A junior ADU (JADU) is a unit of no more than 500 sq ft of interior livable space, built entirely within a single-family home. Under California law, an attached garage counts as part of the home. A JADU needs its own entrance and an efficiency kitchen; the bathroom can be private or shared with the main house.
What are the JADU rules in California?
As of October 2026, the HCD ADU Handbook summarizes these state rules for JADUs:
- Up to 500 sq ft of interior livable space, contained entirely within a single-family residence.
- One JADU per lot zoned for single-family use. JADUs are not allowed on multifamily sites or in detached accessory structures.
- An efficiency kitchen with cooking appliances, a food prep counter and reasonably sized cabinets. A 220-volt circuit is not required.
- If the JADU has no bathroom of its own, it needs a separate exterior entrance plus an interior entry to the main living area.
- No parking can be required.
- Rentals must be for terms longer than 30 days, so short-term rentals are not allowed.
Do I have to live on the property?
It depends on the bathroom. As of October 2026, state law lets a city require the owner to live on site only when the JADU shares sanitation facilities with the main home. If the JADU has its own bathroom, owner occupancy is not required. A deed restriction may be recorded that bars selling the JADU separately from the house.
Are there impact fees on a junior ADU?
As of October 2026, JADUs of 500 sq ft or less are exempt from impact fees under state law. A JADU is also generally not treated as a new residential use for utility connection fees, unless it is built along with a new single-family home. Permit fees still apply.
Can I have a JADU and an ADU on the same lot?
Yes. As of October 2026, state law requires cities to allow a JADU together with other ADUs on a single-family lot, including a new detached ADU, subject to the conditions in the law. We check the combination that works for your lot. See California ADU rules 2026.
Why choose a junior ADU?
- Lower construction scope. No new foundation or roof; the work is interior.
- Multigenerational living. A private space for a parent or adult child with a door to the main house.
- Flexibility. The unit can be rented longer term or folded back into the house later.
The trade-off is size. If you need more than 500 sq ft or a fully separate home, look at an attached ADU or a garage conversion.