betty dunkin
9/15/2011
I need to know the pro's and con's of putting a metal roof over exsisting shingles. Also, I have a well insulated and vented attic so do I need to worry about condensation and mold problems ?
Todd Miller
Isaiah Industries, Inc.
9/15/2011
Metal roofing is much lower weight than most other roofing choices. This encourages installation over existing shingles. Additionally, most metal roofing warranties are not affected if the product is installed over old shingles. Most building codes though stipulate no more than two layers of roofing. We have seen that waived for metal roofs on occasion by building inspectors though. If your existing roof has an weight issues or other structural issues (such as leaks, rot, bad sagging, etc) those should be addressed rather than just install over the top. Keeping the old roof in place helps with home energy efficiency and avoids having to put old roofing shingles in a landfill. If you have good insulation and ventilation including that all plumbing or other exhaust vents are vented to the outside, you should not have any issues with condensation.
Eric Novotny
An informed customer is the Best Customer!
9/16/2011
+1 You should be just fine. Check for the number of layers of asphalt before proceeding.

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