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
Fielding ADU Builders handles ADU construction, garage conversions, and room additions in Montclair, CA, with a written price before any work starts and a one-year guarantee on every project. Montclair’s housing stock runs heavy on mid-century single-family homes on compact lots, which makes setback rules and utility routing the two big variables on most jobs here. If you’re weighing an ADU against a room addition, call (361) 315-4177 and we’ll walk you through what fits your lot.
Why Montclair Homes Are Different
Most Montclair homes were built between the 1950s and 1970s, and the typical lot sits flat with a two-car garage that eats up most of the rear yard. That changes the ADU conversation. On a 5,000-square-foot lot, a detached backyard unit usually means squaring off against setback requirements, and in Montclair that often triggers a setback variance: the city’s written permission to build closer to the property line than the standard rule allows. We handle that paperwork as part of the permit package.
The older housing stock also means galvanized plumbing and 100-amp electrical panels are common. A garage conversion in Montclair frequently needs a panel upgrade before drywall goes up, and we flag that in the written price on day one, not as a change order mid-job. Summers here run hot, so insulation and HVAC sizing for any new living space get more attention than they would closer to the coast.
Our Main Montclair Services
Montclair homeowners call us most often for two jobs: adding square footage to the existing house, or converting underused garage space into rentable or family housing. Each service has its own Montclair page with pricing and project detail.
Room Addition Contractor in Montclair
A room addition in Montclair means tying new framing into a 50-to-70-year-old structure without creating a visible seam or a drainage problem. We match rooflines, run new electrical back to the panel, and pull permits through the city so the addition is on record when you sell. Most Montclair additions stay single-story, and the flat lots make foundation work straightforward. Room Addition Contractor in Montclair covers costs, timelines, and what the permit process looks like here.
Garage Conversion Contractor in Montclair
Montclair garages are usually attached, which makes conversion faster than a detached build but puts more pressure on fire separation and ventilation details. We handle the full scope: raising or replacing the floor, upgrading the panel if needed, insulating, and finishing the space to match the main house. Garage Conversion Contractor in Montclair has line-item pricing and a breakdown of the permit path.
ADU Builders in Montclair
For a backyard ADU in Montclair, we work with prefab platforms like Cover and Dvele where the lot allows, and conventional construction with James Hardie siding where a custom footprint makes more sense. Reed Calloway reviews every Montclair ADU plan before we put a price in writing. ADU Builders in Montclair details detached units, garage-top units, and the prefab options available here.
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 with Cover and Dvele for prefab ADUs in Montclair, and Boxabl when the site calls for a compact, cost-driven unit. Parts for conventional builds, including James Hardie siding and Tuff Shed-style structures, come through our Inland Empire supply chain. Our brands page lists the full lineup and what each platform does best.
Pricing for ADU Company in Montclair, CA
| Service | Typical range in Montclair |
|---|---|
| Detached ADU (prefab, 400 – 600 sq ft) | $180,000 – $260,000 |
| Detached ADU (conventional, 400 – 600 sq ft) | $220,000 – $310,000 |
| Garage conversion ADU (attached, 400 – 500 sq ft) | $120,000 – $180,000 |
| Garage-top ADU (new build above existing garage) | $270,000 – $350,000 |
| Junior ADU (interior conversion, up to 500 sq ft) | $90,000 – $140,000 |
| Single-car garage conversion to living space | $70,000 – $110,000 |
| Two-car garage conversion to living space | $100,000 – $150,000 |
| Room addition (200 – 400 sq ft, single-story) | $90,000 – $160,000 |
| Primary suite addition (300 – 500 sq ft) | $130,000 – $210,000 |
| Second-story addition (400 – 600 sq ft) | $200,000 – $300,000 |
What pushes a Montclair price up: panel upgrades on older homes, sewer lateral work when the existing line is cast iron, and any setback variance the city requires. Whatever the number is, it goes in writing before we pull the first permit, and that number is the one on the final invoice.
Neighborhoods We Serve in Montclair
We cover all of Montclair, including the areas south of the 10 freeway near Mission Boulevard, the older blocks around Benito Street, and the neighborhood clusters north of Brooks Street. Crews coordinate from the Inland Empire office, and most Montclair estimates happen within a few days of your call.
- Mission Corridor area
- Kingsley Street neighborhood
- Benito Street blocks
- Ramona Avenue area
- Brooks Street corridor
Service Area – Cities Near Montclair
Fielding ADU Builders serves the full Pomona Valley and the surrounding Inland Empire. If you’re in a neighboring city, each of these pages has local pricing and permit detail: Claremont, CA, Ontario, CA, Pomona, CA, and La Verne, CA.
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
After you approve the written price, we typically begin the permit drawings within one week. Montclair’s permit review times vary by project type, but most ADU plans clear within 4 to 8 weeks. Call (361) 315-4177 for a free estimate and a realistic start date for your lot.
If your neighborhood has an HOA, you need their written sign-off before we submit to the city. Montclair also applies state ADU law, which restricts how much HOAs can block a unit. We prepare the drawings and documentation both parties require.
We handle it end to end: drawings, submittal, corrections, and inspections. You make one call to (361) 315-4177, approve the written price, and we run the permit through the city until the final inspection passes.
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
"Room addition over the back patio. Framing is square, windows are tight, and the roofline matches."
- Danny L."Foundation and slab poured on schedule. Crew kept the yard orderly."
- Marian J."Garage conversion with a new bath and kitchenette. Permit was handled by them. Inspection passed first time."
- Sheila B.
