A commercial roofing request usually starts with a visible problem: a ceiling stain, ponding water, a failed seam, or a roof that keeps needing patches. Once the building is occupied, the decision gets more involved. Property teams need to confirm where the water is entering, decide whether repair, coating, or replacement fits the roof's condition, and plan the work around tenants and operations.
Comparing the best commercial roofing contractors in Ontario, CA starts with that distinction. A contractor focused on reroofing may assess a problem differently from one that investigates the wider building envelope. The right choice is the provider whose services, experience, and assessment approach match the existing roof and the work it needs.
This comparison covers:
- A weighted ranking of commercial roofing contractors serving Ontario.
- Profiles explaining each contractor's fit and scope limits.
- Guidance for problems that are not actually roofing problems.
- A match table for common repair scopes.
- What to confirm before appointing a contractor.
How We Evaluated Ontario Commercial Roofing Contractors
We reviewed contractors using their published services, Ontario coverage, commercial project descriptions, and available customer feedback. The evaluation focuses on work for existing commercial buildings, including repair, maintenance, restoration, and related waterproofing.
| Criterion | Weight | What it measures |
|---|---|---|
| Existing-roof fit | 25% | Repair, maintenance, restoration, or coating services for existing commercial roofs |
| Ontario service evidence | 20% | Explicit city coverage, a local office, or documented Ontario project work |
| Commercial roofing offerings | 20% | Roofing and related services that match commercial property needs |
| Documented commercial experience | 15% | Identifiable commercial projects and useful scope detail |
| Diagnostic and repair options | 10% | Assessment methods and practical repair or renewal choices |
| Proposal clarity | 5% | Published consultation, scope-development, or estimate processes |
| Occupied-property planning | 5% | Published commitments for working around building operations |
Each factor is scored out of 10, and the final score is weighted. The ranking reflects documented public evidence, not a guarantee of project performance.
The Best Commercial Roofing Contractors in Ontario, CA Compared
| Rank | Company | Existing-Roof Fit | Ontario Evidence | Commercial Offerings | Documented Experience | Diagnostic/Repair | Final Score |
|---|---|---|---|---|---|---|---|
| 1 | Syntech Roofing & Waterproofing | Roof repair, restoration, maintenance, and related envelope repairs (9) | San Bernardino County coverage and Toyota Arena project in Ontario (9) | Roofing, coatings, waterproofing, sealants, concrete restoration (9) | Named roof-restoration, coating, and envelope projects (9) | Moisture scans, infrared detection, leak testing, targeted repairs (9) | 9.0/10 |
| 2 | Central Roofing Company | Commercial roof repair, maintenance, coatings, and replacement (9) | Ontario service pages and an Ontario office listing (9) | Roof repairs, cool-roof coatings, restoration, maintenance, skylights (9) | Published Ontario manufacturing-roof coating case study; customer unnamed (8) | Inspections, condition reports, coating-suitability assessment (9) | 8.8/10 |
| 3 | Angelus Waterproofing & Restoration | Existing-roof renewal and waterproofing restoration (9) | Named Ontario bank project; current availability to confirm (8) | Roofing, deck coatings, waterproofing, sealants, restoration (9) | Named bank, office, and roofing projects (9) | Roof surveys, repair, coating, and retrofit options (8) | 8.6/10 |
| 4 | CRT Roofing Co. | Commercial roof repair, restoration, and maintenance (9) | Ontario commercial roofing page; local project not verified (8) | SPF, coatings, TPO, repair, and reroofing (9) | Labeled commercial portfolio; limited case-study detail (7) | Assessment, targeted repair, drainage correction, monitoring (9) | 8.1/10 |
Column labels are shortened to fit the page. Each factor score out of 10 appears in parentheses. A local address alone does not establish faster response, stronger workmanship, or experience with a particular roof system.
