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  1. #1
    Bruce Thomas's Avatar
    Bruce Thomas Guest

    Question Condensation on windows

    Folks,

    I need a conformation of my opinion. If you disagree, that would be good too.

    This is a 1 1/2 year old home, very well built and the envelope is very tight. Condensation is building up on both the opening and nonopening windows. Last winter it froze along the meeting rail.

    I think that the home is not breathing and the in door humidity is too high. Possibly an air to air heat exchange power vent will help.

    Thanks in advance
    Bruce

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  2. #2
    Join Date
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    Default Re: Condensation on windows

    Yes, it does sound as though there is to much humidity, AND not enough air circulation.
    Suggest:
    Running the kitchen exhaust fan when cooking and for several minutes afterward
    Running the bath exhaust fan when showering and for several minutes afterward.
    Open the HVAC vents nearest the windows
    Run the A/C for a short time to remove humidity
    Get and use a dehumidifier

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  3. #3
    Bob Spermo's Avatar
    Bob Spermo Guest

    Default Re: Condensation on windows

    Recommend you get a competent and qualified energy rater to run a blower door test to calculate the house's air leakage (tightness). Have the rater give you the air exchange rate (ACH) and the natural air exchange rate (ACH/n-factor). You will then know for sure the tightness of the house and how it breathes. If it is really tight there is a great probability the house will need mechanical ventilation. Humidity should be between 30-50% in the winter. Does it have condensation in the warmer months? Condensation in warmer months in many cases is caused by the A/C being too large. Units that are too large do not run for a long enough period to remove the moisture.


  4. #4
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    Default Re: Condensation on windows

    Bruce, just a couple of thoughts to go along with high moisture leves in the house.

    What kind of heat, baseboard or forced air? Is there a register or heat strip beneath the window? If it is forced air is the fan speed set too low to move air across the window? Is there a chance that the wall cavity was not packed with insulation around the window at installation?

    I was raised in the northen part of Michigan where -10 was a common occurance. Register beneath each window, that blew hard. I did love sitting on them when I came in frozen to the knee. Never had any condensate on single pane wood windows with storms. To me, new thermal pane window should never get cold enough to freeze.

    Like I said, just a couple of thoughts.


  5. #5
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    Default Re: Condensation on windows

    Just to cover the physics, condensation forms when the temperature of the surface is lower than the dew point of the air.
    Two main options are to either lower the humidity or raise the surface temperature.

    Lower the humidity - turn off the humidifier, turn on vent fans to rid the home of cooking and other influences, and/or introduce dilution air (outdoor fresh air)

    Raise the surface temperature of the windows - direct heat onto the windows and/or insulated the windows.

    My guess would be a buildup of excess humidity in the home, measure to make sure. If this is only a problem in one room, area, or window type, then I would lean toward a low temperature issue on the specific windows.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

  6. #6
    Bruce Thomas's Avatar
    Bruce Thomas Guest

    Default Re: Condensation on windows

    I didn't put enough detail in my original post.

    • 2 forced air gas furnaces
    • They always use exhaust fans in kitchen, baths and laundry
    • The fixed window above the entry door also condenses
    • The window above the master tub gathers less condensation than the master bed room windows just outside the bathroom door.
    • The windows were leak tested by the manufacturer and passed.
    I'm looking for a blower door guy locally (Pittsburgh)

    Bruce


  7. #7
    Jim Weyenberg's Avatar
    Jim Weyenberg Guest

    Default Re: Condensation on windows

    Bruce,
    We this this alot up here in WI. Too much moisture in the indoor air! Turn off the damn April-Air humidifier if so equipped, be sure the bath and kitchen exhaust vent are plumbed to the exterior and working, (many times I find them covered over with siding or not connected to ducting at all) especially the dryer vent (has to be to the exterior). Watch for back drafting at the WH and furnace, with a tight house. Gas burns with a lot of water vapor! and the vents can act as a make up air provision for a tight house. That is way to much moisture, find the source, then dry out the house.
    Just some possibilities, you'll figure out the cause, your to much of a veteran Hi not to.

