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Catherdral ceiling insulation

HD_DIY | Posted in General Questions on

We have a cape cod and are having a new roof installed. The stairs leading up to the second story, the cathedral part, with two rafter bays of 2×6’s had no insulation in them. The roofers pulled the roofing deck and put in some batt insulation, (R30 with a plastic wrapping that had holes) and some attic cat they put in by hand. They also put in plastic baffles between the decking and the insulation. Unfortunately at the bottom of the rafters it is completely blocked off. So there will be no air being pulled in from the soffets. There isn’t a way to get them open. Not an ideal situation at all, but since the deck is off, should we do something else? There will at least be some gap between roof deck and insulation with the baffles. We are in climate zone 5.

Not ideal, but are we lookign at a disaster down the road?

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    HDS,
    I'm a little worried about the attic cat that they put in the rafter bays... I hope an attic cat isn't like a barn cat. Can you still hear it meow?

    OK, the attic cat must be some brand name for a product I've never heard of.

    If you can't connect the rafter bays to soffit vents at the bottom of each bay and ridge vents at the top, then the type of roof assembly that you are describing is called an unvented roof assembly. The way to insulate these rafter bays is with spray polyurethane insulation, installed from above.

    You can't insulate these rafter bays with fiberglass batts unless you also install an adequate thickness of rigid foam insulation above the roof sheathing, followed by a second layer of roof sheathing and new roofing.

    All of the details you need to implement either of these two options are included in this article: How to Build an Insulated Cathedral Ceiling.

  2. Expert Member
    Dana Dorsett | | #2

    That feline critter is Owens Corning's pink-panther AttiCat blown fiberglass methinks:

    http://insulation.owenscorning.com/uploadedImages/products/images/atticat-expanding-blown-in-insulation-system/atticat.jpg

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