1. Syntech Roofing & Waterproofing
Syntech Roofing & Waterproofing is a Southern California building-envelope contractor that works across commercial roofing, waterproofing, sealants, coatings, and concrete restoration. It is licensed in California under license #1108385 and is family-owned and operated.¹ Its roof services include routine maintenance and repairs, infrared leak detection, moisture scans, leak-prevention programs, patching, and full roof coatings.²
That breadth matters when the visible leak and the actual point of entry are not the same. A commercial leak may involve roof penetrations, window perimeters, wall joints, or concrete cracks. Syntech evaluates the existing roof before recommending repair, restoration, coating, or replacement, and can investigate related exterior systems in the same visit.²³
Its Northrop Grumman project shows that approach in practice. Systematic leak testing traced the water intrusion to the window perimeters, narrowing an initially broader façade-restoration scope to targeted sealant repairs.ⴠFor a property team, that means the repair boundary was set by testing rather than assumption.
Syntech is based in Riverside, and its service area includes San Bernardino County, where Ontario is located.³ⵠIn Ontario, its Toyota Arena VIP Section project involved a custom Tremco pedestrian deck and wall coating system installed around the venue's event schedule, with work windows as short as a couple of days.¹ⴠThat is relevant coating and operating-site experience, not a roof-replacement reference. For roof restoration specifically, its Camino Nuevo project used a Tremco liquid-applied coating system to extend a domed roof's service life within a two-week schedule.â´
| Syntech at a glance | Details |
|---|---|
| Location | Riverside, California |
| Service area | Southern California, including San Bernardino County |
| Assessment approach | Roof evaluation, moisture scans, infrared detection, and leak investigation |
| Documented examples | Toyota Arena deck and wall coating; Camino Nuevo roof restoration; Northrop Grumman targeted sealant repair |
| Services | Roof maintenance and restoration, coatings, waterproofing, sealants, concrete restoration |
| Confirm before appointment | Roof-system references, warranty eligibility, exclusions, and schedule |
Summary of online reviews: Customer accounts mention "thorough and detailed" estimating and "commercial grade materials." Several describe homes, decks, or garages, so this small sample is best used to frame questions about communication and assessment rather than performance on comparable Ontario commercial roofs.
2. Central Roofing Company
Central Roofing Company offers a roof-focused option for commercial owners deciding between maintenance, repair, coating, and replacement. Its Ontario pages cover commercial roof repair, replacement, cool-roof coatings, skylights, and maintenance for warehouses, manufacturing facilities, retail centers, and multi-tenant properties.ⶠThe company states that it recommends repair or coating when viable and explains why when replacement is necessary.â¶
Its Ontario maintenance program describes surface inspections, drain and scupper clearing, flashing checks, sealant touch-ups, ponding evaluation, and photo documentation. Written condition reports give property managers something specific to review when planning the next visit. Central also describes an estimator meeting followed by a free, no-obligation written estimate.â¶
Its published Ontario case study describes silicone coating on a 105,000-square-foot manufacturing facility, after an inspection found the existing roof suitable for coating. The account addresses minimizing disruption at an operating building, although it does not identify the customer or publish a detailed occupied-site work plan. Central is headquartered in Gardena and lists Ontario among its office locations.â¶
| Central Roofing at a glance | Details |
|---|---|
| Location | Gardena, California headquarters; Ontario office listed |
| Service area | Southern California, with explicit Ontario commercial service |
| Assessment approach | Roof inspection, photo documentation, and written condition reports |
| Documented example | Silicone roof coating at a 105,000-square-foot Ontario manufacturing facility |
| Services | Commercial roof repair, maintenance, coatings, restoration, replacement, skylights |
| Confirm before appointment | Which office will run the project, occupied-site plan, and coating warranty terms |
Summary of online reviews: A building customer describes being "very satisfied with the results" of a roof restoration, while other accounts mention professional crews. These are company-hosted excerpts, not a complete independent review sample.
3. Angelus Waterproofing & Restoration
Angelus Waterproofing & Restoration provides commercial roofing, waterproofing, protective coatings, and restoration. Its roofing information describes surveys and recommendations for existing roofs, with options to install over the existing roof or tear off and replace. Listed systems include PVC, spray polyurethane foam, and acrylic roofing.â· That range is useful when an owner needs to know whether a roof can be restored and which system fits.
