1.1 General. 1.1.1 The term roof covering refers to the material or the combination of materials applied on top of the roof deck for weatherproofing and can include insulation. 1.1.2 Since most roof coverings are combustible to some degree, they could be vulnerable to external fire exposure. Some roof coverings propagate a rapidly spreading fire over the surface or allow the fire to penetrate the roof covering and to communicate to the interior of the building and need to be avoided. 1.1.3 Roof coverings over metal and some other decks also should be considered for their possible contribution to fire spread originating on the interior of the building. The heat of the interior fire rises to the ceiling and can cause the liberation of combustible gases and flaming droplets through the joints, overlaps, and distortions of the deck. This can contribute significantly to the fire by means of flame spread beneath the roof and ignition of combustible contents by means of burning droplets of flowing materials. 1.1.4 A wide variety of roof coverings and roof deck constructions have been fire tested and listed by testing laboratories with respect to their characteristic behavior when subjected to both external and internal fire exposure. 1.1.5 Precautions should be taken during the installation of roof decks or coverings and above-deck components to prevent fire. (For further information, see NFPA 241, Standard for Safeguarding Construction, Alteration, and Demolition Operations.)