Informative but slightly misleading. AS1562.1 is concerned with metal claddings for roofs and walls. The 'span' of something has to be taken in proper context. The span of the cladding is the distance between supporting members, or spacing of the supporting members. The supporting members for cladding and decking are the cladding rails (battens, purlins, girts(wall)) As defined in AS1562.1, 'S' is the span of the cladding not the cladding rails. However, the span of the cladding rail is the distance between its supporting members, which would be the spacing of the rafters. This difference is important, as lookup tables will likely involve the spacing of the purlins and their span, the spacing of the cladding rails cannot exceed the span limits of the cladding. Limiting deflections for structural adequacy, are also typically given in terms of span over some number, such as span/150 or if concerned about aesthetics something like span/600 (eg. ceilings), whilst initial warp and distortions have requirements around span/1000. So for a cladding rail spanning 1200mm between rafters, its initial distortion from ideal straightness is 1.2mm. Whilst under load it would be 1200/150=8mm. If rafters are at 600mm spacing, then equals cladding rail spanning 600mm, then the deformations are reduced. AS1562.1 applies similar limits to the strength and serviceability testing of the cladding. I don't have the most recent version of AS1562.1 I have 1992, not a standard generally need unless testing, manufacturers guidelines provide needed information. Manufacturers guides should have limits on straightness and warping and twisting of the rails before installation, so can reject before installing, few do, but there are some general rules for steel work. There are also various state guidelines on acceptable construction tolerances.(eg. NSW guide to standards and tolerances). My version of AS1562 has three clauses, not just the 7mm clause. If I understand the 7mm clause correctly its about the undulation of the roof surface. It is measured at right angles to the plane of the roof. So its about the top surfaces of rafters forming a flat plane, and the top surfaces of cladding rails forming a flat plane, and the roof cladding forming a flat plane, if it doesn't then get impressions which cause ponding. For spacing of cladding rails the tolerance is plus/minus 5mm, hopefully this has not been increased to 7mm. Whilst horizontal and vertical alignment at abutting ends of cladding rails is limited to 2mm. Note the way the tolerance is given, the spacing at one end of a cladding rail can be 5mm greater than nominal and at the other end 5mm less, making a 10mm difference between each end. Which is rubbish, not something to aim for. The general positional tolerance on location of fasteners in steel work is plus or minus 1mm, this is from the original steel structures code (AS4100). So 1mm either side of the centre line, and no more than 2mm between fasteners. Tighter positional tolerances may apply if concerned about alignment of holes and fasteners in multiple members, but they have to be calculated. {This comes from the hole typically being 2mm larger in diameter than bolt, and ignoring small tolerance on hole diameter and bolt diameter.}
@Realroofer
4 ай бұрын
Thanks for your views. It’s excellent to see others looking deeply at these issues. I encourage you to keep up the good work. Please do not hesitate to share these videos or discuss them with others. Cheers
@lizquye8981
4 ай бұрын
is it the same as fasteners?
@Realroofer
4 ай бұрын
Great question, no battens are classed in this case as support members that the faster or fixing is embedded into. Thanks
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