new attic insulation touching roof decking


Old 07-24-08, 10:02 PM
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new attic insulation touching roof decking

I've recently read that if you have insulation touching both the interior ceiling and the inside of the roof decking in the attic then you can easily transfer the heat from the house to the roof-thereby heating snow to refreeze and cause an ice-dam. I just finished rolling some 9 inch fiberglass in my attic and in several places I got the insulation a little far towards the outside of the walls and it is touching on both top and bottom. I wasn't shoving or anything, it is only lightly compacting the ends of some of the batts but now I'm wondering if I need to crawl back up into that darn hole and pull the batts back towards the center a bit.
Any thoughts on the matter?
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Old 07-25-08, 03:41 AM
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In order to ensure plenty of air flow over the insulation, which is absolutely needed, you can install the foam baffles in each rafter bay just over the insulation, pushing it down a little and allowing the air to flow through the channel provided. It is not so much the insulation touching the roof as it is the lack of air flowing in that area that can cause air dams, etc.
Old 07-29-08, 05:59 AM
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Thanks...I'll crawl up there and re-evaluate once the weather cools a bit.
Old 07-29-08, 03:03 PM
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To add to Chandlers comments, without the baffles/ventilation, you can get condensation on the under side of the roof sheathing, resulting in rot. No a good thing.
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