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Community and Q&A

Sealing bottom of exterior roof wool insulation

Salesi | Posted in General Questions on

We will be installing 2″ of rock wool insulation on the exterior of our new house with a 3/4″ rain screen. How would the bottom of the rock wool be sealed from insects, etc. since it is only semi rigid? Should I run a 1 x material cut to 2″ wide around the piermeter of the house and set the rock wool on top of this? Or get a J shaped piece of flashing to set the rock wool into? I do not want to just leave it open. Thanks.

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  1. Expert Member
    Akos | | #1

    Get perforated J channel bent up that is 2 3/4" wide. This would cover the bottom of the rigid as well as the rain screen gap and keep all insects out of both.

  2. Salesi | | #2

    Thanks for the reply. Is this available or something I would have to have fabricated specifically for my job?

    1. Expert Member
      MALCOLM TAYLOR | | #3


      Because that's wider than the typical J channel used on rain-screens, you are probably best to get it custom-bent locally, although you could have to shipped from Menzies:

  3. Expert Member
    BILL WICHERS | | #4

    HVAC contractors that make their own ductwork (that includes most of the commercial shops) can usually fabricate this for you. They can get perforated galvanized sheet, although stainless is better (and more expensive). Any sheet metal shop with a brake and a shear can form the stuff.


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