A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in Montclair, CA
Adding an ADU, a room addition, or a full home addition in Montclair is different from doing it in a newer master-planned suburb. The housing stock here skews toward mid-century single-story homes on lots that were platted decades ago, which means setbacks, utility easements, and lot coverage rules often shape the design before anything is drawn up. Our work starts with a straight answer about what your lot can actually accommodate. If you’re weighing an ADU in Montclair, call (472) 248-8213 and we’ll walk you through what’s realistic before you spend a dollar.
Why Montclair Homes Are Different
Montclair’s residential streets are full of homes built between the 1940s and 1970s, and that age shows up in the work in ways that matter. Older panels, galvanized plumbing, and shallow foundations are common, so an addition or ADU often means upgrading the existing structure to meet current code before we can tie in new square footage. The lots themselves are generous by Southern California standards, but many are long and narrow, which pushes the buildable footprint toward the back of the property. That’s actually good news for a detached ADU. Montclair sits in the Pomona Valley, so we’re working with hot, dry summers and cool winters – nothing extreme, but enough that insulation choices and window orientation genuinely affect how comfortable a new ADU feels in August. The city treats ADUs as an allowed use on most residential lots under state law, though Montclair’s planning department still reviews setbacks, parking replacement rules, and utility connections on every permit. We handle that paperwork as part of the job.
Our Main Montclair Services
Most Montclair homeowners call us about one of two things: adding a detached ADU to a backyard, or expanding the footprint of the existing house. Here’s what each involves on the ground here.
Home Addition Contractor in Montclair
Home additions in Montclair usually mean a master suite bump-out, a larger kitchen, or a new family room that opens to the backyard. On the mid-century lots here, the practical reality is that setbacks and lot coverage rules drive the design, so we start every addition with a site review before pricing. We also look at the existing foundation and roofline, because tying a new addition into a 1960s slab or truss roof changes cost and schedule. If you’re planning a Home Addition Contractor in Montclair, expect the conversation to start with square footage and setback math, not a brochure.
ADU Builders in Montclair
Detached ADUs are the most common request we get in Montclair, and the city’s typical lot shape works well for them. A long rear yard with alley or side access means a 500 to 1,200 square foot unit can often be placed without tearing out the existing landscaping. We work with prefab systems where it makes sense – Dvele and Mighty Buildings both have product lines that fit Montclair’s climate and code requirements – but stick-built remains popular for garage conversions and custom layouts. A detailed look at local permitting and pricing is on our ADU Builders in Montclair page.
Room Addition Contractor in Montclair
A room addition is the smaller sibling of a full home addition, and in Montclair it’s often a new bedroom, home office, or a second bathroom added onto an existing hall. These jobs typically attach to the existing roofline and foundation, so we spend time confirming the existing structure can carry the new load. Many Montclair homes from the 1950s and 1960s have roof framing that predates current seismic standards, which sometimes requires modest structural upgrades as part of the permit. For specifics, see our Room Addition Contractor in Montclair 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 Montclair
We work regularly with ADU brands including Cover, Dvele, and Boxabl, and we keep the common parts for those systems accessible through local distribution. Turnaround on brand-specific modules or cladding usually runs a few days to a couple of weeks depending on the product line. Learn more on our brands page.
Pricing for ADU Company in Montclair, CA
| Service | Typical range in Montclair |
|---|---|
| Detached ADU (500 – 800 sq ft, prefab or stick-built) | $180,000 – $320,000 |
| Detached ADU (800 – 1,200 sq ft) | $320,000 – $480,000 |
| Garage conversion to ADU | $140,000 – $260,000 |
| Room addition (single room, attaches to existing house) | $75,000 – $140,000 |
| Home addition (300 – 600 sq ft) | $150,000 – $275,000 |
| Master suite addition | $130,000 – $250,000 |
| Kitchen expansion | $90,000 – $180,000 |
| Bathroom addition | $50,000 – $90,000 |
In Montclair, the biggest price movers are lot access – if we can’t get a mini-excavator into the back yard, costs climb – and the condition of your existing panel and foundation. Whatever the number is, you get it in writing before any work begins, and the 365-Day Done Right Promise covers workmanship for a full calendar year after completion.
Neighborhoods We Serve in Montclair
We work across all residential neighborhoods in Montclair, from the streets north of Arrow Highway to the quieter blocks near Moreno Elementary and the neighborhoods that border the Montclair Place shopping corridor. Our scheduling team coordinates from the Inland Empire office, and crews generally reach any Montclair address without the kind of delays you see in more congested parts of LA County.
- North Montclair near the 210 corridor
- Areas around Ramona Avenue and Central Avenue
- Neighborhoods west of Monte Vista Avenue
- South Montclair near the Pomona border
- Residential streets around Kingsley Street and Mills Avenue
Service Area – Cities Near Montclair
Beyond Montclair itself, we regularly serve homeowners in nearby cities across the Pomona Valley and eastern Los Angeles County line. Our crews are local to the region, which keeps scheduling simple when a project straddles a city boundary or when you’re comparing options in a neighboring market. We work in Claremont, CA, Ontario, CA, Pomona, CA, and La Verne, CA on the same terms: written pricing first, verified crew at the door.
Serving Montclair, CA - Our Local Coverage Area
We’re based in the Montclair 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 Montclair
Plan review for an ADU or addition in Montclair typically runs 2 to 4 months after submission, depending on current department volume and whether the project triggers extra reviews for trees, drainage, or utility upgrades. We prepare and submit the drawings, pull the permits, and coordinate inspections. Call (472) 248-8213 and we’ll give you a realistic timeline for your specific lot.
Standard side and rear setbacks in Montclair are typically 4 feet for a detached ADU, but corner lots, alleys, and utility easements can change that number. We verify setbacks against your specific parcel before pricing so you’re not surprised later. That setback check is part of our free estimate.
Yes. From the first site visit through final inspection, our team manages the full scope: design coordination, permit submission, foundation, framing, MEP rough-in, finishes, and closeout. You get a written price before we start, and the 365-Day Done Right Promise covers what we build for a full year after completion.
If you’re considering an ADU or addition in Montclair, call (472) 248-8213 to schedule a free estimate. We’ll walk you through what’s possible on your lot, give you a written price, and tell you exactly who will be at your door before the crew arrives.
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 Montclair Customers Say
"They handled the drawings and the permit paperwork for us. All I had to do was pick the finishes."
- Rosa M."Every crew member was vetted and carried a badge, which matters when they are around your family for months. Tidy site every day."
- Daniel F."Itemized estimate with allowances laid out. Final cost was within a hair of the quote."
- Naomi R.
