1 June 1998
resisting the tributary area load of the clip times the design wind pressure applicable to that
portion of the roof multiplied by a safety factor of 3.0.
d. Support Spacing. The supporting structural member spacing will not exceed 750 mm
(2 ft. 6 in.) on-center at all roof edges including corners, eaves, and ridges of the roof and 1,500
mm (5 ft. 0 in.) on-center for the remainder of the roof (field or midfield). Roof zones including
zone widths will be determined in accordance with ASCE 7. Panel manufacturers must provide
laboratory testing in accordance with ASTM E 1592 verifying that the SSSMR system will meet
the designated loads in all roof zones with the support spacing specified. Appendix A is a listing
of SSSMR systems tested and approved by the Corps of Engineers in accordance with the
requirements of CEGS-07416 (October 1991).
e. Roof Slopes and Seam Height. Roof surfaces will be provided with sufficient slope to
prevent the accumulation of rainwater. Maximum slope should be limited to that recommended
by the manufacturer, based upon design, gravity, snow, ice, wind, and down-slope forces.
(1) SSSMR will not be used on slopes less than in 12.
(2) Mechanically crimped and sealed SSSMR system can be used for all roof slopes equal
to or greater than in 12 with a minimum standing rib height of 37 mm (1- in.).
(3) Uncrimped (with factory-installed sealant) SSSMR system with panel widths less than
or equal to 300 mm (12 in.) can be used for all roof slopes greater than or equal to 2 in 12 with a
minimum standing rib height of 50 mm (2 in.).
(4) Uncrimped (with factory-installed sealant) SSSMR system with panel widths less than
or equal to 300 mm (12 in.) with a standing rib height of 37 mm (1- in.) can be used for all
slopes equal to or greater than 3 in 12.
(5) A minimum slope of 1- in 12 will be used in cold regions.
(6) A minimum slope of 1 in 12 will be used in highly corrosive environments.
f. Panel Thickness. The minimum thickness of panels 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.
g. Deflection. Maximum deflection for metal roof panels under loads applied in combinations
as specified in ASCE 7 will not exceed 1/180 times the span. Maximum deflections will be based
on continuous sheets across three or more supports. Deflections will be calculated and
measured directly below the standing seams.
h. Thermal Movement. Attachment clips will be capable of providing the fully anticipated
thermal movement. The maximum temperature range for thermal movement will be stated in the
project specifications. The clips will have the movement slots centered at the time of installation.
Calculations to determine the maximum anticipated thermal movement will be included with the
shop drawings. Expansion joints may be necessary on roof slopes longer than 30 m (100 ft.).
The contract drawings will show the location of the expansion joints.