Cloudy Windows

March 10, 2023

Cloudy or fogged windows are not only an aesthetic issue for homeowners. Air leaks and moisture intrusion caused by failed sealant create a cloudy appearance, and can cause energy costs to skyrocket. Insulated windows have a thin space between the inner and outer glass panes of the window, which may contain no air (a vacuum) or an inert gas such as argon.

The vacuum or trapped gas is maintained by a seal between the glass panes. The vacuum or trapped gas provides an “insulating” layer inside the window, which reduces the flow of heat energy and making the windows and entire house more energy efficient.

On new windows, the ability to reduce heat transfer is measured and noted on labels on the window. The terms “Solar Heat Gain Coefficient” and “U-Factor” are used, and lower numbers mean the more energy efficiency.

What Causes Cloudy Windows

Cloudiness or fogging results when the seal between the glass panes is broken or otherwise compromised. You can look between the panes of glass and see the seal, but may not be able to see the defect or damage. When the seal is broken, normal outside air can enter the space between the window’s glass panels.

This air contains moisture (humidity), which will condense on the glass inside the windowpanes and cause cloudiness. The energy efficiency of the window will be reduced, and it will then function like an older, single-pane glass window.

Repairing Damaged Windows

Correction of the problem comes down to repair or replacement of the affected window section, known as a sash. Repair can be problematic, and requires specialized skills and tools – so this is not a normal weekend DIY project.

Window replacement is usually recommended and can be accomplished by any competent window repair contractor in a short time frame. The repair may not require removal of the entire window frame or surrounding trim, as most insulated windows are designed to accommodate this type of component replacement.

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