Fogging on insulated glass

First, let us establish that if there is fog on the inside of an insulated pane, this does not necessary mean that there is something wrong with the glass. If, however, fog between the panes of insulating glass is a sign of damage, and that the window must be replaced.

There are several things we can do to prevent fogging:
First and foremost, indoor moisture should be kept at a reasonable level.

Cold rooms such as bedrooms are particularly prone to fogging on the windows. Through perspiration and breathing, a great deal of moisture is generated which then collects on the coldest surfaces -- i.e., the windows.

There are some simple steps that can prevent fogging on the windows:

  • Maintain a steady, normal temperature.
  • Ensure good ventilation, preferably through circulating airflow.
  • Heat sources should be placed under the windows.
  • Ensure that air circulation against the window glass is not hindered by curtains, blinds or large, protruding flower boxes.

A good hygrometer will be of good help to keep an eye on indoor humidity. The relative humidity should be at somewhere between 30% and 40% in the living room; however, this level can exceeded significantly for short periods in damp rooms.