Vapor Barrier and Boxes


Old 05-28-07, 07:59 PM
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Join Date: Mar 2007
Posts: 23
Question Vapor Barrier and Boxes

I have just removed two redundant electrical boxes from my basement drywall. This wall is an exterior wall that has been insulated and covered in a clear plastic vapor barrier which is sandwiched between the studs and drywall. Now, having removed these two boxes, I have two holes in the drywall AND the vapor barrier. One of the boxes had a specially moulded plastic vapor barrier behind it and the otrher didn't. I plan on filling these holes, firstly by screwing a block of wood behind each hole and then filling them with drywall filler and then finally painting the wall (hopefully so no evidence of the boxes remains).

My question is do I need to try and patch the plastic sheeting vapor barrier even though I am going to be completely closing these holes up with plaster/drywall filler? The holes in the sheeting are a little over 2" by 3".

If I do need to patch them, how and with what should I patch them. I am concerned that if I patch with plastic and then try and fill the hole with drywall filler, the filler will obviously not bond with the plastic sheeting and will easily fall out.
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Old 05-29-07, 06:46 PM
Join Date: Mar 2007
Location: New Hampshire
Posts: 450
You can also put wood behind the drywall then screw a small square of drywall to that wood then mud around the wood. If you do it that way then you can also put in a square piece of plastic before you screw on the drywall.
Old 05-29-07, 07:04 PM
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Like Adam says, stick a small scrap of wood into the hole, perhaps 2" wide, 6" long. (put a screw into the middle of it so that you have something to hang onto as a handle.) Screw it to the existing drywall so that it sucks up tight. That will give you something to screw a small patch of drywall to. Don't fill the entire hole with mud- use drywall. You will then need to tape the patch, fill and float the patch to make it disappear.

Regarding the vapor barrier, you don't need to patch the plastic. But you can spray some expanding foam into the cavity where the outlet used to be. I'd suggest you use door & window foam (Great Stuff blue can, not red) so that it doesn't expand and bow out the drywall. Don't overfill the cavity. The foam will act as a vapor resistive barrier in place of the poly.
Old 05-29-07, 07:16 PM
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Join Date: Mar 2007
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Doh!!! I took a Homer Simpson moment there. I always intended to screw a piece of drywall onto the wood so that I would only have a small gap to fill with mud around the edges. Took a complete blank though when writing the first post.

Thanks for the feedback and for reminding me what I need to do.

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