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
Westminster is one of the easiest cities in Orange County to add an accessory dwelling unit, and most homeowners here own a 1950s or 1960s ranch on a lot between 6,000 and 7,000 square feet that can comfortably hold a detached unit without sacrificing the yard. We’re Sutton ADU Builders, and we’ve built our home in this kind of work: mid-century lots, 100-amp panels, and ADUs designed for multigenerational living. If you’re wondering what a detached ADU will actually run in Westminster, plan on $180,000 – $320,000 for a standard one-bedroom before site work. Call (562) 317-7042 for a free estimate and we’ll give you a written price before anything starts.
Why Westminster Homes Are Different
Westminster’s housing stock leans heavily to single-story stucco ranch homes built between 1955 and 1975. That’s actually good news for ADUs. Most lots have the room, and because so many houses are one story, sight-line and setback issues tend to be simpler than in cities with mixed two-story infill. A setback, by the way, is the required gap between your new structure and the property line, and Westminster’s ordinance is more forgiving on side-yard and alley-facing placements than most of its neighbors.
Two things catch people off guard. First, the service panel. A large share of Westminster homes still run on 100-amp panels from the 1960s, and that is rarely enough for a new ADU with air conditioning, a kitchen, and modern appliances. You’ll often need a full panel upgrade to 200 amps, not just a small subpanel tapped off the old one. Second, the climate. Westminster’s Mediterranean weather means construction can run year-round, but the summer heat is real. An uninsulated garage conversion becomes an oven by July. We insulate and ventilate every conversion like it’s going to be lived in full-time, because it will be.
Our Main Westminster Services
Westminster homeowners call us most often about three projects: detached ADUs in the backyard, home additions that expand the original footprint, and room additions that convert underused space into livable square footage. Each path has different permit and pricing realities in Westminster, so we’ve given each one its own page.
Home Addition Contractor in Westminster
A home addition in Westminster usually means extending out from the back or side of a mid-century ranch. These jobs touch the original roofline, foundation, and often the existing electrical and plumbing rough-in, so the permit path runs through the city’s plan-check process. Many of these projects start because a family needs a larger kitchen, a true primary suite, or dedicated space for aging parents without giving up the yard. We price the work upfront and send the name and photo of every crew member before they arrive. Full details are on our Home Addition Contractor in Westminster page.
ADU Builders in Westminster
Westminster’s ADU ordinance is unusually permissive for a dense Orange County suburb, and it allows the kind of side-yard and alley-facing units that many other cities reject. That matters here because so many Westminster homeowners come from multigenerational households and want a unit with its own entrance and no shared walls. We help you sort detached new builds from garage conversions and prefab options like Abodu and Plant Prefab. Get the full breakdown on our ADU Builders in Westminster page.
Room Addition Contractor in Westminster
A room addition in Westminster often converts an oversized garage, a covered patio, or dead space beside the house into a bedroom, office, or rental. These projects move faster than full additions because the slab and roofline often already work in your favor. The catch is electrical: many Westminster garages were never wired for living space, so panel upgrades and subpanel work are common here. We’ll tell you exactly what’s needed and lock the price before work begins. See our Room Addition Contractor in Westminster page for specifics.
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 regularly with our brands including Abodu, Plant Prefab, and Tuff Shed structures, plus James Hardie exterior systems. We know which product lines suit Westminster’s lot sizes and which ones make sense for garage and Tuff Shed conversions. Turnaround on parts and panels is straightforward because we keep the common stock local.
Pricing for ADU Company in Westminster, CA
| Service | Typical range in Westminster |
|---|---|
| Detached ADU (1-bedroom, standard finishes) | $180,000 – $320,000 |
| Garage conversion to ADU | $120,000 – $220,000 |
| Home addition (400 – 800 sq ft) | $160,000 – $380,000 |
| Room addition (single room, 150 – 300 sq ft) | $70,000 – $150,000 |
| Electrical panel upgrade (100-amp to 200-amp) | $3,500 – $7,000 |
| Site work, foundation, and utility trenching | $15,000 – $40,000 |
| Permit fees and plan-check | $5,000 – $15,000 |
| Insulation and ventilation package for garage conversion | $8,000 – $18,000 |
What pushes price up in Westminster specifically is panel age and lot access. A 1960s panel that needs a full 200-amp upgrade adds real cost, and a narrow side-yard or alley-fed lot can make equipment access more involved than a flat backyard pull. Every Westminster project gets a written price before work starts, with no surprise invoices later.
Neighborhoods We Serve in Westminster
We cover all of Westminster, from the older tract neighborhoods north of Westminster Boulevard down to the neighborhoods along the 405 and into the Little Saigon area. Most of our Westminster jobs are within a short drive, and scheduling is coordinated through our Los Angeles office, with crews serving Westminster locally.
- Little Saigon area
- North Westminster tracts near Bolsa Avenue
- Neighborhoods along Westminster Boulevard
- Areas near the 405 corridor
- South Westminster along the Santa Ana border
Service Area – Cities Near Westminster
In addition to Westminster, our crews regularly work in nearby cities including Huntington Beach, CA, Stanton, CA, Hawaiian Gardens, CA, and Signal Hill, CA. If you’re on the edge of Westminster, call (562) 317-7042 and we’ll tell you exactly which crew covers your street.
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
Scheduling an initial site visit in Westminster typically happens within a few days of your call. Call (562) 317-7042 and a live person answers, day or night. We’ll set a time for a walkthrough, then send the name and photo of the person coming before they arrive.
Some Westminster homes sit in HOAs, especially in newer pocket developments, and CC&Rs can restrict placement even when the city’s ordinance allows it. We check your specific address against city code and any HOA rules before we quote, so you’re not surprised mid-project.
No. The written price you sign is the price you pay unless you request a change to the scope. Every Westminster project follows the Threshold Standard: a written price before work begins and a 365-Day Done Right Promise covering workmanship for a full year after completion. Call (562) 317-7042 and we’ll walk you through sample Westminster pricing by phone.
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
"Itemized estimate with allowances laid out. Final cost was within a hair of the quote."
- Naomi R."They handled the drawings and the permit paperwork for us. All I had to do was pick the finishes."
- Rosa M."Insulated the walls and ceiling properly. It stays comfortable even in July."
- Tamika W.
