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Window glazings interior temperatures in cold outside and condensation

jinmtvt | Posted in General Questions on

I am unsure that my windows perform as they should,
this is our second winter in the new house, and the first one we had to get rid of ridiculous humidity level caused by the building time.

Now humidity as set to 35-40% for now,
and i still see condensation at bottom of all windows on the first real cold night.
Yesterday was a ~ -15c and i’ve measured down to 0c at the bottom of the glazings.

What is supposed to be normal temps for inside pane of high eff. windows ?
Is there any test results or tables somewhere i could check ?

mine are triple double argon with low E , and a similar but with a little higher heat gain on south windows …

i have never had window condensation at my previous house, and they were hybrid alum/pvc with regular IGU with argon and low e

never took temp measurements ..but still i’m sure it never hit 0c from the interior

Please let me know what you think before i investigate more on this matter
i may have been fooled once more in purchasing from this manufacturer

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  1. jinmtvt | | #1

    This is what i had last year on the coldest days ( -30c night )
    thinking about it now, i was given answer by the manuf that the humidity level
    in the house was too high , which was true, but that does not explain as to why
    their fiberglass frame are way below 0c on interior surface

    what do you guys think about this ??

    Looking back at my contract, it states 0.15U for north fixed windows
    and 0.45U for south with high SHG windows ( 0.2U and 0.5U for operables )

    i don't see how a window with a frame that freezes all winter can get anything near 0.15U
    nah ??

    Then second pic, i did a quick sketch on top of their detail pictures of the windows
    to depict what i believe is a major flaw.
    The glazings are in a pocket of the main fiber glass frame,
    that is all empty all around the glazing

    and they drilled some pee holes at the bottom of this and installed some output shields
    through accumulated water could go out ( depicted in red on the drawing )
    problem is that cold air gets in the frame from there, and goes ALL around the damn
    glazing, touching the edge of all the 3 panes directly,
    yes that includes the edge of the interior glass ( WTF??? )
    so the empty space within the frame is probably filled with outside very very cold air during winter

    i mentioned that to them and they seem to think that this is normal
    to me it is simply unacceptable as far as design and engineering goes

    again, what do you think ?
    i asked them why this space was not filled with backer rods or something else
    and i got the followign" glazing manuf asks for this for warranty "
    but i also got later on that " this is a special option usually asked for by architects only " ( talking about the filling of this pocket )

    i've purchased for 50 000$ of windows ( more than 30 units )
    and i do not believe they are what was sold to me
    at least, i don't think it should be icing on the interior
    ( hell i've never even seen that on any really cheap windows of prior houses )

  2. GBA Editor
    Martin Holladay | | #2

    You wrote, "Now humidity as set to 35-40% for now." I'm not sure what you mean.

    How do you "set" the indoor humidity? Do you have a humidifier? (I hope not.)

    Indoor humidity meters (hygrometers) can give bad readings -- so you may need to get another meter to verify your readings.

    If you have triple-glazed windows and you're getting too much interior condensation, my guess is that your indoor humidity levels are too high. It's time to increase your ventilation rate in order to lower your indoor humidity.

    For more information on this issue, see Rating Windows for Condensation Resistance.

  3. gusfhb | | #3

    My circa 1970 sliding glass doors used to frost on the inside due to their unbroken aluminum frame and massive air leakage. I cannot see how a fiberglass surface could frost as in the picture without a big air flow, unless the room temp were very low. Notice how the window sash has no frost. I suspect air flow.

    I don't believe the weep holes cause as much air flow as you fear.

  4. jinmtvt | | #4

    When i contacted the manuf ( will not name for now ) last year, they told me that i was getting this becuase of excessive house humidity.

    At the time i thought it was the answer, but thinking about it now, condensation is something,
    getting ICE on the frame of a window in a room that is in between 21c and 23c is anormal.

