathroom with the main house or have its own. That makes it a practical option for a caregiver, a young adult, an aging parent or a modest rental.

What a JADU needs

An efficiency kitchen typically means a sink, a cooking appliance, a counter and storage. The unit needs its own exterior door and, if it shares a bathroom, an interior connection to the main house. An attached garage counts as part of the home, so it can become a JADU too. Fire-separation and egress details are confirmed with the building department during design.

Owner occupancy and rentals

Since January 1, 2026, state law (AB 1154) allows a city to require owner occupancy for a JADU only when the JADU shares a bathroom with the main house. Give the JADU its own bathroom and that requirement generally falls away. JADUs also may not be rented for 30 days or less. Many cities still record a deed restriction, so confirm the paperwork your city requires.

JADU plus ADU

On a single-family lot, a JADU can be combined with a detached ADU, which can give you three living spaces on one lot. Planning both together means utilities and permits are handled once. See the California ADU rules guide for current limits.