Roof Assembly Fire Standards: Ultimate Guide
Before buying a steel roof, I’d check the tested assembly – not just the panels. Ask for the assembly reference and confirm that the deck, insulation, underlayment, fasteners and slope match its documented limits.
Here’s what I’d verify before ordering and pricing:
- External-fire protection: CAN/ULC-S107 has 3 classes – A, B and C – for severe, moderate and light exposure.
- Fire endurance: An S107 class does not replace an hourly fire-resistance rating under CAN/ULC-S101.
- Local requirements: Confirm the governing provincial or territorial code and permit requirements with your building official.
- Documents and changes: Get the roof classification records, installation details and any required steel-building certificates. These are standard for Canadian-made steel buildings. Have substitutions, penetrations and rooftop equipment reviewed before work starts.
My buying rule: <u>get the roof package checked before you commit</u>, then keep approved drawings, product records and installation photos for repairs and future additions.
Roof Fire Compliance: Verify Before You Buy
Canadian Codes and CAN/ULC-S107 Roof Classes
CAN/ULC-S107 classifies roof coverings as Class A, B or C for external fire exposure. Choosing a class is only part of the process. You also need to check the supporting documents.
Roof Coverings, Assemblies and Fire Ratings
Steel’s noncombustibility is a material property – not a roof-assembly rating.
| Term | What it means | What to verify |
|---|---|---|
| Roof covering | Outer weather-protective layer | Permitted use within the documented roof configuration |
| Roof assembly | Covering, deck, insulation and other specified layers | Materials and configuration covered by the test documentation |
| CAN/ULC-S107 classification | Resistance to external fire exposure | Class A, B or C and supporting configuration limits |
Hourly fire-resistance ratings, commonly established under CAN/ULC-S101, describe fire endurance. Flame-spread ratings under CAN/ULC-S102 describe surface-burning performance. Neither can replace an S107 classification.
Class A, B and C External-Fire Ratings
| Classification | External exposure level | Assessment |
|---|---|---|
| Class A | Severe | Highest external-fire resistance of the three classes |
| Class B | Moderate | Moderate exposure |
| Class C | Light | Light exposure |
Tests measure flame spread, burning-brand resistance and flame penetration. The classification applies only within the documented test limits. Changes such as thicker insulation or a steeper roof slope may require re-testing or engineering review.
How Location and Building Use Affect Requirements
The National Building Code of Canada is a model code. The adopted provincial or territorial code, along with local amendments, governs your project. Requirements depend on occupancy, building area, height, construction type and spatial separation.
Before finalising specifications, confirm the governing code edition and S107 edition with the authority having jurisdiction. Then check that the chosen roof package meets those requirements.
Confirm the building’s use and any living space with the building official. Provide dimensions, storey count, intended use and setbacks so they can identify the applicable requirements. Before ordering, verify the tested roof assembly and its supporting documents.
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How to Verify a Tested Roof Assembly
Once you know the required class, check the exact tested assembly before ordering. Ask for the classification record, listing number, proposed roof specification and manufacturer instructions. Match every component to the tested assembly. Steel’s noncombustibility alone does not prove roof performance. Changes to listed components – including insulation thickness, roof slope or materials – require re-testing or written acceptance from the authority having jurisdiction.
Roof Components and Required Documents
Before buying, check that the listing, certification record and installation instructions all match the tested configuration. The rating covers only that configuration. Confirm which documents the authority having jurisdiction will accept, including separate fire-resistance documentation if an hourly rating is required.
| Component | Details to match | Documents to check |
|---|---|---|
| Steel deck or roof panel | Profile, thickness and supporting configuration | Manufacturer specifications and certification record |
| Fasteners and attachments | Type, length, spacing and attachment pattern | Installation instructions and listing |
| Roof covering | Exact product, attachment method and permitted slope | CAN/ULC-S107 classification record |
| Underlayment and cover board | Product, thickness and required position | Assembly listing and manufacturer instructions |
| Insulation | Type, facers, thickness and number of layers | Assembly listing and applicable fire-test reports |
| Air- and vapour-control layers | Specified materials, location and compatibility | System instructions and supporting technical documents |
Insulation Choices and Material Substitutions
An insulation change is an assembly change, not just a product swap. Insulation type alone does not determine the roof class. Before approving a substitution, check thickness, facers, layers, joints, air spaces, cover boards and fasteners against the listed assembly.
