The National Building Code of Canada (NBC) includes requirements for the protection of foamed plastics for both combustible and noncombustible construction. Depending on the application, current acceptable solutions to achieve this protection include a variety of prescriptive options (e.g., interior finishes) or use of a thermal barrier conforming to certain fire test method standards (e.g., CAN/ULC-S124:2018, "Standard Method of Test for the Evaluation of Thermal Barriers for Foamed Plastic" (PCF 1476)).

As demonstrated in CCMC Evaluation Report 14036-R[1], some products that are typically classified as “protective coverings” rather than as “thermal barriers” were found to offer an acceptable level of performance when pursued as an alternative solution to the Code requirements. Intumescent coatings are an example of these products.

As more options for protective coverings enter the market, it becomes more critical to provide manufacturers, regulators and Code users with an additional compliance path that specifies a minimum level of performance for these products to be considered acceptable solutions where incorporated in a tested assembly. Not including these specifications in the Code presents the danger of leaving the door open for the definition of the acceptable minimum level of performance by others and for protective covering products to be applied inappropriately in practice. Either scenario could result in insufficient protection that might lead to harm to building occupants and damage to the building.

Furthermore, if no additional compliance path for assemblies that incorporate protective coverings is offered, regulators and authorities having jurisdiction may continue to struggle to accept such products, which could cause economic hardship to the protective covering industry.

In the last Code cycle, the Standing Committee on Fire Protection was asked to review CCMC Evaluation Report 14036-R (the CCMC Report)[1], which introduced a new test method to assess the fire performance of a protective covering (DC 315 Intumescent Coating) over foamed plastic insulation. There was a desire to investigate, and potentially introduce in the Code, the room corner test method as an option for evaluating the performance of an entire assembly.

According to the intent statements of the NBC, the current requirements for the protection of foamed plastics aim to limit harm to persons and building damage due to early fire growth and spread.

The fire hazard of foamed plastics is their risk of contributing to the onset of flashover, after which point the chance of safe evacuation is greatly reduced, the potential for greater building damage increases, and the potential to contribute to fire growth and spread significantly increases. To mitigate this hazard, the NBC requires that foamed plastics be protected. The desired level of performance for this protection is to limit the foamed plastics from contributing to the onset of flashover, which is measured by the time to flashover.

Since the last Code cycle, and pursuant to the CCMC Report, a new standard (CAN/ULC-S145:2018, "Standard Method of Test for the Evaluation of Protective Coverings for Foamed Plastic Insulation – Full-Scale Room Test") was developed for the evaluation of protective coverings over foamed plastic insulation using a test method based on CAN/ULC-9705, "Fire Tests – Full-Scale Room Test for Surface Products." Feedback from many Canadian fire experts indicated that the proposed 10 min and 20 min classifications (representing 100kW and 300kW exposures, respectively) in CAN/ULC-S145 for protective coverings relate more directly to the hazard that the NBC intends to limit (versus existing performance tests).

Performance test options currently in the NBC (including the proposed update of CAN/ULC-S124:2018 (PCF 1476)) use a furnace test to evaluate a thermal barrier’s ability to prevent the ignition of the foamed plastics by measuring the temperature transmission performance of the thermal barrier during fire growth in its early stage. The 10 min thermal barrier requirement was intended to limit the contribution of foamed plastic insulation to fire growth. CAN/ULC-S124 was deemed to be a conservative evaluation of that condition.

Alternatively, the new standard, CAN/ULC-S145, offers a room corner test method to evaluate the integrity of an assembly during fire growth and includes performance metrics associated with the onset of flashover. Because their approaches are fundamentally different, the furnace and room corner test methods are difficult to compare and cannot be equated. However, as both test methods support the overall intent of the requirement (including the mitigation of the fire hazard and establishment of a minimum level of performance with related metrics), CAN/ULC-S145 can be introduced as a suitable alternate test option for the protection of foamed plastics.

For combustible construction, an option is introduced in Sentence 3.1.4.2.(1) for assemblies incorporating protective coverings to meet the 10 min classification of CAN/ULC-S145. For noncombustible construction, the 20 min classification of CAN/ULC-S145 is introduced in Sentences 3.1.5.15.(2) and (3). This proposed change follows the hierarchical structure of the existing Code requirements, which considers a building’s use, construction type, height and whether or not it is sprinklered when stipulating the level of protection needed.

Furthermore, this proposed change is consistent with the existing NBC intent statements. Performance-based room corner tests provide a clear indication of the onset of flashover, which impacts both the time available for egress and the potential contribution of a material to fire growth and spread. These tests are recognized and relied on worldwide in building code regulations to determine the contribution of room linings to the onset of flashover.

References

[1] Canadian Construction Materials Centre. “CCMC 14036-R: CCMC Canadian code compliance evaluation”. National Research Council of Canada. Ottawa, Canada; June 2016.
https://nrc.canada.ca/en/certifications-evaluations-standards/canadian- construction-materials-centre/ccmc-
publications/document.html?id=14036-R&type=cert (as of December 2022).

This proposed change provides an additional option for compliance through testing, which would allow for a broader range of material to be used for the protection of foamed plastics. This proposed change provides flexibility to designers and fosters innovation without compromising safety.

The proposed change benefits manufacturers and Code users by clarifying the minimum level of performance required for assemblies incorporating a protective covering, which facilitates enforcement for regulators and authorities having jurisdiction.

Because the introduction of CAN/ULC-S145:2018, "Standard Method of Test for the Evaluation of Protective Coverings for Foamed Plastic Insulation – Full-Scale Room Test," is not meant to replace the existing options for acceptable solutions, there are no new forced costs to builders with respect to meeting the requirements for the protection of foamed plastics.

Also, any additional costs associated with the testing of materials when using this proposed option could be offset by avoiding the time and expense of needing to pursue this option as an alternative solution.

This proposed change could be enforced by the current enforcement infrastructure for the Code.

Regulators are familiar with assessing compliance through product testing in accordance with referenced standards. Having a performance-based requirement in the Code facilitates the interpretation and enforcement of the requirement and ensures consistency of the application throughout the country.

Furthermore, in jurisdictions where alternative solutions have been sought for protective covering products, it is anticipated that there is already familiarity with these types of products.

This proposed change would affect:

• regulators and authorities having jurisdiction, who would need to be aware of the new standard,
• builders, architects, engineers and building owners, who would be able to consider additional products that are allowed for their projects, and
• manufacturers, who should consider further developing new and existing products to comply with the new requirements.