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  1. #1

    Default Vapor Barrier and basement

    I am getting ready to finish my basement. The issue of vapor barrier has me up in the air. I have heard and read all kinds of things. Should I apply 6 mil plastic directly to the cinderblock with construction adhesive, then put the studs up, then used insulation with no batting? Should I use rigid foam? Please forward your suggestions.

  2. #2
    Join Date
    Feb 2008
    Posts
    69

    Smile Re: Vapor Barrier and basement

    Quote Originally Posted by Aaron Easley View Post
    I am getting ready to finish my basement. The issue of vapor barrier has me up in the air. I have heard and read all kinds of things. Should I apply 6 mil plastic directly to the cinderblock with construction adhesive, then put the studs up, then used insulation with no batting? Should I use rigid foam? Please forward your suggestions.
    The best way to do this is to first install your new studded walls, making sure the sill plate is treated lumber, with the insulation blanket under the treated plate.

    Mike Holmes, on "Holmes on Homes" did this to a house recently. He built the new wall against the concrete blocks, then used the blue, "closed cell" spray foam, which does not need a vapor barrior. The closed cell spray foam is much better than the open cell, plus gives better insulation quality. The spray foam is much better, becaue it will seal any little crook or cranny, to prevent any airflow. The spray foam is a little more expensive per square foot, but you will have no voids.

    I wish I knew which episode he did this. Perhaps, if you go to the Holmes on Homes site, you might find it, because each episode is labeled. Do not use a plastic vapor over the concrete, because moisture will develop between the 6 mil and the concrete.

    Besides TOH, Holmes on Holmes is another great program I watch all the time, for lots of great tips.

    Good luck,

  3. #3
    Join Date
    Feb 2008
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    69

    Smile Re: Vapor Barrier and basement

    Quote Originally Posted by reenieandrod View Post
    The best way to do this is to first install your new studded walls, making sure the sill plate is treated lumber, with the insulation blanket under the treated plate.

    Mike Holmes, on "Holmes on Homes" did this to a house recently. He built the new wall against the concrete blocks, then used the blue, "closed cell" spray foam, which does not need a vapor barrior. The closed cell spray foam is much better than the open cell, plus gives better insulation quality. The spray foam is much better, becaue it will seal any little crook or cranny, to prevent any airflow. The spray foam is a little more expensive per square foot, but you will have no voids.

    I wish I knew which episode he did this. Perhaps, if you go to the Holmes on Homes site, you might find it, because each episode is labeled. Do not use a plastic vapor over the concrete, because moisture will develop between the 6 mil and the concrete.

    Besides TOH, Holmes on Holmes is another great program I watch all the time, for lots of great tips.

    Good luck,
    Another note.........If you decide on fiberglas insulation to save money, use the 6 mil vapor barrior on the warm side, not against the concrete, like I mentioned above.

  4. #4
    Join Date
    Apr 2008
    Location
    Binghamton, NY
    Posts
    20

    Default Re: Vapor Barrier and basement

    Is there a reason behind doing this, reenieandrod?
    New homeowner in need of Hidden Content assistance.

  5. #5
    Join Date
    Feb 2008
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    69

    Smile Re: Vapor Barrier and basement

    Quote Originally Posted by rachael24 View Post
    Is there a reason behind doing this, reenieandrod?
    Are you asking why to use plastic on the warm side? If so, I was assuming the owner might decide to forgo the spray foam and use fiberglas instead, when 6 mil plastic is needed. If using just the spray foam, NO 6 mil palstic is needed. Basement walls are always cold, so you want to keep out moisture and drafts.

    Sorry for the misunderstanding.

  6. #6
    Join Date
    Aug 2007
    Location
    The Great White North
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    4,045

    Default Re: Vapor Barrier and basement

    The first thing to consider .... issues with moisture penetration from the basement (foundation) walls.... if so ..... that needs to be properly addressed first.

    If the foundation walls are clear from any issues .... another method you may consider ....... try using 2 inch rigid foam sheet insulation.

    You could attach the foam sheets using an adhesive that's formulated for the foam .... if you use the wrong type it will ruin the foam sheets.

    Attach the sheets of foam to the foundation walls first .... completely covering the walls.... making sure to seal the joints with a house wrap tape.

    This will eliminate the need for the vapor barrier preventing the warmer moist air from the living space from contacting the cold foundation wall surface.

    Then put up your framing studs and finish as desired. .... and if you wish to add batt insulation into the stud bays .... no problem.

    Having the foam sheets completely covering the foundation and behind the studs will improve the insulating performance by providing a continuous thermo break.

    Just a thought.

  7. #7
    Join Date
    Feb 2008
    Posts
    69

    Default Re: Vapor Barrier and basement

    Quote Originally Posted by canuk View Post
    The first thing to consider .... issues with moisture penetration from the basement (foundation) walls.... if so ..... that needs to be properly addressed first.

    If the foundation walls are clear from any issues .... another method you may consider ....... try using 2 inch rigid foam sheet insulation.

    You could attach the foam sheets using an adhesive that's formulated for the foam .... if you use the wrong type it will ruin the foam sheets.

    Attach the sheets of foam to the foundation walls first .... completely covering the walls.... making sure to seal the joints with a house wrap tape.

    This will eliminate the need for the vapor barrier preventing the warmer moist air from the living space from contacting the cold foundation wall surface.

    Then put up your framing studs and finish as desired. .... and if you wish to add batt insulation into the stud bays .... no problem.

    Having the foam sheets completely covering the foundation and behind the studs will improve the insulating performance by providing a continuous thermo break.

    Just a thought.
    Very, very good suggestion. I agree with this 100%.

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