Its portfolio includes named commercial roofing work, such as a reroof at Long Beach Airport Business Park and modified bitumen roofing at Carmel View Office Plaza.⸠For Ontario, the clearest example is Pacific Mercantile Bank, where Angelus sealed slab cracks and installed a 12,000-square-foot vehicular traffic deck coating system.⸠That is local deck-protection work, not a roofing project or proof of an Ontario office.
Angelus is headquartered in Huntington Beach, so confirm current scheduling availability for Ontario.⸠The company says it strives to minimize disruption during working hours, but a project-specific occupied-property plan should be requested.⸠Ask about access, curing restrictions, and work sequencing for the chosen system.
| Angelus at a glance | Details |
|---|---|
| Location | Huntington Beach, California headquarters |
| Service area | Regional portfolio includes Ontario; confirm current availability |
| Assessment approach | Commercial roof surveys and recommendations |
| Documented example | Pacific Mercantile Bank slab sealing and vehicular deck coating, Ontario |
| Services | Roofing renewal, waterproofing, protective coatings, sealants, restoration |
| Confirm before appointment | Survey fees, proposal timing, coating eligibility, and warranty terms |
4. CRT Roofing Co.
CRT Roofing Co. offers commercial roof installation, repair, replacement, maintenance, and inspection, with a dedicated Ontario commercial roofing page.â¹ Its repair process moves from assessment of weakened areas and water-intrusion points to targeted repair, drainage and seal correction, and follow-up monitoring.â¹ That sequence suits a property team that wants a specific roof problem evaluated before committing to broader work.
Its maintenance program includes scheduled inspections, minor adjustments, debris and drainage management, coating checks, and performance tracking over time.â¹ CRT is based in Bloomington and is listed as a GAF certified roofing contractor.¹â°
The company's portfolio labels commercial spray-foam and reroofing projects, but entries provide less scope detail than a developed case study. A named Ontario commercial project was not verified. Request a matching commercial reference and confirm how access, work areas, and the written scope will be handled.
| CRT Roofing at a glance | Details |
|---|---|
| Location | Bloomington, California |
| Service area | Southern California, with explicit Ontario commercial roofing service |
| Assessment approach | Roof assessment, targeted repair, drainage correction, follow-up monitoring |
| Documented example | Labeled commercial SPF and reroofing projects |
| Services | Commercial roof repair, maintenance, restoration, SPF, coatings, TPO, reroofing |
| Confirm before appointment | Itemized proposal format, occupied-site controls, comparable references |
Summary of online reviews: A company-hosted account calls flat-roof repair and insulation "Great professional service." The customer is labeled a homeowner, so this is not a verified reference for comparable commercial roofing work.
When the Problem Is Not the Roof
Some commercial repair requests are not roofing problems at all. Interior reconfiguration, HVAC failures, plumbing issues, and finish repairs call for a general contractor rather than a roofer. Two Ontario-area general contractors may fit those needs.
CBX Construction is based in Ontario and describes commercial remodels, repairs, and tenant improvements for offices, retail, and industrial properties. Its services include electrical and lighting upgrades, HVAC and plumbing, finishes, and HVAC and sewer-camera diagnostics. Project detail is limited, so request references for similar scopes.
S-Line Contractors publishes commercial renovation and tenant-improvement services for Ontario from a Riverside office. Its MRC Entertainment example covers drywall replacement, patching, and repainting in active office and studio spaces. A named Ontario project was not verified.
| Condition observed | Appropriate contractor type |
|---|---|
| Roof membrane leak or ponding | Commercial roofing contractor |
| Water around window perimeters | Building-envelope or sealant specialist |
| Parking deck or plaza deterioration | Waterproofing and traffic-coating specialist |
| Leak with multiple possible sources | Building-envelope contractor with leak-testing capability |
| Interior buildout or tenant improvement | General contractor such as CBX or S-Line |
| HVAC or plumbing failure | General contractor with mechanical trades |
Syntech can address the first four conditions under one scope, which helps when a roof leak turns out to involve sealants, coatings, or concrete.²³
Match the Contractor to the Repair Scope
The best commercial roofing contractor depends on the problem the building actually has. Use the table below to narrow the shortlist before requesting proposals.
