Kitchen remodeling
Bathroom remodeling
Home additions & ADU
Roofing
Windows & doors
Driveway & pavers
FenceFree written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
Fast, Reliable General Contractor Across Ontario
Most Ontario homeowners call us after getting three bids that all look the same on paper, but none of them explain what actually happens when a 1960s kitchen wall comes open. A true General Contractor in Ontario isn’t just scheduling subs. We’re the ones who know that a 1962 ranch off the 91762 grid likely has cloth-insulated wiring behind the drywall and a load-bearing header someone notched with a Sawzall in 1987. That’s why we bid inspection-first, write allowances into the contract, and price surprises in writing before we touch another stud. If you’re planning a kitchen, bath, addition, or ADU in Ontario, call us at (855) 473-5620 and we’ll walk the property before quoting.
Why San Bernardino Contractors Is Ontario’s Preferred General Contractor Company
Ontario isn’t a suburb where every house is the same. Drive north of the 60 through 91762 and you’ll pass 1950s tract homes with original framing, then hit newer master-planned pockets south toward 91758 where construction standards shifted completely. Our crews work both ends of that spectrum every month, which means we don’t show up surprised by what’s inside your walls. Homeowners here consistently tell us the same thing: the estimate from another contractor looked cheaper until the change orders started. We write the inspection findings into the bid before you sign, so the number you approve is built on what’s actually behind the drywall, not a guess.
Response time to Ontario matters when you’ve got a bathroom gutted or a garage conversion mid-permit. We’re based in Fontana, minutes from the Ontario border, and our material suppliers along the 10/60 corridor stock everything from GAF roofing underlayment to Grohe rough-in valves, so we’re not waiting on shipments from LA or Orange County when a project hits a snag. Ruben Castillo runs the company and still reviews every Ontario bid personally before it goes out. No subcontractor shuffle. One contractor, every phase, from the roof down to the pavers.
Styles & brands we work with
Licensed General Contractor in Ontario
A Licensed General Contractor in Ontario handles the full build: structural framing, permits, trade coordination, inspections, and final sign-off. In a city where so much of the 1950s-1970s housing stock was built before current code, the license isn’t a formality. It means when the Ontario building inspector fails a rough-in because the original floor joists were undersized, we’re the party accountable for fixing it. Typical costs for a licensed GC’s scope within a remodel run from $14,000-$45,000 for kitchens, $9,000-$28,000 for bathrooms, and $45,000-$130,000 for a full home addition. Those ranges assume the walls come open and we find what’s actually in there, not what the seller’s disclosure said.
Permit and Inspection Navigation
We pull permits before any demolition starts, and we schedule inspections as the city requires them. Ontario’s permit office treats the process as a third-party wall inspection, which is exactly what you want on a postwar tract home. Wires, framing, and waterproofing get looked at by someone without a financial interest in the outcome. That inspection is where cheap bids fall apart.
Written Allowances for What’s Hidden
On older Ontario homes, we build allowances into the contract for specific known risks: outdated wiring, undersized headers, failed shower pans, root-damaged subfloor. Each allowance gets a line in the contract with a defined price range. If we open the wall and find cloth-insulated wire, the framing repair and rewiring goes to you as a written change order with a fixed number, and nothing happens until you approve it. That’s how Ruben’s crews have always run Ontario jobs.
Residential General Contractor in Ontario
A Residential General Contractor in Ontario works on the homes people live in while the work is underway. That changes everything about how we phase a project: dust containment at the door, daily cleanup, sequencing the plumbing and electrical so you can still use the second bathroom. Homeowners in Ontario’s 91761 and 91764 zip codes often choose to stay in the house during a kitchen or bath remodel, and we plan the build order around that reality. A residential addition or ADU in Ontario typically runs $45,000-$130,000 for the addition and $90,000-$220,000 for a full ADU build, depending on whether you go traditional frame or one of the prefab systems we’re authorized to install.
Interior Remodels With Residential Phasing
Kitchens and bathrooms get sequenced so you’re not living out of a microwave for eight weeks. We bring in plumbing rough-in early, pass inspection, then close walls while cabinet lead times run. When you pick CertainTeed or Grohe fixtures, we verify stock at our Ontario-side suppliers before we write the schedule, so the job doesn’t stall waiting on a faucet.
Additions and ADUs Around Ontario Zoning
Ontario’s specific zoning and Title 24 requirements apply to additions and garage conversions, and they’re stricter than what neighboring cities tend to trigger. We handle setbacks, egress, and energy compliance as part of the job, not as an afterthought. A garage conversion in Ontario runs $30,000-$80,000 and includes the permit set, structural reinforcement, and final inspection.
Trusted Brands We Service in Ontario
You pick the brand, we handle the build. We’re authorized to install and service a deep roster of named products across every trade category, and we stock common Ontario parts locally so turnaround stays tight. Roofing systems from GAF and CertainTeed cover six of the industry’s most trusted shingle lines, and plumbing fixture expertise spans Grohe, Kohler, Moen, and Delta. Countertop access runs from Cambria quartz to Silestone and Caesarstone. Cabinetry includes KraftMaid and Wellborn. That’s over 50 named brands across cabinetry, countertops, plumbing, roofing, windows, fencing, and hardscaping. You’ll never hear us say “whatever the supplier has.” You tell us the brand, we order it, we install it, we warranty the workmanship.
