If you’ve noticed condensation or fogginess between the panes of your double-glazed windows, it’s likely that the seal has been compromised. A broken window seal not only affects the appearance of your windows but also their insulating properties, leading to higher energy costs and potential damage to the window frame. In this comprehensive guide, we’ll explore the different types of window seals, the causes of seal failure, and the various repair options available to you.
Understanding Window Seals
Modern windows feature two or more glass panes separated by a layer of air or gas, which is sealed around the edges to prevent air and moisture from entering. This sealed unit is known as an insulated glass unit (IGU) or double-glazed window. The seal is responsible for maintaining the insulating properties of the window and preventing condensation from forming between the panes.
There are three main types of window seals:
- Silicone caulking or sealants around the window frame
- Weatherstripping on operable windows
- The seal of the IGU itself
When any of these seals fail, it can lead to air leaks, moisture infiltration, and reduced energy efficiency.
Causes of Window Seal Failure
There are several reasons why window seals can fail over time:
- Faulty installation resulting in pressure on the glass panes
- Settling of the house creating pressure on the panes
- Damage to the sealant material from heat guns used for paint stripping
- High winds putting pressure on the glass panes
- The use of chemicals that can dissolve the sealant material
- Repeated expansion and contraction of the glass due to temperature changes (known as “solar pumping”)
Windows that receive a lot of direct sunlight, particularly on the west and south sides of a home, are at an increased risk of seal failure due to the effects of solar pumping.
Signs of a Broken Window Seal
The most common sign of a broken window seal is the appearance of condensation or fogginess between the panes of glass. This happens when humid air seeps into the space between the panes, causing moisture to accumulate. Other signs include:
- Distortion of the glass, even if no condensation is present
- Drafts around the window
- Increased energy costs due to reduced insulating properties
If you notice any of these signs, it’s important to address the issue promptly to prevent further damage to your windows and home.
Repairing a Broken Window Seal
There are several options for repairing a broken window seal, depending on the extent of the damage and the type of window you have.
Replacing the IGU
If the window frames are in good condition, you may be able to replace the insulated glass unit itself without replacing the entire window. This involves removing the sash (the frame that holds the panes), popping off the window bead used to hold the glass in place, breaking the silicone seal between the sash and the glass, and then removing the old IGU. You can then install a new IGU using silicone sealant tape and clear silicone.
This is a relatively straightforward DIY project for experienced homeowners, but it’s best left to professionals if you’re not confident in your abilities.
Full Window Replacement
If your windows are old or in poor condition, or if you want to upgrade to more energy-efficient frames, a full window replacement may be the best option. This involves removing the old window, ensuring the framing behind it is in good condition, and installing a new window.
This is a more expensive and involved process that is best left to professional window installers.
Defogging
For a more temporary fix, you can opt for defogging services to remove condensation from between the window panes. This process involves drilling a tiny hole in the glass pane’s exterior and pumping a condensation-drying chemical inside. The installer then seals the hole with a plug or epoxy.
While defogging can provide a quick solution, it’s not a permanent fix and may need to be repeated if the seal fails again.
Resealing
A professional glazier can reseal a window by installing a valve and pump to remove the moist air from between the panes, and then applying a new seal. This process is best left to professionals, as it requires specialized equipment and knowledge.
If your windows contain argon or other inert gases for enhanced insulation, resealing may not be an option, as the gas will need to be refilled, which requires equipment that most glaziers don’t have.
Preventing Future Seal Failure
To reduce the risk of window seal failure in the future, consider the following tips:
- Choose high-quality windows with a good warranty against seal failure
- Ensure proper installation by hiring experienced professionals
- Avoid using heat guns or chemicals near window frames
- Regularly inspect windows for signs of wear and tear
- Consider upgrading to more energy-efficient windows if your current ones are outdated or in poor condition
By taking proactive steps to maintain and protect your windows, you can extend their lifespan and enjoy a clear view for years to come.