Junior ADU
A junior ADU: a second home inside the first
A junior ADU is built from space already inside your house, such as a bedroom with a bath, a den or an attached room. It is no more than 500 sq ft, has its own entrance and includes a kitchenette.
It is the least expensive way to add a separate unit and the quickest to build. The trade-off is the rules: the owner must live in the house or the unit, and the junior unit may share a bath with the main house.
Up to 500 sq ft, inside the existing house
10 to 14 weeks to build
Priced after a visit to the rooms, in writing
What moves the price
What a junior ADU takes
The rooms are there; the work is making them separate.
A door of its own
The unit needs an exterior entrance. If there is none, we cut one and add a landing.
Fire and sound
A rated wall and door between the unit and the house, and insulation to take the edge off sound.
A kitchenette
A sink, a counter, a small refrigerator and a cooking appliance. A full-size range is optional.
The bath
Sharing the house bath costs least. A bath of its own means opening a wall and a floor.
Heating and cooling
A mini-split on its own thermostat, so the unit does not depend on your house system.
Power
A sub-panel or new circuits when the house panel is already near its limit.
The build weeks
What the weeks hold
A one-room junior ADU, 10 to 14 weeks.
- Weeks 1 to 3
Step 1: Separation
Cut the new entrance, frame the rated wall and set the door.
- Weeks 3 to 8
Step 2: Kitchenette and bath
Plumbing, circuits and the mini-split go in; the city inspects.
- Weeks 8 to 14
Step 3: Finishes and final
Drywall, floor, cabinets, paint and final inspection.
Rules to know
Owner occupancy and rental
A junior ADU requires the owner to live in either the main house or the junior unit. That rule is recorded on the property. If you plan to rent both, talk to us before you choose this type.
A junior ADU can generally be rented for 30 days or longer. It cannot be sold apart from the house.
If your house was built before 1978, ask us about lead paint before you sign. Work that disturbs painted surfaces needs specific lead-dust practices by a certified firm, and your quote says who holds the certification.
Questions
Asked about this type
Can I rent it out?
Usually yes, for stays of 30 days or longer. Rules on owner occupancy and on selling the unit apart from the house differ by unit type and city. A junior ADU, for example, needs the owner to live on the property. We write down the rules for your address.
Can we stay in the house during the build?
Yes for a detached unit, which is built in the yard. A junior ADU or garage conversion may mean a day or two without power or water; we tell you which days ahead of time.
How long does it take?
Design takes about two months, the city review varies, and the build runs 10 to 36 weeks depending on the type. The weeks on the cards are build time only.
My house was built before 1978. Does that change anything?
It can. Homes built before 1978 may have lead paint. If work disturbs more than 6 square feet of painted surface inside or 20 outside, or touches windows or demolition, federal rules require specific lead-dust work practices by a certified firm. Tell us the year; we say before you sign whether the rule applies and who holds the certification.
Could a room of yours become a unit?
Describe the room and who it is for. We tell you what a junior ADU would take.