Simplified Window Glossary

Small honeycomb spaces within the sash and frame, which help to insulate and strengthen the window.

The amount of air that passes between a window sash and frame. In windows it is measured in terms of cubic feet or air per minute, per square foot of area. The lower the number, the less air the window lets pass through.

Latch mechanism on the interior face of the sash which retains the window in a partially open position for ventilation.

A sloped extension from the frame that adds an aesthetically-pleasing dimension to the exterior of the window.

An odorless, colorless, tasteless, non-toxic gas which is six times more dense than air. It is used to replace air between the glass panes to reduce temperature transfer.

A top-hinged window that swings outward for ventilation.

An angled combination of three windows that project out from the wall of the home. The windows are commonly joined at 30- or 45-degree angles.

A device for counter balancing a sash of a double hung window to hold it in an up position. There are four basic types:
Block & Tackle - Sometimes referred to as string balance. A type of balance that employs a block and tackle apparatus and coiled spring. This type balance allows the sash to be easily removed from the window frame. A block and tackle balance can normally carry a heavier load than a spiral or friction balance.
Spiral - A balance using a spirally-wound spring.
Spring - A balance using a spring for counter-balancing; introduced in the 1980. Constant Force - A coiled steel tape under spring tension for balancing the sash, located in the head jamb of the window frame.

A series of windows installed in a bay which is two flanker units and a center sash; a bay may be an arc or a polygon; when a bay is or closely approaches an arc, the window is termed a bow.

An angled combination of windows in 3-, 4- or 5-lite configurations. The windows are attached at 10-degree angles to project a more circular, arced appearance.

The mechanisms which pull the sash together when placed in the locked position.

A window with a side-hinged sash that opens outward for ventilation.

A measure of the effectiveness of a window or glazing system to reduce the potential for condensation. The higher the condensation resistance factor, the more efficient the window and glazing system.

Energy transfer from one material to another by direct contact.

Device for holding vertically sliding sash in any desired position through the use of a spring or weight to counterbalance the weight of the sash.

Heat transfer by currents that flow from a warm surface to a colder one.

The space between the panes of glass of an I.G. unit.

A piece of glass or I.G. unit with a sash profile around it; not set within the main frame of a window unit.

A window that has two operable sash which slide vertically.

Glass with a thickness of approximately 1/8"

The code that requires a minimum opening of a window for persons to exit or firefighters to enter a building.

Different from a Rollformed frame, this frame is pressed through a form or die.

The process of joining materials by melting them together with extreme heat (over 500ºF), resulting in the materials uniting into a one-piece unit.

Specially designed windows classified as either Straight line Geometrics such as rectangles, triangles, trapezoid, octagons, pentagons, etc., or Radius Geometrics which include Half-rounds, Quarter-rounds, Circles, Ellipses, Eyebrows, etc.

An inorganic transparent material composed of sand (silica), soda (sodium bicarbonate), and lime (calcium carbonate) with small quantities of alumina, boric or magnesia oxides. Available Styles: clear, bronze tinted and grey tinted.

The process of sealing the glass to the sash.

Strips of profiled wood or vinyl used to hold the glass in position in the sash. Wood glazing bead is attached to the rails and stiles of the sash using staples, small nails or vinyl barbs. A vinyl bead is held in place by extruded barbs positioned in the kerf. Aluminum caps may be used over the vinyl bead in some cases.

Decorative horizontal or vertical bars installed between the glass panes to create the appearance of the sash being dividing into smaller lites of glass.

The horizontal top portion of the main frame.

A window with a bottom-hinged sash that opens inward for ventilation.

Two or more lites of glass separated by a spacer and hermetically sealed at the glass edges.

Integral extension on the outside of a new construction window that eases installation on siding applications.

Vertical sections of the main frame.

The horizontal section of the sash where the keeper is attached.

The vertical section of the sash where the keeper is attached.

An inert, odorless, colorless, tasteless, non-toxic gas which is about 12 times denser than air. It is used to replace air between the glass panes to reduce temperature transfer and deter convection.

Specially designed glass where two panes of glass are bonded to a durable interlayer, providing increased safety, UV protection and noise reduction. If the window or door gets broken the glass will adhere to the to the plastic interlayer-preventing glass fallout in the home.

