Repair a Double Pane Window Unit

Repairing your double pane windows because they’re foggy is often a better solution than replacing them. If fog is not your problem, and the double pane window is broken, don’t worry – you can still fix it.

The great thing about double or triple glass windows is their insulating properties. They help tremendously to keep extreme hot and cold temperatures from passing through. A trapped layer of pressurized air or gas is key to their function. But what happens when these glass chambers are compromised, such as a broken seal somewhere, hole or crack?

Well, two things: The obvious is that the window loses it’s ability to insulate dramatically. Even the tiniest penetration means hot and cold air can move more easily through the window. The second is actually something you’ll notice, if not right away, for sure over time. Moisture, dirt and other contaminants enter and take residence in between the panes of glass. From there, the rest is history. You start seeing fog in your double pane windows. Sometimes it gets much worse, and condensation forms in between the panes. Water droplets begin forming and running down the inside of the glass.

The visual obstruction doesn’t just go away either. It’s as if what’s trapped in there is there to stay and ruin your view through those windows. You either need to fix your double pane windows, or replace them. Luckily, there are ways to go about making a repair. This will save you a lot of money and get your insulated windows working and looking like they should again.

What makes your double pane window hard to see out of?
It’s obvious, the seal to the insulating chamber between the glass is broken somewhere and “stuff’ is getting inside. Water begins to saturate the air inside, and at some point condenses on the inside of the glass. You’ll see this as a light haze at first. Then it will look misty (foggy), then finally water bubbles may appear. In some cases, you may not even notice moisture but see a silica-like appearance within the glass. This looks like tiny snow-flakes frozen in time on your window. These little flakes are an indication that the glass system is becoming damaged permanently.

Options for double pane window repair
When assessing the fix for your double pane windows, let’s break it down based on what might be going wrong with your windows. The first will deal with double pane windows that are fogged up. The second will consider actual broken glass (cracked or missing pieces).

If double pane window is foggy or water inside:
There are two things to understand in this scenario. First, you do NOT have to replace, but rather you can repair your foggy dual glass window. Second, you will still need to hire a professional to implement the fix. But the good news is repairing your insulated windows is a lot cheaper than buying new ones! It equates to about 50% cheaper on average. What’s more is you’ll probably save that money back in your energy bill when you get back a window with a higher R-Value (insulating quality). And don’t forget, your view to the outside world will be clear again!

Here’s how a professional repairs a double pane window.  There are a few methods the pros use to make your dual pane windows clear again. No matter the approach, each involves carefully drilling a small hole in a corner of the window. Methods that attempt to clean and restore your windows will involve pumping cleaners in to remove trapped dirt and minerals from within your window system. Through a second hole, these products will then be sucked back out carrying the bad stuff with them. Finally, a drying agent is shot through, then the holes are sealed up. You’re left with a like-new window.

Other methods don’t trust the sealing capabilities of your insulated window system anymore, and thus just fix the symptoms instead:  the moisture-filled air now inside your thermal pane windows. This is perfectly fine as it can theoretically last forever. This way is done by strategically drilling out and placing small vents and valves in the thermal panes. This allow the moisture to escape, leaving behind dry air between the panes. The dry air virtually returns the window’s original R-value. It also returns the appearance, eliminating the haze or fog. The sooner you can do this remedy, the better.

If thermal window glass is broken:
To save money, don’t replace these valuable insulating windows. You can still repair them, but replacing just the glass. This is a lot less expensive than getting new frames measured and fitted. There are a few methods used in these cases, and they depend on the design of your window:

  • Windows with a rubber gasket: Usually windows have wooden sashes. Remove the sash first and then the small screws that hold the rails (horizontal) and stiles (vertical) together. Use a rubber mallet or small wooden block to loosen the frame from the gasket and double pane glass. Remove the gasket from around the glass system and use it on your new double-pane unit. Push the frame around everything and fasten back together. Use caulking (silicone) to seal small gaps and corners.
  • Windows using sealing tape: First, pry out all the window’s stops with a putty knife. With a utility knife, cut the existing tape – be sure blade is sharp. Remove all of the old tape completely and clean surface where tape was thoroughly using an all-purpose solvent. Apply your new sealing tape on frame, then lower down the new double-pane unit on top to stick. Seal all gaps with silicone caulking (clear kind)
  • Using caulking: Gently pry and remove wooden stops. Slice through old caulking with the blade of a utility knife. If you need to “break” the window out be sure to cover first with something like an old comforter or carpeting. Use a hair dryer or heat gun to soften old adhesive and scrape and clean all edges until they’re clean. When dry, apply bead of caulking to the frame and lower in your new double-pane window. Silicone sealant should be applied on the stop side before reinstalling the stops.

This information should help give you an understanding of not only what’s going, but how a double pane window repair can be done. It’s worth going for a fix rather than living with the fog because you think you have to get new windows.


  1. Jo Ann Jensen says;
    01 Sep 2011 - 8:38

    The white silicone is dripping down 2 of my double pane windows. I don’t know how to remove the frame and windows as the frame appears to be white metal flush with the opening.

    Please help….don’t know how to work with this. Thank you. Jo Ann Jensen

  2. Drilling the holes requires a diamond drill bit and patience. However, even after a couple of weeks it didn’t change the appearance of the fog, in either the badly fogged or the minimally fogged test window I chose.

    Tried filling windows with vinegar and soaking overnight before draining. Didn’t work, so I tried Calcium Lime Rust remover the same way. Didn’t work.

    Tried taking glass out and cutting the seal. The minerals inside were rock-hard. Using a razor scraper and CLR, I was able to clear about 10″ by 10″ of window pane in about half an hour. Mind you, that is on only one of the two panes of the double paned window. Quick arithmetic told me that the value of my time was worth much more than the $60 per window I had been quoted to replace the glass.

    I am now enjoying my newly-installed clear windows!

  3. Orin Baker says;
    12 May 2012 - 11:05

    I would like to repair a fogged double pane window that’s about 48 in by 34 in. I have no idea where a repair company exists. I’m located in Garfield, AR about 12 miles from Rogers, about 25 miles from Fayetteville, AR. Would you know of any company close that could fix the window pane?

  4. Orin, I would find a contractor local to your nearby cities and see who they use to install windows. There’s a good chance they can lead you to a window repair specialist who can help provide you a fix or replacement.

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