Room addition
Enlarge or add a room, adapt to your changing lifestyle and combine existing rooms with new space seamlessly.
Licensed design-build contractor · CSLB #1080660
San Jose Home Addition Contractor
Room and second-story additions that maximize your lot and give your family more space to live. Our designers, architects and engineers plan an addition that matches your home, and our builders bring it to life. One team handles design, permits and construction.
or call (800) 992-5997
★★★★★5.0 Google · 63 reviews
5/5 Houzz · 105 reviews
5/5 Thumbtack · 130 reviews
CSLB #1080660
One team
Everything your addition needs, in one orbit.
Consultation, design, engineering, permits and construction, plus every type of addition we build, handled by the same team.
Consultation
Site review
3D design
Plans
Engineering
Permits
Build
Room addition
Second story
Garage conversion
Master suite
★★★★★5.063 Google reviews
★★★★★5/5105 reviews on Houzz
CSLB #1080660Licensed & insured
5.0 Google · 63 reviews
5/5 Houzz · 105 reviews
5/5 Thumbtack · 130 reviews
CSLB #1080660
San Jose office
One team
We do it all, from design, plans & permits to construction.
Is your home feeling overcrowded? Additions and extensions are often necessary as families grow and more space is needed. Adding to your home can increase your space, make your layout more functional and add value to your property. Our designers, architects and engineers collaborate to create the framework for your new space, and our builders bring it to life, with project management in-house for peace of mind through your home addition.
3D design & floor plansArchitectural plansStructural engineeringPermitsConstructionProject management
ON
Design & engineering
Permitting
Construction
Project management
Additions
The addition that fits your home.
We add rooms, build second stories, convert garages into living space and design ADUs, blending new space seamlessly with your existing home.
Second-story addition
Add a second floor and gain living space without giving up your yard, engineered to match your home.
Garage conversion
Turn a garage into valuable living space, often simpler than building out from the home.
Home gymOfficeMeditation roomGuest room
ADU
A granny flat or in-law unit that adds value to your property and can bring in rental income.
Together with our craftsmanship, ingenuity and high-quality building materials and practices, we combine existing rooms with new spaces seamlessly, so your addition feels like it was always part of your home.
Projects
Additions and expansions we designed and built.
Finished work from our project library, including home additions, master suites, backyard units and garage builds across the Bay Area.
Additions gallery
Home addition · San Jose
Backyard addition
Master suite addition · Sunnyvale
Sunroom enclosure · San Jose
Backyard unit
Backyard cottage
Garage · Redwood City
Full-house remodel · Redwood City★★★★★5.063 Google reviews
Design → Permits → BuildManaged in-house
CSLB #1080660Licensed & insured
How it works
A clear process, from first call to handover.
Consultation, design, permitting and construction are managed by our own team, so you always know what comes next and who to call.
01
Consultation and site review
A free consultation to look at your home, lot, goals and budget, and to review next steps before any commitment.
02
Design & engineering
Our designers, architects and engineers collaborate on the layout, architectural plans, structural engineering and 3D designs, matched to your existing home.
03
Permits
We prepare and submit plans and work with your city or county building department through approval.
04
Build & handover
As a licensed general contractor (CSLB #1080660), we build your addition from foundation to final finishes, then complete final inspection and handover.
Reviews & trust
Trusted by Bay Area homeowners.
Integrity, quality and customer care, in our clients’ words.
5.0
★★★★★
Google · 63 reviews
“I have to say that I worked with several other contractors before and it’s very hard to find a good and reliable one that you can really trust, working with ON Design & Remodeling feels that I found the right one!”
Yelp review
Licensed & insured
Active California General Contractor License CSLB #1080660, with full liability insurance on every project.
5/5
★★★★★
Houzz · 105 reviews
“The crew was very thoughtful when working and passing through our living areas, and the final results came out above our expectations.”
Client testimonial
5/5
★★★★★
Thumbtack · 130 reviews
“The communication and the process went very smooth and I will definitely work with them in future projects that I have.”
Client testimonial
Design, permits & build · one team
Designers, architects, engineers and builders work under one roof, with project management in-house through final handover.
Service areas
Serving the Bay Area from our San Jose office.
1762 Technology Dr, Suite 226, San Jose, CA 95110
FAQ
Frequently asked questions
ON Design & Remodeling designs and builds room additions, second-story additions, master suite additions, garage conversions and ADUs (granny flats or in-law units). We combine existing rooms with new space so the addition matches your home.
Yes. Our designers, architects and engineers collaborate on the layout, architectural plans and structural engineering. We prepare and submit plans and work with your city or county building department through approval, then build as a licensed general contractor (CSLB #1080660).
Yes. Homeowners can book a free consultation so we can look at your home and lot, your goals and budget, and review next steps before any commitment.
We design and build home additions across the Bay Area from our San Jose office (1762 Technology Dr, Suite 226), including San Jose, Palo Alto, Redwood City, San Mateo, Sunnyvale, Mountain View, Fremont, Santa Clara, Cupertino, Los Altos, Los Gatos, Menlo Park and many other cities throughout the South Bay, Peninsula, East Bay and Santa Cruz area.
Adding to your home can increase your living space, make your layout more functional and add value to your property. An ADU can also bring in extra income if you rent it to a tenant.
Yes. We hold an active California General Contractor License (CSLB #1080660) and carry full liability insurance on every project.
Let's build
Planning a home addition?
Book a free consultation and talk to one team that handles design, engineering, permits and construction.
Emailinfo@onremodeling.com
Office1762 Technology Dr, Suite 226
San Jose, CA 95110
San Jose, CA 95110
LicenseCSLB #1080660
Phone(800) 992-5997