A junior ADU, or JADU, is a small unit created inside the walls of a single-family home, including an attached garage. It has its own entrance and an efficiency kitchen, and it can share a bathroom with the main house or have its own.
What are the junior ADU rules?
As of October 2026, under state law as summarized in the HCD ADU Handbook:
- Up to 500 sq ft of interior livable space, inside a single-family home (an attached garage counts).
- One per single-family lot; not allowed in detached structures or on multifamily sites.
- An efficiency kitchen is required: cooking appliances, a food prep counter and reasonably sized storage. A city cannot demand more.
- The bathroom can be shared with the main home or separate.
- No parking can be required.
- Any rental has to run more than 30 days.
Is owner occupancy required for a JADU?
Only in one case. As of October 2026, a city can require the owner to live on site only when the JADU shares a bathroom with the main home. Give the JADU its own bathroom and that requirement cannot be imposed.
Can I have a junior ADU and a backyard ADU?
Often, yes. The HCD Handbook describes a junior ADU combined with a new detached ADU on a single-family lot, subject to the law's conditions, and the City of San Diego's planning page describes one ADU plus one JADU on a single-family lot. We confirm the combination for your address.
What does a junior ADU cost in San Diego?
As of October 2026, San Diego contractors publish ranges of about $90,000 to $200,000. A JADU of 500 sq ft or less is also exempt from impact fees under state law. Moving plumbing for the kitchenette and any new bathroom is usually the largest cost.
Who is a junior ADU good for?
Homeowners who want a private space for a parent, an adult child or a long-term tenant without building in the yard. Because the unit sits inside the home, sound separation and a clear, separate entry make a big difference to how livable it feels.