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  1. #1
    Join Date
    Jan 2014
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    Condensation Help - Windows are covered and not sure what to do

    --reposting this here per site


    Thank you in advance for reading and input.

    Live in Toronto where we experience all 4 seasons. 5 people live in the house.
    In the summer we completed a renovation and extension on an older brick home (1950's). We gutted everything on the main floor and basement. The upstairs we left as is but we did re-insulate the attic. The upstairs walls that we left are plaster with red brick outside, there is no vapour barrier. We left the upstairs windows as they were not that old, they were from 1999. Downstairs/basement everything is new drywall and well insulated. A brand new forced air HVAC system with humidifier was installed as well.

    We have a condensation issue that persists throughout the entire house on the windows. I have 3 separate temperature units (including 1 nest) reading the humidity levels in the house. The main floor is usually 35-38% and the upstairs is 40-45%. It has gotten to the point where part of my morning routine is to squeegee all the windows with a power squeegee on the top floor. On cold mornings the windows are completely frozen. It is occurring on all windows but is worse upstairs. We were away for a week and I came back to find puddling upstairs on the window sills and floor in the front of the windows. There was so much water that it was creeping through the bottom of the windows inside and to the outside windowsill.

    We inspected the house before we purchased it and there was no evidence of this issue.

    Our current hvac guys are at a loss and have basically left me stranded. I have toyed with running the furnace fan all day and all bathroom vents etc... This has provided no relief.

    My research leads me to believe that it may be a ventilation issue and an HRV unit may help? But I am not sure as the upstairs is certainly not "air tight" as there is limited insulation in the walls (does this matter when discussing ventilation?)

    Looking for some guidance/assistance.

    Thank you,

    updated 24 hours after post above:
    there are 5 people living in the house. no fish tanks, no exposed crawlspaces. There is plenty of water close to or underneath the house. The surrounding earth is clay, sump pump goes a couple times an hour all year.

    I removed all mechanical moisture aiding devices from the house ie/turned humidifier off yesterday around lunch time. When I woke up this morning the main floor was 30% and upstairs was 40% humidity. Outside temp was -7C. there was very little moisture on the windows, just a bit at the bottom.

    I plan to try and dry the house for the next couple of days while the weather is suppose to be a bit warmer and see if I can determine any correlation to the moisture problem. I will track the humidity and outside temperature and other variables.

    I figure if all mechanical moisture devices are off for a couple of days yet the humidity stays up there must be another source to the problem. The water table under the house was one thought.

    The other side of the equation is I have brand new hardwood floors which I have been advised to keep the humility in the house between 35-50% to ensure the floors dont split, separate etc...

    Question - how will I know if I need a de-humidifier vs an HRV?


  2. #2
    Join Date
    Jan 2007
    Minneapolis, MN
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    What type of windows? Brand, casement or D hung, low e? If you suspect the moisture is coming from the ground then that should be addressed first. The source of moisture needs to be controlled then look to mechanical solutions. Hardwood floors do not split because they get dry, if that was the case now one would have them in the dry southwest. Wood splits or buckles from rapid moisture changes. Was your new furnace a high efficiency unit replacing an older lower efficiency unit? If so it can cause a decrease in air exchange leading to higher humidity.

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