    All rooms were heated ( floor heating ) at high than 21c
    we usually like to set at 22c at switch level, since we all walk barefoot and do not wear much clothes inside of the house

    so the walls are at 21C if i measure them now with my laser temp thingy
    the wood 2X12 around the window goes from 20C to 16C near the windows

    mid glazings i get 14-17c

    bottom of glazing is anything in between 0c and 3-4c
    and bottom frame is also 0c-5c

    frames if i move higher has a much higher temp, up to 16-17c

    so this means that convection is in cause else it would have all same temp
    on the frame height

    that means only 1 think ...air leaks ..nah ?

    i really really think that the holes in the frame lets air enter at outside temp and is not ok at all

    are there weeholes at bottom of all windows frames usually ?
    i actually think i've never seen any ( not that i've ever looked for it )

    I had my dad measure his window temps this morning ( was around -12c )
    and he lowest he had was 12c at bottom of glass
    ( he has hybrid alum ext on pvc interior frames with double pane argon lowE glazings )


    What should i do now ? have a professional come and measure the windows ?

    This is not an isolated problem,
    all of the 30 something windows i have here exhibit the exact same condition

    if i read curves and graphs correctly, at 21C and 40%RH the dew point is 5C

    no wonder why i am having already condensation on my windows,
    they bottom of the glazing and the frame are down to 0c

    super efficient 0.15U total product windows!!! and premium pricing!!

    already had a very badluck where they forgot to caulk the exterior aluminum trimline and
    this make some major leaks on the window frames the first year .... looks bad now

  5. jinmtvt | | #5

    Used the IR thermo gun again today to compare how my glazings perform vs ones at my parent's house.

    Outside temp was between 0c and 2c

    Parent's : mid glazing = ~ 17c to 19c
    bottom of glazing = ~17c to 18c ( i'd say at max 1c lower )
    indoor temp = ~ 21c
    frame temps ( vinyl interior) = ~ 18c to 21c

    My house

    interior temp = ~ 21c
    temperature on wood bucks around windows = ~ 17-19c
    mid glazings = ~ 19-22c
    bottom of glazings = ~10c to 16c
    sides and top of frames = ~16c to 19c
    bottom frame = ~9c to 14c

    I can only guess that my glazings are good ( triples double argon etc.. )
    as i've even measured 21-22c on many of them ( when the wood bucks measured no more than 18-19c )

    the only explanations i find that the bottom portion of the frame and the glazing are colder is

    A - air leaks from the outside into the frames..but that would mean that they ALL leak or almost all
    B- very bad design of FG frame
    C- both of the above

    i believe that C is the unfortunate answer

    but i would like to have your opinons

    Also, where in Quebec province can we get windows tested ??
    i'd have no problem removing a window from the top exit room while redoing it ,
    and send it to some test agency of some sort

    Let me know what we need to investigate to be able to determine the origin of the problem
    i really need to take care of this asap, and if the windows are flawed i will need to think about the suite of actions ...many implications

    thanks all for your time!

  6. jinmtvt | | #6

    Hi again all,
    i believe may have found the major issue here.

    What do you guys think would happen if one would remove the insulation that is within the base frame of the windows ?

    This would leave only a few mm of fiberglass / 3" of air/ another few mm of fiberglass
    to insulate from exterior to interior !!!

    PLEASE HELP ME i need your opinion ASAP!!

    I've drilled 4 window frames up to now, and another has such a large spacing in a bottom corner that i can see inside the frame ... and none of those has any insulation at all in the frames ...

    that may explain why during the first winter, we had a leak under 2-3 windows ,
    and then i drilled a frame on a corner and water poured out of it ..probably something like a full cup of water

    if humidity leaks into the base frame, it is allowed to touch directly the exterior frame layer

    OUCH ... smells more and more like i'll need to call my lawyer now :(

  7. GBA Editor
    Martin Holladay | | #7

    Take a deep breath.

    You cause of your problems cannot possibly be the fact that your fiberglass window frames lack foam inserts. The difference between the U-factor of a foam-filled fiberglass frame and a fiberglass frame without foam is trivial. The purpose of the foam is mainly public relations, not thermal performance.

