Prescriptive vs. Tested systems in the U.S. and Canada
The term “thermal barrier” is used frequently in spray foam projects, but it is often misunderstood. Not every fire-resistant material qualifies, and not every coating can be left exposed over foam plastic.
To understand what counts as a thermal barrier, it is necessary to look at how building codes define compliance and how those definitions differ between prescriptive materials and tested systems.
Prescriptive Thermal Barriers
Building codes in both the U.S. and Canada include prescriptive thermal barriers. These materials are explicitly accepted without additional testing because their fire performance is well established. The most commonly accepted materials are gypsum board and some wooden or cementitious barriers.
However, prescriptive barriers are not always practical. They require framing, fastening and access, which can make them difficult to install in retrofit situations or in areas with exposed structural elements.
Tested Alternative Systems
To address these limitations, building codes allow the use of tested alternative thermal barrier systems. These systems are not named directly in code but are approved through large-scale fire testing, third-party evaluation reports and clearly defined installation requirements. Our thoroughly tested intumescent coatings are internationally accepted alternative thermal barriers.
In the U.S., this often involves special approval pathways supported by standards such as NFPA 286 or, UL 1715 and NFPA 275-based evaluation frameworks. These tests are designed to measure real fire behavior, including flame spread, heat release and flashover potential.
What matters most is that the testing reflects the actual end-use configuration. The foam type, coating, thickness and installation conditions must all match those tested for the system to remain compliant.
The Canadian Pathway
In Canada, the pathway is structured differently but follows the same underlying principle. Thermal barriers are commonly evaluated using CAN/ULC-S124 testing, supported by product listings from an accredited agency and provincial code requirements.
Some jurisdictions allow materials that meet Classification B under CAN/ULC-S124 to function as thermal barriers, provided they are installed in accordance with their evaluated conditions.
The Canadian Building Code allows the use of Alternative materials that carry an Evaluation Report from an accredited body, such as CCMC. Alternative materials do not mean lower performance or a less safe system; rather, they offer a product that meets the same goal but may be tested differently than a Prescriptive product or system. DC315 is currently an alternative material that is fully evaluated by CCMC and is widely used throughout Canada.
With the new 2025 National Building Code of Canada, once adopted by the Provinces, our DC315 is a prescriptive solution tested to the new CAN/ULC S-145 standard. This standard offers a significantly more robust method of fire testing than the current CAN/ULC S-124. Some performance characteristics, such as the stability of the protective covering, may differ significantly between these two methods. S-124 is a small-scale test and does little to evaluate the ability of the material to remain in place. In contrast, the CAN/ULC S-145 is a full-scale test that offers significantly better evaluation of not only the ability to limit the contribution of the foamed plastic but also its ability to remain in place for the specified duration.
Thermal Barrier vs. Ignition Barrier
A common source of confusion is the difference between thermal barriers and ignition barriers. A thermal barrier is intended to delay heat transfer and prevent the foam from igniting in occupied spaces, providing a higher level of protection.
An ignition barrier is used in concealed or limited-access spaces and does not offer the same level of fire resistance. Confusing these two classifications is a frequent cause of inspection failure. A coating may perform well in a controlled surface test, but that does not mean it qualifies as a thermal barrier.
Approval depends on full assembly testing, documented performance and third-party evaluation. Large-scale testing must represent the actual installed system, including the maximum intended thickness and configuration, to ensure reliable results.
Getting the Thermal Barrier Right the First Time
Thermal barrier compliance is not just about passing inspection. It is about ensuring predictable fire performance and avoiding costly rework.
At Paint to Protect, we focus on systems that are fully tested, documented and aligned with U.S., Canadian and international code pathways. If you are planning a project, we can help confirm that your chosen system meets current requirements before installation begins.