Purlins traditionally support the roof deck / cladding / sheeting and are in turn supported by the principal rafters / steel beams etc. Lightweight purlins are a cost effective structure that provides the basis for a perfectly straight roof. The steel sections are sufficiently ridged to ensure a perfect base for roof cladding. Steel does not tend to warp with age and a high quality finish is maintained over the full life span of the building.
INSTALLATION AND DOCUMENTATION
Always use the correct size and quantity of fasteners as specified. Screws at connections must be directly in line (parallel with the supporting member). One screw to be fastened on each side of purlin at the point of connection with rafters.
Minimum 15 cm of overlap is recommended, with minimum 4 screws per overlap. "The recommended screw size is 5mm diameter with minimum 20mm length.
Structural laps for Lightweight purlins require a minimum 15% lap length. End fastenings of Lightweight purlins should be 25mm from the section end irrespective of whether this occurs at the structure end or at an internal support.
Maximum span of rafters is 800 mm.
Cutting is preferably done by shear or hacksaw. When using abrasive disc blades care must be taken to ensure the swarf produced does not affect other materials and the burred edge should be cleaned off at the completion of cutting.
We do not recommend the welding of lightweight purlins. It should only be screw fastened to the supporting structure.