Analyzing How 2x10s & Flak Jacket Aren't Equivalent to a 15-Minute Membrane

Originally published by: SBCRI-SBCA Investigative Report #2October 15, 2015

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Underwriters Laboratories (UL) Research issued a report based on their ASTM E119 floor assembly fire testing, which provides excellent analysis of 100% design load testing. Based on the data in this report, as well as the testing done by SBCA, it appears clear that while 2x10s and Weyerhaeuser’s Flak Jacket joist product are deemed equivalent to a 15-minute membrane in fire conditions, they are not.

A summary of the UL test data follows as created by Mr. Sean DeCrane, Battalion Chief of the Cleveland, OH fire department for an Ohio Residential Advisory Committee hearing July 1, 2014:

SBCA fully agrees with the contents of the Underwriters Laboratories Fire Safety Research Institute report, specifically the following:

  • Page 67 (emphasis added):


  • Pages 3 and 68:

  • Page 64 (emphasis added):

  • Page 52 (emphasis added):

The goal of SBCA is to create a fair market for competing products. SBCA’s NGT ASTM E119 test data clearly shows that 2x10s and Flak Jacket are not equivalent to the performance of a ½ inch gypsum wallboard membrane. Flak Jacket times are 3 minutes less than 2x10s and equivalent to one of three floor truss tests. 2x10s are 5 to 8 minutes less than the 15-minute membrane performance level and another 5 to 8 minutes less than the 20-minute rule. SBCA undertook this testing to provide the substance needed to make our case. SBCA is working hard to overturn this inaccurate and inappropriate code provision.

The UL report states clearly that all unprotected floor systems are dangerous. UL and SBCA testing confirm the following facts:

  1. There is no safe operating time with an unprotected 2x10 floor system.
  2. The collapse time of 2x10 fire test experiments occurred within the time of the arrival of the fire service.
  3. 2x10 fire test performance emphasizes the importance of protecting all types of floor systems, including dimensional lumber.
  4. Regardless of what the floor system is made of, no factor of safety can be assumed, if the floor system is unprotected.     

AWC, NAHB and any jurisdiction that adopts R501.3 should also be concerned about the public policy implications of this law, considering the following concepts:

  • Injury.
    • What if a firefighter accident occurs in a basement fire?
    • What is the justification for IRC R501.3 or for using an ICC-ES AC 14 equivalency based product, such as Flak Jacket?
    • What is an accurate and fair policy that embraces firefighter and general public safety, given the ASTM E119 public data and UL reports?
  • Assessment.
    • Has the market for normal product trade been altered in favor of 2x10s?
    • Given the UL fire test data and report, could this be a high risk/high liability issue that requires immediate corrective action?
    • Attorneys that have looked at this issue believe it could be quite serious. What are the legal and negligence considerations given the public domain knowledge that is readily available? What action should be taken?

To see how SBCA is educating the market on these inequities, click on the state links (CM-member login required) to access the PowerPoint presentations  that provide an overview of the IRC R501.3 provision in the context of the state laws of MinnesotaPennsylvania and Iowa. The presentations show SBCA data in clear and concise terms and provide counsel on how to interpret the NGT test reports. We are working very hard every day on these issues. Our goal is to provide a market that is based on sound science that allows for robust free and fair trade.

If you are having problems in your state or local jurisdiction, please contact Sean at 608-310-6728.

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