Commercial Roof Warranty: What Ontario Owners Should Get
The types of commercial roof warranty, how long they run, what voids them, and five questions to ask before you sign.
Call 1-833-775-7663 Oakville head office · Flat roofs for commercial, industrial and institutional buildings across Ontario
Karol Rajkowski
Vice President, OYH Roofing
Published October 5, 2026 · 8 min read
Short answer
A commercial roof warranty in Ontario should come in writing from two sides: the manufacturer, for the membrane or the whole system, and the contractor, for the workmanship. Manufacturer terms usually run 10 to 20 years and up to 30 on some systems. Check who backs it, whether it is prorated, and what voids it.
What types of commercial roof warranty are there?
There are three common manufacturer warranties plus the contractor's own workmanship warranty. They differ in who stands behind them and in how much of the roof they cover. IKO, the maker of the modified bitumen on two of our projects, publishes all three manufacturer levels for Canada, which makes it a useful example.
| Warranty type | Who backs it | What it covers | Example |
|---|---|---|---|
| Material, prorated | Manufacturer | Defective membrane, with the value reduced over time | IKO Material Limited Warranty; the contractor does not need to be registered |
| Labour and membrane | Manufacturer | Labour and materials to repair membrane with a manufacturing defect that leaks; not prorated | IKO L&M Limited Warranty; registered contractor required |
| System, workmanship included | Manufacturer | Membrane and other system materials, including workmanship defects that cause leaks | IKO Diamond Shield; Holcim Elevate Red Shield, with no dollar limit |
| Workmanship | Contractor | Installation errors, for the term set in the contract | Written into your roofing contract |
The best protection usually combines a manufacturer system warranty with a clear contractor warranty, so that a leak is covered whether the cause is the product or the installation.
How long should a commercial roof warranty last?
Most commercial roof warranty terms run 10 to 20 years, and some systems reach 30. The term follows the build: IKO's modified bitumen program, for example, lists 10, 15 and 20-year warranties, and the 20-year level calls for heavier membrane combinations. Holcim Elevate's Red Shield runs from 5 to 30 years. These are the terms on roofs we have installed:
| Project | System | Size | Warranty |
|---|---|---|---|
| 777 Niagara St, Welland | IKO 2-ply modified bitumen | 52,300 sq ft | 20-year system warranty |
| City of Mississauga, 3185 Mavis Rd | IKO 2-ply modified bitumen | 8,500 sq ft | 20-year system warranty |
| Mississauga Industrial (recover) | 2-ply modified bitumen | 53,000 sq ft | 20 years on labour and materials |
| Marriott Hotel, Vaughan (new build) | 2-ply modified bitumen | 15,000 sq ft | 20 years on labour and materials |
| Millomat Stampings, Mississauga | 60 mil TPO | 50,000 sq ft | 20 years on labour and materials |
| Devi Mandir, Pickering | 60 mil TPO | 6,500 sq ft | 20 years on labour and materials |
| Residential building, Sault Ste. Marie (new build) | PVC | 17,500 sq ft | 30 years on labour and materials, the most OYH Roofing offers on any system |
A longer term is not automatically better. A 30-year warranty on a roof that will be replaced in 15 years adds cost without value, and a long term with heavy exclusions can protect less than a shorter, broader one. To compare the term with how long the roof itself should last, see our commercial flat roof lifespan guide.
What is the difference between a system warranty and a labour and materials warranty?
A system warranty means the manufacturer backs the roofing system as installed, not just one roll of membrane. On our project pages, a labour and materials warranty means the membrane and the workmanship are covered for the term. In both cases the written terms decide what is included.
Manufacturers use the same words differently. IKO's L&M Limited Warranty covers labour and materials to fix membrane with a manufacturing defect, while its Diamond Shield also covers workmanship. Holcim Elevate's Red Shield covers the membrane, insulation and metal edge to edge. Two warranties with the same name can protect very different things, so ask for the actual system warranty document, not a brochure.
What can void a commercial roof warranty?
The manufacturers' own documents point to the usual ways coverage is lost: changes nobody reported, products nobody approved, and maintenance nobody did.
| Risk | What the documents say | How to avoid it |
|---|---|---|
| Roof changes after the warranted inspection | Holcim Elevate: report any changes made to the roof; not notifying it may jeopardize the warranty | Tell your roofer before new units, vents or solar panels go on |
| Products that are not approved | IKO: its products must be used, and substitutions need approval from IKO Technical Services | Ask what is in the system before work starts |
| Installer not registered with the program | IKO: the L&M warranty requires a registered contractor, and Diamond Shield a Diamond registered one | Ask for proof of the contractor's status in the program |
| Missing maintenance | NRCA: most warranties require the roof to be properly maintained | Inspect in spring and fall and keep the reports |
| Warranty not set up before the job | IKO: the Diamond Shield application goes in at least two weeks before work starts, with the roof plan and specification | Choose the warranty while the roof is being designed |
Not sure what your commercial roof warranty covers?
If we installed your roof, ask us for the warranty document for your project. If not, we can look at the roof and the warranty terms together during an assessment.
