Code Commentary

LTTR R-Value of MD CC SPF

Every once in a while, it is a good idea to review the Rules of SPF as it pertains to the MD CC SPF Market in Canada. Canada benefits greatly from having a unified model building code. BC, Alberta, and Ontario maintain their own versions Provincially, but these are still largely unified with the Canadian NBC. The process by which a manufacturer wishes to bring a MD CC SPF foam to market in Canada is to confirm compliance with the long established CAN.ULC S705.1 Material Standard. This standard, outlines, in detail, the required performance tests to be completed, along with the set minimum, maximum, or declared value as required in the standard. While not an implicit requirement in the code, it has become a normal process that a manufacturer (proponent) would enlist the services of a third party ISO-17025 accredited Evaluation Agency such as CCMC or more recently ULC, in order to review the test(s) results and provide either a product Listing or Evaluation Report as requested. At this point it should be noted that there is a difference between a Product Listing and an Evaluation Report.

The CCMC Product Listings are designed to confirm full compliance with the established standards published for a given product. An Evaluation Report is less rigorous and is essentially an Opinion of Product suitability for use. As always, the reader needs to read the report and also the limitations of liability they are

acknowledging in their disclosure statements. (aka:fine print)

Back to LTTR specifically. The CAN/ULC S705.1 Material Standard requires that an S770 LTTR test be completed on a 50mm thick sample. The actual SPF Sample Preparations for ALL tests are detailed in the S705.1 Material Standard.(see attached reference on sample preparation.)

As the S770 test is not unique to spray foam products but includes all gas trapped insulation materials including board stocks, the S770 sample preparation requirements are much broader to allow for these other products which still have trapped gas cells. Some of these are foil faced boards which would have greatly reduced gas loss with the addition of a foil faced membrane.

What does the National Building Code say about LTTR?

The Canadian NBC has specific language used in defining the design R-value of Spray Foam material. It specifically references the requirement of the test results of the MD CC SPF @ 50mm as the defined design R-value when completing the S770 test. In broader terms there are references that the MD CC SPF must meet the CAN/ULC S705.1 Material Standard AND it must be installed in compliance with the CAN/ULC S705.2 Installation Standard.

We have included references below that clearly support that it is the RESULTS of the S770 test at 50mm that dictate the design R-value the NBC demands be used in determining compliance with respect to product R-Values.