| Building need | Strongest initial fit | Why |
|---|---|---|
| Leak source is uncertain | Syntech | Leak testing, moisture scans, and building-envelope evaluation |
| Recurring roof maintenance | Central, Syntech, or CRT | Maintenance programs with inspections and condition tracking |
| Existing-roof coating evaluation | Syntech, Central, or Angelus | Restoration and coating experience with suitability assessment |
| Defined roof repair | CRT or Central | Roof-focused repair processes with drainage and seal correction |
| Roof replacement | Central or CRT | Published replacement and reroofing services |
| Deck or plaza waterproofing | Syntech or Angelus | Traffic and pedestrian coating projects |
| Multi-system exterior leak | Syntech | Roofing, sealants, coatings, waterproofing, and concrete under one scope |
The first proposal should define the failure, not simply repeat the symptom reported by the occupant.
What to Confirm Before Appointing a Commercial Roofing Contractor
Ask for enough information to compare proposals on the same scope. This matters most when one contractor recommends a coating and another recommends replacement.
| Confirmation item | What to request |
|---|---|
| Inspection findings | Photos, moisture results, leak source, affected areas, and limitations |
| Existing roof system | Membrane type, age, prior repairs, and current warranty status |
| Proposed repair | Materials, preparation, sequencing, and expected service life |
| Alternatives | Repair, coating, restoration, and replacement options where appropriate |
| Occupied-property plan | Access, staging, noise, odors, safety, phasing, and tenant communication |
| Commercial references | Comparable projects with contacts and completed scope |
| Credentials | Current license, insurance, and manufacturer approvals |
| Warranty | Labor, materials, exclusions, and maintenance requirements |
Syntech identifies itself as California licensed, bonded, and insured, and advertises a 20-year no-dollar-limit warranty option on labor and materials.¹ Confirm whether the proposed system and project qualify.
Choose a Contractor for the Roof Your Building Actually Has
Compare Ontario commercial roofing contractors by diagnostic ability, roof-system experience, project delivery, and proposal clarity, not location alone. Central and CRT fit roof-defined repairs, maintenance, and replacement. Angelus is relevant for coatings and waterproofing restoration. Syntech is the strongest overall fit when a roof problem may involve the wider building envelope, because it can find the source before a larger scope is committed.
Book a Free Site Visit with Syntech
Last updated: October 28, 2026
Sources
- Syntech Roofing & Waterproofing, "Building Envelope Contractors in Southern California." https://www.syntechbuilding.net/
- Syntech Roofing & Waterproofing, "Roof Restoration & Maintenance Services." https://www.syntechbuilding.net/roofservices
- Syntech Roofing & Waterproofing, "Commercial Roofing Company in Riverside." https://www.syntechbuilding.net/commercial-roofing-company-riverside
- Syntech Roofing & Waterproofing, "Commercial Roofing Projects." https://www.syntechbuilding.net/services
- Syntech Roofing & Waterproofing, "Contact Syntech." https://www.syntechbuilding.net/book-a-consultation
- Central Roofing Company, "Commercial Roof Replacement in Ontario." https://centralroof.com/service-areas/san-bernardino-county/ontario-roofing/ontario-roof-replacement/
- Angelus Waterproofing & Restoration, "Commercial Roofing Contractor." https://www.angeluswp.com/roofing.html
- Angelus Waterproofing & Restoration, "Commercial Projects." https://www.angeluswp.com/commercial.html
- CRT Roofing Co., "Commercial Roofing Services in Ontario, CA." https://crtroofing.com/commercial-roofing-ontario-ca/
- GAF, "CRT Roofing Co." commercial contractor profile. https://www.gaf.com/en-us/roofing-contractors/commercial/crt-roofing-co-bloomington-ca-1133790
