[CCMC 14036-R] CCMC Canadian code compliance evaluation

For combustible construction, the NBC 2015 requires foamed plastic insulation that forms part of a wall or ceiling assembly be protected from adjacent spaces other than concealed spaces in attic or roof spaces, crawl spaces and wall assemblies. The intent of this requirement is to limit the probability that foamed plastic insulation will become exposed to a fire or subjected to high temperatures, which could lead to its ignition and contribution to early fire growth and spread and could in turn negatively affect the ability of persons to escape from a fire and cause them harm. The role of the thermal barrier is to retard the contribution of the foam plastic insulation to the fire growth to allow for occupants to evacuate before flashover. The benchmark time-to-flashover is based on the current known performing thermal barriers providing acceptable performance (i.e., acceptable solution).

The CAN/ULC-S124 is a test procedure with a pass or fail assigned, which is prescriptive, with respect to the temperature rise behind the designated thermal barrier. The prescriptive criterion of temperature rise is based on measurements of traditional panel products. However, an intumescent coating requires initial heating before it intumesces. During this initial period, the temperature rises at the interface between the intumescent coating and the foam plastic and may exceed those specified in CAN/ULC-S124 for Classification B.

A more complete assessment of a fire situation is through a performance-based approach as with full-scale room tests. A performance-based full-room test method, CAN/ULC-9705, which is similar to NFPA 286, was recently promulgated in Canada. Although this test method is similar to the NFPA test method, CAN/ULC-9705 is considered more severe and, as such, there are differences that make it impossible to directly compare test results. In particular, the ignition source and its heat output prescribed in the Canadian test method are different than in the NFPA 286 test method. In this evaluation, tests are conducted in conformance with the CAN/ULC- 9705 test method to determine the potential effect of a MD spray polyurethane foam protected using an intumescent coating on the fire growth and fire characteristics. The criterion used in these full-room tests is the ‘time-to-flashover.’ Flashover is the near-simultaneous ignition of most of the directly exposed combustible material in an enclosed area. The time-to-flashover indicates the time at which fire will spread to other objects in the room remote from the ignition source. In standard room tests such as CAN/ULC-9705, the time at which flashover occurs is determined by the earliest time at which two of the following criteria occur:

1. Heat release rate including burner ≥ 1 MW.
2. Incident heat flux at the floor ≥ 20 kW/m2.
3. Flames through doorway.
4. Crumpled paper on floor ignites.
5. Average temperature at ceiling in the room exceeds 600ºC.

In addition, similar testing must be undertaken for benchmarking of the NBC-specified acceptable solutions or the acceptable solutions specified by the provincial and territorial regulators. Based on the provincial and territorial consultation, the proponent in consultation with the CCMC evaluation officer determined the tests and criteria to be met for the decision making by the local AHJs across Canada.

The CCMC sought the opinion of Canadian provincial and territorial authorities from October 2015 to January 2016 to determine any variation in acceptable solution across jurisdictions related to minimum benchmarks for thermal barrier protection and protection from mechanical damage.