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  1. #1
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    Jan 2009
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    Default Sealing an exposed exterior concrete foundation wall

    Live in a 1950's house in Kansas. The basement walls are made of poured concrete with half of the wall above ground level in the back of the house. The interior side of this wall has condensation only on the part of the wall that is above ground. The basement is finished and heated. There was mold growing where the condensation is. I killed the mold but I want to stop the condensation so that the mold issue does not come back. This has been a particularly cold winter which I think has contributed to this problem. Any ideas as to the solution to this problem?

  2. #2
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    Jan 2009
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    Needham, MA
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    Default Re: Sealing an exposed exterior concrete foundation wall

    when you can get the wall dried out for a few days, you can clean it and paint it with Drylock or home depot's version of Drylock, which i prefer to Drylock. both work very well, just make sure you use two coats, then cover the wall with foil faced rigid foam insulation (if you have the space for it) or d**** and seal plastic over it.

  3. #3
    Join Date
    Jan 2009
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    Default Re: Sealing an exposed exterior concrete foundation wall

    Thank you for responding. I just want to clarify do I use the drylock and foam on the inside wall and outside wall? I had someone suggest that I use the foil foam on the outside exposed basement walls and then stucco over it. I am a novice at home repairs - thank you for clarifying for me.

  4. #4
    Join Date
    Aug 2007
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    The Great White North
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    Default Re: Sealing an exposed exterior concrete foundation wall

    Quote Originally Posted by Meeko View Post
    Live in a 1950's house in Kansas. The basement walls are made of poured concrete with half of the wall above ground level in the back of the house. The interior side of this wall has condensation only on the part of the wall that is above ground. The basement is finished and heated. There was mold growing where the condensation is. I killed the mold but I want to stop the condensation so that the mold issue does not come back. This has been a particularly cold winter which I think has contributed to this problem. Any ideas as to the solution to this problem?
    Sounds as though the issue is simply a case of warm moist air within your basement contacting the cold surface of the concrete.

    The area above ground level will be the coldest portion since it doesn't have the soil to act as an insulator.


    Adding any type of paint on concrete sealer really won't help ..... adding insulation would raise the temperature of the concrete preventing the condensation.

    Using the foam sheet would work for this area .... however putting it on the outside prevents the concrete to breathe. It would be benifical to apply it to the inside though you would likely be required to cover it with something like drywall for a fire rating.

    Also .... regardless what type of insulation is used it needs to be air tight. In other words there should be no air allowed to circulate behind any insulation for 2 reasons.....
    - moving air will reduce the insulating performance.
    - you will still end up with condensation behind the insulation.


    Just a thought.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  5. #5
    Join Date
    Jan 2009
    Location
    Needham, MA
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    559

    Default Re: Sealing an exposed exterior concrete foundation wall

    foam insulation and stucco on the outside would obviously be even better than just finishing the interior. ideally, everyone would want the entire exterior of their foundation waterproofed and insulated then on the inside a vapor barrier, layer of rigid foil covered insulation, your stud wall with standard batt insulation between the studs. then you'll be dry and warm forever.

  6. #6
    Join Date
    Aug 2007
    Location
    The Great White North
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    Default Re: Sealing an exposed exterior concrete foundation wall

    Around here we never seal the exterior of a foundation from above grade level.
    This is to allow the concrete to breathe .... allowing any moisture that will be contained in the concrete an avenue to evacuate.

    This includes the waterproofing or damproofing as well as exterior foundation insulating is done from grade level down.

    The above grade portion of the foundation is always insulated from the interior around here.
    "" an ounce of perception -- a pound of obscure "
    - Rush

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