A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in Westminster, CA
Fielding ADU Builders handles ADU construction, garage conversions, and room additions in Westminster, CA. Most Westminster homes we walk were built in the 1950s and 1960s as single-story ranch houses on flat, rectangular lots, which means the two things that decide whether an ADU makes sense here are the size and position of the existing garage and the distance from the back wall of the house to the rear property line. The city runs on a standard 20-foot rear setback in most residential zones, and a detached ADU under 16 feet in height can often fit within that without a variance. That is the kind of lot math we do on the first visit, before anyone starts drawing. Call (361) 315-4177 and we will walk the lot with you.
Why Westminster Homes Are Different
Westminster sits on flat ground a few miles inland from Huntington Beach, so the construction issues here are less about slope and drainage and more about age. The housing stock is dominated by postwar subdivisions: Little Saigon stretches across the west side, the blocks around Bolsa Avenue and Goldenwest Street are dense with 1960s ranch homes, and the neighborhoods near Westminster Boulevard and Beach Boulevard hold a mix of original single-story houses and mid-century duplexes. Many of these homes were framed with 2×4 walls and sit on raised foundations, which matters when we are tying a room addition into the existing roofline or running new electrical from a 100-amp panel that was installed when the house was built.
Two other Westminster realities shape nearly every ADU job here. First, the city’s permit office expects plans to show the property’s exact lot coverage ratio before they will approve a detached unit, so we survey the lot and calculate impermeable surface area as part of the written price, not as a surprise later. Second, a good number of Westminster homes are in HOAs, particularly the newer pockets east of the 405, and while California law limits an HOA’s ability to block an ADU, the HOA still controls things like exterior paint color and fence height. We flag that early so you are not fighting a design review board after the plans are done. All of it is work we have done in Westminster, and all of it goes into the price before we start.
Our Main Westminster Services
Westminster homeowners most often call us for three jobs: adding a bedroom or living space onto the existing house, converting an attached or detached garage into a dwelling unit, and building a new detached ADU in the backyard. Each one has its own page with local pricing and the specific permit path for Westminster.
Room Addition Contractor in Westminster
A room addition in Westminster usually means extending off the back of a ranch house, and the main local condition is the shallow rear lot depth on older blocks. We tie the new foundation to the existing slab or raised floor, match the roof pitch so the addition does not read as a bolt-on, and run the permit through Westminster’s building division before the first stud goes up. Reed Calloway walks every addition site personally before we price it. See Room Addition Contractor in Westminster for the full breakdown.
Garage Conversion Contractor in Westminster
Garage conversions in Westminster work best on the original 1960s detached garages that sit at the rear of the lot, because the structure is usually sound and the access alley is already there. The local wrinkle is the slab: many of these old garage slabs were poured without a vapor barrier or perimeter footing, so we often pour a new interior slab and add a stem wall before framing interior walls. Details and current Westminster pricing are on the Garage Conversion Contractor in Westminster page.
ADU Builders in Westminster
A detached ADU in Westminster is the most involved of the three, and it is the job where the choice of build method matters most. We have built conventional stick-frame units with James Hardie siding in Westminster backyards, and we have also delivered prefab units from companies like Abodu and Cover where the lot access and budget pointed that direction. The full ADU process for Westminster, including the number we quote per square foot, is on the ADU Builders in Westminster page.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Brands We Service in Westminster
We work with the major prefab ADU platforms Westminster homeowners are already researching: Abodu, Cover, and Dvele, plus conventional builds using James Hardie siding. For Westminster, the local factor is usually lead time, and we plan material delivery around the permit issuance date so nothing sits in the yard. See our brands for the full list.
Pricing for ADU Company in Westminster, CA
| Service | Typical range in Westminster |
|---|---|
| Detached ADU (conventional build) | $310 – $410 per sq ft |
| Prefab ADU (Abodu, Cover, Dvele) | $280 – $380 per sq ft installed |
| Garage conversion to ADU | $190 – $270 per sq ft |
| Room addition (bedroom/bath) | $250 – $350 per sq ft |
| Site prep and grading | $4,000 – $12,000 |
| Foundation work (new slab/stem wall) | $15,000 – $30,000 |
| Electrical panel upgrade (200-amp) | $4,500 – $8,500 |
| Plumbing rough-in for new bath/kitchen | $9,000 – $18,000 |
| Drywall, paint, and trim package | $12,000 – $22,000 |
| Permit fees (Westminster city + school district) | $6,000 – $14,000 |
The thing that pushes an ADU bid up in Westminster is almost always the site work: old sewer lines that need replacing, a garage slab that has to be demoed and repoured, or a main panel that cannot carry the new load. That is why our price is written after a site visit, not before. You get one number in writing, and the number you approve is the number on the final invoice, backed by the 365-Day Done Right Promise.
Neighborhoods We Serve in Westminster
We cover the entire city of Westminster, CA. The neighborhoods below are the ones we are in most often, but if you are inside city limits and not listed, call and we will come out.
- Little Saigon (around Bolsa Avenue and Brookhurst Street)
- Westminster Village (near Westminster Boulevard and Goldenwest Street)
- Midway City-adjacent blocks east of Beach Boulevard
- Neighborhoods along Trask Avenue and Hazard Avenue
- East Westminster / HOA pockets near the 405
Typical response for a Westminster estimate visit runs about one to two business days from your call, depending on how full the schedule is that week.
Service Area – Cities Near Westminster
Fielding ADU Builders serves Westminster and the surrounding Orange County cities. If you live just outside the city line, we work in Midway City, CA, Huntington Beach, CA, Stanton, CA, and Fountain Valley, CA as well. Same written pricing, same guarantee, same crews.
Serving Westminster, CA - Our Local Coverage Area
We’re based in the Westminster area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs About ADU Company in Westminster
Most Westminster estimate visits happen within one to two business days of your call. Reed Calloway does the first walk-through himself on ADU and addition projects. Call (361) 315-4177 and we will set a day and a two-hour window.
California state law prevents HOAs from banning ADUs outright, but an HOA in Westminster can still require its own design review for exterior color, fencing, and roofline. We identify whether your association has a review process on the first visit and build that timeline into the written schedule. Call (361) 315-4177 if you want us to check your specific HOA’s requirements before you commit to plans.
Yes. We prepare the plans, submit them to Westminster’s building division, pull the permit, schedule inspections, and close out the permit. The permit fees show up as a line item in your written price. Estimates are free. Call (361) 315-4177 and we will walk the lot before you spend a dollar.
If you own a home in Westminster and you are weighing an ADU, a garage conversion, or a room addition, start with a site visit. Homeowners who call get a specific number in writing, not a vague estimate. Phone (361) 315-4177, ask for Reed, and we will come look at the lot.
What happens when you call
- 1A real person answersNo phone trees - talk to a local adu pro.
- 2You get an upfront price rangeHonest numbers before anyone is dispatched. No surprises.
- 3We come out and measureLicensed & insured, at a time that suits you - the visit and the quote are both free.
- 4You get the price in writingLine-itemed, yours to keep, and nothing starts until you say go.
What Westminster Customers Say
"Solid job. Cabinet delivery was a week behind but they worked around it."
- Ben G."Insulation, drywall, and finishes were all well done. Feels like part of the house."
- Pete O."Built a detached ADU behind our house. The builder is a veteran and runs the site like a platoon: schedule posted, crew on time, everything labeled. Finished within a few days of the date."
- Ken W.
