Andersen oval condensation

favabeans5January 16, 2012


I have a number of Andersen casement windows with the classic oval condensation on the inside of the glass. Note I mean inside the house not between the panes. I ran a straight edge along the glass and it is clear that the glass in the middle is collapsed towards each other. Also surprising how much the temperature varies from the edge to the center of the glass on my ir thermometer. I turned down the humidifier to stop the condensation. But I would like to fix the windows.

From what I understand the fix is too drill a hole in the frame to let air in to the space but how is the frame sealed afterwards? Seems like I can drill a hole as well as the next guy so considering fixing this myself. Anyone out there with experience or know about the process that can walk me through it?


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You are misunderstanding what you have read. Drilling a hole in the glass of a window that has condensation on the exterior surface inside your house will do nothing but make the problem worse. There maight be some value in doing this if the condensation was between the panes. The only way to get rid of the condensation is to reduce the humidity level in your home and allow for greater air circulation around the glass.

    Bookmark   January 16, 2012 at 4:58PM
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Hi skydawggy,

I think you might not be following what I am saying. The reason for the condensation is that the panes have been pulled together in the middle thus decreasing the temp in that area. Drilling the hole allows air to enter the space between the panes and allows the panes to return to their original position and no longer be collapsed I the middle. Thus increasing the space between the panes where they should be. There have been other posts on this topic in this forum but I didn't see details in them for exactly how the repair is completed. Note I also didnt say drill a hole in the glass but the frame.


    Bookmark   January 16, 2012 at 6:08PM
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Windows on Washington


Sky was referencing what is a very common phenomenon with seal failures and the resultant accumulated moisture in between the panes of glass.

What you have is the classic Andersen failure in which case the argon has leaked out and not been replaced by other atmospheric gases. As a result, the negative pressure inside the IGU has narrowed the space across the middle and created a closer thermal bridge and therefore dew point location.

I would suggest you first call Andersen. It was my understanding that they had replaced or at least offered cost on replacement units with the newer spacer system and Low-e. If that is not an option, drilling the IGU (provided it is not tempered glass) should relieve the pressure and allow the panes to return to normal spacing.

Be careful doing it as it can pop back somewhat suddenly. Use PPE and gloves if you go that route.

    Bookmark   January 16, 2012 at 6:49PM
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Hi windows,

You got it. Question is do I go thru the frame or the glass? And in either case what do I use to seal the hole. I am in touch with Andersen so waiting to see what they have to say. The windows are pretty old so we'll see.

Thanks for the warning on the glass I was wondering about that.


    Bookmark   January 16, 2012 at 7:58PM
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Windows on Washington

Through the glass is usually easiest but if you can access the spacer that is a bit safer and minimizes your chance for foul up.

They sell these little breather tubes online but you might be fine with nothing.

Let me know what Andersen says.

    Bookmark   January 16, 2012 at 8:04PM
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You are describing a classic example of collapsed glass.

For a bit of background, collapsed glass is not a seal failure, in the sense that there was a physical breach in the IG seal system, rather collapsed glass occurs in argon-filled windows when the argon decides to leave the IG airspace and it isn't replaced resulting in a partial vacuum within the IG airspace which draws the panes of glass inward. This is why you can use a straight edge to see that the glass is concave.

You cannot have both seal failure and collapsed glass at the same time (okay, there is an exception - there always is - but I won't go into it unless someone asks), because by definition with collapsed glass the IG seal is still intact and with seal "failure" the seal is no longer intact.

If the seal fails then air can get into the airspace and the glass in your IG unit will no longer be concave the vacuum is gone - so the simplest fix for collapsed glass is to vent the airspace by drilling a tiny hole either thru the glass or thru the IG spacer which will allow air into the space, equalizing pressure. The hole is then sealed and the window is again performing at close to the original energy performance specification - less the argon fill.

Collapsed glass is directly related to the materials and techniques used to manufacture the original IG units. At the time yours were made they were state-of-the-art and no one had even the slightest idea that argon could dissipate thru the spacer material without being replaced by air or that collapsed glass was even possible.

