Junior ADU · City of San Diego
Junior ADUs in San Diego
A junior ADU is a small home carved out of your house, up to 500 square feet, with its own entrance from outside and an efficiency kitchen. It can share a bathroom with the house. It stays part of the house: it can't be sold separately, and the owner lives on the property unless it has its own bathroom.
BHI Builders designs, permits and builds junior ADUs, along with detached ADUs, attached ADUs and garage conversions, across San Diego County's 19 permit authorities, as one team, under California contractor license 738313, issued in 1997.
- 1997Licensed in California sinceCheck the license
- 111Permits on the public record, 2000 to 2025See the projects
- 5.0Google rating from 17 reviewsRead the reviews
- A+Better Business Bureau ratingSee the BBB profile
A small home inside the house
A junior ADU usually takes one bedroom: its own door from outside, an efficiency kitchen along one wall and room to live, with the bathroom shared or its own.
Right for your lot when
You want a place for a parent or a caregiver inside the house, up to 500 square feet, at the lowest cost of the four.
The wrong choice when
You want to rent it out and live elsewhere: a junior ADU that shares a bathroom needs the owner on the property, and it never has a full kitchen.
On the call we tell you which type fits your lot, including if the answer is none.
The rules for a junior ADU
| Rule | What applies |
|---|---|
| Size | 150 to 500 square feet. |
| Where it goes | Inside an existing or new house, including an attached garage. Not in a detached garage or another separate building. |
| Entrance | Its own entrance from outside. A junior ADU without its own bathroom also needs an inside door to the house. |
| Kitchen | An efficiency kitchen: a cooking facility with appliances, a food preparation counter and storage cabinets of reasonable size. A city can't ask for more. |
| Bathroom | It can share the house's bathroom or have its own. |
| Owner on site | The owner lives on the property, in the house or the junior ADU, unless the junior ADU has its own bathroom. |
| Selling it | Never apart from the house. The owner records an agreement with the City that says so, and it binds future owners. |
| Rental term | Longer than 30 days. Short-term rentals aren't allowed. |
| Fire sprinklers | Needed only if the house has them. When the house is sprinklered, the junior ADU is too. |
| Fees | State law bars impact fees on a junior ADU of 500 square feet or less, and school districts can't charge school fees on one under 500 square feet. |
Outside the City of San Diego, your city or the County sets these rules within state law. Who issues my permit?
What a junior ADU costs
Our calculator's planning range at a plain spec: about 400 square feet, standard finishes, a flat lot and easy access. Your size, site and finishes move it.
$82,560 to $112,734
Questions about junior ADUs
What is the difference between an ADU and a JADU?
A junior ADU is made from space inside your house, up to 500 square feet, with an efficiency kitchen, and it can share the house's bathroom. An ADU can be up to 1,200 square feet in the City, built new or converted, with a full kitchen and bathroom. A single-family lot in the City can have a junior ADU in addition to its ADUs.
Do I have to live in the house?
Yes, in the house or the junior ADU, unless the junior ADU has its own bathroom. Then the owner doesn't have to live on the property.
Can it have its own kitchen and bath?
It has an efficiency kitchen: a cooking facility with appliances, a counter and storage cabinets. A bathroom of its own is allowed but not required. Without one, it shares the house's and needs an inside door to it.
Can I rent it?
Yes, for longer than 30 days. Short-term rentals aren't allowed.
Can I sell it?
No. A junior ADU can't be sold apart from the house, and a recorded agreement with the City binds future owners to that.
Does it need fire sprinklers?
Only if your house has them. When the house is sprinklered, the junior ADU needs them too.
Talk to us about your lot.
Tell us where it is and what you want the ADU to do. We'll walk it with you and tell you what fits.
