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Inspection Inspection of purlins and girts should be carried out prior to installation. The ease of inspection, and cost and time lost if remedial action is required, will be substantially less favourable once the purlins have been installed. Inspection should comprise of checks that labelling is in line with specifications and detailing, and that the section dimensions, hole positions and thickness are exactly to the manufacturer's stated values. Even small deviations to these values may lead to significant variations in performance from that used in design. It is imperative that this be resolved immediately and prior to installation. Purlins and Girts supplied by Stramit will be made from high tensile galvanised steel. Final inspection of the installed purlin, girt and bridging system should check for correct bolting of laps and that bridging is correctly in place. If practical, a check of bolt tightness is highly desirable, both on the purlins and on bolted bridging connections. Walking Stramit® Purlins, Girts and Bridging are not designed for walking on. Residual oil may be present on these components from manufacturing. The use of appropriate cradles or cherry pickers is recommended. As a minimum, follow these rules: Never walk on purlins without safety mesh in place. Always use a safety harness if walking on girts. Never walk or place body weight on to bridging. Bridging Stramit® Boltless Bridging can be installed either up or down the roof slope. However, as the starting and finishing components will be different, the directions of fixing must be established at the design/procurement phase. For walls, where more than one row is to be installed, always complete the bridging for each girt before commencing on the next (i.e. Do not complete one row of bridging before starting the next). Fixing Up the Slope Laps Purlin laps must be bolted in the top web hole and the lower flange holes at both ends of the lap as shown below. Bolting only in the web of lapping purlins does not provide full structural continuity and excessive loads could be placed on to roofing screws that penetrate both purlins within a lapped region. Bolts/Fastening Always use the correct size and grade of bolts as nominated by the design engineer. Ensure that all bolts are tightened. It is essential that all bolts are fully tightened prior to roofing installation and before any loads are applied to the purlins, girts or bridging. Swivel assemblies require additional screw fastening prior to roofing and the application of loads. Fly Bracing If the lower web hole in a lap is used for attaching fly bracing ensure that an additional bolt is used. Welding Stramit does not recommend the welding of purlins, girts or bridging. The heat produced in welding will affect the material properties of the high-tensile cold-formed steel used by Stramit in all its purlins. In many instances considerable stress concentrations are likely to arise, even with good quality welding. In addition welding will locally remove the galvanised coating leading to a potential reduction in durability. Roof Meshing If using insulation blanket, do not overtighten roofing mesh as this may impede the installation of roof sheeting.

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