Understanding the UL Fire Resistance Directories - Ron Blank ...

Page 10 – Wall and Partition AssembliesUnderstanding UL1. Wood Stud Walls• The fire stopping requirements for wood stud assemblies is to bedetermined from the Authorities Having Jurisdiction. Horizontalbridging is included in most fire test samples in order to fully loadthe wood studs. This horizontal bridging should not beconsidered d as a means of fire stopping.• The hourly fire ratings for load bearing wood stud walls werederived with a superimposed p load applied to the wall assemblyintended to theoretically develop maximum working stresses notexceeding the design values published in the Supplement to the1991 Edition of the National Design Specification for woodconstruction. In addition, the design load per square inch ofcross sectional area for any wood stud shall not exceed 385 psi.• Wood stud walls may contain fire retardant t treated t studs as wellas untreated wood studs.