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Old 11-11-2009, 09:05 PM
metalmanmania metalmanmania is offline
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I have worked for a sheet metal shop that sells metal roofing for over 13 years. The shop I work for is the largest distributor of metal roofing in northern ca. we sell hundreds of thousands of square feet a year and make in our shop 300,000-400,000 lineal feet of trim to go with those roofs.
Metal roofing is like tools, you get what you pay for, if you go with the cheapest, (we wont even consider your great grand daddy's corrigated junk) 3' wide standard screw down panels, they work well , however if they are installed over a wood substrated the wood and the metal expand and contract at different rates. That difference of rates makes the panels work the screws loose, and then once loose it warbles the holes out. If the panel lengths are over 20' it is a real possiblity that the thermal expansion could shear off some of the screws.
The next panel up from that is residental hidden fastner. They can be installed to allow for expansion and contraction since nearly every manufacturer has slotted holes that you attach the panels with. Very nice panels and could easily last 50 to 60 years, probabley longer then that.
The next would be comercial standing seam panels, they are all attached using clips to allow for maximum panel expansion, they come in many diffrent configurations. They also have the best paint available (hylar and kynar paint), the paint is warrented for 30 years just for fading, plus it would take another 40 years for that paint to wear off, then they are all coated with zincalume, or galvalume, so that would last 60 years by its self.
The copper and turn coat stainless roofs are all nice, but realistically a good installed painted steel roof can last a very long time.
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