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Jtice13 | Posted in General Questions on

Just bought a condo built in 2001 in Northeast Ohio, moved in Jan 15, 2021.  Has Anderson 400 windows and everyone of them are covered in condensation on the inside everyday, and dripping. Humidity inside is around 55 percent. This morning woke up to 15 degrees outside and had condensation on one wall of cathedral ceiling in living room, the inside wall. Also half the condo is built on slab and half has basement. Rooms on slab are very cold even with thermostat on 74 degrees.  PLEASE HELP !!! 
Thank you.

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  1. maine_tyler | | #1

    55 RH is pretty high for winter. At 74 degrees F that's a dewpoint of about 56 degrees F. So in theory any object below that temperature will form condensation.

    What are your sources of moisture? Lots of showering going on perhaps? Tight structure and low levels of ventilation? Bathroom fans, range hoods, etc. being used?

    "had condensation on one wall of cathedral ceiling in living room, the inside wall." What is meant by this? Do you mean the interior of the ceiling has condensation? Is it uniform, in strips, or other?

  2. Jtice13 | | #2

    Thanks for your response. Pic shows white ceiling, green is the wall where you can see about 3 lighter spots which were the condensation areas that were dripping. Structure is tight and since my first post I found that the two bath vents were emptying into the attic ! But every window is showing much condensation on inside everyday even if bath vents not being used for a few days. Thanks

  3. [email protected] | | #3

    From University of Minnesota:

    Maximum Recommended Humidity Levels based on engineering studies at 70° F conducted at the University of Minnesota Laboratories.

    • Relative humidity levels above these are not recommended at the low
    outside temperatures indicated, unless special provisions are taken in
    building construction.
    • If higher relative humidity levels are required because of special interior
    environmental conditions, the window manufacturer should be consulted.

    Outside Air Temperature Inside Relative Humidity
    -20° F or Below Not over 15%
    -20° F to -10° F Not over 20%
    -10° F to 0° F Not over 25%
    0° F to 10° F Not over 30%
    10° F to 20° F Not over 35%
    20° F to 40° F Not over 40%

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