Zip-Tek 440™ is similar to Zip-Tek 420™ but wider and incorporates transverse stiffener ribs in the pan. Please note, Zip-Tek 440™ is only available for exports, into SADC and African countries. There are not many Concealed Fix profiles available for site rolling in Africa and GRS’s mobile mill resolves this problem.
Zip-Tek 440 is only milled on site. Sheet lengths to be rolled in long lengths without laps.
End lapping negates the concealed fix concept for water tightness.
End lapping, due to corrosion, reduces the life expectancy of the roof.
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The profile shall be roll-formed with two ribs at centres not exceeding 440mm, and the pan shall incorporate transverse stiffener ribs with a cover width not exceeding 440mm. These will include a male and female rib with capillary action breaks. When seamed, the minimum sheet depth shall be 68mm.
The Zip-Tek 440™ sheets shall be fixed to every purlin using a patented halter. The halter must be secured using suitable fasteners as detailed in the GRS Installation manual. The female rib must be mechanically seamed using a seaming machine 440 over the entire length of the sheet.
Zip-Tek 440™ can not be Bullnosed or cranked. Reverse cranking is not possible.
Zip-Tek 440 can be sprung to a minimum radius of 55m (convex or concave), subject to gauge and cover width.
The springing of Zip-Tek 440 can result in stresses in the material, resulting in oil canning.
Care must be taken in checking the structure line of the curve carefully, plus ensuring that all halters are in line. Any discrepancy will affect the line of halters, resulting in poor aesthetics.