    Jim Weyenberg
    HouseMaster Inc.
    Green Bay Franchise
    Neenah WI.
    jimweyenberg@new.rr.com


  8. #8
    Ted Menelly's Avatar
    Ted Menelly Guest

    Default Re: Condensation on windows

    Hey, there is always the low tech way. Just have them take a towel and dry it off


  9. #9
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    Default Re: Condensation on windows

    Quote Originally Posted by Bruce Thomas View Post
    I didn't put enough detail in my original post.
    • 2 forced air gas furnaces
    • They always use exhaust fans in kitchen, baths and laundry
    • The fixed window above the entry door also condenses
    • The window above the master tub gathers less condensation than the master bed room windows just outside the bathroom door.
    • The windows were leak tested by the manufacturer and passed.
    I'm looking for a blower door guy locally (Pittsburgh)

    Bruce
    Good info Bruce,
    Forget the blower test, IMO. You already know the house is tight.
    Just get a good HVAC guy to verify proper venting of the gas equipment, bath & kitchen vents, and turn off the humidifier.
    I agree with the other Jim!

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

  10. #10
    John Allingham's Avatar
    John Allingham Guest

    Default Re: Condensation on windows

    An HRV will help.


  11. #11
    Michael Koser's Avatar
    Michael Koser Guest

    Default Re: Condensation on windows

    Are there humidifiers on the forced air furnaces and if so what are the humidistats set on? I saw this a lot on cold Maryland days and almost always the humidifiers were set way too high.


  12. #12
    Join Date
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    Default Re: Condensation on windows

    The home still needs to be blower door tested just to cross off any doubts.

    Those numbers can be used to get a very rough estimate of fresh air needs for the home by someone who knows how to do the math.

    Any recommendations on how to correct this issue without more test data is going to be a whooping guess.

    Measured Performance more than just a buzzword

  13. #13
    Ralph Smith's Avatar
    Ralph Smith Guest

    Default Re: Condensation on windows

    When inspecting a 50's ranch here in central NY, the buyer/present tenant, asked about the new thermal pane windows that, since they were installed, had been "condensing like crazy". This was a low income/1st time home owner purchase with a community action grant that has they're own employee/inspector that goes through with a safety inspection ahead of the home inspector that is hired by the buyer. He stated "they're cheap windows, ya get what ya pay for". I told her we would most likely find the source before the inspection was complete. When inspecting the crawl space, I turned on my combstable gas detector and started along the gas pipes. I got to the furnace and discovered that an HVAC tech had replaced the rotted flue vent connector to the lowboy furnace but did not screw it together. I found both pieces, rotted and new, lying on the dirt floor. Learned two things that day. Start the detector in open air, stick it in the confined space before entering. When I reset it outside and stuck the pickup through the window it started wailing in the CO rich air!
    The windows were fine. No vapor barrier on the floor and the furnace dumping the moisture rich flue gases in the crawl space was the culprit.


  14. #14
    Brandon Chew's Avatar
    Brandon Chew Guest

    Default Re: Condensation on windows

    Keep in mind too that the home is 1 1/2 years old. There can be a lot of moisture tied up in the building materials that can cause condensation problems during the first winter or two, until everything has had a chance to completely dry out. This shows up as a problem more frequently on homes with very tight building envelopes.

    For sources of moisture you also need to check for and rule out improper venting of combustion appliances, and any large BTU vent-less appliances that may be present.


  15. #15
    Jay Ray's Avatar
    Jay Ray Guest

    Default Re: Condensation on windows

    Bruce,

    Go to www.cmhca.ca . It is Canada's mortgage and housing corp. Look for the "Moisture and Air" publication. They will mail you this very well put together booklet that expains everything to do with condensation. I am a fenestration expert and deal with this in Maine every winter. I have several copies and can mail you a few if you cannot get them from the site I listed above.

    The images lead me to believe insulation around the window is not an issue. If there was little insulation or improperly placed insulation the condensation would be just around the perimeter of the glass. The home is too tight and most likely the heating system is an issue. Are there heat vents/registers directly under the windows?


