Certain roof system types historically have been granted building code waivers from testing to determine their external fire-resistance classifications. However, changes incorporated into the International Building Code, 2009 Edition (IBC) alter these waivers and necessitate fire testing to serve as the basis of most roof systems' fire-resistance classifications.
If you are involved with roof system manufacturing, sales, design or installation, I encourage you to be familiar with these code changes and the specific roof system types the changes affect.
Most building codes divide roof assemblies into three classifications for the purpose of designating their resistances to external fire exposure. Class A roof assemblies are effective against severe fire exposure; Class B roof assemblies are effective against moderate fire exposure; and Class C roof assemblies are effective against light fire exposure.