5 Takeaways from the Live Webinar: “Protecting Pipes in Plenums with Fiberglass”

We recently hosted a live webinar, “Protecting Pipes in Plenums with Fiberglass.” This webinar tackled some of the big questions people have about interpreting building codes and what it means for the types of insulation materials that are permissible for use in plenum spaces. You can watch a recording of the full webinar here.

Our co-hosts, Eric Alley, JM’s Northern Regional Sales Manager, and John Elverum, JM’s Senior Technical Services Specialist, discussed the code interpretation, permissible insulating materials in plenums, and installation details to consider when designing insulation systems for plenum spaces.

Here are 5 key takeaways from the presentation for you to consider when specifying insulating materials for use in plenum spaces.

  1. Code requirements became more rigid in 2015. As technology advances, codes undergo evolutions to incorporate new practices, information, and resources, and the International Mechanical Code (IMC) is no exception. In 2015, the IMC changed in three key ways: 1) intent and wording, 2) increased emphasis on the wordslistedandlabeled,and 3) interpretation of the application. These changes, while seemingly minor, impacted the types of materials that were permissible for use in plenums.

  2. Interpreting “listed” and “labeled” is key to understanding what materials are permissible in plenums. One of the key changes that strongly influenced which materials could be used in plenums was the emphasis on the words,listedandlabeled.  The outcome was that any material used in a plenum to insulate combustible pipes had to have a 25/50 fire hazard classification per ASTM E84 and belistedandlabeledfor such an application. As a result, the code became more exclusive regarding the materials that were permitted to be used in plenum spaces, prohibiting any materials that were not listed and labeled as meeting the 25/50 fire hazard classification.

  3. Even though a material may have a 25/50 fire hazard classification per ASTM E84, it doesn’t necessarily mean it can be used in plenum spaces. Per the changes to the code, insulations intended to be installed over combustible pipes in plenums had to be tested in an assembly over a combustible pipe. For example, while Micro-Lok®HP(JM’s preformed fiberglass pipe insulation) already had a 25/50 fire hazard classification, it had to undergo new testing to meet the change in code requirements. This requirement applies to any material being used over combustible pipes in a plenum space – even ones that had previously been code compliant.

  4. Some pipe insulations have been tested and approved for use in plenums over combustible pipes while others have not.Some preformed, fiberglass pipe insulations, like Micro-LokHP, have undergone the appropriate testing to become listed and labeled as having a 25/50 fire hazard classification. This is not the case, however, for all 25/50 rated materials. If you are curious as to whether your specified insulation meets the new code requirements, check with the product manufacturer to confirm it has been tested appropriately and is listed and labeled for the application.

  5. There is a distinct and critical difference between a fire hazard classification and a 1-hour fire rating. It’s crucial to understand that a 25/50 fire hazard classification and a 1-hour fire rating are not the same thing. When an application or a code calls for a material that has a 1-hour fire rating (or more), the material should be able to withstand up to 1 hour fire testing per ASTM E119 or another appropriate test method. Some codes may require longer fire hour ratings for certain applications. Typically when hour-long fire ratings are required, plenum wrap, or similarly rated materials, are an appropriate insulation for the application.

In contrast, a material with a 25/50 fire hazard classification will ignite more quickly. The fire hazard classification is in place to allow building occupants sufficient time to exit the building before the flames and smoke spread to dangerous levels. It is not indicative of a nonflammable material.

Despite the changes in the IMC, local codes may still require fire hour ratings. Be sure to confirm the material you specify is appropriate for the local building code requirements.

Eric and John addressed much more in their webinar, and you can get all the details in the recording of the webinar on our Exclusive Content Portal. If you are looking for more information about this code change specifically, we encourage you to read our blog, What You Need to Know About Using Micro-Lok HP In Plenum Spaces.

If you have additional questions about using fiberglass in plenum spaces, please contact our technical support line: