Within the low-slope roofing marketplace, there has been confusion between a Class A fire rating and a Class 1 fire rating. There are significant differences between a Class A and Class 1 rated roof system. The class of fire rating for a roof system is an important part of roof design and not only determines the ability of the roof system to resist fire but the extent to which the system has been tested. To examine the difference, we first need to look at what each fire rating tests.