If the change falls outside the listed limits, require re-testing or written project acceptance from the authority having jurisdiction before installation. A supplier’s claim of equivalence is not enough.
Roof Edges, Penetrations and Rooftop Equipment
Check more than the roof field: edge and penetration details must also match the listing. Before buying, confirm that edges, joints, curbs, smoke vents and rooftop equipment are covered by the listing or approved separately. If standard details do not address the condition, get a project-specific design accepted.
Review solar panels, mechanical penetrations and equipment additions before work starts. Their supports and attachments must not introduce unreviewed changes to the roof configuration.
A penetration through a fire-resistance-rated assembly may also need separate firestop documentation. Flashing alone does not establish that protection. Send field changes to the manufacturer or a qualified professional, and obtain any required approval before concealing the work.
Permits, Purchase Checks and Installation Records
Permit Documents to Check Before Ordering
Confirm requirements with the local building department before ordering a roof package. Establish the required S107 class, any hourly fire-resistance rating, and setback and separation requirements. Then use the permit file to match the roof package to the approved assembly. Qualified design professionals should coordinate structural, roof and envelope requirements, with fire officials involved where required. Check that the permit file names those responsible for design, fabrication and erection.
The quote should match the permit set. Don’t accept substitutions or added components that haven’t been reviewed.
The permit file should contain roof plans, sections, assembly specifications, classification records and structural information, with professional seals where required. For steel building systems, check the manufacturer’s CSA-A660 certification in the CWB Group registry. Obtain the project-specific Certificate of Design and Manufacturing Conformance, signed and sealed by a licensed Professional Engineer. CSA-A660 certification does not replace roof fire-classification documents.
Buyer Checklist for Roof Packages
Before accepting the quote, check that it lists the assembly reference, permitted deck and insulation options, attachment details and installation limits. Submit any proposed substitutions for formal review before acceptance. Ask the supplier to list included materials separately from owner-supplied items and accessories.
Request project-specific drawings, certificates and assembly documents from the manufacturer or design professional.
Installation Checks and Owner Records
After delivery and during installation, check that the installed roof matches the approved documents before concealed work is covered. Permit approval does not replace installation to the approved details. Record delivered product names and any approved material substitutions. Photograph insulation layers and other concealed work before covering them.
Keep approved drawings, assembly specifications, manufacturer instructions and the conformance certificate together in one project closeout file. Where applicable, retain CCMC documents for listed products or assemblies. These records support future repairs and rooftop additions, so keep them available for inspection and future work.
Conclusion: Verify the Roof Assembly Before Buying
Once you’ve checked the code and documents, the buying rule is simple: Class A is not a fire-resistance rating. CAN/ULC-S107 covers external fire exposure; CAN/ULC-S101 covers fire endurance.
The whole roof package – not just the panels – must match the tested assembly. That includes the deck, underlayment, insulation and slope. Any substitutions must align with the tested assembly or be supported by documented engineering analysis.
Compliance depends on local code, supporting records, approved installation details and acceptance by the authority having jurisdiction. Buy the documented assembly, not a material claim.
FAQs
What if my roof has no assembly listing?
Without a listing, you can’t assume your roof assembly meets fire safety requirements. Ratings apply to specific tested materials and configurations. Changes to insulation thickness, slope or other tested details require re-testing or professional analysis to determine equivalency.
Designers often rely on published certification listings or established research reports. Check with a building official or engineer to confirm what documentation your assembly needs.
Does replacing my roof trigger new fire requirements?
Yes. Fire ratings apply to specific roof assemblies that have been tested. Under the National Building Code of Canada, changing tested components – such as insulation thickness, materials or roof slope – requires re-testing or analysis to confirm that the assembly still meets the required fire-resistance or flame-spread standards. Local requirements vary and may change, so check with your local building authority and consult a qualified professional before replacing your roof.
How can I verify an older roof’s fire classification?
Find your roof design’s alphanumeric fire identifier, then use it to locate the original listing in ULC’s online certification or product directory. Compare the listed materials, configuration and assembly conditions with your roof as it is today.
Changes over time may invalidate the original fire classification or fire-resistance rating. If the assembly has been altered, retesting or an engineering analysis is typically needed to confirm that it still complies.