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Community and Q&A

Taping Exterior Foam Insulation Around Window Flashing

bonai | Posted in General Questions on

Hi there,

We are almost done doing the insulation on our new house.

Walls consist of:

Blueskin + 1 1/2″ GPS foam + 1×4 strapping + siding

The decision to add insulation was done after the initial design of the house, therefore we had to use custom metal flashing around the windows to accommodate the extra thickness of insulation and to have the sidings butt against the metal.

Before installing the insulation, the top and sides seams of the windows were flashed with some quality tape.

I started taping the insulation with the metal flashing, I did that only for the top of the window, so it prevents water from leaking back towards the wall.

I am wondering if this is necessary, and also if the sides of the window should be taped with the insulation.

Let me know your suggestions!


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  1. Patrick_OSullivan | | #1

    Was the flashing (top and sides) taped to the Blueskin? Or, alternatively, did the Blueskin lap over the flashing?

    1. bonai | | #4

      Hi Patrick, I replied to your comment, let me know what is your suggestions. Cheers

  2. bonai | | #2

    Hi Patrick,

    The blueskin doesn’t lap over the flashing. The flashing is over the blueskin.

    I taped the metal flashing to the blueskin on the top only, not the sides. I thought because the windows were already taped to the blueskin, this was enough.

  3. bonai | | #3

    If anyone else want to chime in, you are welcome to do so.

    1. Expert Member
      MALCOLM TAYLOR | | #5


      I don't think it matters much either way. Presumably the cladding and returns at the windows will be detailed to stop water getting at that joint.

      1. bonai | | #6

        Thank you Malcolm!

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