    I've said it before, and I'll say it again: your problem is elevated indoor humidity. It's highly unlikely that you have a window problem. I urge you once again to read this article: Rating Windows for Condensation Resistance.

  8. jinmtvt | | #8

    Hi Martin, as much as i thank you for your words,
    i understand what is the difference between humidity related problem and the lack of thermal performance from a window.

    Right now what is bugging me is that i spent nearly 50K$ on windows that are far surpassed in efficiency ( and problems ) by very cheap PVC windows from the corner store.

    Idon't believe that temperatures lower than 0c degree on any interior parts of recent windows is normal .

    I contacted several agencies and will have people come and evaluate and prepare reports.
    Unfortunately no choice :(

    Just too many errors has been done on this windows purchase.
    Many many workmanship defects that i was going to arrange myself,
    but now this is the worst.

    Martin the problem with the foam within this unit,
    is that the frame is a like a rectangular tubbing, it is fully open in 1 chamber,
    if it at least would've been devided or something , now air within this chamber touches directly both inside and outside temps, condensation occurs in some windows ( i'd say most, since it seems they forgot to "caulk" most of the corners and they are almost all open to some degree )
    and this portion of the frame is pretty large .. fully opened 1" height almost all the way from exterior to interior.

    They also forgot to caulk between the exterior aluminum moulding and the frame when in assembly, which resulted is several major leaks that has damaged many of my wood bucks during the first year ( before i found out what was happening )

    i'd say that i've endure enough problems with this product as of now
    ( missing parts on the patio doors that i never received, motors on awnings that just won't fit with any of the brackets they sent me , most window have at least 1 rubber seals on the stops that is not long enough ...etc.etc... )

  9. davidmeiland | | #9

    I think you should have a blower door test done, with IR inspection before and after (IR cam, not thermometer). You will find it very illuminating and useful, and it may show you that in fact there is air leakage around the sash on your windows. I think Martin is right, humidity is too high, but a BD test is still going to be worth the cost for you, since you are still working on the house and trying to solve problems.

  10. jinmtvt | | #10

    OK i will discuss the possibility of getting a simple blower test done as soon as i meet a building inspector since both of you are suggesting.

    OK please have a quick look at the quick drawing i made.

    Please tell me a few things :


    air temperature within the red boxes

    this is what i've got right now + a lot of leaks in the frames
    ( some 1/8" + corner gaps without any caulk )

  11. jinmtvt | | #11

    oops forgot drawing file :)

  12. GBA Editor
    Martin Holladay | | #12

    It sounds indeed as if your windows were not well manufactured. What's the brand?

  13. jinmtvt | | #13

    Martin : INDEED !!

    I will not divulge ( am i using this word correctly ? ) for now as my goal is not to tarnish
    anyone reputation until they've been given a final chance to repent from their sins.

    Ils fabriquent des vitres a base de fibre de verre et sont au Canada ...

    i'll unfortunately need to analyse all that and send a lawyer letter and see how it goes ...

  14. jinmtvt | | #14

    Inspector came this morning with thermal camera and hygrometer etc ..
    We measured the same on almost all windows.

    And he told me that with his measurements, my windows probably perform
    ( the frame itself ) worse than old 1 part wood frame windows as it is right now :(

    He confirmed that there is no insulation at all within the frames,
    and the windows are missing some "around the IGU" air stops and insulation.

    Definitely not what it is written on my contract and spec sheet,
    and nothing close to "total product" 0.15U value etc...

    Unfortunately, i will have to change all the windows ( almost 40! :( )
    and patio doors next summer ... and now i can't finish the interior around the windows since most window bucks are good for scraps

    superb experience!

  15. davidmeiland | | #15

    Can you post any of the thermal images from the inspection?

  16. jinmtvt | | #16

    I have nothing yet, i was promised to receive a complete report
    ( including digital pics etc.. ) within 2 weeks so .

