Home addition builder in San Mateo
More room for your San Mateo family, without moving out.
Growing family, same address. We design your addition, get it approved by the City of San Mateo and build it, 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
The City of San Mateo sets how close an addition can come to your property lines and how tall it can be. We check your lot against those rules 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. They depend on your project, 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.
Pleasanton · Sunnyvale · Fremont · San Jose
Family ADUs we’ve built near San Mateo
Separate homes we built for parents, grown children and growing families, by the same team and process that build our additions.
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.
Family ADU with game room
630 sq ft · 2 bed · 1 bath
2-bedroom ADU for parents
672 sq ft · 2 bed · 1 bath
Family ADU with French doors
749 sq ft · 2 bed · 2 bath
Poolside family ADU
1,000 sq ft · 2 bed · 2 bath
Want to see our work in person? After our first meeting, we can arrange a visit to an active job site. Before you sign, we can put you in touch with a past client.
The short version
An addition with Loona, in four lines
Typically $365 - $470 per sq ft, the same range as our ADUs, for design, engineering, permits and construction. Your exact price comes after we see your home, and it is locked in your contract.
How pricing worksOne 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.
See the detailsAn addition makes your house bigger. An ADU is a separate home. We check what your lot allows for both.
Compare the twoHow 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
Addition questions from San Mateo homeowners
Something else on your mind? Call (510) 453-0400, Monday to Friday, 9am to 5pm.
More addition questionsYes. We build in San Mateo and across San Mateo County. Our office is in Newark.
Yes. A second-story addition adds bedrooms without giving up the yard. We engineer how the new floor sits on your house and check what the City of San Mateo allows before you commit to anything.
If the family wants to live together, an addition usually fits. For privacy or rental income, an ADU does. We check what the City of San Mateo allows for both before you commit to anything.
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.
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.
Yes. Many families add on and remodel together. We design both at once, so it’s one plan, one team and one schedule.
Nearby
Additions in nearby cities
Next step
See how much space you can add to your San Mateo home.
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.
