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FM 4450 (Approval Standard for Class 1 Insulated Steel Roof Decks) is a test conducted on roof deck constructions to a standard internal (under-deck) fire exposure. The results depend on the flame spread potential of a roof covering assembly by measuring its heat release potential. Due to the nature of this test, a burn-through of the roof assembly is not allowed. If it is a burn-through, the potential heat release cannot be measured. Thus, the test assembly does not meet the requirements. To meet the requirements of this standard, the insulated steel roof deck must meet the following requirements:

 TestPerformance Requirement
 Internal fire resistancePass calorimeter test
 Wind resistanceResist 60 psf wind uplift load (minimum)
 Foot traffic resistancePass 
 Corrosion of steel fastenersPass 
 Impact resistance of plastic fasteners/platesPass 
 Susceptibility to heat damage of cellular plastic insulationPass