There are a number of resources online that discuss exterior condensation on the surface of a High Performance Window or Door. Exterior Condensation is not considered a product or glass seal failure. However, if you have condensation between the panes of glass in an insulated glass unit, this is a failure.
When condensation builds up on the exterior pane of glass, which is refereed to as Surface #1 in the glass industry, it is likely caused by moisture in the exterior air in relation to the surface temperature of the glass surface.
Condensation on the exterior surface normally occurs during the following conditions:
- Glass temperature is below the dew-point
- Clear sky with little air movement
- High relative humidity
- Well insulating, high performing glazing.
Below are a couple links to online documents that further explain exterior condensation.
Fleetwood Windows and Doors: Condensation Information Sheet
Marvin Windows and Doors: Condensation Information
Cardinal Glass, Residential Glass Brochure (Refer to page 17)
