LOPCO Blogs

Cloudy & Foggy Glass Window Panes

One of the best benefits of modern windows is how energy-efficient they are.

Among the many reasons they are so energy-efficient is because of the way the glass is set up in them.

The glass panes of these windows are typically made with some version of two panes of glass with gas in between (usually argon or krypton, though, just to err on the side of caution, I am not sure if Superman would have krypton in his window panes or not…).

These glass panes come in the form of what are called Insulated Glass Units (IGUs) which double the R-value (a measure of how well an insulated material resists the flow of heat, the higher the R-value, the better the insulating ability) of a glass window.

In this specific case, energy-efficiency refers to keeping temperature-controlled air on the inside of your home (vs. having it leak out and heat up the neighborhood!).

If you happen to see a cloudy or foggy window, the culprit is a seal that has been compromised in the particular pane of glass you are looking at.


The seal can become damaged for a number of reasons.

Exposure to water, particularly after a flood or in a situation where the seal is subjected to frequently getting hit with water can lead to the seal weakening.

Being subjected to heat over time can also lead to the seal failing, especially with direct sunlight where the Sun’s Ultraviolet (UV) rays tend to accelerate things.

As windows age, the seal may also naturally wear out.

Moisture from air escaping from the glass panels can lead to condensation and ultimately the cloudy or foggy look that is observed in these types of situations.

If you happen to notice a cloudy or foggy glass pane, contrary to some opinions out there, the entire window unit itself does not need to be replaced.


The approach that we most often take toward correcting this type of issue is replacing the individual pane which is exhibiting the problem.

When done by a skilled technician, this can be accomplished in a manner in which the replaced pane looks like it was original to the window itself (or at least to the point where unless one is laser focused on discovering it, will not be noticed).

The best way to not have a cloudy or foggy window issue is by doing what can be done to stay ahead of it from happening.

Inspecting your window panes at least once per year for cloudy or fogginess can be quite beneficial in this regard.

Making sure that your home is well ventilated is very important in general and can certainly help lessen the chance of premature wear on your windows.


Alleviating any potential moisture challenges can be invaluable. This may mean utilizing a dehumidifier on the interior of your home in areas that seem to be overly humid and ensuring that your window areas are not exposed to any unnecessary excessive water on the exterior (a leaking gutter constantly spilling/dripping water on to a window, etc.).

Another option may be purchasing window film kits to add another layer of protection to your windows, although this can be done by the “average” homeowner, one has to be super particular while doing so, or else they can easily have a mess on their hands!

Cloudy or foggy glass panes can surely be annoying, especially if they are located in a spot of your home that tends to draw your eye every time you walk by it.

Aiming to prevent them from occurring in the first place can be extremely helpful in terms of avoiding this unsightliness, but if cloudy or fogginess in your window panes does happen to happen, fortunately this is a situation that is fairly easy to address.

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