What Causes Condensation Between Window Panes?

Causes of Window Condensation

• Condensation occurs when trapped air between the panes of glass on a window leak out and humid air draws into the space when the window cools down. The moist air and the cool window cause the panes of glass to fog. The flow of air between the glass panes occurs when the window seal is broken.

Causes of Window Seal Failure

• The seal on the window may fail after years of daily contractions and expansions, which occur when the sun warms the air between the glass. The window expands during the heat of the day and contracts as the window cools during the evening. The constant contractions and expansions cause the seal between the panes to damage over time. The windows on a part of the home that receives direct sunlight may experience greater stress and broken seals. Windows may have defective seals, which can cause condensation and seal failure sooner than it should.

Window Repair

• According to the International Association of Certified Home Inspectors, homeowners reglaze problem windows 75 percent of the time and replace them only 5 percent of the time. Defogging is another method that can remove the condensation between the windowpanes. The defogging method removes the moist air from the window, cleans the space and inserts a defogger that will release the damp air. While the process does not actually repair the cause of foggy windows, it does eliminate the symptoms.

Window Replacement

• Replacing the window is a permanent solution for foggy windows. Replacing the windows, including the frame and sashes, is an expensive option for homeowners. It may require repainting the interior of the home, which adds to the cost of the replacement.