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Ridge assembly for single skinned roofs See diagram below On most modern steel clad buildings the ridge assembly is controlled by the girth of the ridge sheet. The popular standard size being 400mm (16") girth with 200mm (8") wings. This no doubt being so because 3 no. ridge sheets can be produced from the standard steel coil width, although any girth width can be produced up to the full coil width of around 1230mm (4ft). To strengthen the ridge sheet the edged are given a 10mm welt (fold). The sheet in folded to a 120 degree angle, but is flexible enough to bend to most roof angles. The roofing sheets cannot be allowed to clash at top dead centre (TDC) so they are usually drawn back at least 50mm (2") The ridge sheet only having an 8" wing, this limits the placing of the purlin centre to between approx. 4 to 6" from TDC. The roofing sheet is secured in the trough of the profile with a self drill and tap screw (Tek screw) thus not fouling the ridge sheet when put in place. Before fixing the ridge sheet, profiled foam fillers can be placed in the sheet troughs to prevent access by birds, snow and dust. to hold these in place whilst the ridge sheet is fitted, stick them down with a little silicon sealant. Secure the ridge sheet to the roof sheet with seam stitchers which are miniature tek screw at 300mm to 400mm centre (12" to 18") Cover the tek screws with push on colour caps that match the colour of the roofing sheets See diagram below which is not to scale. |
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composite and built up double skinned roofs See diagram below Here the same basic principles as for single skinned roofs apply. The only extras are the need to fit a ridge liner sheet (manufactured from white polyester coated steel to the same size as the top ridge sheet) over the purlins before placing the composite panels into position. After positioning the composite panels, the void between the tops of the 2 panels must be filled with an insulation material, this can be quilt insulation or any other insulation material to hand, but see that it meets relevant fire standards so as not to invalidate your insurance policy. Before fixing the top ridge sheet it is advisable to cover the void filling insulation with a vapour barrier. this can be roofing felt or plastic |
