I have 30-year-old insulated windows. A salesman told me that the seals are broken, and I am losing heat. To me the seals look fine and I speculate that broken seals should lead to condensation in the double panes. What is the best way to determine if the seals are leaking and windows need replacement?
-Deepak

Hi Deepak,
While condensation or discoloration inside the glass usually occurs when the seals are broken, there are other factors to consider that can affect the insulation performance of your windows even if the seals are intact, such as:

• The insulating qualities of the argon gas used between layers of glass diminishes over time as it slowly leaks out at a rate of about 1% per year, which can cause a reduction in the insulating value of windows.
• Newer windows can be ordered with Low-E coatings designed for your climate that can reduce energy loss by as much as 30%-50%.
• The weather stripping around your windows may have become worn, allowing air leakage.
• Newer vinyl clad wood frames insulate better than older metal frames.

The bottom line is that replacing your windows (or the glass in them), may increase the insulation value, but you will have to weigh the savings against the cost incurred.

Further Information

• Choosing the Right Windows
• How to Select Insulated Windows
• Advantages of Low-E Glass in Windows and Doors
• Problem with Moisture Trapped Between Glass on Windows
• How to Repair Fogged Double-Pane Glass Windows
• How to Remove Moisture from Double-Pane Glass Windows

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8 Comments on “How to Know if Insulated Windows Need Replacing”

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1. Katie Says:
   July 30th, 2010 at 6:16 pm

   Dear Danny,

   I recently bought a house with double-pane vinyl windows with fake muntins (or grills) between the panes. I really hate the cheap and inauthentic look of the fake muntins. I have been trying to research whether it is possible to remove these fake muntins– perhaps by having a glazier unseal the IGU and take out the muntins. But is this even possible? And if it is possible, is it wise? Can the windows be effectively sealed again?

   Many thanks for your advice,
   Katie

2. 

   Ben Erickson Says:
   July 31st, 2010 at 10:30 am

   Hi Katie,
   As far as I’m aware, it’s not possible to unseal dual pane glass to remove the mullions, nor would you want to if you could, since the space between the glass contains a special gas (usually argon) that increases the insulating properties of the window. In addition you would be sealing humid outside air into the space when you resealed them, which could cause condensation to form between the glass.

3. Dave Fouser Says:
   November 6th, 2010 at 6:22 am

   Dear Danny,
   We live in a modular home and find that the front door is gaping at the opening side on the top; along with the storm door. The siding continues to look level and we really don’t know what we can do to remedy this problem. We’re on fixed income, live in a modular home park and wondered if you had any ideas.

4. 

   Ben Erickson Says:
   November 7th, 2010 at 6:46 pm

   Hi Dave,
   Sounds like the wall has settled on the hinge side, or the door unit frame wasn’t installed square and level in the first place. In either case, it’s not an easy fix and will require removing the frame and rehanging the door. Other fixes that aren’t as good include cutting the top of the door at a slant and rehinging it, or cutting a wedge shaped piece of wood the thickness of the door and attaching it to the top with adhesive and nails or screws. Good luck with your project!

5. Vanessa Says:
   March 2nd, 2011 at 6:40 am

   Dave,
   We built a house 5 years ago and have double pained windows. My problem is that the windows have been having condensation on the inside. It isn’t between the glass it is on the inside. I can wipe it off but I really don’t want to have to to this to about every window in the house everyday. Is there something that I can do to correct the problem?

6. Wendy Says:
   April 8th, 2011 at 10:24 am

   I had this same problem with the moisture forming and it got old washing the windows every day so I stopped and mold formed. I called our neighborhood handyman and he told me that the house was sealed up to tight and that we needed to vent more, open windows, run a fan periodically and open our drapes.
   I got into the routine of opening the front and back door every moorning and left them open while i opened all the drapes and blinds, then i closed the doors. I made sure everyone used the vents int he bathroom when showering and used a vent when I cooked and that fixed the problem. We did use dry-z-air for about the first week in the living room which had the most moisture on the windows.

7. Don Says:
   November 3rd, 2011 at 11:05 am

   We had a triple pane window installed in our living room about 6 years ago. About 3 years ago, we noticed “dirt” marks between the panes. It looks like someone cleaned the windows, but left streak marks and it is between the panes of glass. Looks terrible and is getting worse. I assume that the seal must be broken and if so, do I need to replace the whole window or what can be done to fix it?

8. Mike Dowling Says:
   May 16th, 2012 at 2:53 pm

   Is it possible to inject Argon or Krypton gas back into a window? If so, how?

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