Framing components of steel buildings are classified into structural framing members and secondary framing members. Purlins are secondary structural members that provide support for roof coverings of steel buildings. The most common purlin shapes are “C” and “Z” sections.
The two main types of metal roofing systems are the standing-seam and lap-seam (or through-fastened) systems. Standing seam is a type of metal roofing system that uses concealed clips. This roofing system comes in a variety of panel configurations to suit a wide range of applications – trapezoidal, pan, and batten.
The standing seam roofing system has two main advantages when compared to a through-fastened system:
1. The standing seam roofing system provides a better seal against the elements.
2. Changes in dimensions of the roofing system components due to thermal changes, are not restrained.
In standing seam roof system for steel buildings, the panels are not directly attached to the purlin flange. Instead, they are connected to the purlin flange via panel clips or fasteners that are concealed under the roof panels. Clips are specially designed, proprietary fasteners seamed into mating panels of a standing seam roof, to connect the roof panels to the structural members.
A standing seam roof system for steel buildings is installed by sequentially placing the roof panels, starting at the eave of the metal structures. The high ribs at both edges of a standing seam roof panel consist of a male and female rib. The panel clips are attached to the male rib. Then the female rib of the next panel is placed over the male rib, where the clips have been attached.
The standing seam is sealed once the two ribs are in position, with the clip tab positioned between the male and female plies. The sealing process is the technology that makes the standing seam roof system provide extreme weather protection to steel buildings.
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Source: http://www.steel.org/AM/Template.cfm?Section=Home&TEMPLATE=/CM/ContentDisplay.cfm&CONTENTID=13201
Tags: Metal roofing systems, Standing seam roofing system, steel buildings