CEMP-ET
EI 01S908
1 June 1998
compensate for the differential movement between the roof panels and the substrate. For wood
structures, insulated roofs and buildings that are temperature sensitive or are extreme climate
areas, consider a greater temperature range. Dark roofs in mountain areas may be subject to a
temperature of 116 degrees C (240 degrees F) or more. For lateral expansion the thermal
movement may be assumed to be absorbed in the standing seam rib. Amount of thermal
movement will affect the panel length and seam configuration required to accept clip movement.
f. Load Tests. The uplift resistance of the nonstructural standing seam metal roof system
will be in strict accordance with performance testing UL 580. Test for uplift resistance of roof
assemblies must show a class 90 approval for all system assemblies including components,
fastening devices, and substrate applied to supporting structural roof framing members or
structural deck.
g. Substrate. The roofing panels should be installed over a solid continuous substrate
capable of supporting all design loads including live, dead, and collateral conditions. Wood, rigid
insulation, and concrete deck are typical materials used as a substrate. The substrate material
and its anchorage into the structural frame must be in complete accordance with a
manufacturer's listed UL Class 90 uplift classification, or SMACNA criteria.
h. Pull-out Test. For re-roof applications, pull-out tests should be made to establish the
tensile strength and anchorage capacity of proposed fasteners for the substrate anchorage to the
structural system and for panel anchors' installation into an existing substrate for new metal
cover. Fasteners used in multiples of 2 or more should resist a load consisting of the tributary
area multiplied by a safety factor of 2.25. Single fasteners should be avoided where possible, or
should use a safety factor of 3 when used. Substrates must be directly connected to the
structural system and capable of proving equivalent fastener capacity for panel anchors.
9. CORRUGATED (THROUGH-FASTENED) ROOFING.
a. General Design Philosophy. The design loads and performance requirements should be
shown on the contract drawings and/or included in the specifications. The design is typically
performed by the manufacturer with results submitted in tabular form as part of the
manufacturer's data sheets. Submitted tables should show suggested uniform loads for various
spans and should be reviewed by a structural engineer to ensure that flexural and deflection
criteria used to develop the tables are consistent with that specified and that all other
performance requirements are met.
b. Roof Slopes. Roof surfaces will be provided with sufficient slope to prevent the
accumulation of rainwater. Corrugated (through-fastened) metal roofing will not be used on
slopes less than 2 in 12. In cold regions this minimum will be 3 in 12.
c. Panel Thickness Requirements. The minimum thickness of sheets for roofing will be 0.81
mm (0.032 in.) for aluminum and 0.61 mm (0.024 in.) for steel. The thickness of uncoated
panels will not be less than 95 percent of the design thickness.
d. Thermal Movement. Design provisions should be made for thermal expansion and
contraction consistent with the type of system used. Sheets in excess of 9 m (30 ft.) may require
additional design provisions such as stepped expansion joints for thermal expansion and
contraction.
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