ADU builder and home additions in San Jose
A backyard cottage for your parents. A garage that starts paying rent. A second story for the family you have now. Tell us which one, and we coordinate the design, the permits and the build, from first sketch to final inspection.
- CSLB #1050108
- Licensed, bonded and insured
- 1-year labor warranty
Who this is for
- You want a backyard unit or a junior ADU and need someone to build it.
- You have outgrown the house and want to add a room, a primary suite or a second story.
- You would like to know what your lot allows before you spend money on drawings.
Not sure which fits? Room addition vs ADU and ADU vs garage conversion compare them.
San Jose lots hold more than most people think. A detached ADU in the backyard can carry rental income or keep family close. A garage conversion turns dead storage into a real living unit. A room addition gives you the space you've outgrown without leaving the neighborhood you love.
Impact fees, size limits, setbacks and utility connections decide your budget and your timeline. Sometimes the smart move is keeping a unit under the size limit that avoids impact fees. Sometimes it is a garage conversion or a JADU instead of a detached build. We lay out the options before you commit.
How the job runs
- Walk the lot.We look at what you have and tell you what is possible.
- Price in writing.You get a detailed price in writing after the walkthrough.
- Design and permits.We coordinate the design and handle the City of San Jose permitting.
- Build.Foundation, framing, plumbing, electrical and finishes run on one schedule.
- Inspections.We take the project through to final inspection.
What's included
Detached ADUs and guest houses
A freestanding backyard home: rental income, space for parents, a guest house, or the office with its own front door.
Garage conversions
The square footage already exists. We turn a garage full of boxes into a comfortable, code-compliant living unit.
Junior ADUs
A smaller unit carved from your home's existing footprint, often the fastest, most affordable path.
Room additions and second stories
Push the kitchen out, add a bedroom or bath, or build up with a full second story.
Room additions and home additions in San Jose
A room addition grows the house you already live in: a bigger kitchen, a primary suite, an extra bedroom and bath, or a second story. It ties into the existing foundation, roof, plumbing and electrical, so the design has to match the house and the structure has to carry the new load. We coordinate the design, the City of San José permit and the inspections, and build it on one schedule with one written price.
Not sure whether you need an addition or an ADU? Our guide to room addition vs. ADU in San Jose compares the two side by side.
What an ADU or addition costs in San Jose
The main factors are the type of project (garage conversion, junior ADU, detached ADU or addition), its size, the site work and utility connections, the finish level, and City fees. Our ADU cost guide goes through each one for San Jose, and the ADU feasibility guide explains what your lot allows.
Get a real number for this job
We come out, measure, and put a line-item price in writing. Free, and there is no obligation to use us.
- CSLB #1050108 · licensed and insured
- Serving San Jose and the South Bay
Prefer to talk? Call or text (408) 667-4946. Office hours: Monday to Friday, 7 am to 3 pm.
Curious about cost? See our ADU cost guide and garage conversions in San Jose. We work across Los Gatos, Santa Clara, Sunnyvale, and the South Bay.
“David Mirassou and his team did a fantastic job… The team got the job done in just two days and even helped with a few other minor repairs.”
David D. · Yelp
“This company does it all… Always fast, reliable, on budget and quality work… I highly recommend David and his crew.”
Jeff M. · San Jose · Yelp
“The owner David and his workers are very professional and got all the work I needed to get done.”
Sandra L. · San Jose · Yelp
More real reviews on our Yelp page.