NBC 2025 Guide: Flame-Spread Ratings for Interior Finishes in London, Ontario
Sarah's Expert Insight
Senior Consultant at empcontracting.ca Inc.
"Navigating the 2025 flame-spread requirements is essential for ensuring your project passes local inspections in London without costly rework. At empcontracting.ca Inc. your construction contractor in London, Ontario, we meticulously select interior finishes that exceed NBC standards, providing peace of mind for homeowners and commercial developers alike."
Understanding Flame-Spread Ratings (FSR) under NBC 2025
The National Building Code of Canada (NBC) 2025 establishes rigorous standards for interior finishes to minimize fire hazards. Flame-spread ratings (FSR) measure the speed at which flames spread across the surface of a material, providing a critical metric for life safety in residential and commercial structures.
Classification of Interior Finishes
Materials are generally categorized based on their performance in standardized tests, such as CAN/ULC-S102. These classifications ensure that materials used in high-risk areas—like exits and public corridors—have a lower flame-spread potential.
- Class A (0-25): High fire resistance, typically required for vertical service spaces and exits.
- Class B (26-75): Moderate resistance, suitable for most corridors and public spaces.
- Class C (76-150): Standard resistance for general room interiors.
Key Requirements for Interior Walls and Ceilings
Per NBC 2025 Page 363, the maximum flame-spread rating allowed depends on the building's occupancy type and the specific location of the finish. For example, in high-rise buildings or assembly occupancies, requirements for ceilings are often stricter than those for walls. It is essential to verify that all decorative finishes, including wood paneling and acoustic treatments, comply with these limits.
Compliance in London, Ontario Construction
When renovating or building new in London, Ontario, local building inspectors look for documented FSR values. Choosing the right materials early in the design phase prevents costly delays during the inspection process. At empcontracting.ca Inc. your construction contractor in London, Ontario, we prioritize fire-rated materials that harmonize safety with aesthetic design.