National Building Code of Canada Updates Insulation Requirements

Originally published by: Newkerala.comJuly 8, 2019

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Thermal insulation materials are critical to a building's design and its ability to reduce energy consumption.

In 2017, the ULC Standards Committee on Thermal Insulation Materials and Systems approved an updated fifth edition of the CAN/ULC-S701.1, Standard for Thermal Insulation, Polystyrene Boards. This standard specifies the requirements for rigid insulation.

Following the S701.1 standard update, the Canadian Commission on Building and Fire Codes has recognized the Fifth Edition as the new reference document for EPS and XPS insulation in the interim revision to the 2015 National Building Code of Canada. Now that NBC 2015 recognizes S701.1, Canadian provinces can adopt the requirements in Provincial jurisdictions. Three provinces, Alberta, British Columbia, and Saskatchewan have already adopted the NBC 2015.

Two changes to the Fifth Edition were significant for providing greater clarity on thermal performance. First, this edition removed the conditioned thermal resistance requirements in favor of requiring the Long-Term Thermal Resistance (LTTR) determined using CAN/ULC-S770-15, Standard Test Method for Determination of Long-Term Thermal Resistance of Closed-Cell Thermal Insulating Foams.

This test method is used to determine the LTTR for products that contain a cell gas (other than air) which diffuses over time, CAN/ULC-S770 predicts the 5-year aged R-value (equal to the 15-year time-weighted average R-value). 

The second change mandated that the LTTR, rather than the initial R-value or conditioned R-value, be marked on the insulation products. These two changes are consistent with the requirements of the building code to use LTTR values in energy calculations.

To characterize the effective R-value of polystyrene insulation considering the effects of aging and conditions of application, the EPS Industry Alliance has recently published a paper, Polystyrene Foam Insulation in Long-Term Building Applications, Effective R-Values, that provides a method to estimate R-value by accounting for these factors.

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