Fire Protection of Floors
Recent ASTM E119 testing (using 100% design load conditions as required by that standard), conducted independently by Underwriters Laboratory (UL) and NGC Testing Services (NGC), confirm that an unprotected floor assembly constructed of 2x10s or Flak Jacket coated I-joists do not provide “equivalent performance” to a floor assembly that has a ½” gypsum wallboard membrane ceiling as prescribed by R501.3 (IRC-12) and R302.13 (IRC-15). Standardized E119 testing shows all unprotected structural floor assemblies perform for far less than the 15-minute membrane time provided by a ½” gypsum wallboard membrane ceiling, as defined by code (IBC-12 Section 722.6.2).
UL concludes on page 67 of its test report, “There are little if any warning signs of collapse so it is very important to understand the hazards associated with a basement fire because the consequences of falling through a floor into a basement fire are pinnacle.” Further, on page 66, the UL test report concludes, “This [the fire service response time scenario] assumes ….. the fire department begins their firefighting operation in 8 minutes…. This emphasizes the importance of protecting all types of flooring systems, including dimensional lumber.” (emphasis added.)
A failure to eliminate Exception 4 from R501.3 and R302.13 could lead to a firefighter falling through an unprotected 2x10 or Flak Jacket coated I-joist floor and being maimed or killed due to an erroneous assumption the system adheres to the traditional “20-minute rule.” In contrast, by providing a ½” gypsum wallboard membrane ceiling to all floor systems, 20 minutes of actual performance time is likely to be present.
In general, the law states the purpose of a building code (See R101.3 Intent), “is to establish minimum requirements to safeguard the public safety, health, and general welfare…..and to provide safety to firefighters and emergency responders during emergency operations.”