Double Pane Windows

double pane windows Questions and Answers


double pane windows questions


Double Pane Windows


Just bought a house (8-9 yrs old), It’s brick, & has a large (arched-top) window in the very Double Pane Windows front. Not including the arch it is around 8′ tall x 7′ wide (maybe a bit smaller). The double pane windows glass  is real foggy.  I have been told it has a pinhole (they didn’t say inside or out), and has allowed gas(?) to enter the double-pane (and one guy said possibly ‘stain’ the inside of the window?). My question is, is there ANY WAY to siphon the gasses/fog out, and fix the pinhole?? Or am I looking at a whole new window? If I DO need a new window, do you have any suggestions on the least expensive way to go? Is it worth it (energy-wise) to get double pane windows – like that one was? ANY advice GREATLY appreciated!!

Thank you,


Hi Millie,

Double pane windows consist of two pieces of glass separated by a spacer around the perimeter and made air tight usually with a butyl based sealant applied between the spacer and the glass panes. The size and shape of the spacers varies with different manufacturers and some designs do perform better than others. The space between the glass panes may contain air or, to improve thermal and acoustical properties, it may bedouble pane windows filled with argon, krypton or xenon gas. Changes in temperature, stress during transport and installation, settling of the structure, faulty manufacturing, or impacts to the glass may cause the butyl seal to fail. Once the seal fails temperature differentials between the interior and exterior panes of glass will result in condensation forming between the panes. This condensation leads to the foggy appearance typical of seal failure in double pane windows. Once this happens there is no reliable way to reverse the damage. Repairs may be effected either by replacing the entire window unit or removing the panes from the unit and having new double pane glass installed in the existing frame. Some double pane windows may have a tag with the manufacturers name and a serial number affixed to the jamb. If a serial number is available, ordering a replacement glass, sash or unit from the manufacturer is often the most economical way to proceed. If no serial number is available many glass companies specialize in fabricating replacement glass in single or double pane configurations and will often come to your home and remove the old glass and install the new. Double pane windows are substantially more energy efficient than single pane windows. On a window of the size in question replacing it with single pane glass would result in a cold spot in your home, increase energy costs and lower resale value.

Good luck with your window repairs,


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About Tony Wood

Tony is a life time resident of North Carolina with over 40 years experience in multiple facets of the industrial, commercial and residential construction industry. For the past 33 years he has owned and operated Wood's Home Maintenance Service, providing services primarily in Johnston, Wake and Sampson Counties of North Carolina. ______________ ______________________________________________________ The information contained in this Blog is opinion derived, from hands on experience of over 40 years in the construction industry and by extensive research by the author. All postulations are referenced to the geographic location in which this experience was gained.
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3 Responses to Double Pane Windows

  1. Millie says:

    Tony – I want to apologize for taking so long to read your EXCELLENT response. I’m still trying to move in the house and juggle everything else, and I’ve just been too busy . I can’t thank you enough for taking the time to give me a little of your informative expert advice.

  2. Tom Macy says:

    I have a technical question concerning double pane glass. What causes the filmy look inside double pane windows with failed seals? I need more than the moisture answer. Here’s the situation: On July 26, we experienced a severe hail storm with 1 1/2 inch hail driven nearly horizontal into three sides of our home. Prior to the hail storm we were aware of one “fogged” window of which we were in the process of arranging for glass replacement. After the hail, we noticed 8 more windows were “fogged.” They might have been fogged prior to the storm, but I doubt it since at least 2 are opened nightly. The insurance company refuses to cover them because the “film on the interior of the double panes indicates a long duration of failure.” However, might there be another explanation for the film producing the foggy appearance?
    * We live in northern Colorado.
    * The eight additional windows are on the sides of the house hit by the storm.
    * I know impact rarely causes fogging.
    * I understand that “solar pumping” can cause moisture to enter the evacuated area between the windows.
    * All double pane windows eventually fall victim to solar pumping.
    * According to your diagram, the “low-E soft coating” is on the evacuated side of the interior window.
    * The “film” referenced by the insurance company is on the inside of the outside pane.
    One of the windows is in our sunroom. That room has a dampened temperature variation curve that follows the outside temperatures. The window forms frost on the house side of the inside pane during winter nights.
    * These are Hurd windows (known to have deficient seals) installed in 2005.
    * An inverted canned air test showed 30 of our 40 windows have moisture in the evacuated cavity, while only 9 show visible failure.

    Could the gas in the cavity, the “low-E” coating, or something else play a part in the filmy appearance?

  3. Tony Wood says:

    Mr. Macy,
    Check your email for my reply

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