ROOF SURFACING AND ASSEMBLIES
BACKGROUND: The fire resistance of roofs is an important factor in the
ability of structures to withstand fires from exterior sources.
Ignition of buildings may occur from exposure to fires by radiated or
convected heat; direct contact of flame and from flying brands and
embers. Major conflagrations have been caused by flying brands on roof
ROOFING MATERIALS: NFPA No. 203M, Roof Coverings, divides materials
hating suitable fire resistance into Classes A, B, C. The listings of
built-up and prepared roof materials are found in UL, Building
Materials Directory. Insulated roof decks are composed of metal
decking with materials (adhesive, vapor barrier, insulation and roof
surfacing) added in layers to the deck. The combustibility of the
assembly is a function of the materials used and method of
application. The UL listing is referenced for details on acceptable
roof deck construction from an interior fire exposure standpoint.
APPLICATION: MIL-HDBK-1008A (most current edition) specifies
the use of either class A, B, or C roof surfacings. Materials shall be
listed in UL Building Material Directory. Wood shingles are, acceptable
only when treated to meet UL requirements for Class C listing.