As the cooler months approach, many homeowners notice their double glazed windows becoming foggy or misty. This is a sign that the sealed unit has failed and moisture has entered between the two panes of glass.
Why Does It Happen in Autumn?
Throughout the summer, your windows are under constant pressure from daily sun heating and cooling — a process known as solar pumping. Each day the sun heats the sealed unit, the air inside expands. When it cools, the air contracts. This constant cycle gradually weakens the edge seal.
By autumn, many seals have been weakened to the point where they allow damp air to be drawn in. As the temperature drops, this moisture condenses on the cold inner surface of the outer pane, creating the familiar mist or fog between the glass.
What Can You Do?
Glazing companies will tell you the only solution is to replace the glass — typically costing £100-£300+ per window. However, the sealed unit can often be repaired for a fraction of the cost using the Condensation2Clear DIY kit.
The repair takes about 20 minutes per window and involves drilling two small holes, applying drying agent, and fitting one-way vents. The window typically clears within 7-14 days.
What About Argon Gas?
Some people worry about losing the argon gas in their sealed units. However, once the seal has failed, the argon has already escaped and been replaced by damp air. Argon adds only 1-2% additional thermal efficiency over dry air — yet replacing the entire sealed unit costs significantly more than a simple repair.