Modern materials and manufacturing techniques have virtually eliminated this problem (with a few very rare exceptions - almost always related to fabrication error), but back in the early 90's when your IG's were fabricated - different story.

Ironically, and as I mentioned previously, collapsed glass ultimately means that the IG's were very well made and that the seals have held up very well over the years which is why drilling a hole to vent the space works. Again, if the seals had failed then there wouldn't be a collapsed glass issue.

You need to contact Andersen right now...I mean immediately today since the IG's with this issue are coming very close to the end of the 20 year warranty period.

In the event that your glass has actually touched in the center, then the best option is IG replacement rather than repair...but that is something you would have to discuss with Andersen.

Also you will find that Andersen is very customer service oriented on this issue and will be receptive to your preference for replacing the IG's or "fixing" them.

The fix works very well and is the least disruptive alternative to solving the problem, but replacing the IG's or in many cases the sash (its ultimately easier than replacing an IG so they do that quite often), means getting a state-of-art unit 20 years more advanced than the current windows that you have now.

Again, you need to discuss alternatives with Andersen so call them asap and tell them you have a collapsed glass issue!!

Please reply back here with their response

    Bookmark   January 17, 2012 at 12:47PM
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and I so need to learn to read entire threads before replying since WoW had already described it perfectly (+1).

Anyway, if you insist on fixing it yourself I can tell you how to do it exactly as they would do it, but first I really (strongly) recommend calling Andersen - its a free fix so take advantage of it.

    Bookmark   January 17, 2012 at 1:00PM
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Hi Oberon,

Thanks for the response your reply to a similar question is now I was even able to understand what is going on in the first place. Always awesome to have people like yourself and wow who are willing to get on here and share your knowledge. I think my windows are over the 20 years which is really unfortunate because I have been in this house for 5 years and just now figured this out. These windows with the problem are in an addition that i believe was completed in the late 80s. The hole house has these windows but I only noticed it in the addition. Makes me think I should check the rest. I'll keep you posted.

    Bookmark   January 17, 2012 at 8:14PM
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hi favabean,

You are welcome.

In the lower right corner of your windows you will see the AW logo. In that logo will be a manufactures date code telling you the quarter and year of fabrication.

Even if the windows are older than 20 years, tell AW that you have a collapsed glass issue and see how the respond. Call AW directly (you can find the number on their website) rather than calling a distributor.

    Bookmark   January 17, 2012 at 8:38PM
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Yeah they are mostly 4-89 and 1-90. I sent them an email over the weekend and they responded already with some questions. No sense yet of what they are willing to do. I just checked and the sliding patio door and another window are both collapsed. I would guess most of the remaining 8 windows also have this issue to some degree. In the email they clearly stated that my issue is the collapsed panes so thats a start.

    Bookmark   January 17, 2012 at 11:26PM
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Windows on Washington

You can't drill the patio door through the glass so don't try that one.

You will get more than your bargained for.

    Bookmark   January 18, 2012 at 7:56AM
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Much more for sure

    Bookmark   January 18, 2012 at 9:14AM
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Yep. Tempered glass on that one.

Heard back from Andersen. They offered to sell me new sashes or directed me to a repair shop but sounds like I am on my own. They don't seem to want to help cover any of the cost. The windows are outside the warranty but I was hoping they would work with me a bit given this particular issue clearly being a manufacturing problem. So it's repair time. Anybody have any idea what the cost per window might be if I hire it out? Also mind sharing a step by step guide thru the repair. Sounds like it's drill hole in glass. Patch hole in glass but I am sure there are some extra details in there.

On the patio doors could I drill through the frame there instead or is there some other way to repair this? Andersen said they can't be repaired because of the tempered glass but figure it was worth asking. I am considering replacing that door with french doors anyway. The big issue is this room is pretty much nothing but windows and this door and they all have this issue. So it's by far the coldest room in the house.

Thanks again,

    Bookmark   January 18, 2012 at 12:01PM
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Send me an email please

    Bookmark   January 18, 2012 at 1:03PM
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I sent another note to Andersen and they said they are now going to have a Senior Technical Advisor give me a call. Not sure what to expect from that conversation. I will say they have been pretty responsive but I am thus far not completely thrilled with their response. We'll see.

