Equivalent Thickness. Testing every possible wall combination is
not feasible. The equivalent thickness method accurately predicts
Part 1 of this guide describes ASTM E-119 testing, which is one way that building components such as walls, partitions
and floor/ceiling assemblies qualify for fire ratings. When an assembly passes such a test, which usually is conducted at an
independent testing lab such as Underwriters Laboratories, Inc., that specific combination of products assembled exactly as
tested receives a UL Classification number that can be used to designate it in project specifications.