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  1. #11
    Join Date
    Aug 2007
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    The Great White North
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    Default Re: Window Condensation, A/C & Mold??

    You're welcome Mike.

    Some additional information :

    In an average home up to 20 gallons of moisture per week can be generated during the winter months.


    A second problem is the possibility of high humidity in the winter with the temperature set too far down at night.


    Cool air can hold less moisture than warm air, so the relative humidity (RH) rises as the air cools.
    For instance, house air at a reasonable 35 % RH at 70 F will see an increase to 50 % RH when the same air is allowed to cool to 61 F.


    This can lead to condensation on windows ,ceilings and walls (for instance, in closets or behind furniture). The warm moist air will condense on a cold surface.

    So if the humidity inside the home is at 50% with the temp at 70 degrees then it will be considerably higher if you lower the temp down at night for example.


    Basically, you are creating a more humid environment, all things considered, when you allow the house temperature to drop significantly. This may not be a problem in a dry house or one where you can modify the humidity, for instance by turning off a humidifier.

    The house humidity should be monitored, especially in winter.
    Last edited by canuk; 01-11-2008 at 10:21 AM.

  2. #12
    Join Date
    Nov 2007
    Posts
    980

    Default Re: Window Condensation, A/C & Mold??

    I just happened to instal some counter tops in a house a couple of weeks back in a house that was having this problem. and since you say it dates back to the time that the house was built I would assume that the cause could be the same.

    the manufacturer of the windows sent a rep from alabama and was there while I was finishing up and so I heard the conversation between him and the home owner. the cause ended up being improper instalation. the outside of the window was never properlly sealed the rep said that as the window is put in it should be set in caulk and then the edge of the window framing should taped to seal it off to the house wrap.(tyvek) He explained that with out that process cold outside air was able to enter the window framing and this was the cause of the condensation, but if it was sealed off then it became an insulation barrier.

  3. #13
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
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    Default Re: Window Condensation, A/C & Mold??

    Surface temperature also plays a huge part in this.
    Windows surfaces are one of the coldest areas of the outside walls.

    For example ...... today the outside temperature is at 10 degrees F and using a digital infrared thermometer I took temperature readings of the glass surface of a window and also the surface temperature of the adjacent wall.

    The wall gave a surface temperature of 60.7 degrees and the window surface was 50.9 degrees.

    Since the window's surface is a full 10 degrees colder than the wall surface the humid air in the room will contact the window surface and will condense.

    The higher relative humidity inside the home the increased moisture will form on the window's surface.

  4. #14
    Join Date
    Nov 2007
    Location
    Sand Springs, OK
    Posts
    467

    Default Re: Window Condensation, A/C & Mold??

    I'm going to say dehumidify the house first. Start with a decent vent hood for the kitchen and good fan in the bathroom(s) vented to the outside. Then put a dehumidifier in the house. Humidity indoors should never be near 50%. I have a friend with compromised breathing issues and her doctor says humidity indoors should only be 20-25% at the most.


    Remediation is a good idea since there's damage to the wood surrounding the windows. Check out the resources from the current project house to learn how.
    Debby in Oklahoma

  5. #15

    Default Re: Window Condensation, A/C & Mold??

    Dehumidifing will help but you need to find the source.
    Here is an infrared picture of a poor window installation (new house).
    The blue is cold air getting in.Using vent fans and the like may be worse if there is a hi infiltration area. Notice the outlet below the window-a simple gasket or yellow foam will fix it.Cold air could be coming in from many places.
    A Picture says 1000 words.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  6. #16
    Join Date
    Aug 2007
    Location
    The Great White North
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    Default Re: Window Condensation, A/C & Mold??

    Here are some recommended humidity levels to allow safe levels with comfort.


    Outside Air Temperature (C) .......... Maximum Inside Humidity (68 F)


    –30 or below ............ ............................... 15 percent
    –30 to –24 ............................................. 20 percent
    –24 to –18 .............................................. 25 percent
    –18 to –12 ............................................... 35 percent
    –12 to 0 (32 F)..........................................40 percent
    Last edited by canuk; 01-13-2008 at 02:49 PM.

  7. #17
    Join Date
    Aug 2007
    Posts
    612

    Default Re: Window Condensation, A/C & Mold??

    Quote Originally Posted by debbysewn View Post
    I have a friend with compromised breathing issues and her doctor says humidity indoors should only be 20-25% at the most.
    I guess it is a matter of personal preference. When our humidity gets below 40% my nose and throat really dry out. We keep a pot on the stove all the time boiling off about 4 gallons of water per day.

  8. #18
    Join Date
    Jun 2007
    Location
    New Hampshire
    Posts
    13

    Default Re: Window Condensation, A/C & Mold??

    You need to keep your humidity down around 35 to 40%. You also have windows that are 20 yrs old and don't have the insulation value of modern windows. Condensation is a matter of dew point. You need two things, high humidity and low glass temperature. Sounds to me that you need to correct both problems.

    Best of luck,
    Todd Fratzel

  9. #19
    Join Date
    Jan 2008
    Posts
    8

    Post Re: Window Condensation, A/C & Mold??

    Thanks to everyone for the suggestions. We've taken steps to ensure our vent hood fan in the kitchen is always running while cooking dinner and the casement window slightly cracked. We've also kept the bathroom doors closed and the bathroom windows open as well after showers/baths until we can install some exhaust fans.

    It seems it's just something I'll try and manage and see where it goes from here. Worst case, I'll look into a dehumidifier - can someone recommend a well functioning quiet one? - to reduce the humidity. It's only been a short time, but seems to be okay so far.

    One thing I failed to mention. I did purchase two new Andersen windows for the two bedrooms that face West. They came in too late to install last year so they'll be done in the Spring. In the event one is truely leaky (I'm suspicious of one), I'll know for sure. Besides the wood staining from the condensation and the possible lack of insulative properties after 20 years, we were interested in the UV sun protection the new windows will provide for the rooms facing West during the summer months. I'll be able to check the insulation/area around the window and ensure the new ones are properly installed and sealed. We'll likely move our way around the house and replace all the windows over time too.

    Also, we don't have mold anywhere in the house other than, on a rare occasion, along the bottom of the top and bottom panes of the windows. The mold only develops if the moisture is left unattended and doesn't dry for a period of time. The damage is mostly darkening of the wood from repeated moisture. I don't believe I have a need for mold remidiation.

    Again, thanks to everyone for the homeowner education. I appreciate each and every response. I've seen other forums where questions go unanswered but I'm glad that's not the case here. I hope to be able to return the favor.

    Mike

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