A handhold for raising and lowering the sash. Handle implies that the handhold is not continuous across the sash.

A handhold for raising and lowering the sash. Rail implies that the handhold is continuous across the sash.

A unit of glass in a window.

The horizontal section of the sash where the cam lock is attached.

The vertical section of the sash where the cam lock is attached.

Glass with a transparent metallic oxide coating applied onto or into a glass surface. The coating allows short-wave energy to pass through but reflects long-wave infrared energy which improves the U-value.

The head, sill and jambs sections of a window.

Refers to frames fastened with screws.

The horizontal sections of a pair of sash that meet when the sash are closed.

The vertical section of a pair of sash that meet when the sash are closed.

Fabric made of either fiberglass or aluminum, used in the making of screens.

A vertical or horizontal connecting unit between two or more windows.

An extrusion attached to the main frame of a window used to secure the unit to the rough opening.

Glass that has been made translucent instead of transparent.

A window with the meeting rail located off center of the frame. Most oriels have a 60/40 configuration.

A glass door that slides open and close on adjustable tandem rollers. Available in 2- or 3-lite configurations with the operable panel available in any position.

A window that has no moveable sash.

A handhold for sliding the sash back and forth. Handle implies that the handhold is not continuous across the sash.

A handhold for sliding the sash back and forth. Rail implies that the handhold is continuous across the sash.

A handhold for sliding the sash back and forth. Stile implies that the handhold is continuous across the sash.

Lineal profiles of constant cross section manufactured by combining plastic resin and continuous glass fiber reinforcement. These thermally insulating and structural components are ideally suited for applications where strength, thermal stability and weather resistance are required, such as in patio door frames and commercial windows.

Resistance a material has to heat flow. The higher the R-value, the greater the resistance.

The horizontal sections of the sash.

An angled extension from the frame that adds an aesthetically pleasing dimension to the exterior of the window.

The relative humidity level at which visible water vapor or other liquid vapor begins to form on the surface of the sash or frame, based on an inside temperature of 70° F and an outside temperature of 0° F. The higher the percentage, the more moisture the air can hold before condensation will occur.

A method of fabrication in which a flat (usually metal) material is placed on a machine where the material is formed into shape using differently shaped rollers and pressure.

The part of the window which contains the glass.

The ratio of solar heat that is transferred through a glazing material relative to the solar heat transferred through 1/8" clear glass. The lower the number the more efficient the window is at reducing solar heat gain.

The horizontal, bottom section of the main frame.

A window in which one sash slides vertically and the other sash is fixed.

Glass with a thickness of approximately 3/32".

A window in which the sash move horizontally. Sliders are available in a 2- or 3-lite configuration, with the 3-lite having operable end vents.

The sill of the window that has a downward slope to the outside. This sill has sufficient degree of slope to aid in water runoff.

The percentage of heat gained from both direct sunlight and absorbed heat. The smaller the number, the greater the ability to reduce solar heat gain.

Material placed between two or more pieces of glass in order to maintain a uniform width between the glass, and prevent sealant distortion.

The vertical sections of the sash.

An extrusion used in stucco home installations that is attached to the main frame to create a smooth, finished look for both the window and the stucco.

Two-sided tape used to secure and seal the glass to the sash.

Float glass panels heated and then cooled rapidly in a controlled environment. This process makes the glass several times stronger than regular glass. It also makes it safer because when broken it yields small pebble-like fragments.

Mechanism that unlocks the sash and allows it to tilt in from the main frame.

A sash that can be tilted to the interior and removed for cleaning and is manufactured by welding.

A window above a window or door. Transoms can be either stationary or operating.

Amount of heat transferred through a material. The lower the U-value, the slower the rate of heat flow and the better the insulating quality.

The percent of ultraviolet rays blocked from being transmitted through the glass. The higher the number the lower the percentage of ultraviolet rays transmitted through the window.

The percentage of light that is transmitted through glass in the visible light spectrum (380 to 720 nanometers). The higher the number the higher the percentage of visible light transmitted through the window.

Material used to form a weather-resistant seal around operable sash.

Slots or holes in the sill (bottom) member of the sash frame that allows water to escape. Weep flaps add a vinyl flap to keep insects out.

The letters OX or XO identify the operation of window or door units as viewed from the exterior. The letter O stands for stationary while the letter X stands for operating.