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Community and Q&A

Interior Air Barrier with Exterior Insulation

aladybuilder | Posted in Energy Efficiency and Durability on

We are retrofitting an existing small house in zone 6A in Central VT. I have installed r23 comfort batt in the 2×6 16oc stud cavities and plan on doing either rockwool or polyiso and a rainscreen on the exterior next year when we redo the siding. My question is whether I need an air barrier between my drywall and my Rockwool? If I’m understanding correctly, rockwool is an air barrier and my exterior insulation will serve as my primary air barrier when installed, so do i really need an additional one on the interior?  I could see that we might if we went with rockwool on the exterior but if we go with polyiso we can probably skip it?

If we do skip it, any suggestions on what to put up simply to keep the dust down and protect it somewhat before drywall goes up? I have a bunch of extra rosen paper from a flooring project, is there any reason I couldn’t install that? Would it be a bad idea to leave it up when we do install drywall?

thanks for your help

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  1. Expert Member
    BILL WICHERS | | #1

    Rockwool is not an air barrier, but drywall is. Your interior drywall will be your interior side air barrier, but I do recommend you install it with the airtight drywall method for best results, which is mostly just putting a bead of sealant around the perimeter as you put up the panels.


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