Thermal barriers and the protection of foamed plastic

Preparing the foam for a CAN/ULC S101 wall test. Photo courtesy W.R.Grace and Co.

Current market situation
Until recently, thermal barriers have typically been one of two types—fibre-based or cementitious. These products protect the foamed plastic from fire, while also providing physical protection for the foam from abuse, allowing for longer in-place service life. Many of these materials have a long and successful track record, and are listed with testing agencies such as ULC, Intertek, and QAI, passing many CAN/ULC S124 or CAN/ULC-S101 tests as thermal barriers.

Recently, this author has seen unfounded claims by companies marketing paintable ignition barriers that are certified for use in Canada as thermal barriers. These products are often intumescents—typically, ammonium polyphosphate-based—which begin the intumescing process at 240 C (464 F), which is higher than the maximum allowable temperature limits of the code. (In other words, they begin their protective actions too late.) Unfortunately, in most cases, these companies have attempted to confuse the marketplace by intentionally running fire tests where the thermocouples were not properly located to comply with NBC.

For example, in some cases, a single material was tested using CAN/ULC-S101 with the thermocouples on the unexposed side of the assembly, behind the wallboard. This procedure is appropriate for qualifying a wall assembly, but cannot be used to qualify a material as a thermal barrier (i.e. because such a process requires the thermocouples to be at the interface of the thermal barrier and the foam).

Another inappropriate test had the thermocouples buried within the foam, which obviously does not meet the code. When this information was brought to the attention of one of the manufacturers that had run tests where thermocouples were not placed in accordance to the NBC requirements, the company stated it did not think the material would pass as a thermal barrier when using the required thermocouple placement.

In addition to erroneously promoting products with claims their products are certified for use in Canada, some companies have been supplying results from testing in the United States done in accordance to UL 1715, Fire Test of Interior Finish Material—a completely different and less severe test method that does not meet NBC requirements.

Thankfully, there has recently been the introduction of certain intumescent paints that do pass the CAN/ULC S124 test. By meeting the requirements of the test, these companies have negated the argument the CAN/ULC S124 test is too severe to act as a test method for intumescent thermal barriers.

Further, there exists in Canada a process whereby the developers of new and materials may use the Canadian Construction Materials Centre (CCMC) to demonstrate compliance with the requirements of NBC or provincial/territorial building codes. Regretfully, this author has seen engineering judgments appearing to ‘okay’ the use of intumescent thermal barriers. In some instances, the claims made have been factually incorrect; in others, the basis for approvals have been the alternate method for code compliance provisions, given in 1.2 of Division A of NBC where compliance with the code can be achieved by meeting a prescriptive test or by showing through performance testing a product meets the objectives of the prescriptive code section.

Considering the wide variety of thermal barriers choices now available, can one really state the alternate, but untested, product is as good as or better than those products currently available? This author does not believe such a claim can be made, especially when code-compliant test processes are available at a reasonable cost.

Contractor liability
Ultimately, it is the responsibility of the installer of the thermal barrier and the AHJ to provide and approve products conforming to the relevant provincial building code. Unfortunately, the contractor may also be held liable if he or she installs a product that does not conform to the applicable standard—even when the building inspector has incorrectly accepted products that do not meet the intent of the NBC. Architects and specifiers could also face legal liability, to say nothing of the moral issues for design professionals.

Canadian Construction Documents Committee (CCDC) documents suggest, it is the responsibility of the prime consultant to include in the contract documents the criteria required for the constructor to comply with the code requirements. It is the constructor’s responsibility to provide the work in compliance with the contract documents and the code. That said, the constructor is not responsible to verify the contract documents are in compliance with the code. The constructor may be liable if it installs a material not in compliance with the contract documents, or if it proposes a substitution material that does not meet the code requirements. The reality is all parties involved risk some legal liability, to say nothing of the moral issues.

To avoid any unnecessary liability, the specifications should request a submittal of a letter from the manufacturer stating the material being supplied has been tested in accordance with the requirements of the National Building Code (item and passed its criteria established for a thermal barrier. One should also ask for the test report that supports the requested letter. There are many products in the market that have successfully passed the NBC criteria as thermal barriers; selecting and using a product that has not met these criteria would be taking on unnecessary liability, and is a threat to life safety.

The fire protection industry (including manufacturers, engineers, architects, and the contractor community) has a duty to provide the public with a reasonable level of safety in buildings in compliance with the applicable building codes. It is the responsibility of all parties to perform their due diligence to ensure public safety is not put at undue risk. Accepting only code-conforming materials is an important aspect in the process.

DaltonJohn A. Dalton is technical service manager for W. R. Grace & Co.’s fire protection products division. He is the task group chair of the ASTM E06.21 committee on serviceability and a principal member of the U.S. National Fire Protection Association (NFPA) 502, Standard for Road Tunnels, Bridges, and Other Limited Access Highways. Dalton has degrees in mathematics and industrial chemistry. He can be reached at

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