    Bookmark   January 18, 2012 at 2:24PM
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Ha ha. Let us know if the "Senior Technical Advisor" turns out to be a salesman trying to talk you into new windows.

    Bookmark   January 18, 2012 at 4:27PM
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If you go to Andersen's website you can locate your closest Andersen Service Provider. They have the tools to repair collapsed glass. If the windows are older then 20 years, they are no longer covered. It's a relatively easy fix and should not be expensive compared to replacing the glass or new windows. I do it all the time......

    Bookmark   January 19, 2012 at 7:12PM
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Finally talked to them. They refused to do anything about it. Thanks Andersen. I tried to tell them about other companies I have dealt with that built known defective product and how they extend their warranties or provided some recourse for consumer to not pay full price on the repair. But they wouldn't do squat. I tried other tricks but they didn't go for it.

Oh well. Time to drill holes in 20 wndows.

    Bookmark   January 21, 2012 at 3:41PM
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Windows on Washington

Email Oberon.

He will be able to help you navigate the process a bit more precisely.

    Bookmark   January 21, 2012 at 4:10PM
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It's a bit surprising how much this impacts the temp of the glass. There is a 5-8 degree difference between the edges of the glass and the center. That's a significant amout of wall space in this room occupied by this glass. The visible glass is 24 x 55 and there are 8 panes like that in this part of the house with 7 of them in one room. Plus the panes on the patio slider.

Looking forward to the fix and seeing how much better the temp is in this part of the house.

    Bookmark   January 21, 2012 at 6:35PM
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Windows on Washington

I wouldn't count on seeing any change (at least that you can feel) in the room.

It should get rid of the thermal bridging and resultant condensation but the over impact in the total wall R-Value will be almost imperceptible.

    Bookmark   January 22, 2012 at 9:20AM
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No offense intended to WoW, but you should be well able to feel a difference. 3 most common things I hear after repairs:
1. More comfortable
2. Less HVAC activity & lower utilities.
3. Exterior noise diminished.

To address the R-value quotient-a single pane glass, which is essentially what you have when two panes of glass are touching, is about 1 RV. Bringing them back apart to the correct spacing with a repair results in about a 3 or 4 RV, depending on product & air space size.

    Bookmark   January 23, 2013 at 5:11PM
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never mind

This post was edited by millworkman on Wed, Jan 23, 13 at 20:12

    Bookmark   January 23, 2013 at 8:10PM
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Windows on Washington


I am sorry if you post up based on what you feel is the truth but the actual truth is something else.

The R-Value of a dual pane unit (unsealed, without Low-e and/or argon) is going to be about 2.

While and R-2 is 2X that of a monolithic pane of glass (R-1), the total value of that IGU (even under large negative pressure) was not and R-1 on average and only that low near the center where the glass was near bridged.

Changing increasing the R-Value via resetting the IGU spacing to its intended depth will help, but the difference will be slight in total impact.

If you averaged out the decreased R-Value across the center and the improvement, it still won't account for anywhere near a 2X increase in R-Value.

    Bookmark   January 23, 2013 at 8:12PM
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This post is a real DOOZEy.

Argon does not leak out and cause a vacuum.

Don't drill into the insulated space. You'll regret that in more than one way.

What altitude are you at, at home? Sounds to me like your windows needed capillaries for altitudes above 4000'??

    Bookmark   January 30, 2013 at 9:03PM
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I almost never tell people on line that they have no idea what they are talking about.

I am making an exception for you.

    Bookmark   January 30, 2013 at 9:33PM
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lmao, felt that way myself after reading more than one post of his. A veritable source of misinformation!

    Bookmark   January 30, 2013 at 9:37PM
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Windows on Washington


Oberon...this is a side I have never seen out of you.

I must say...I LIKE IT!!

    Bookmark   January 31, 2013 at 8:34AM
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I agree!


LOL and thanks!

    Bookmark   February 1, 2013 at 1:48PM
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