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Detailing a Cellulose-Insulated Attic

Wesley James | Posted in General Questions on

Hi I’ve looked through a lot of great info on insulating the attic with cellulose, and I have a good strategy in mind based on this.  While I’m insulating the attic I’m planning to replace a drywall ceiling with rough cut pine planking, so I’m going to do the 1×3 strapping 16″oc as described somewhere in the sagging drywall article. What should I put above the strapping to seal against the joists? Was thinking 3/4 inch eps? I couldn’t find a recommendation anywhere because most are using the drywall.  Thank you

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  1. Expert Member
    Peter Engle | | #1

    With rough cut planking, you are going to need an air/vapor barrier as well as physical support for the insulation. Depending on where you live, one of the smart vapor retarder membranes would be a good choice. The strapping will help hold the membrane up and the membrane will keep and and moisture out of the attic. Make sure to tape all seams and edges with a high-quality air sealing tape that is compatible with the membrane.

  2. Wesley James | | #2

    thanks Peter, I thought I had seen a detail in the past with foamboard sealed to the joists, then drywall. Thank you for the advice on using a vapor retarder.

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