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TOPIC: Insulation Concerns

Adding insulation under new metal roof to existing home

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I have a searched this forum and have some ideas, but want to confirm some ideas on my project. I have a 1.5 story home in Dallas with an existing composite shingle roof. My utility bills after one year in the home are way too high, particularly in the summer. The upstairs is basically a solar furnace that is difficult to cool. The home is around 4200 sq ft. I had an insulation guy that does spray foam an other insulation inspect the place. He confirmed my suspicion that the attic space is too broken up, crowded with A/C equipment and in some cases nonexistent to effectively add insulation either to the roof deck underside or the ceiling. The composite roof still has plenty of life on it, but I am considering options to reduce my utility bills (including moving). I really liked the option of insulating the roof deck with foam and mostly 'sealing' the attic space, but that is not an option. Another thought is to put on a new roof and somehow apply a large layer of insulation below the metal roof. There would be some added value in having a nicer roof and in having better insulation. However this would not keep the attic as cool and a foamed and sealed attic. I see some references to structural insulation that can go below metal roofing and also references to air space between the metal roof and the insulation. So if I were to tear off the composite down to the wood decking, what could I add to a metal roof for insulation/ How cost effective would it be? Thanks
Guest User

5/8/2009
I am sorry I have not answered this question sooner. There are rigid foam systems you could use. However, my suggestion is to choose a couple of metal roofing products and manufacturers you like and then work with them to try to engineer a solution. Sometimes a lot can be done with ventilation as well. Todd Miller
Todd Miller
Isaiah Industries, Inc.

6/2/2009