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Side and End Laps
It's good practice to use mastic lapping tape and stitching screws to ensure a robust weather resistant joint on side laps.
Lapping tape with a section of 9mm x 1.5mm mastic should be run along the crest of the profile that is to be lapped. Lapping tape is considered more effective than silicone.
Sheet to sheet stitching screws should then be used at 600mm intervals down the lap to consolidate the bond created by the lapping tape.
A minimum sheet over sheet overlap of 250mm should be allowed for where sheets lap, this lap must be supported underneath by a purlin.
As with side laps, it's good practice to use lapping tape to help create a robust weather resistant joint and a strip of tape should be placed across the full width of the lap approximately 25mm from the end of the top end of the overlapped or bottom sheet.
Top tip - Remember it is very difficult to separate sheets once they are joined by lapping tape, make sure of your sheet position before placing one sheet on another!