metal roof over asphalt shingles

Greg Crawford
10/2/2005
My wife and I bought a our home last year. The inspector told me that the shingles were approx 20 years old. He did not find any damage other than it was just getting old. He stated that he did not feel that there would be any problems w/leaking due to the roof having a good pitch to it. I am intrested in having a metal roof installed over the existing asphalt shingles (one layer only). I have received one bid at this time. The contractor did not say anything about underlayment. Another contractor I called for a bid stated that he attached the metal roof directly over the asphalt shingles but would do it however I wanted. Please help!!! How do I want it to be installed?
Todd Miller
Classic Products, Inc.
10/4/2005
When installing over old shingles, I feel there should always be a new underlayment. For one thing, if there is direct contact between the back of the metal and the old shingles, with expansion and contraction of the metal over time, the rough surface of the shingles can damage the back side of the metal.
Greg Crawford
10/16/2005
I am leaning toward a standing seam metal roof and plan to have the existing shingles removed. My broter-in-law use to work of a sheet metal company and now works for an metal insulation company. He suggested that I put down a type of insulation w/a reflective foil on it. One of the contractors that I have received a bid from stated that he has seen this type of insulation turn black and mold under a metal roof. Have you heard of this? My house has vaulted ceilings w/2x6 rafters. There is no venting in this space. Should I use a reflective heat insulation or not? Thanks.
Todd Miller
Classic Products, Inc.
10/17/2005
I have not heard of that issue but I will tell you this, the onmly way a reflective barrier like that is really effective is if it facses an airspace. It does not sound to me like you have an opportunity for that. Contact the manufacturer of your roofing and see what ideas they have for making the roof more efficient and for dealing with the lacko of venntilation.
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