Cutting And Drilling
Areas adjacent to all cutting, sawing or drilling operations on cladding and flashings should be protected from deposits of swarf that can be carried by the wind—such areas can include motor vehicles parked in the street below.
When nails are used, or where holes are punched, care should be taken to prevent localised distortion of the profile. Holes in roof sheeting should penetrate vertically through the crest of the ribs or corrugations except where pan fixing or side lap side fixing is specified.
Pre-drilling sheets before nailing prevents distortion. It is easier to remove swarf when the sheets are drilled on the ground before lifting them onto the roof. However, the purlin distances should be checked and aligned to within ±10 mm.
Where sheets or flashings are to be sealed, the rivet hole should be drilled before sealing, and swarf and any protective film should be removed from the lap.
Only the correct size of drill should be used for drilling rivet holes or pre-drilling roof sheets, but where oversize holes are required for washered screws, it is good practice to drill a pilot hole first.
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