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Superinsulated Sunroom (4): Installing Outie Flanged Windows

August 15, 2016
Read time: 3 mins


Windows cannot rest on the foam, so they hang from wood bucks


Now that the rough openings in the superinsulated sunroom are flashed, it’s time to set some windows. Because there are six windows in two walls, it is important to align them perfectly. They begin with the center window and move toward the corners.


Step by step:

  • It begins with a level line to keep all the window tops consistent. They also mark center of opening and center of window to keep the side casings consistent.
  • The windows are triple-glazed with vinyl frames, and they will not bear on the sill, they will be supported by the side and head flanges.
  • John pries the window to the line, and David centers it.
  • Then Damien and Calvin nail off the bottom corners when it is level.
  • After squaring the window, they put a few more nails in the side flanges, but they do not nail ‘em off until all three windows are in place.
  • So they move on to the corner. Calvin nails the top left corner when it planes out with the first window.
  • And when the window is level (according to David’s level) and plumb (according to Calvin’s), Calvin nails the bottom corner. They double-check that the jamb casing will be consistent and put a few nails in the side flanges.
  • David extends the line to the third window and they put that one in the hole.
  • When all three are in the right place, they fill the flanges with nails.
  • Now, they turn to the other wall, beginning in the middle and working toward the corners. 
  • With all the windows set and nailed, the guys turn to the tape.
  • One four inch roll of tape is not quite wide enough to span both flanges between the windows, so they use a two inch strip and an overlapping four inch strip.
  • On the outer edges, four inch tape is used to seal the flange to the window buck, and it turns the corner. 
  • Across the head, six inch tape is used to seal the flange to the face of the window buck, then to the top of the buck, and ultimately to the face of the first layer of foam—beginning in the middle and working toward the ends.

This flashing tape forms a Z-flashing for the second layer of foam, which we will see next time. 


—Thanks to David Joyce, of Synergy Construction for opening his jobsite to our film crews. Thanks also to Calvin Cutts, PJ Burke, Damien Higgins, and John Albert for working with us and playing through the pain.


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