Problem - How Windows Fail
There is much more to insulated glass unit (IGU) failure than common window legend tells. The fabled 'ruptured' seal that brings moisture into the sealed unit is, in most cases, a small breach that is easy to manage and control with our Moisture and Damage Control service. Over the life of a sealed unit, a litany of loads acts upon it. And while manufacturing, transport, installation, exposure and building pressure can all compromise an IGU's seal integrity, it is the day-to-day atmospheric pressures and temperatures acting on the unit, that take the biggest toll. Among these stresses the radiant heat from the sun is the most destructive.
You may have noticed the most of the failed IGU's are on the sunny side of the building. Why? This is a factor of temperatures pressures and time. When the sun shines on the window, the temperature increases which increases the pressure inside the IGU. In the evening this is reversed as the temperature decreases a negative pressure is exerted on the seals this activity within the IGU this action is called Solar pumping.
"Solar pumping" exploits or creates fissures in the seal that allow air to travel into the IGU. This daily movement of air into the chamber brings moisture with it. Over time this moisture builds up to the point that it becomes visible.