Window Components Terminology

Search our window components terminology section and explore glossary terms related to window parts and features. The following is 1 of 4 pages on our section dealing with definitions and terminology.

Window Components Terminology | Parts And Features

Air Space
In double or triple glazed windows, this is the space that exists between the panes, which is filled with air for added insulation. Some windows replace the air in this space with gas for its increased insulative properties.

Argon Gas
A type of gas that is used to replace the air in double or triple glazed windows to increase the energy efficiency of the window by decreasing the amount of heat loss.

Balance System
A series of springs and/or weights placed within the sides of window frame that function to balance the weight of the sash so it remains in place when opened.

Center Hung Sash
A sash that is hung or mounted on pivot pins in the center of the window so the sash can be pivoted open in order for easy cleaning.

A material that absorbs moisture and may be used between insulated glass panes in multi-glazed windows.

Electrochromic Glazing
A special type of laminated glazing, or coating, that can be switched from tinted to clear and back again. This can reduce the amount of heat gain a window experiences, and can also increase privacy (when tinted).

Evacuated Glazing
Glazing within double or triple glazed windows that is vacuum sealed between the panes.

The fixed part of the window (the perimeter) within which the sash or panes of glass are mounted.

Glazing Bead
A strip that holds the edges of a pane within the frame. This strip is removable and is typically made from wood or plastic.

The frame along the top of the window. Also called the ‘header.’

Head Expander
U-shaped filler (usually made of vinyl) on the head.

Heat Treated Glass
These have been strengthened by being treated with heat, also known as heat strengthened or fully tempered.

Hermetically Sealed Glass
Double or triple panes that are vacuum sealed in order to prevent the escape of air or gas within and to avoid the introduction of moisture.

The frame members on each vertical side of a window (similar to the ‘head’ which is the frame member on the top of the window).

Additional Window Terms

Krypton Gas
A type of gas that is sometimes used to replace air in the space between double and triple glazed windows to reduce heat transfer.

Laminated Glass
This includes a layer of plastic nestled between the multiple panes to improve impact resistance. Often used in hurricane or high wind prone areas.

Individual panes/frame sections within a larger window pane.

Main Frame
The main parts of a window frame (the jambs (sides), head (top) and sill (bottom)).

Meeting Rail
Horizontal rails of two opposing window sashes that meet when the window is closed.

Obscure Glass
Translucent panes that comes in different patterns and is intended to provide added decoration, light diffusion or privacy.

Diamond shaped panes within a larger window pane, such as is found in Gothic styles.

The horizontal member of a sash on the top or bottom.

Rough Opening
The opening in the wall in which a window is mounted.

The part of the window that contains the panes of glass. It can be fixed to the frame or can be movable.

The horizontal shelf that sits along the bottom interior of a window frame.

Tempered Glass
A process by which the pane is heated to improve its strength and safety. When a pane breaks, it breaks into small square-ish pieces, rather than sharp shards.

True Divided Light
Windows made of multiple, small panes that are connected to one another with the use of muntins to create a larger sash.

A window sash that provides ventilation by swinging open.

Vinyl or Polyvinyl Chloride (PVC)
A popular material used in the construction of vinyl windows.

Weep Hole
Small holes in the exterior sill that encourages water to drain.

Related Topics

Construction Terms
Frame Concepts
Installation Terminology