Window Terms

Argon Gas

An odourless, colourless, non toxic gas used to replace air between glass panes to reduce temperature transfer and increase energy efficiency. Argon is not an effective solar performer by itself which is why it is only used in conjunction with Low E insulated glass.

Awning Window

A top hinged window that swings outward for ventilation

Bay Window

A three window combination that projects outward beyond the exterior of the home.

Bow window

An angled combination of four or more windows that projects outward beyond the exterior of the home in a curve.

Casement Window

A side hinged window that opens outward

Divided Lite

A single pane of glass divided by grilles or multiple panes of divided glass in a window.

Double Hung Window

A vertically sliding window with two operable sashes

Fixed Window

A non-operable window that can be used in combination with all other operable windows.


Plastic, wooden or metal assembly placed in or on the exterior of a thermal unit that gives the appearance of divided lites.

Head Jamb

The horizontal top portion of the main frame in a window

Interior Stop

Moulding along the inner edges of a window frame.


The vertical portions of wood frame that surround a window

Laminated glass

Laminated glass is two pieces of glass with a strong plastic layer sandwiched in between. Laminated glass is highly effective in reducing noise and ultraviolet rays that can cause drapes and upholstery to fade. Laminated glass also offers a high level of security.

Low-E (Low Emissivity) Glass

Glass that has a thin layer of metal oxide applied to the exterior face of the interior glazing in a double glazed window. This coating allows the sunlight to pass through, but blocks the heat from escaping. Low-E glazing filters out the suns ultraviolet (UV) rays, which can fade furnishings. It can also reduce condensation on the window by keeping the indoor surface of the glass and frame warmer.


Two or more pre-attached units such as a window combination unit


The vertical or horizontal connecting unit between two windows

Nailing Fin

An extruded attachment for the main frame of a window or brickmould used to secure the unit to the rough opening.


Perfectly vertical; at right angles to horizontal


The horizontal sections of the sash


The opening between the window frame and the side of the wall

Rough Opening

An unfinished opening in the wall into which the window will be installed


The section of the window containing the stiles, rails and glass


A thin often tapered piece of material (as wood, metal, or stone) used to fill in space between things (as for support, leveling, or adjustment of fit)


The supporting horizontal base that forms the bottom of the window frame

Single Hung Window

A window that has one operating and one fixed sash

Sliding Window (Slider)

A window in which the sash moves horizontally along a track.


Description of a true right angle


The vertical pieces of the sash


A component of an operable window, and provides a seal between the window frame and the operable sash.