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Exposed Insulation Kraft paper in attic


Neal Lewis
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This is new construction. There is R 38 Insulation between the 2x12 rafters, insulation baffles, ridge and soffit vents. There is no insulation in the ceilings/walls adjacent to the attic. There is a Cat IV furnace in the attic.

Why would someone insulate this way, and how the heck does the building dept approve this??

I searched and couldn't find the most recent discussion on this.

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Five years from now the kraft paper backing will be covered with drip stains and the underside of the roof will be nice and damp and might even be punky to boot.

Can't install that insulation like that. They could have gotten away with unfaced batts but then they'd have to worry about them falling down.

ONE TEAM - ONE FIGHT!!!

Mike

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If the baffles completely isolate the insulation from the deck, and if the baffles are perforated to allow vapor to pass to the ventilated cavity, and if the insulation meets the depth requirement, it meets the energy code. Except for the exposed kraft, how is the installation any different from a cathedral ceiling?

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Could be new thinking on the building envelope. It may be more beneficial to include the attic in the conditioned space to avoid the problems associated with them, one being a heat source in the attic. If the exposed paper is a problem it could be covered to improve the fire rating. This is likely the shape of things to come. GAF (I think) has developed a roof panel system that does the same thing.

This thinking is also being applied to crawlspaces.

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Could be new thinking on the building envelope. It may be more beneficial to include the attic in the conditioned space to avoid the problems associated with them, one being a heat source in the attic.

Agreed.

The question now is what to use to cover that insulation. It's a bit too late to be hauling wallboard up there, eh? The insulation contractor screwed up, IMO.

Unless the Authority is packing a ladder around with him, he didn't see it.

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If the baffles completely isolate the insulation from the deck, and if the baffles are perforated to allow vapor to pass to the ventilated cavity, and if the insulation meets the depth requirement, it meets the energy code. Except for the exposed kraft, how is the installation any different from a cathedral ceiling?

It needs to be covered and it's not going to stay. Sooner or later, gravity will take over - sooner if there is even one tiny mouse somewhere in that attic.

Drywall does, to a certain degree inhibit the movement of moisture through a ceiling plane. probably even more so in your area, no? Don't thay use plastic behind drywall where you are on the warm side of the wall cavity to minimize vapor diffusion into cathedral ceilings?

Around here they don't use any plastic barrier. When there's a layer of wood or drywall beneath the insulation and adequate ventilation it seems to work but when there's just the insulation it always seems to be screwed up.

ONE TEAM - ONE FIGHT!!!

Mike

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