As you can see, at the top of my door there's an open panel with fixed glass panes attached to allow airflow through. How should I best seal that giant gap up so that I can install air-conditioning in this room?

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  • How does air go through that opening if it is covered with fixed glass panes?
    – Michael Karas
    Feb 6 '20 at 12:10
  • 1
    What's on the other side of that door and why is there a fixed air gap over it? Is there something in there producing heat that needs to escape to prevent something from over heating?
    – FreeMan
    Feb 6 '20 at 13:24

I would go the home improvement store and buy the following:

A piece of plexiglass (PG), a plexiglass cutter, some clears silicone adhesive caulk, some painters tape and piece of 220 grit sandpaper.

Cut the plexiglass to fit, Measure and mark your PG and use a straight edge to run the cutter against, this scores the PG and then you can snap it on the score line. Search YouTube for visual tutorials.

Lightly sand the edges of the cut to take of the burrs.

Run a bead of caulk around the perimeter and press the PG into place.

put some tape strips over the plexiglass in both directions to keep it from sliding down or moving for 24 hours.

Gently remove tape, have a beer.


Tape plastic over it. If you tape the perimeter fully, it should work pretty well.


If visual appeal is not a concern, you could also get a piece of closed-cell foam-board insulation, and cut it to fit. Fitting foam is usually simpler than plexiglas, and it has some R-value if you are air-conditioning the room.

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