    I can tell you the following ...
    outside temp was ~ -2C
    inside temp ~22c
    my RH% sensors @ 40% ...theirs was at 46%

    most glazing center temps were in the 19-21C range

    upper half of frames from 12c to 16c

    lower portion of frame from 8c to 14c
    lower center of glazings in the 10-14c

    He told me that we shoud've seen at maximum a diff of 4-5c worst case on the frame
    but that usually the center part of the glazing is approx the same temp as the frame
    on quality windows ( but double pane .. i have tripple double lowE so that explains the higher temp at center glazing )

    But what is the worst is obviously the fact that there isn't any insulation anywhere within any part of the frame, and the frame section is approx 1.25" X 3.25" 1 section fully opened all around the window.

    so the frame section should represent approx an R1-R2 value at most,
    probably not even to that because of the convection ???

  17. homedesign | | #17

    Hi Jin,
    see my attachment
    are you saying that the window frame (B) is not insulated ?
    or are you saying that the "drained glazing cavity" (A) is not insulated?

  18. gusfhb | | #18

    I will maintain that no lack of insulation in the frame assembly is going to cause the frost in his picture above. It has got to be airflow, one way or the other

  19. homedesign | | #19

    I believe it is very likely that there is at least some airfow near the bottom of the window unit and some airflow thru the bottom of the window to house connection.
    I think Jin may have a perfect storm going on.

    a poorly and or non (intentionally) ventilated house
    Exceptional Stack Effect
    Some nice Thermal Bridges
    Maximum Wind Effect....

    and not to mention the Magic of "COLD EDGE EFFECT" & Flanking Effect

  20. homedesign | | #20

    The commercial window in This BSC paper might be Similar to Jin's window
    note that the interior seal on the commercial window is not 100% airtight...
    I think It is very likely that Jin's "glazing cavity" is not 100% airtight to the interior either

  21. homedesign | | #21

    Cold Edge Effect is explained very well in Bill Rose "Water in Buildings" page 117

    Beware of Thermal Flanking" Effect was illustrated in Lstiburek's 2012 Experts Session (slide 69)

    (I could give you the link to Joe's slides .. but then I woud have to shoot you) ;--)

  22. homedesign | | #22

    I think John Klote's Stack Effect Paper (page 9)
    (thank you Lucas Durand)
    illustrates that the air pressure at the the bottoms of openings/window systems
    (below the neutral pressure plane)
    is stronger than the air pressure at the tops of "openings"

  23. davidmeiland | | #23

    Just for the heck of it, I took a few IR images of windows today, for comparison. These are with outdoor temp around 3 C, and indoor temp around 21-23 C. Very calm day outside. This first image shows a low-end Milgard vinyl single-hung window with clear insulated glass. There is almost certainly no insulation in the sash extrusion. The image shows the meeting rail, and both the upper and lower glass. The temps shown are a bit higher (1-2 C) than actual because I didn't take the time to let the imager stabilize (10-15 minutes, and I gave it 5).

  24. davidmeiland | | #24

    Here's a different window type, a Marvin wood/clad casement with low-e2 insulated glass. Temps on this image are probably closer to actual. It was a couple of degrees colder in the room with this unit, and the unit is lower in the wall.

  25. davidmeiland | | #25

    Here's another of the wood/clad unit, where there is an obvious air leak in the corner of the sash, around the weatherstripping. This is by far the coldest temp I saw.

  26. jinmtvt | | #26

    Please DAvid explain what is to be learned from your images ??

    John: there is no insulation in the frame section .. at B on ur image..all empty :(

  27. davidmeiland | | #27

    Jin, I don't have any strong opinions yet, but quickly comparing to your post #16, with slightly lower outside temp and similar inside temp, you have much lower temps on your windows. I would still like to see your inspector's report and thermal images. Any blower door test yet?

    Notice that my numbers seem to have a wide range. It is hard to collect solid data quickly from a few sample areas like this. No one should draw any real conclusions from this, just general ideas.

