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  1. #1
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    Default Tears in foil backed insulation ok?

    Im almost ready to blow in my cellulose insulation on top of the existing foil backed fiberglass in the attic. I have been upgrading electric and some other things in the attic. I noticed that when I pull up the existing insulation, there are quite a few tears and finger pokes, ect. in the foil. Should I worry/fix these tears by either removing and installing a 4 mil plastic vapor barrier underneath the fiberglass? or clear tape the rips in the foil? Or will these rips and holes not really matter.
    Thanks,
    Joe

  2. #2
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    Default Re: Tears in foil backed insulation ok?

    To my thinking it might be best to remove the FG bats and blow in the cellulose then place the FG bats over top with the foil facing up.

    If placed on top the cellulose will compress the FG ... this will severally decrease any insulating performance of the FG bats ... reducing the overall R value that might be gained .

  3. #3
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    Default Re: Tears in foil backed insulation ok?

    I agree with Canuk
    Debby in Oklahoma

  4. #4
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    Default Re: Tears in foil backed insulation ok?

    Would that trap moisture in the cellulose insulation between the drywall and the foil?

  5. #5
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    Default Re: Tears in foil backed insulation ok?

    Ideally it would be preferable to remove the facing from the insulation ..... but being the FG bats will allow air to pass through this should allow any moisture that may accumulate to breath out and in the summer with boil off.

    This was reason for mentioning putting the facing up and not down.

  6. #6
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    Default Re: Tears in foil backed insulation ok?

    Ok, so I can remove the foil faced fiberglass completely and blow the cellulose right on the drywall ceiling? There isnt a need for a vapor barrier at all in the attic? The moisture from the house will make it through 16" of cellulose without being absorbed into the cellulose?

    So in summary, a vapor barrier is NOT necessary in the attic at all?

    I live in Cleveland, OH.

    Thanks,
    Joe

  7. #7
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    Default Re: Tears in foil backed insulation ok?

    Quote Originally Posted by joew623 View Post
    Ok, so I can remove the foil faced fiberglass completely and blow the cellulose right on the drywall ceiling? Yes ... then to recycle the old insulation place it on top to benefit from some added R value.

    There isnt a need for a vapor barrier at all in the attic? The moisture from the house will make it through 16" of cellulose without being absorbed into the cellulose? Well the foil backed insulation provided little to no vapor barrier to begin with ..... so there will likely be little to no difference.

    So in summary, a vapor barrier is NOT necessary in the attic at all? If you were to install a continuous and sealed layer of plastic sheeting over the rafters and then down over the ceiling and up the next and so on ... it wouldn't hurt.

    The ceiling's surface and multiple coats of paint will contribute to the desirable perm value of about 1 .

    Here's the thing about the condensation issue .... it's mainly from the warm air from inside the living space that leaks into the cold attic space.
    The humidity contained in that warm air condenses when it mixes with the cold air.

    Most condensation is from air leakage areas like plumbing vent stacks , electrical penetrations , etc. that aren't air sealed.

    I live in Cleveland, OH.

    Thanks,
    Joe
    Hope this helps some more.

  8. #8
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    Default Re: Tears in foil backed insulation ok?

    Thank-you very much for clarifying!

    I was reading on this site and many books that say to install a faced insulation to prevent moisture from condensing. Other sites were saying to not install faced insulation. I was trying to figure out why multiple experts were saying install and not to install the faced insulation.

    So basically the foil facing provides little to no difference in the travel of moisture, therefore it doesnt really matter if it is there or not.

    Thank-you again for explaining why it isnt necessary to have faced insulation.

    Joe

  9. #9
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    Default Re: Tears in foil backed insulation ok?

    joew623 .... You're welcome.

    So basically the foil facing provides little to no difference in the travel of moisture, therefore it doesnt really matter if it is there or not.
    Just to expand on this particular topic of faced insulation.

    The kraft paper faced or any other faced types have been discontinued up here simply because they offer little or no vapor barrier performance.

    In Canada the kraft paper faced has also been removed from the market years ago for concerns of the paper being combustible.
    Last edited by canuk; 02-04-2008 at 05:21 PM. Reason: clarification as to location

  10. #10
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    Default Re: Tears in foil backed insulation ok?

    Kraft face insulation is still on the market. It is meant to be used in walls & covered with drywall because of combustibility. The same is true with foil face insulation.
    Removing the existing insulation before blowing in the cellulose is a waste of time & effort. Even if it does get compressed some, it is still providing insulation. The fiberglass on top of the cellulose will compress it too.
    A vapor barrier in the ceiling isn't required, so holes poked in the existing insulation shouldn't matter much. If turned over & placed on top of the cellulose, the foil or kraft face doesn't meet code because of the combustible surface. I would be more concerned about trapping moisture if placed that way. Any condensation that occurs in the insulation will be close to the outer surface, so you don't want any vapor barrier there to trap it .
    More important to blowing in insulation in the attic is to maintain any air flow from the soffits & not blow it into the soffits. Plastic or foam baffles are available that go against the underside of the roof deck to maintain airflow.

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