Key Takeaways
-
- ASTM E136 is the standard used to determine whether building materials can be classified as non-combustible.
- Recent clarification to ASTM E136 did not change the technical requirements of the test method, but clarified how pass-fail criteria must be determined.
- The updated language reinforces that neither internal nor external thermocouple readings may exceed the allowable temperature threshold during testing.
- NEXGEN MAXTERRA® continues to meet ASTM E136 requirements, providing confidence for fire-resilient construction applications.
ASTM E136 is the standard test used to determine whether building materials can be classified as non-combustible, and it is a critical confirmation as to which products construction stakeholders can confidently specify for fire-resilient construction.
Fire performance standards like these are designed to create consistency for testing laboratories, manufacturers, and code officials. However, even a single word leading to ambiguity within the standard can influence how it is interpreted. For fire testing pass-fail benchmarks, exactness is critical.
Therefore, when ASTM E136 recently received a clarification intended to eliminate a narrow but important area of inconsistent interpretation, building material manufacturers took notice.
While the requirements of ASTM E136 have not changed in regard to the way the test is conducted, the clarified language now provides unmistakable guidance on how pass-fail results are to be determined. This refinement eliminates confusion and strengthens the integrity of material evaluations. It’s a nuanced but important change to the standard that further strengthens the confidence in using third-party certified products such as NEXGEN’s MAXTERRA lines that account for these evolving codes and standards.
Enhanced Clarity, Greater Compliance
Magnesium Oxide (MgO) boards like NEXGEN’s MAXTERRA have grown in popularity as a choice for structural wall sheathing, floor panels, and wall boards in commercial and residential construction in over the last 10 years.
Despite this growth, building codes and standards that impact those who specify and build with it are subject to change every few years. Even in instances where testing procedures and measurement requirements have not been altered, ambiguous or new language can risk misinterpretation in the field.
This was the case for ASTM E136, where the need for clarification centered on section 15.2.1 of the standard editions adopted by the 2021 and earlier I-Codes. This section establishes the pass-fail criteria for the vertical tube furnace test used to evaluate building materials like MgO board.
Previous versions of this section stated, “The recorded temperatures of the surface and interior thermocouples do not at any time rise more than 30 °C (54 °F) above the stabilized furnace temperature measured at T2 prior to the test.”
The use of the word “and” proved to be confusing, leading to an interpretation by a limited number of testing labs allowing a passing result if only one thermocouple (internal or external) exceeded the temperature limit while the other did not. Under this interpretation, a test would not be considered a failure unless both thermocouples exceeded the limit. However, this was not the intent of the code; the requirement was that neither thermocouple could exceed the prescribed temperature.
As a result, the topic was brought before the ASTM E05 committee, which approved a clarification to the language but no technical changes to the standard. This clarification was subsequently adopted into the 2024 I-Codes.
The updated standard now separates the requirements into two distinct provisions, specifying that neither the internal nor external thermocouples may rise more than 30°C (54 °F) above the stabilized furnace temperature for the assembly to pass the test.
Assessing Combustibility
The purpose of the vertical tube furnace test is to determine whether a material can be considered “non-combustible” for use in Types I-IV construction as defined in Chapter 7 of the International Building Code.
The test itself involves subjecting a sample of the material to rigorous heat, simulating a fire scenario.
Fitted with a pair of thermocouples on the surface and in the middle of the specimen, it is then placed in a vertical tube furnace where it’s exposed to 750°C (1382°F) heat for a minimum 30 minutes. Throughout this process, the sample’s reaction to heat and flame is carefully monitored and evaluated.
For a material to be labelled “non-combustible,” the specimen temperature cannot exceed 30°C above the stabilized furnace temperature. Furthermore, flaming is prohibited after the first 30 seconds if the material exhibits less than 50% weight loss. If material weight loss exceeds 50%, there is no flaming from the specimen permitted at any time during the test.
By setting these exacting standards and updating language in the code to eliminate confusion, ASTM E136 helps to ensure tested building materials will not significantly contribute to an ambient fire in a real-world situation.
In the Clear: NEXGEN MAXTERRA®
Clear and consistent language within building codes is important for how materials are specified, tested, and approved for use in noncombustible construction. The recent clarification to ASTM E136 reinforces the importance of rigorous, consistent evaluation across the industry.
For architects, builders, and code officials, this clarification also underscores the importance of selecting third-party certified MgO products that can confidently meet the latest clarification within the standard. NEXGEN MAXTERRA® remains compliant with ASTM E136 requirements under the clarified pass-fail criteria, providing construction stakeholders with confidence when specifying materials for fire-resilient applications.
In addition to non-combustibility performance, NEXGEN MAXTERRA® delivers the exceptional durability, moisture resistance, and environmental friendliness expected from advanced MgO boards, and offers a strong alternative compared to materials like Portland Cement board, wet-applied gypsum, and standard OSB.
As testing standards and code language continue to evolve, manufacturers capable of meeting their stringent performance expectations will play an increasingly important role in advancing safer, more resilient construction practices. The ASTM E136 clarification helps ensure all products are evaluated through the same lens, while high-performance solutions like MAXTERRA® boards continue to provide trusted results for fire-rated floor, ceiling, and wall assemblies that qualify for use in Types I-V construction under the IBC and all types under the IRC.
Watch Eric’s Explanation of the ASTM E136 Changes