Call 1-833-775-7663Request an assessmentWhat should you ask before you sign?
Ask these five questions about any commercial roof warranty, and get the answers in writing:
- Who backs it? The manufacturer, the contractor or both, and is the contractor registered in the manufacturer's program?
- Is it prorated, and is there a dollar limit? IKO's L&M and Diamond Shield warranties are not prorated, and Holcim Elevate's Red Shield has no dollar limit.
- What does it cover? Only the membrane, or the whole system, including insulation, metal and workmanship?
- What does it ask of you? Inspections, records, approval before rooftop changes and how fast you must report a leak.
- Does it transfer? Holcim Elevate's Red Shield transfers from owner to owner; check yours before you sell the building.
Ask about cost too. Some manufacturer warranties carry a fee: IKO lists its 20-year Diamond Shield at $0.20 per square foot, minimum $2,000, in its 08/2025 guide.
How does a roof warranty differ from insurance and Ontario law?
A commercial roof warranty pays for defects in the product or the installation. Insurance pays for sudden, accidental damage such as a windstorm. Neither pays for a roof that has simply worn out. Our guide to commercial roof leak insurance covers the insurance side.
| Protection | What it covers | Typical example |
|---|---|---|
| Manufacturer warranty | Defects in the product, and on some programs the workmanship | A seam that fails because of a membrane defect |
| Contractor warranty | Installation errors for the contract term | A flashing detail that was installed wrong |
| Property insurance | Sudden, accidental damage, subject to the policy | Wind tears off part of the roof |
| Consumer Protection Act, 2002 | Consumers acting for personal, family or household purposes, not business purposes | Not a commercial building; the contract and warranties set the terms |
Keep the warranty, the contract and every inspection report together with the building records, and pass them on if the building is sold. Our guide on how to prepare a flat roof for winter covers the fall inspection most warranties expect.
Frequently asked questions
What is the normal warranty on a roof?
For a commercial flat roof, manufacturer warranties usually run 10 to 20 years, with some systems reaching 30, plus a separate contractor warranty on workmanship. IKO's commercial programs, for example, offer 10, 15 and 20-year terms depending on the build. On OYH Roofing projects, 20 years is the most common term.
What is covered under a 30-year roof warranty?
It depends on who backs it and what it says. On our Sault Ste. Marie PVC roof, the 30-year warranty covers labour and materials, so both the membrane and the workmanship are covered, subject to the written terms. Some 30-year manufacturer warranties also add puncture, hail or wind coverage as options.
What is an NDL warranty on a roof?
NDL means no dollar limit. The manufacturer's liability for repairing covered leaks is not capped at a set dollar amount. Holcim Elevate's Red Shield, for example, offers material and labour coverage with no-dollar-limit liability on the membrane, insulation and metal. Exclusions and owner duties still apply.
How long is a roof covered under warranty?
For the term written in the warranty, usually counted from when the roof is completed, as long as you meet its conditions. Commercial terms usually run 10 to 20 years, and up to 30 on some systems. Coverage can end early if the roof is altered without notice, unapproved products are used or required maintenance is skipped.
What are the requirements for a warranty under the Ontario Consumer Protection Act?
The Consumer Protection Act, 2002 protects consumers, which it defines as individuals acting for personal, family or household purposes, not people acting for business purposes. A roof bought for a commercial building is a business purchase, so the written contract and warranties set the terms. Homeowners should check the Act or Consumer Protection Ontario.
Is a roof warranty the same as insurance?
No. A commercial roof warranty covers defects in the product or the installation, for the term and under the conditions it states. Property insurance covers sudden, accidental damage, such as a storm, under your policy. Neither covers a roof that has worn out with age, which is why maintenance records matter for both.
Karol Rajkowski
Vice President · OYH Roofing
Karol Rajkowski is Vice President of OYH Roofing, an Oakville-based ICI flat-roofing contractor whose projects include the City of Mississauga building at 3185 Mavis Rd and the Marriott Hotel in Vaughan. Learn more about the OYH team.
Sources
- Limited Warranty Programs, Commercial Roofing, IKO Commercial guide MM1L189 (08/2025).
- Red Shield Warranties, Holcim Elevate, Canada.
- Tech Today, Professional Roofing (NRCA), October 2013: warranties and maintenance.
- Maintaining compliance, Professional Roofing (NRCA), February 2024.
- Consumer Protection Act, 2002, S.O. 2002, c. 30, Sched. A, section 1, definition of consumer, Government of Ontario.
- Water Damage and Flood Protection, Insurance Bureau of Canada.
- OYH Roofing project records: 777 Niagara St, Welland; City of Mississauga, 3185 Mavis Rd; Mississauga Industrial; Marriott Hotel, Vaughan; Millomat Stampings, Mississauga; Devi Mandir, Pickering; residential building, Sault Ste. Marie (October 2026).
OYH Roofing, 2120 Speers Rd, Oakville, ON L6L 2X8 · 1-833-775-7663 · info@oyhroofing.ca