ADU builder in the Bay Area
Your ADU, handled by one team.
Detached ADUs, attached ADUs and garage conversions across the Bay Area. Design, engineering, permits and construction by one team.
Prefer to talk? Call (510) 453-0400
Pleasanton · Mountain View · San Mateo · Fremont
Recent ADUs
A few of our 50+ successful projects, each with its city and size.
ADU models
Start from one of our models
Six layouts from 450 to 1,200 sq ft. Change what you want, and we design it for your lot.
1 Bed ADU 450
450 sq ft · 1 bed · 1 bath
Typically $164k - $212k
See the layout
1 Bed ADU 600
600 sq ft · 1 bed · 1 bath
Typically $219k - $282k
See the layout
2 Bed ADU 750
750 sq ft · 2 bed · 1 bath
Typically $274k - $352k
See the layout
2 Bed ADU 900
900 sq ft · 2 bed · 2 bath
Typically $328k - $423k
See the layout
3 Bed ADU 1100
1,100 sq ft · 3 bed · 2 bath
Typically $402k - $517k
See the layout
3 Bed ADU 1200
1,200 sq ft · 3 bed · 2 bath
Typically $438k - $564k
See the layout
Images are 3D renderings of the base designs. Final plans are drawn for your lot after the site visit.
Under a minute each
What to know before you build
Short explainers: where to start, why one team matters, what to check at framing, and how a garage becomes an ADU.
What we build
Three kinds of ADU
Not sure which fits your lot? We look at your property and tell you what can go where.
Detached ADU
A separate small home in your backyard, with its own kitchen, bathroom and entrance. A common choice for rental income.
Attached ADU
Built onto your house, with its own entrance and kitchen. A good fit when the backyard is small.
Garage conversion
Turns an existing garage into a full home, with a kitchen, bathroom and living space.
One team
What’s included
Design, engineering, permits and construction are planned by one team from day one. Licensed crews do the trades, and we manage every one of them.
Included in your price
Design with renderings and a detailed materials list
Architectural plans and structural engineering
Title 24 energy calculations, required in California
Permit application, answering the city’s questions, and final approval
Construction, with every crew (framers, electricians, plumbers and the rest) managed by us
All city inspections, scheduled and attended
Final sign-off and site cleanup
Not included: city permit fees, PG&E connection fees, and extra inspections some cities require from outside inspectors.
You’re never the middleman.
- Designed to be builtOur designers, engineers and builders plan together, so your drawings use standard sizes and materials.
- Questions solved on siteWhen the crew needs the engineer, we call directly. You never pass messages between companies.
- One team owns the resultIf something comes up, it’s ours to fix. There’s no one else to point at.
Pricing
What an ADU typically costs
$365 - $470
per square foot
That includes design, engineering, permits, construction and a finish allowance of about $20,000. Choose custom finishes and the allowance goes toward them; anything above it is added as you choose.
Example: a 600 sq ft ADU comes to about $219,000 - $282,000, plus city permit and PG&E fees.
Your exact number comes after we see your property, and it is locked in your contract.
Two ways to finish
What moves the price
Size, access to your backyard, site work (preparing the ground and running utilities), your finish choices, and what your city requires.
Why city and PG&E fees are separate
You pay them directly to the city and to PG&E, and neither can be priced exactly up front. We run the utility lines as far as we’re allowed, and PG&E makes the final connection. What they charge depends on what their crew needs to do, which can be more if the connection runs under a street.
How payments work
- $1,000Deposit to start
- DesignDesign and engineering paid in stages as the plans are completed
- BuildConstruction paid in milestones, each one only after that work is done
- FinishFinal payment after the city signs off and we’ve fixed everything on the final walk-through list
Timeline
A typical ADU takes under a year
City approval takes time, so starting the paperwork early means you can build as soon as you’re ready.
- 01Design and engineering · up to 2 months
Plans, renderings, engineering and a materials list, built around your lot and budget. The full budget is priced and scheduled before we break ground, so the money lasts to the finish.
- 02City approval · 2 to 3 months
We send the plans to the city, answer every question the city sends back, and resubmit until your permit is approved.
- 03Construction · 3 to 5 months
We manage every crew and book each city inspection while the work is finishing, so the site isn’t left waiting on the city’s calendar.
- 04Move in · long-term warranty
Final inspection, final walk-through, and a long-term warranty on labor and materials, written in your contract.
Working with Loona
What to expect while we build
- One point of contactFrom first drawing to move-in, one person answers your questions.
- Updates every week, with photosPlus a note after every inspection and milestone, so you know where your project stands without asking.
- Your private project hubPhotos, inspection reports, permits and every document in one place online, updated as the work happens. Open it anytime.
- Payments you can see comingThe hub shows every payment made and when, and which milestone payment is next, so you can plan ahead.
- Questions answered the same business dayCall, text or email.
Payment schedule
- DepositPaid
- Design and engineeringPaid
- FoundationPaid
- FramingNext
- Plumbing and electrical (inside the walls)Upcoming
Reviews
What our clients say
“Owning an older home means unexpected issues always come up, but Eric and his team never left us to figure things out alone. They were responsive, supportive, and always had solutions.”
“Great experience with Loona Construction, especially Ed and Eric. They helped me with literally everything on my project: design, plans, engineering, permits, inspections, materials…”
“Loona Construction’s bid was the highest I’ve got, but after the completion of the job, I understood why, and I’m sure that the money spent on the project was worth every penny.”
FAQs
ADU questions
Something else on your mind? Call (510) 453-0400, Monday to Friday, 9am to 5pm.
Typically $365 - $470 per square foot. That covers design, engineering, permits, construction and a finish allowance of about $20,000. A 600 sq ft ADU comes to about $219,000 - $282,000, plus city permit and PG&E fees. Your exact number comes after we see your property, and it is locked in your contract.
It depends on the project, but a typical ADU takes under a year from first drawing to move-in: up to 2 months for design and engineering, 2 to 3 months for city approval, and 3 to 5 months of construction. Custom designs and changes during design take longer.
Most single-family lots in California can have one. Lot size, your city’s rules and how far it must sit from your property lines decide what fits. We check your lot before you commit to anything.
Yes. Many clients choose a custom design and pick every finish. The allowance of about $20,000 goes toward what you choose, and you pay the difference. For rentals, our standard package (vinyl plank floors, new LG appliances, solid cabinets and quartz countertops) is a popular choice.
City permit fees, PG&E connection fees, and extra inspections some cities require from outside inspectors. You pay them directly, and none of them can be priced exactly before the city and PG&E review your project.
Your price is set in the contract, based on the approved plans and a detailed scope of work. It changes only if you ask for a change, or if we find something nobody could see before work started, like a problem under the ground. Either way, you get the new price in writing and approve it before any work is done.
Yes. After our first meeting, if we’re moving forward together, we can arrange a visit to an active job site. Before you sign, we can also put you in touch with a past client.
Yes. Every project comes with a long-term warranty on labor and materials, written in your contract. We carry general liability insurance and workers’ compensation, stated in every contract.
Service areas
ADUs in your city
Our office is in Newark. Choose your city for local details.
Next step
See what you can build on your lot.
We review every request within 1 business day. If it’s a project we take on, we call you to talk through your lot, your city’s rules and a rough budget. There’s no cost to find out.
Or call (510) 453-0400, Monday to Friday, 9am to 5pm.
