Built indoors, in our Lathrop factory
Every Bay Modular home is fabricated under one roof in Lathrop, CA — steel, framing, insulation, windows and finishes — then delivered to your backyard nearly complete.
Our Lathrop facility has been fabricating steel containers for over a decade.
Structural welding is done by an AWS-certified fabrication team.
Quality processes are certified to international ISO standards.
Our plans carry California HCD approval as factory-built housing.
Why a factory
The quality of a factory. The feel of a real home.
On a schedule, indoors, and to the same standard every time.
Your site and your home, at the same time
Bay Modularparallel
Typical site-builtone after the other
Illustration only — your timeline depends on your lot and permits.
Built faster
Site preparation and building construction happen at the same time — not one after the other — because your home is built off-site.
Protected from the weather
Rain, heat and wind don’t stop work or soak materials. Every module is framed, insulated and finished indoors.
Checked at every step
Factory work follows documented quality procedures, so every weld, wall and window is inspected before it ships.
Less disruption at home
Most of the noise, dust and trucks stay at the factory. Your neighbors see a short install, not months of construction.
Recycled steel
We repurpose shipping containers, reducing waste while giving your home a durable, fire-resistant steel structure.
Inside the factory
From raw steel to a finished home
Every step happens under one roof — and you can see it for yourself.
Steel & welding
Containers are cut, reinforced and welded into modules by certified welders.
Framing & insulation
Walls are framed and insulated with spray foam for comfort year-round.
Windows & doors
Openings are cut and fitted with energy-efficient windows and doors.
Kitchens & finishes
Cabinetry, appliances, flooring and finishes are installed before delivery.
Paint & coatings
Modules are painted in our paint booth with durable exterior coatings.
Delivery & install
Finished modules travel to your site and are set on the foundation by crane.
Visit us
See your future home being built
- Walk through a finished model and feel the space
- See modules being built at different stages
- Compare finishes, materials and options in person
- Ask our team about your lot, permits and budget
Lathrop, CA 95330
by appointmentHours in Pacific time
Can I visit the Bay Modular factory?
Yes. Our factory in Lathrop, California is open for tours Monday to Friday, 6 am – 5 pm, by appointment. Book a tour and we’ll confirm a time.
Where is the factory?
17100 S Harlan Rd, Lathrop, CA 95330 — in California’s Central Valley, east of the Bay Area.
Is a factory-built ADU as strong as a site-built one?
Yes. Our homes use a steel container structure that is durable, waterproof, fire-resistant and earthquake-rated, and our plans carry California HCD approval.
Does a factory-built ADU still need permits and inspections?
Our HCD-approved units don’t need additional local plan check for the structure itself. Site work — foundation and utility connections — is still permitted and inspected locally.
How does a factory build save time?
Your site is prepared while your home is being built in the factory, so the two happen in parallel instead of one after the other.
Ready to start?
See it for yourself — then start yours
Book a factory tour, or send your address and our team will get back to you about next steps.