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Is it good to include vapour barrier when insulating a basement?


Photo by Michel Ngilen


My son and I are doing a basement reno. We put Styrofoam on the outer walls and 2x4 interior walls. We were planning to put batts of insulation between the wall studs, and my son was wondering if we should put up a vapour barrier. Is this a good idea? If so, on which walls?

—Moe LeBlanc

The general rule on vapour barrier applies here as well: You need it on any exterior walls, and it always goes on the “warm in winter” side of the insulation.  Don’t forget to continue the insulation (and vapour barrier) all the way up into the joist pockets of the ceiling as well—that’s where a lot of rot problems start. Careful attention to detail at this step will definitely pay off.

Ryan Shervill

Ryan Shervill is a field editor and contributor to Outdoor Canada, as well as an avid hunter and shooter. He is also Canadian Home Workshop’s online Ask a Pro and contributing editor.


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Dec. 29, 2012

6:29 pm

I believe in Manitoba if you have installed 2 inches or more of styrofoam insulation on the outside of the concrete that a interior vapour barrier is not required. Having said that I believe that a vapour barrier wouldn't do any harm.


Nov. 26, 2012

1:13 am

Hello Ryan I had writtien to about putting a vapour barrier in the basememt on the walls which I had put a stlyrofoam first on the cement of the wall then battens in between the joices...... I had seen programs on DIY that you didnt nessasarilly need the vapour barrier due to perhaps sweating of the plastic..... Now I know maybe I answerig my own question that you have to fill every gaps there is so no cold air gets in so not to have contact with warm air that will create moiture........But if I dont put the vapour barrier wont I still have the warmfed of my house and seal without the scare of having moisture from the vapour barrier..........Moe

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