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How do I prevent condensation in our brick/clay block/cement plaster home?

figureitout1 | Posted in Energy Efficiency and Durability on

We bought a foreclosure home, which is constructed of brick exterior, clay block interior wall which is covered with a layer of cement plaster. No one was able to afford the utilities on this home since there is no insulation, or the ability to insulate, without altering the unique interior design. We repainted (2 coats) with ceramic microbeads, which cut the heating utilities from $600/mo to under $300/mo. But in the process, we have created a condensation problem. To reduce the temperature contrast between the interior and exterior surfaces, we repeated the 2-coat microbeads paint process on the outside of the house. Still having condensation issues, for if we even hang a picture on the wall, it builds condensation behind it. We are running out of ideas for correcting the problem. Any ideas anyone?

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  1. Richard Beyer | | #1

    Condensation? House needs ventilation (HRV or ERV) and possibly dehumidification.

    Cement block walls can be insulated from within as shown here....
    and read this

  2. GBA Editor
    Martin Holladay | | #2

    The fact that your heating bills dropped from $600 a month to $300 a month has nothing to do with the insulating paint. Insulating paint is a scam, and if you paid more than $1 a gallon for it, you were robbed.

    If your heating bills went down, something else must have changed: perhaps the weather, or perhaps the thermostat setting. Or maybe someone finally closed a window that was accidentally left open.

    For more information on the crooks who sell paint with "microbeads," see ‘Insulating’ Paint Merchants Dupe Gullible Homeowners.

    The reason that you have condensation on your cold masonry walls is because they are uninsulated. The solution is to add insulation (probably rigid foam), either on the exterior or the interior.

  3. Richard Beyer | | #3

    Hey Martin... You addressed the wrong guy! ;)

    Here's a tip for you... You can update your SPFI fire data... '

    "An official cause of the massive blaze has not been determined, but officials believe spontaneous combustion is the likely reason."

  4. GBA Editor
    Martin Holladay | | #4

    Thanks for pointing out my error. I have corrected it.

    If any GBA readers are curious to know what Richard is talking about, he's referring to this GBA news story: Another Spray Foam Fire?

  5. Expert Member
    Dana Dorsett | | #5

    Setting the lack of thermal efficacy of magic-mouse-milk paint aside, let's get down to the fundamentals:

    Where is this house located? (I'm guessing it's not Antarctica. :-) )

    What is the wall construction stackup, including any air gaps or filled/empty block cores?

    How deep are your roof overhangs?

    What is (are) heating & cooling source(s) of this house?

    Is there good surface slope directing bulk water away from the house &/or surface drains or "French drains"?

    If you don't have a capillary break between the exterior brick and the interior you could easily end up with dew/rain moisture ending up on the interior surface of the wall, and anything you hang on it that blocks it from drying toward the interior can end up with mold-inducing levels of moisture. Any surface or foundation moisture that reaches the wall can also wick moisture upward several feet, with clay-blocks & cement plaster finishes.

    There are probably multiple ways to insulate this house, but none are likely to be very cheap, but if the moisture in the wall is ground water insulating may not necessarily reduce the moisture conditions in the wall.

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