Covering a window with drywall

bobbysgirl

I am wanting to drywall over a small, six-sided "port hole" window in my mainfloor family room. The home was built in the 80's and the window was placed for design esthetics of the day. I do not wish to disturb the outside stucco and plan on leaving the existing metal blind in the window for outside appearances. The window is not needed for lighting. There are three windows in the room, all on the same wall and the largest is 7 x 9 feet. Natural light is not an issue. I want to cover the window because it sits above a corner gas fireplace and I wish to place my television above the fireplace. I have a professional drywaller that sees no difficulty in doing the job and getting a good result. The window is double glazed. My concern relates to possible moisture problems and how I could insulate the space between the drywall and the window to ensure that mold and condensation will not be a future problem. Thanks for the help.

Ron6519

Cut a piece of foamboard to tightly fit the opening. Seal any gaps with a caulk.
Ron

bobbysgirl

Thanks for the speedy and encouraging reply. Any suggestions about how thick the insulating board should be and what R value I should be looking for. A suggestion about the caulking would also be helpful. How far back from the window and the blind camoflauge should the insulating insert be placed? Should it be closer to the window or should I be getting it as close to the drywall as possible. Is the dead air space a positive thing? Thank you.

Ron6519

If you're using foamboard, you'll be buying a 4x8 sheet. I'd look around to see where else you could use it, like the rim joists and buy that thickness.
Leave a 1" or so space from the blinds and fill in the rest with insulation.
Silicone caulk would work, but so would a latex caulk. It just seals the gaps.
The blinds give you a built in air space.
Ron

bobbysgirl

Thanks, Ron. I have also checked with a local building inspector. He concurs with you and suggests using a 2 inch piece of insulation board to ensure that the insulation value of the insert matches that of the surrounding walls. All in all, he says, its not a big deal and a pretty easy, quick fix. Thanks for sharing your wisdom,Ron.

bobbysgirl

Interesting exercise, but it did not stop the condensation and so I am back to the octagon window I hate. Left the drywaller installing the foamcore and went on the hunt for caulking. By the time I got back he'd taped the the foamcore as opposed to caulking it and had the finished drywall insert in place. Looked great but a few days later we had a real cold spell. All the windows in the house were sweating profusely---including the one we'd covered. You could actually see water droplets on the glass in front of the blind we left for aesthetics and when, at the end of the day, they had not dissipated and the window was completely fogged---I ripped out the drywall insert. I suspect that although the windows are double glazed they are pretty crappy. I think it may also be that the drywaller failed to properly weather seal the insulation. If had it to do over, I would fit the foamcore, seal it and then tack the drywall over the hole to see if it was going to work. This would allow tweaking of the insulation before the laborious process of fitting and mudding the drywall.
Thanks for your help, though.

Ron6519

If cold air is getting in from the exterior, the window will experience condensation. If the interior foam is not sealed with the proper materials, the window will experience condensation.
You need to figure out which issue(or maybe both issues) is the cause.
Ron