Vistalux Fixings Pack for 6'' Asbestos Profiles - Pack of 10 Recommended support centre 1372mm. Sheets required Divide the roof width by the cover width - 1016mm. Fixings required Divide the roof width by the fixing centres. Divide the roof length by the support centres and add 1. Multiply these two values together approximate number of fixings required. Fixing Start fixing sheets at the end of the structure which is downward of the prevailing wind. When joining sheets end to end, ensure an overlap of at least 150mm: when the roof slope is less than 10o the overlap should be increased to 300mm.  Using a strip of Ariel Butyl Sealing Tape between sheet laps close to edges and ends will prevent ingress of dust and dirt. For lean-to structures the Ariel Wall Flashing at the top of the slope acts as a closure flashing between the profiled roof sheet and adjacent wall. Ariel Foam Fillers should be used under the sheet at all support positions to prevent roof chatter and support the sheet when fixed. Use Ariel screws, caps and washers to secure the sheet: the screw is sufficiently tight when the washer under its head can just be rotated with finger and thumb.