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TOPIC: Roofing over existing roof

ventilation pipes in metal roof

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Question: My contractor is installing a metal roof over my existing shingle roof. He said he is going to cut off the ventilation pipes that normally extend from the roof as they are not needed since they can still vent under the metal roof. The roof is being installed on boards/battens. Is this an acceptable practice? Thanks.
Jamie Leach

10/29/2008
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No.
Guest User

10/29/2008
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Can you give me any details as to why this is unacceptable so I can discuss with my contractor with intelligence? Thanks.
Guest User

10/30/2008
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It is very much against building code. Depending upon exactly what is done, you could end up with fumes in your house and condensation and resulting problems in your attic. Todd Miller
Todd Miller
Isaiah Industries, Inc.

10/31/2008
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Is this also against building code in a mobile home? There is no attic space, only insulated space between the shingled roof and the ceiling. Our contractor, too, has mentioned just cutting off the ventilation pipes (kitchen/bath/etc) and roofing over those, and that no problems will be created. He has also only mentioned using 1x4's and the metal roofing itself, but made no mention of any type of underlayment or insulation as I'm reading here. I googled the company that was on the galvalume color sheet, and it is simply a supplier of coil metal, so I'm assuming he makes his own panels. Please reply on this thread and also to bethanial11 @ netscape (dot) net
Guest User

8/3/2010
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Oh, and just so you know, we have not signed a contract or anything, we've just gotten an estimate from this guy. I did just use the "find a contractor" gizmo on your site (only 1 within 100 miles of us), but we'll call them and see what he has to say also. Thanks for all the invaluable information you provide!
Guest User

8/3/2010
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Yes. This would be against code regardless of structure. Eric Novotny
Eric Novotny
An informed customer is the Best Customer!

8/4/2010
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Thanks for your help. So even with soffit/ridge cap ventilation, cutting off existing ventilation is not a good idea is what you are saying? What about the fact that he hasn't mentioned any underlayment? Is that a big issue? Or is that handled by the fact that the existing roof is staying put? Thanks so much for any additional help!
Guest User

8/4/2010
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I do suggest a new layer of underlayment always. Cutting off exhaust pipes in the attic is against building code and will introduce a lot of unhealthy and potentially dangerous moisture into the attic Todd Miller
Todd Miller
Isaiah Industries, Inc.

8/5/2010
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