ADU Construction in Westminster, CA
Serhal Builders builds ADUs in Westminster, including detached backyard units, garage conversions, attached ADUs and junior ADUs. Our office is in Fullerton, a short drive away.
Westminster offers a preapproved ADU standard plan program for detached ADUs, so you can skip paying for a brand-new architectural design. As the city puts it, the plans are preapproved, not pre-permitted: you still need a site plan, plans of the existing house and a plan check.
We’re a licensed, veteran-owned general contractor (CSLB #1074208) with more than 31 years in construction, and we’ve built ADUs throughout northern Orange County.
Complete ADU Services in Westminster
One licensed contractor from design and permits to the final inspection.
Detached ADUs
A separate backyard home built from the ground up, with its own entrance, kitchen and bathroom.
Garage Conversions
We turn an existing garage into a full living space, often the most budget-friendly way to add a unit.
Attached ADUs
An addition connected to your home with its own entry, kitchen and bath, so family stays close but independent.
Junior ADUs (JADU)
A unit of up to 500 square feet created inside your existing home, with its own entrance.
Design & Floor Plans
In-house design, plans from our design partner, or your own architect’s plans. We work whichever way suits you.
Permits & City Approval
We prepare and submit the permit package and handle plan-check corrections with the city.
Utilities & Systems
Electrical, plumbing, sewer, water and gas tie-ins planned early so there are no surprises mid-build.
Kitchens, Baths & Finishes
Cabinets, counters, tile, flooring and fixtures, all handled by the same team that remodels full homes.
Solutions & Benefits
Every lot is different. These are the three ways most homeowners add a unit.
Detached ADUs & Garage Conversions
A detached ADU gives you a separate backyard home with its own entry, kitchen and bath. A garage conversion reuses an existing structure and is often the most budget-friendly way to add a unit.
Attached ADUs & Junior ADUs
An attached ADU connects to your home but lives independently. A junior ADU is up to 500 square feet created inside your existing home, a good fit for family members who want their own space nearby.
Plans & Permits Your Way
Use our in-house design, our design partner, or plans you already have. We prepare the permit package, respond to plan-check comments and coordinate inspections until final sign-off.
What Westminster Homeowners Should Know
Our Working Process
Building an ADU in Westminster has more steps than a remodel. Our process keeps it clear and manageable.
ADU Construction in Nearby Cities
We also build ADUs in these Orange County cities:
Frequently Asked Questions
Are ADUs allowed in Westminster?
Yes. Westminster allows ADUs and junior ADUs under its local code and California ADU law. Your lot, utilities and any easements decide which type and size work best.
Does Westminster have pre-approved ADU plans?
Yes. Westminster has a preapproved ADU standard plan program for detached ADUs. We help you decide whether a standard plan or a custom design fits your lot.
Do pre-approved plans mean my ADU is already permitted?
No. Westminster says the plans are preapproved, not pre-permitted. You still need a site plan, plans of the existing house and a plan check before a permit is issued.