metal batten & purlins when fastening up to 1.6mm thick to timber battens See sheeting manufacturers recommendations® PolyZIPS® PolyZIPS M6.5-14 x 50mm Hex Hd M6.5-14 x 50mm Hex Hd 6-030-0316-6CS6-030-0316-6CS Fibreglass Roofing Appox. Fasteners Fixing roof profile heights Fixing roof profile heights per sq metre 18mm to 29mm 40mm to 62.5mm