Window defogging in the Laurentides (QC)

Defogging should be taken seriously and take place as soon as possible. First, there are several reasons why a window fogs up after a certain number of years.

The sun creates pressure by heating up the window and patio door in the daytime, and when night falls, the process is reversed due to the cooler temperatures. This causes what is referred to as a pumping action. After several years, the seal on the window and patio door is broken and moisture seeps in, fogging up the window between the two thermal panes.


When a window or patio door fogs up, it no longer has a R-value insulation rating. A thermal insulation window and patio door derives its thermal pane value from a 95% dry air space.

Defogging is simple, effective and reliable. Technicians will drill two holes (1/8" diameter) in one upper and one lower corner of the window or patio door to create a chimney effect.

The window or patio door is cleaned using a special solution to remove the moisture and any dirt that may have infiltrated along with the moisture. Then, defogging automatically takes place, removing the fog through the vent valve located at the top of the window or patio door.

As soon as the fog is removed, your window or patio door will regain its original thermal insulation rating and its R-value, as the dry air space is restored.


The thermos windows and patio doors undergo significant temperature changes and react in a dynamic and incessantly manner. In fact during the summer, the temperature of the air between the glass tends to grow. It therefore leads to increased pressure which grow to glasses. During the winter, the glass will tend to contract.

Over the years, these continuous movements bring micro cracks on the sealing thermos, saturating humidity and silica beads contained in the dividers. This results in fogging and/or white dust on the internal walls of the glasses. This event reduces the transparency of the glass, but also the thermal insulation factor.

Note that some windows and patio doors will rather let it show discoloration of the rainbow color glass.


Most thermal pane windows are manufactured with an aluminum, metal or PVC spacer. Inside this spacer?s cavity, manufacturers insert small pieces of silica to attract the humidity between the two panes. When the silica becomes saturated, fog starts to appear between the panes of your thermal insulation window.

Silica is a porous stone that breaks down into a white powder, which becomes trapped inside with the condensation. The sun heats up the window and cooks the silica in the moisture, causing stains, mostly at the bottom of the window. If you wait too long before restoring your windows, you risk getting whitish stains that cannot be removed, even with cleaning.