Window Traditions LLC | The Best Views in the Lone Star State.

Window Traditions LLC

office (214) 357-3100
fax (214) 366-7888
Dallas, Texas

Glossary of Terms

A glossary of commonly used window and door terms for your reference.

Air Infiltration
The amount of air that passes between a window sash and frame.
Argon Gas
An inert, nontoxic gas used in insulating glass units to reduce heat transfer.

A mechanical device used in a single and double-hung windows that provides a counterbalancing of the weight of the sash to provide an ease of opening and closing.
Bay Window
An arrangement of three or more window units that project from the building at varying angles.
A narrow strip of wood in which a swinging sash closes.
Bow Window
A composite of four or more window units that projects from the wall in an arc or bow formation.

A window that is fixed or more commonly hinged, to open either outward or inward. In-swing windows are often referred to as French casements. Out-swing windows are known as English casements.
Decorative molding or framing around a window or door.

Double-Hung Window
A window with two movable sashes that slide in a vertical track.
Double-Paned/Insulated Glass
A window pane where two panes of glass are set together to improve insulation.

Fixed Light
A window pane in a non-operating frame.
Fixed Panel
An inoperable panel of a slider window or a sliding glass door.
Fixed Window
A window with no operating sashes.
The installed frame of a window that holds the sash or casement.

Friction Hinge
A type of hinge which allows casement windows to open and stay in place.

The wood surround (top, two sides and the sill) to a window or door that fits into a rough opening in a structure. A sash fits inside the jamb.

Light or Lite
A piece of glass surrounded by wood, a pane. Often used when referring to multiple panes.

Virtually invisible metallic coating used to reflect heat back to its source. It is applied as a thin coating on the inside panes of glass.

The narrow strips of wood between lites.

Operable Panel
A panel which can be opened or closed, therefore operable. Usually used with a fixed panel in the same window or door.

As in window pane, also called a lite.
Parting Bead
A small strip of wood that runs vertically to separate the upper and lower sash of a double-hung window.

Picture Window
A large, fixed window that is usually longer horizontally than vertically to provide a panoramic view.

A horizontal member that fits between vertical members to form a window sash. There is a top and bottom rail on each window sash.

Rough Opening
The dimensions of the opening in a wall into which a door or window is to be installed.

The framework that holds the panes of a window. Consists of a top rail, bottom rail, a stile on each side and muntins if more than one lite.

The horizontal member at the bottom of a window frame.

Simulated Divided Lites or SDL
Muntin bars are permanently adhered to both sides of a piece of glass to give the impression of separate panes.

A window in which the sashes more horizontally.

The vertical members of each side of each sash, joined together by top and bottom rails.

The shelf-like wooden member on the inside of a window commonly referred to as the "window sill".

Thermal Break
Materials used to lessen the transfer of heat from one component to another.
Thermal Expansion
The increase in the dimension or volume of a material due to temperature change.
Tilt Window
A window in which the sash can be tilted inward for cleaning and ventilation.

The horizontal lintel or beam across a window, dividing it into stages or heights. It also can refer to a fixed window over a door or another window.

True Divided Lites or TDL
Sometimes known as Authentic Divided Lites or ADL. When wooden muntins surround individual panes of glass in a sash.

U-Factor or U-Value
Measure of heat flow though a material. The lower the U-Factor, the greater a window’s resistance to heat flow and the better its insulating value is.

Wall of windows