Custom modular projects
Studios, offices and multi-level builds, made in our factory.
Free consultation · no obligation · factory in Lathrop, CA
Our work
Custom projects we have built
Real photos from our custom modular builds — in the factory, on the crane and finished on site.
How it works
From idea to installed — one team
Consultation
Tell us what you want to build, where and how you'll use it.
Design & price
We sketch the layout and send a price for your project in writing.
Permits
Custom projects need city approval — we prepare plans and handle the submittal.
Factory build
Steel modules are built and finished in our Lathrop factory.
Delivery & install
Modules arrive by truck and are set in place by crane, then connected and inspected.
Custom project questions
More in our All Models, or call (209) 214-6845.
What can you build as a custom project?
Stacked multi-level units, studios, offices and storage built from steel modules — see the photos above. Tell us your use and site and we'll tell you what's possible.
How much does a custom project cost?
It depends on size, layout and site. After a consultation we send a price for your project in writing.
Do custom projects need a permit?
Yes — custom projects need city approval. We prepare the plans and handle the submittal.
Where are they built?
In our factory at 17100 S Harlan Rd, Lathrop, CA. You can visit by appointment.
Do you also have standard ADU models?
Yes — from the Backyard Studio to the 2 Bedroom ADU, with all-in prices fixed in writing. See All Models.
Free · no obligation
Have a custom project in mind?
Tell us what you want to build and where. We'll talk it through, check your site and send a price for your project in writing.
Factory in Lathrop, CA · visits by appointment
Photos: Bay Modular custom projects. Custom projects require city approval; scope and price are confirmed in writing. Updated October 2026.