CLASS B ROOF ASSEMBLIES
Class B roof assemblies are those that are effective against moderate fire-test exposure. Class B roof assemblies and roof coverings shall be listed and identified as Class B by an approved testing agency.
This code implies that all roof materials that pass the testing provided in the ASTM E 108 fire testing under the moderate category are identified as Class B roof assemblies. The fire test standard—ASTM E 108—tests roof assemblies for three fire categories; Severe, Moderate, and Light. The designation primarily differentiates between burn rates.
Roof assemblies with designation Class A or Class B can be applied on Class B structures.