Common General Contractor Problems We See in Ontario Homes
- Cloth-insulated wiring behind original drywall: In 1950s-1970s tract homes across 91761 and 91762, the original wiring is often still live and nowhere near current code. Opening a wall for a pass-through or cabinet run means that wiring has to be addressed before inspection will pass.
- Load-bearing headers notched by previous owners: We see DIY-era framing cuts on ranch homes all over 91764. A header that’s been notched for a pipe or duct loses load capacity, and the city inspector will flag it. That means structural repair before drywall goes back up.
- Failed waterproofing in original bathrooms: Old shower pans and unsealed tub surrounds leak into subfloor over decades, and the damage is hidden until demo. On Ontario homes with original 1960s baths, we plan for subfloor repair as a standard allowance, not a surprise.
- Title 24 and zoning triggers on additions and ADUs: Ontario requires energy compliance upgrades when you add square footage or convert a garage. We price those upgrades into the bid from day one so the permit phase doesn’t blow the budget.
See the difference
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After
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AfterPricing for General Contractor in Ontario, CA
Here’s what a General Contractor in Ontario charges for the most common project scopes, as line-item ranges we see repeatedly in this market:
| Project Scope | Typical Ontario Range |
|---|---|
| Kitchen Remodel | $14,000 – $45,000 |
| Bathroom Remodel | $9,000 – $28,000 |
| Home Addition | $45,000 – $130,000 |
| ADU Construction | $90,000 – $220,000 |
| Garage Conversion | $30,000 – $80,000 |
What moves the number in Ontario? The age of the house, whether it’s a tract home built before 1975, the condition of the original wiring and framing, and whether your Ontario permit triggers Title 24 upgrades or zoning review. We give written line-item estimates after a site walk so the number reflects your actual house. Call (855) 473-5620 to schedule a free estimate. You’ll get a quote built on inspection, not assumption.
We Also Serve Cities Near Ontario
Our crews work across the western Inland Empire, so if you’re in Montclair, Upland, Chino, or San Antonio Heights, count us as your General Contractor in Ontario team serving the surrounding area. Same inspection-first bidding, same written allowances, same single-point accountability. If your home sits in one of those neighboring cities, call (855) 473-5620 and we’ll schedule the site walk the same week.
Serving Ontario, CA — Our Local Coverage Area
We’re based in the Ontario 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 General Contractor in Ontario
Because the original wiring, framing, and waterproofing in 1950s-1970s Ontario tract homes rarely match what’s on the floor plan. The quote moves when a contractor discovers cloth-insulated wiring or a notched load-bearing header after demolition, then prices the repair as a surprise change order. Our fix is inspection-first bidding: we walk the house before quoting, flag the likely hidden issues, and write allowances into the contract so those costs are visible before you sign. Call (855) 473-5620 for a quote built that way from the start.
We stop, write a fixed-price change order, and wait for your written approval before touching another stud. On a 1962 ranch-style home off the 91762 grid, our crew opened a kitchen wall for a planned pass-through and found cloth-insulated wiring and a load-bearing header notched by an earlier owner. That risk was already an allowance in the signed contract, so the framing repair and rewiring went out as a written change order, got approved, and passed inspection on the first visit. No surprise ballooning, no gray area.
Yes. Ontario requires permits for structural wall changes, electrical work, plumbing relocations, and garage conversions, and the city enforces Title 24 and zoning requirements for additions and ADUs. Skipping the permit to save time creates a bigger problem at resale and during any future inspection. We pull permits on every Ontario project, including interior wall removals. Call (855) 473-5620 if you want to know what your specific project triggers before you commit.
Cloth-insulated or ungrounded wiring, undersized floor joists, notched headers, old termite or water damage at the plate line, and sometimes asbestos in the drywall compound or flooring adhesive. That’s the reality of 1950s-1970s Ontario tract stock, and it’s why we price these as allowances, not wishful thinking. A small kitchen remodel in Ontario runs $9,000-$20,000 and a bathroom vanity replacement $800-$3,000, but those numbers hold only if the hidden work is identified and written into the bid. That’s how we bid every Ontario job.
Ontario has a mix of postwar tract homes and newer master-planned subdivisions plus the logistics and warehouse corridor along the 60/10, which means a GC here has to handle both old-assembly residential work and strict modern code on newer builds. Neighboring cities like Montclair or Upland share some of the housing age pattern, but Ontario’s specific zoning and Title 24 triggers for additions and ADUs are different, and we build those into the bid from day one. Call (855) 473-5620 and we’ll explain what applies to your specific Ontario parcel.
Ready to Talk to a General Contractor Who Opens Walls Before Quoting?
If you’re planning a remodel in Ontario and want a number you can actually build to, call (855) 473-5620. We’ll schedule a free on-site estimate, walk the house, open the relevant access panels where possible, and write you a line-item quote with allowances for what’s hidden. Ruben Castillo and the team at San Bernardino Contractors have handled every phase of Ontario residential work, from kitchen walls that open onto old wiring to full ADU builds that pass Ontario permitting on the first visit. One contractor, every phase. Call us today.
Written by Ruben Castillo, Owner at San Bernardino Contractors, serving Ontario and the surrounding Inland Empire with inspection-first general contracting.