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Protection of Foamed Plastic with the Use of Effervescent Paints or Latex Paints

Effervescent or any other paints cannot be used as a protection of foamed plastics in accordance with the requirements set forth in the National Building Code. - Article 3.1.4.2 Protection of Foamed Plastic.

Article 3.1.4.2 allows three options for protection, interior finishes as outlined in 9.29.4 to 9.29.9, sheet metal meeting specific requirements, or a thermal barrier.

Paints of any sort do not meet the requirements of the interior finishes, they are not sheet metal and they do not meet the requirements of a thermal barrier.

Effervescent paints have been used to meet USA Code requirements as an ignition barrier. The Canadian 1995 National Building Code does not require an ignition barrier over foamed plastics.

Paints of any sort do not meet the requirements of a thermal barrier. A thermal barrier is described in Article 3.1.5.11.(2) as being 12.7 mm thick gypsum board, lath and plaster, masonry, concrete, or any thermal barrier that is a class B when tested in accordance with CAN4-S124-M – Standard Method of test for the Evaluation of Protective Coverings for Foamed Plastic. Appendix A of the 1995 National Building Code states that the standard fire exposure temperature in CAN/ULC – S101-M – Standard Methods of Fire Endurance Tests of building Construction and Materials is the same as in CAN2-S124-M. A thermal barrier that, when tested in conformance with CAN/ULC S101-M will not exceed an average temperature rise of 140ºC on its unexposed face after a period of 10 minutes satisfies this requirement.

A thermal barrier can be described as a material which limits the speed by which heats transfers through a material. If you review the CAN4-S124-M standard, you will see that essentially the material is installed over a furnace which produces a temperature of 704ºC. The protective coating is installed over a piece of foamed plastic with thermal couples between the thermal barrier and the foamed plastic. The specimen is placed with the thermal barrier exposed to the furnace. When the test commences, the furnace provides the 704ºC of heat and the temperature rise is measured over time between the thermal barrier and the foamed plastic. To be a class B thermal barrier the maximum temperature increase recorded shall be no greater than 140ºC when measured at the ten minute interval.

Figure 1 Thermal Barrier Test Assembly

So if a thermal barrier is defined as a material which significantly slows the heat transfer through the material, it would be hard to imagine any type of paint would meet the requirements outlined for a thermal barrier.

Fire in buildings is a serious health and safety issue. The spray polyurethane industry has spent countless hours and incurred much cost to ensure that spray polyurethane foam, properly installed, is a safe product to use in any construction type. The industry has included limitations in the CAN/ULC S705.1 Material Standard on flame spread when tested in accordance with CAN/ULC S102. Installers of spray polyurethane foam, when they are installing the material on the inside of a building, are required in CAN/ULC S705.2 to either install a thermal barrier or to inform the owner in writing that a thermal barrier is required.

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