Fire resistance is a fundamental factor in the design and construction of buildings. The National Building Code defines several standards to regulate fire protection requirements.
But what exactly does fire resistance mean? It refers to the ability of a material or assembly to slow the spread of flames and thus limit damage caused by a fire. In the context of roofs, it is essential to protect the structural integrity of a building as well as to allow occupants to exit in the event of a fire.
In addition to the material-specific requirements, the fire resistance of roofs is divided into two main categories in the Code: Standard CAN/ULC-S107, which addresses roof assemblies, and Standard CAN/ULC-S126, which applies specifically to roof decks. To better understand the CAN/ULC-S107 and CAN/ULC-S126 standards, let’s start with explaining what CAN/ULC is.
What is ULC?
UL (Underwriters Laboratories) is a company specializing in safety certification and consulting, which develops standards recognized by industries and regulatory authorities.
In Canada, ULC (Underwriters Laboratories of Canada) follows the same principles and offers fire resistance testing specifically adapted to roofing materials and assemblies. In addition to carrying out these tests, ULC provides certification and verification services to ensure compliance with fire safety requirements.
Products certified and tested by UL or ULC bear their logo, indicating that they have been tested according to their standards.
Fire Resistance Standard CAN/ULC-S107 for Roof Assemblies
CAN/ULC-S107 is the primary reference for evaluating the fire resistance of roof assemblies. It aims to measure the performance of roofing systems when exposed to fire originating from sources outside the building. This standard covers the entire roofing system from the deck to the cap sheet membrane.
The assessment is based on several tests designed to characterize the way the assemblies react to an intense heat source and exterior flames. Roof assemblies are assigned a fire resistance class based on their performance.
- Class A – Maximum protection against flame spread
- Class B – Moderate protection
- Class C – Minimum protection
The classification is obtained according to the results of the roof assembly to the following tests.
Evaluation Criteria
1. Spread-of-Flame Test
This test measures how far a flame applied to the assembly spreads over a set period of 10 minutes for Classes A and B and 4 minutes for Class C. The assembly is tested on a slope of up to 5:12 (5 vertical units to 12 horizontal units). A steeper slope represents an additional constraint, as it facilitates the spread of flames.
The flame spread limits are defined as follows:
- Class A – Maximum of 6 feet
- Class B – Maximum of 8 feet
- Class C – Maximum of 13 feet
If the deck is non-combustible, only this test is required for classification. The next evaluation criteria will therefore only apply to assemblies with combustible decks.
2. Intermittent-Flame Test
The assembly is exposed to flames on an intermittent basis over several cycles. The test is considered successful if the wooden deck has not ignited after completing all the cycles over a predefined period of time.
3. Burning Brand Test
One or more pieces of burning wood are placed on the roof where they are left until they are completely extinguished. The test is considered successful if no flame appears on the underside of the deck.
Fire Resistance Standard CAN/ULC-S126 for Roof Decks
Unlike CAN/ULC-S107, which applies to the entire roof assembly exposed to external fire, this standard ensures that the materials used do not promote rapid flame spread in the event of a fire originating from inside the building.
For this purpose, the roof assembly is installed above a test tunnel and is subjected to a flame coming from below for 30 minutes. The distance travelled by this flame under the deck is measured throughout the test.
This is a pass/fail test based on the spread of the flame, which should not spread more than 10 feet during the first 10 minutes and should not exceed 14 feet for the duration of the test.
If these limits are respected, the assembly is considered compliant with the standard.
Conclusion
Compliance with CAN/ULC-S107 and CAN/ULC-S126 requirements directly influences the choice of materials and construction methods. This is why it is important for professionals to understand their distinctions and applications.
While CAN/ULC-S107 assesses the overall performance of a roofing system against external fires, focuses on the combustibility of the roof deck and its ability to limit the spread of fire within the building.
SOPREMA offers a wide selection of roofing systems tested and approved according to these standards. All certified SOPREMA roofing assemblies can be found by searching the company name in the UL database using the following link: UL Database.