Steel Buildings in Europe

Part 8: Building Envelope 8 - 8 2.2.5 Fasteners A wide variety of proprietary fasteners are available, which where required, can be watertight. Most fasteners used for metal cladding applications are both self-tapping and self-drilling, although screws which are only self-tapping are also available for use in pre-drilled holes. Fasteners can be used to connect sheeting to supporting steelwork (or other materials) or to connect adjacent sheets. For most fastener applications, a choice between plated carbon steel and stainless steel (typically grade 304 austenitic stainless steel is used) is made. Visible fasteners have the option of factory coloured plastic heads to suit the weather sheet. Further information describing these and other fasteners (e.g. secret fix fasteners) is available from MCRMA Technical Paper No 12 Fasteners for Metal Roof and Wall Cladding: Design, Detailing and Installation Guide [2] . 2.3 Insulated (composite or sandwich) panels Insulated roof and wall cladding panels consist of a rigid layer of insulation sandwiched between two metal skins, as shown in Figure 2.6. The result is a strong, stiff, lightweight panel with good spanning capabilities due to composite action in bending. These panels are commonly used on industrial buildings and retail ‘sheds’ in place of the built-up cladding described in Section 2.2. In this case, the panels span between cold formed purlins or side rails, which in turn span between the primary frame members. However, for commercial buildings, where the secondary steelwork is not needed for restraint purposes, it is quite common for composite wall cladding panels to span directly between the columns. Standing seam and through-fixed systems are available, with either a trapezoidal weather sheet and shallow profiled liner, as shown in Figure 2.6, or two flat / micro-ribbed sheets. Profiled composite panels are used for roofs to allow rainwater to run off without penetrating the fastener holes, while flat panels are favoured for walls due to their better appearance. 1 2 1 Insulation 2 Metal sheets Figure 2.6 Insulated panel Unlike built-up systems, there is no need for a spacer system, as the rigid insulation is strong and stiff enough to maintain the correct spacing of the sheets. Any loads applied in the plane of the cladding (e.g. down-slope loads