National Building Code 2025: Fire Performance Standards for Roofing Materials Guide
Sarah's Expert Insight
Senior Consultant at empcontracting.ca Inc.
"In London, Ontario's evolving urban landscape, adhering to the NBC 2025 fire ratings for roofing is essential for both insurance eligibility and community safety. At empcontracting.ca Inc. your construction contractor in London, Ontario, we recommend high-performance Class A assemblies for all new builds to ensure maximum protection against embers and radiant heat, which are significant risks in our growing residential sectors."
Understanding Fire Performance Standards in the NBC 2025
Page 365 of the National Building Code (NBC) 2025 outlines the critical requirements for the fire performance of roofing materials, specifically focusing on how roof assemblies resist external fire exposure. For projects managed by empcontracting.ca Inc. your construction contractor in London, Ontario, these standards are fundamental to ensuring the safety and longevity of building envelopes.
Roofing Material Classifications (Class A, B, and C)
The NBC 2025 classifies roofing materials into three distinct categories based on their performance under fire tests defined by CAN/ULC-S107, "Methods of Fire Tests of Roof Coverings":
- Class A: Materials effective against severe fire test exposures, providing a high degree of fire protection to the roof deck.
- Class B: Materials effective against moderate fire test exposures.
- Class C: Materials effective against light fire test exposures.
Specific Requirements for Roof Assemblies
The code specifies that roof coverings must not only resist ignition from burning brands but also prevent the spread of flame across the surface. This is particularly vital for buildings located in high-density areas where the proximity of structures increases the risk of fire hopping. When selecting materials, empcontracting.ca Inc. your construction contractor in London, Ontario evaluates the thermal barrier requirements and the integration of components to ensure the entire assembly—not just the top layer—meets the 2025 safety mandates.
CAN/ULC-S107 and Testing Protocols
Compliance requires that all roofing systems undergo rigorous testing to determine their fire-resistance rating. The 2025 update emphasizes the importance of testing complete assemblies, including insulation and underlayment, to provide an accurate representation of how the roof will behave during a real-world fire event.