  28. jinmtvt | | #28

    ok yes i understand ..
    i am eager to see the thermal images and the report myself !!
    should receive it this week ..

    What i can tell you is that most of the windows have at least 1 easy to spot air leak,
    but not necessairly on the bottom portion
    as to many have a separation on the frame corners and or some too short glass seals on the glass stop
    I doubt there are many leaks from the bucks and walls connectin
    as the bucks are jammed with extrusions in the concrete, tapped to the foam and to the plywood inside, and i've "foamed" the countour of the windows to the bucks completely a few years ago :p
    probably something like 5-6" long of polyurethane gun foam around the windows,
    so air leaks are pretty much impossible there

    anyhow, the lack of insulation within the base frame is the major problem, i could've deal with the air leaks and small defects, but this exceed my tolerance limit on how bad a product can be manufactured.

    Will look into the links later this week ..way to busy now !
    thanks all again, much appreciated!

  29. homedesign | | #29

    Jin, I changed my comment because I did not want to put you "on the spot" to name the window company.
    I am still curious how you "know" that the insulation in the frames is "missing"
    Did you drill holes in the frames?

  30. jinmtvt | | #30

    Please do not post the company name yet, i do not wish to provoke anything at this point ..not my goal at all.

    Yes i have now drilled more than 8 different windows ( frames )
    will get a probing camera sooon to record and i'll post it then.

    Still need to drill the patio doors to verify if the same issue.

  31. davidmeiland | | #31

    I don't think the frame insulation (or lack thereof) is the issue, although it might be nice to have. I think you have air leakage issues based on the temperatures you reported compared to mine (very significant issues with getting accurate temperatures notwithstanding).

    For what it's worth, some window companies are very good at servicing their product in the field. I deal primarily with Loewen, and while I have had few issues, there have been a few, and they have sent a very good tech out in the field to handle them. Seems like what you need is for a factory trained person to come out and evaluate your windows in the field, and make repairs and/or replace parts as needed. I worry that by drilling all those holes you may complicate things.

  32. jinmtvt | | #32

    David Meiland: you are missing the point here ... my contract states high efficiency windows
    with a total product U value or 0.15 , and i do not have this at all.

    I have nearly 40 window units that are not half of what they are supposed to be,
    and each of them have multiple manufacturing defects, and unfortunately, some of these
    defects are not really servicable ( cie : openned up corner of frames, lack of sealant at some exterior joints and missing insulation )

    I do not understand why the lack of insulation within the frame seems unimportant to some of you.
    This is not a multi chamber frame, it is a single chamber.

    Right now the frame portion of my windows perform exactly the same as if i'd only have 2 poly sheets tapped to the bucks and the windows, with air in between.
    How is that supposed to qualify for a super efficient 0.15U value window frame ??

    Let met propose it again ..

    How would a window opening performed on cold climate if it was only 2 layers of thin glass pane
    with 3-4" of space between them ??? would that quality as efficient ?

    on a 48"X60" widow, my frame makes up to near 10% of the surface area
    and right now at -10C outside temp,
    pretty much all bottom portion of frames are between 5c and 8c temperature.
    Imagine at -20c and -30c.

    If you move up a few inches on the glazing, it gets back to 16c-19c

    still waiting for the inspector report!
    will post as soon as i get it!

  33. squibt | | #33

    How bout an update Jin?

  34. jinmtvt | | #34

    I forgot to update the thread ( holidays head )
    I will do it this week end.
    I can tell you that the final decision of the building inspector is that the windows
    are defective in multiple areas, but the main problem still is that they've missed the insulation within the frame, that was supposed to be insulated in the contract, is not, on every windows.
    ( we drilled holes in the frames and use a small flexibe camera to confirm )
    Also they didn't glue the corners on many units, wich led to corners opening
    from the weight of the IGUs.

    unfortunately, he also told me that he does not believe that it could be fixed on site.

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