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We are a metal roofing company that specializes in metal roofing and just recently had a Residential job that required a twelve-inch wide one-inch high rib snap loc nail strip panel. We decided to go with a 24 Ga panel with a kynar paint finish. The material was 13,000 dollars, not a big job but not to shabby either. When we got the metal, we notice humps in the panel every 8 inches up that whole panel. We laid a panel on a perfectly flat surface out of the sun in the shade and in the sun. We did not notice any improvement in or out of the sun. If any thing it was worse in the sun. I can take my hand and go up the panel with my palm on the flat of the metal and feel the humps...the hump run from rib to rib. The manufacture said that is standard in the industry. However, our panel has only nine and one-quarter inches in the flat portion of the pan because of two screw relief ribs that run beside the male and female ribs. My point is it is not a wide panel and we are getting worse results with it then the wider panels we use. What Can I do about this problem and is this common or not? Thank you,
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Oilcanning (or the appearance of it) can occur for several reasons:
1) Improper fastening on the roof. This isn't the case with your job, obviously, because you're seeing this before the panels are even installed.
2) Improper gauging on the rollformer when the product is produced.
3) Various inconsistencies which are inherent to flat metal and impossible to avoid.
It is hard to determine the difference between #2 and #3 on finished product.
Going to heavier gauge can help although 24 gauge is already pretty heavy. Using a panel which has more ribs and formation in the "pan" area can also help. You are correct also in that this problem can be more apparent on wider panels.
There are a few independent consultants around who specialize in metal roofing and can be found on the web. If you contacted one of them, they might be able to help in determining whether the oilcanning you had on this job was strictly metal-related (and hence unavoidable) or if it was forming-related.
8/13/2002
Isaiah Industries, Inc.
8/16/2002