  16. #16
    Jay Ray's Avatar
    Jay Ray Guest

  17. #17
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    Default Re: Condensation on windows

    Jay,

    Is this the one you are referring to? (If this direct link works.)

    https://www03.cmhc-schl.gc.ca/b2c/ca....do?next=cross#

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  18. #18
    Jay Ray's Avatar
    Jay Ray Guest

    Default Re: Condensation on windows

    No.

    Canada Mortgage and Housing | Société canadienne d'hypothèques et de logement
    613-748-2003
    publication #61033 "Moisture and Air"

    I have always called and ordered 25 booklets at a time. I ordered 25 of them last spring.


  19. #19
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    Default Re: Condensation on windows

    Quote Originally Posted by Jay Ray View Post
    No.

    publication #61033 "Moisture and Air"

    I have always called and ordered 25 booklets at a time. I ordered 25 of them last spring.
    Check the number on your booklets, that #61033 is the number on that document, I get the same document searching Moisture and Air as I do searching 61033.

    I suspect that the one showing up now is a new document, newer than yours.

    Maybe the new document is "dumbed down" for homeowners?

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  20. #20
    Jay Ray's Avatar
    Jay Ray Guest

    Default Re: Condensation on windows

    It is one and the same. True, it is written for the homeowner to understand. You would not believe the number of proffesionals who don't understand condensation.

    Most window companies recomend a humidity level between 28% to 40%. Log home manufacturers recomend 50%. Log home and the window plants have settled to 35% to 40%. These numbers are likley to cause light condensation but manageable. In New England a good old wood stove helps dry the air. In other northern areas where natural gas is used to heat the home, a lot of water is added to the air when heating the home. New homes need to "burn off" the wet building materials which can take several years.

    I always run a hygrometer to measure the R/H in the home when conducting any investigation


  21. #21
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    Default Re: Condensation on windows

    Quote Originally Posted by Jay Ray View Post
    In other northern areas where natural gas is used to heat the home, a lot of water is added to the air when heating the home.

    Would you mind commenting on this further Jay?

    Measured Performance more than just a buzzword

  22. #22
    Jay Ray's Avatar
    Jay Ray Guest

    Default Re: Condensation on windows

    DavidR

    A picture is worth a thousand words. Here are some infrared which show the water vapor burning off. Gas pipes have traps in the line for water. (condensation) When you fire up the burner the pressure pulls along the water and it get evaporated into the home. Not an issue in the dessert but up north it contributes to condensation on the windows. (The dark blue at the top of the flame is the water vapor in the images attached.)

    Here is a fun experiment you can do at home. Next time you take a nice hot shower you will see condensation on the mirror. Take a wad of toilet paper an wipe a wall. It will show you water is condensation on the walls as well as the mirror. Now in a room the window shows the bulk of the condensation as the glass gets much colder than the walls but the walls can collect some water as well. It gets in the carpet and furniture which in extreme conditions can lead to mold.

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  23. #23
    Join Date
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    Default Re: Condensation on windows

    Is the dryer venting into the house?
    Are the exhaust vents actually vented to exterior?
    Do the homeowners have a lot of plants, aquariums, pets, how many occupants?

    Place a 12"x12" piece of 6 mil plastic on the concrete floor of the basement and tape the edges with duct tape to the floor. Leave it for 24 hours, then check. If there is condensation on the underside of the plastic you know there is moisture coming up from the concrete. Hopefully the builder installed a 6 mil plastic vapour barrier beneath the concrete.


  24. #24
    Herb Scott's Avatar
    Herb Scott Guest

    Default Re: Condensation on windows

    Unless this is truly a custom house with special attention paid to tightness and efficiency I would be hesitant to call it too tight. All the suggestions so far are good ones but the first thing I would check would be the moisture conditions in the basement and the attic.
    Maybe it just needs a dehumidifier and / or ridge & soffit vents. If the basement is dry and the attic is properly ventilated with no evidence of moisture than move on to the next step.
    Herb Scott


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