Insulating over roof shingles

Guest User
1/18/2017
Good morning, I am about to remodel an older home that has about a 12:4 pitch and it currently has shingles on it that are not leaking. We want to strip (over shingles) with 2"X4"s and then apply a metal roof (for astetic purposes). Is it advisable to insulate in between the 2"X4" stripping (directly over the existing shingles) with a styrofoam/foil type insulation, then apply the metal roofing over it? My reasoning behind this application is due to the fact we would like to take down the 8' interior ceilings and expose the cedar wood (creating a cathedral interior ceiling with no interior insulation to take away from the cedar which is currently an attic space. Thanking you in advance for your assistance, Bennie
Todd Miller
Isaiah Industries, Inc.
1/18/2017
I definitely think that for this application, battens are important. Make sure that the metal panels being installed are approved by their manufacturer for installation over battens, and make sure the battens are spaced appropriately. That said, I am still concerned about condensation inside the home. You live in an area prone to it. Adding insulation would help. You also could cross-batten perhaps -- vertical battens followed by horizontal battens, The chamber created by the vertical battens could be insulated partially and then have a gap remaining for ventilation -- bringing air in at the bottom of the roof and exhausting it out at the top. This will help with energy efficiency and help avoid condensation.
Eric Novotny
An informed customer is the Best Customer!
1/18/2017
In this case, you should remove the asphalt roof in entirety, cover the whole roof with Ice/Water shield, apply rigid insulation (thickness depends on location), and possibly some above deck venting. If you don't do this correctly, it will plague you with condensation and leak issues all the while being horribly inefficient.

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