Glossary - I

A Glossary of window terminology

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Insulating glass Unit (IGU)

A combination of two or more panes of glass with a hermetically sealed air space between the panes of glass. This space may or may not be filled with an inert gas, such as argon. 

Integral Light Technology™

The technology developed by Pella which incorporates a foam grid between the panes of insulating glass. Muntins (grilles) are then permanently bonded to the interior and exterior pieces of glass. Provides the look of True Divided Light with the performance of insulating glass.

Insulating air chambers
Various chambers within the sash and masterframe, which help to insulate and strengthen the window.

IntegraWeld
The fusion-welding process of some Alside windows.

Inner Casing
An entrance member that fits over the outside edges of the side and head jambs, thereby providing a base for the pilasters; an entrance casing nearest to the opening that provides a base for the pilasters.  

Inner Frame
On a panel door, the intermediate panel member between the stile and door panel that accentuates the sticking of the door.  

Interior Casing
A casing that trims the interior of window and door frames.  

Intermediate Rail
A rail of a door located between the top and bottom rails.