02.09 Rainscreen Panels
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Sheet materials
Fibre cement sheets are manufactured in thicknesses between 5 and 10mm and in sizes up to 1220mmx3050mm. Both cellulose and glass fibres may be used and a wide range of finishes is available including untreated, various types of paint and resin bonded aggregate. Sheets are normally supplied to site ready cut to size and with predrilled fixing holes.
Various fixing methods may be used ranging from timber battens, image, to proprietary aluminium cladding rails. Lightweight cladding rails, image, require continuous support and provide little scope for adjustment to accommodate deviations in the background wall. Heavier gauge cladding rails, image, can span between floors for situations where the backing wall does not provide suitable support for the cladding rails and are fixed using brackets which allow adjustment to accommodate deviations in the supporting structure.
Sheets may be fixed to the supporting rails using screws, rivets, edge cover strips or adhesive. Sheets are flat with square cut edges. Joints may be left open or closed with proprietary jointing strips.
Similar panels are available using fibre reinforced calcium silicate, resin laminate, compressed mineral wool with an acrylic facing and glass reinforced polyester. The precise formulation of these panels varies according to the manufacturer and a range of surface textures and colours is available. In some materials corner profiles are available in addition to flat sheets and the panels may be hung from supporting rails by brackets fixed to the back of the panel, image.
Metal
Panels may be made from both aluminium and steel sheet. and may be given increased stiffness by folding the edges. A common method which also provides a convenient method of supporting the panels by hanging them from supporting rails, is to form trays as shown in this image.
Composite panels
Thin composite metal panels may be formed from two layers of aluminium separated by a layer of polyethylene giving an overall panel thickness of 3 to 8 mm. The composite action of the layers gives a stiffer panel than the aluminium alone. Panels can be used as flat sheets but can be bent to form curved panels or folded to form sharp corners if the inner layer of aluminium is first cut along the line of the fold.
Stone
Stone has traditionally been used as masonry to form an external facing material for buildings but is now being increasingly used as a non loadbearing cladding as a result of developments in stone processing which allow stone to be cut into thin panels.
Stone types used for cladding are granites, marbles, hard limestones, slates, quartzites, limestones and sandstones that offer a range of colours and surface textures with good durability. Section 11.01 describes the use of stone cladding in greater detail.
Terracotta
Interlocking terracotta tiles are available in a range of colours and sizes up to approximately 250mm high and 400mm long, image. The tiles may be solid or cellular and are supported on proprietary aluminium cladding rails. Retention of the tiles relies on the interlocking design of the joints giving a dry fixed system which does not require the use of mortar or sealant.