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Detailing the Tyvek house wrap at window with Dudley boxes and exterior foam

kenorakq | Posted in General Questions on

The Dudley boxes have a 6″ wide face frame (3/4″ thick like the furring strips)  to accomodate 4″ wood face trim and a J channel. 

Please point me to the detail on how to do the Tyvek at the window!


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  1. kenorakq | | #1

    I have to start this Monday so I would really appreciate knowing how to do this right... my preliminary plan is to carry the Tyvek over the 6" wide furring around the window, taping it to the vinyl window frame flanges with Tyvek tape in a shingle fashion....ensuring the Tyvek overlaps the top of the window.
    I have seen several videos detailing the tyvek at windows but none with wide furring surrounding the window...

    1. Expert Member
      MALCOLM TAYLOR | | #2


      I have edited my reply. A few questions first:

      - Are the boxes already installed?
      - Are the windows in?
      - Are you planning on installing metal head-flashing?
      - Will the window trim be installed directly omg the baking, or on top of the siding?

  2. Expert Member
    Michael Maines | | #3

    Tim, I'm interested in your responses to Malcolm, but I'll also say that I would not trust Tyvek to be waterproof long-term wrapped around projecting window bucks. I have used Pro Clima Mento for that and know that it works, and other high-quality WRBs probably would be fine as well. In your case I would probably use Vycor, Protecto Wrap or similar to ensure long-term durability.

  3. kenorakq | | #4

    the extensions (3") are in but the face frame is not on yet..the foam is on. I'm uncertain if metal head flashing will be used but I'm open to that idea, the colonial trim will go on the face flashing (or is it called furring?).
    The window bucks end at the exterior face of the foam, the furring extends 3/4 past that and the window (flanged) is mounted on that..
    here is a photo taken during construction (the old window sizes are apparent)... the window are just plugging the holes for now and neither the foam nor fame frame is on yet..
    fwiw...the orig 1 1/2" of XPS can be seen... it will be patched and another layer of 1 1/2" XPS will be added

    1. Expert Member
      MALCOLM TAYLOR | | #5


      Thanks for the reply. Based on them this is what I would suggest:

      - Wrap the foam in Tyvek right up to the 3" extensions, and then cover it with the face-frames.
      - Hold back the furring strips at the window-head several inches to allow the head-flashing to be installed at a later step.
      - Cover the front of the face-frames in Tyvek, continuing 2" into the openings, and lay a sill-pan of membrane extending several inches up the jambs.
      - Install windows in a bead of caulking placed at the head and jambs.
      - Cover the flanges with flashing tape wide enough to extend to the outer-edge of the face-frame.
      - Install your window trim
      - Slit the Tyvek behind your furring strips. Install your head-flashing in a bed of caulking, sliding the vertical leg behind the Tyvek through the slit you made.
      - Lay a bead of caulking on the face-frame against the window trim, and bed the siding in it as you install it.

  4. kenorakq | | #6

    Malcolm.... that's the kind of detail I needed... thanks... I'll post a pic when done :)

    1. Expert Member
      MALCOLM TAYLOR | | #7


      Looking forward to seeing it!

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