Vapor Barrier

Old 01-02-03, 10:47 AM
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Vapor Barrier

Where is the best place to install a vapor barrier? I've read that a person can put it between the poured foundation and the studs or between the studs/insulation and the drywall.

What thickness would you recommend?

I assume that the best way to install the barrier is to run it vertically. Correct?

What kind of tape should a person use to seal the seams?

Should a person paint a type of waterproofing to the poured concrete walls before starting a basement finishing project? What about applying the waterproofing to the floor?

Thanks for your help.
Old 01-02-03, 12:00 PM
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Waterproofing the walls - I would agree that some type of waterproofing paint should be applied, like DryLok - Good product and some added insurance against problems. The floors however are another story...if you live in an older home, there is most likely cracks showing in floors - no waterproofing can really be done since hydronic pressure is greater than water pressure from walls. If the home has drain tile, this would be dispersed in most cases. However, leaks at wall/slab locations are more prevelant than cracks in floors. I wouldn't bother with the floor unless you are inclinded to do so, however, cearmic tile, linoleum flooring applications cannot be done as the waterproofing products tend to provide pour adhesion for these types of floors.

Let's first discuss the stud wall location in regards to a masonry/concrete wall. I have made reference to this many times and the best application is to install wood studs 1" from the wall. With 2x4 studs, use only R-13 Kraft Faced (this eliminates the need for 6 mil poly since kraft faced is a vapor barrier). I have suggested 6 mil poly between the stud and the concrete if you are desiring to place your wall directly against it and the 6 mil poly will keep the standard wood studs from wicking the moisture that could occur. The other instance is if you did place the stud walls 1 inch from the concrete and installed R-19 insulation, the poly would keep the insulation dry as you do not want it to touch the concrete if moisture would occur. In either case use W/T bottom plates.

There is no reason to tape up the poly at joints. I would get 10 feet wide rolls and staple to the floor joists if you desire to hang poly against the concrete. We do not want to seal it with tape or glue it to the concrete as we need air flow so any condensation would evaporate. We don't need mold or mildew problems.

Hope this helps!

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