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

Editor's Note: The following article was originally published as a CM-Member Only story on October 15, 2015, and is now being republished for the general public.

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 NIST/ARRA/UL 2012 report entitled; “Improving Fire Safety by Understanding the Fire Performance of Engineered Floor Systems and Providing the Fire Service with Information for Tactical Decision Making”.

More specifically the SBCA agrees with the following statements as quoted from the report:

On page 67, the report states (emphasis added):


On pages 3 and 68, the report states:

On page 64, the report states (emphasis added):

On page 52, the report states (emphasis added):

The goal of SBCA has been to create a fair market for competing products, where test data clearly states that 2x10s and Flak Jacket are not equivalent to the performance of a ½ inch gypsum wallboard membrane. Given this SBCA undertook testing that provides 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:

1.    Injury - What if a fire fighter accident occurs in a basement fire?

a.    What is the justification for IRC R501.3 or for using an ICC-ES AC 14 equivalency based product, such as Flak Jacket?

b.    What is an accurate and fair policy that embraces firefighter and general public safety, given the ASTM E119 public data and UL reports?

2.    Assessment - Is it not reasonable to consider, the following concepts?

a.    Has the market for normal product trade been altered in favor of 2x10s?

b.    Given the UL fire test data and report, could this be a high risk/high liability issue that suggests immediate corrective action?

c.    Attorneys that have looked at this issue believe it could be found to be quite serious. What are the legal and negligence considerations given the public domain knowledge that is readily available? What immediate action(s) should be taken?