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Community and Q&A

Rockwool for walls and roof

bluesolar | Posted in Green Products and Materials on

Hi all – Mineral wool insulation seems ideal for both walls and roofs.

But someone at GBA said it was better suited for walls than roofs (I can’t find the source). Why might mineral wool be less suitable for roofs? I’m thinking of batts in particular – obviously the boards wouldn’t work.


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  1. jberks | | #1

    It's great for roofs in my opinion.


  2. Expert Member
    RICHARD EVANS | | #2


    Mineral Wool batts can work great between rafters so long as a few rules are followed:

    1.) batts are air-permeable (fluffy insulation) so all six sides of the batt must be covered to avoid convective loops. You'll need some kind membrane or wall board in the attic.

    2.) You'll also want an airspace under the sheathing so baffles are needed so fully enclose the mineral wool batts

    3.) Or you can skip the air gap and add a layer of rigid foam or mineral wool on the exterior of the sheathing to 'warm it up' using proper climate-specific ratios.

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