Torn vapor barrier


Old 03-24-06, 08:39 PM
Thread Starter
Join Date: Jan 2005
Location: USA
Posts: 119
Torn vapor barrier

In the process of tearing out the drywall in my bathroom, in caused some tears in the vapor barrier of the insulation in the wall. Is it important that I fix these and if so how? I have a lot of plastic sheeting that I will be using behind the tile of the shower. Should I staple some of that over the insulation where the tears are? Thanks.
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Old 03-27-06, 11:09 AM
Join Date: Jul 2005
Location: Ottawa, Canada
Posts: 857
A tear in the VB should be fixed.

Cut a sheet of poly 6" larger than the tear and seal it with either Tyvek tape or acoustical sealant.
Old 03-27-06, 03:26 PM
Join Date: Mar 2005
Location: USA
Posts: 6,126
Torn vapor barrier

If you just have "poly" and not a real vapor barrier, any tape will probably be better than the poly.

Vapor barriers are relative.

Old 03-28-06, 05:29 AM
Join Date: Oct 2004
Location: New Jersey
Posts: 1,132
A correct answer cannot be given based on just the information you provided as there are 2 completely opposite answers.

In your bathroom on walls were you are using greenboard or cement board with poly behind it, then do more tearing of the existing vapor barrier. Never have poly behind the greenboard. Enough tears or cuts will make the poly void as a vapor barrier behind greenboard. Same with the installation of cement board in wet areas, slice the poly facing on the insulation as you will be installing poly over the studs and flange of the tub or shower pan. You never wany double vapor barriers. Anywhere you are using a topical waterproofing membrane over the cement board, you also do not want a vapor barrier behind it.

Anywhere you are using regular sheetrock on insulated exterior walls, then yes, repair the vapor barrier. Tyvec tape works great for that.

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