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General => General Forum => Topic started by: mand0092 on March 10, 2012, 08:00:10 PM

Title: Correct Vapor barrier install?
Post by: mand0092 on March 10, 2012, 08:00:10 PM
Hi everyone, I'm ready for floor insulation. I have my joists about 12-16 inches off the ground and will be installing the undelayment, insulation and subflooring tomorrow. I've been told to put the vapor barrier between the underlayment and insulation and also told to put the vapor barrier between the joists (above the insulation) and subflooring. Which one is correct? Ground side or top side? Also if I do install it above the joists, how do I glue the subflooring to the joists with the poly in between?
Title: Re: Correct Vapor barrier install?
Post by: MountainDon on March 10, 2012, 09:27:54 PM
Not sure I'm following your layers from the joists upwards... but if you are using T&G OSB, Advantec or plywood that alone acts a a pretty good barrier. The ground should have a 6 mil plastic barrier covered by a thin layer or earth or stone. And of course it should be graded to promote water draining away from the perimeter of the structure.
Title: Re: Correct Vapor barrier install?
Post by: mand0092 on March 10, 2012, 11:08:57 PM
I've got the 6 mil, but I was told to have the vapor barrier installed either under the 3/4 osb subfloor and I was told to put it above the bottom 1/2" green treet plywood I'm using as underlayment under the insulation. Not sure which advice to follow.

Title: Re: Correct Vapor barrier install?
Post by: MountainDon on March 11, 2012, 12:05:27 AM
What climate zone or geographic location? Building climate zone, not agricultural.
Climate Zone By County Info Here (http://energycode.pnl.gov/EnergyCodeReqs/)

What will the final flooring be?
Title: Re: Correct Vapor barrier install?
Post by: mand0092 on March 11, 2012, 07:56:31 AM
I live in WI and I'm going to have a tiled entry and oak hardwood throughout eventually.