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steel panels installed over asphalt

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Guest User
6/25/2009
Recently the company I work for had a customer cancell their contract due to information that was given to them about Standing seam. They were told that Standing Seam is not recommended to be installed over asphalt shingles (even with an underlayment). They now belive the company to be unproffessional. It is their understanding that there should be strapping or that the roof must be stripped before installing the metal. I don't personally know of any roofing contractor that hasn't installed metal to the asphalt many times. What is the truth?
Todd Miller
Isaiah Industries, Inc.
6/26/2009
As we have pointed out numerous times on this site, installation over existing shingles, without strapping, is done regularly and results in successful installations. Every job must be looked at on its own meerit and an experienced professional metal roofing contractor will be able to figure that out. Probably a more common mistake I see is installing products on strapping that were never designed nor tested nor intended to be installed on strapping.
Guest User
6/26/2009
Todd, We are considering a metal roof for our home. The current roof includes 2 courses of asphalt shingles (the second course was apparently added for cosmetic reasons (color) and they didn't want to absorb the cost of removing the first course) . Is there an industry standard to indicate whether applying a metal roof over the 2 layers of asphalt shingles is a good or bad idea? We have one contractor saying that it is not a problem and they do it all the time and another saying he recommends stripping the 2 layers off before applying a metal roof. I also wonder if you have any preference for steel vs. aluminum? We live in NH and are hoping it will deal with ice and snow backups. Thanks and we look forward to your reply. Bill White
Todd Miller
Isaiah Industries, Inc.
6/26/2009
Bill, Quality roofs are made from both steel and aluminum. I am more concerned about the coating quality and the product design than I am the base metal. The more heavily formed a product is, the more forgiving it will be at going over old shingles. Please understand though that if you're in an area where building codes are enforced, going over two layers will require special approval. A major key to avoiding ice dams is good ventilation. Metal roofing can help but not necessarily be the end all and be all. I do not normally make referrals from here to my own site but I will in this case as I think there may be some things on my site that are of value to you. www.asktoddmiller.com All Best.
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