ADU builder in San Mateo
Your San Mateo ADU, handled by one team.
Detached ADUs, attached ADUs and garage conversions in San Mateo. Design, permits and construction by one team, with every licensed crew managed by us.
Prefer to talk? Call (510) 453-0400
Building in San Mateo
What the City of San Mateo decides, and what we handle
California law allows an ADU on most single-family lots. The City of San Mateo sets the local details, like how far it must sit from your property lines and how tall it can be. We check your lot against them before you commit to anything.
We submit the plans to the City of San Mateo, answer every comment the city sends back, and resubmit until your permit is approved.
Permit fees are set by the City of San Mateo and paid directly to the city. PG&E connection fees are paid to PG&E. Neither can be priced exactly up front, so they are not part of our price.
The City of San Mateo inspects the work at each stage. We book each inspection as the work finishes, so the site keeps moving.
San Mateo is in San Mateo County. Our office is in Newark. We also work in Redwood City, Palo Alto and Mountain View.
Mountain View · San Jose · Pleasanton · Fremont
ADUs we’ve built in San Mateo and nearby
On this site you’ll find 5 finished projects in San Mateo: 1 ADU, 2 kitchens, 1 bathroom and 1 full house remodel. Nearby, we’ve also finished 1 ADU in Mountain View.
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.
The short version
An ADU with Loona, in four lines
$365 - $470 per sq ft, including design, engineering, permits, construction and a finish allowance of about $20,000.
See full pricingOne team handles design, engineering, the city approval and construction, and manages every licensed crew.
See what’s includedA $1,000 deposit, then milestone payments, each one only after that work is done.
How payments workDetached ADUs, attached ADUs and garage conversions.
Compare the threeHow long it takes
Approval by the City of San Mateo is the longest wait before construction, so starting the paperwork early means you can build as soon as you’re ready.
Check my lot and budgetWorking 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 from San Mateo homeowners
Something else on your mind? Call (510) 453-0400, Monday to Friday, 9am to 5pm.
More ADU questionsYes. We build in San Mateo and across San Mateo County. Our office is in Newark.
Most single-family lots in California can have one. The City of San Mateo sets the local details, like how far it must sit from your property lines. We check your lot against them before you commit to anything.
They are set by the City of San Mateo, paid directly to the city, and depend on your project, so no one can price them exactly up front. PG&E connection fees are separate for the same reason.
Typically 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.
Nearby
ADUs in nearby cities
Next step
See what you can build on your San Mateo 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.
