Glossary

Argon

An inert, colourless, and harmless gas used instead of air in sealed spaces between panes of glass in insulating glass units to increase insulation. Argon is less conductive to heat than air. It is injected in the airspace of an insulating unit, to improve energy efficiency

Awning window

Practical and attractive, awning windows improve air movement while protecting your room from the elements. Hinged at the top and opening outward with a durable handle, they’re often placed above or below other windows, or above doors for increased ventilation and light

Balance

A mechanical device used in vertically operating windows that counter-balances the weight of the sash during opening and closing

Bay window

A composite of three windows, usually made up of a large center unit and two flanking units at 30 or 45 degree angles to the wall.

Bow window

A composite of four or more widow units in a radial or bow formation.

Brickmold

A type of external casing which frames windows and doors.

Casement window

 A type of window with a side-hinged sash that opens like a door – the best window for catching breezes and crosswinds. The sash are usually operated by means of roto-operators or a handles

Casing

Molding of various widths, thicknesses and shapes applied to the framework of window and door units.

Circlehead

A generic term referring to any of a variety of window units with one or more curved frame members, often used over another window or door opening.

Cladding

The application of one material over another to provide a skin or layer intended to control the infiltration of weather elements, or for aesthetic purposes.

Clerestory window

A venting or fixed window above other windows or doors on an upper outside wall of a room.

Cottage double-hung

A double-hung window in which the upper sash is shorter than the lower sash.

Dormer

A space which protrudes from the roof of a house, usually including one or more windows.

Double glazing

 Double glazing is the glazing process in which a window is formed by two panes of glass with a space between the panes. The space between the glass is usually ½”- ¾”thick. Air is trapped between the panes of glass and forms a layer of insulation

Drip cap

A molding placed on the top of the head brickmold or casing of a window frame.

Fenestration

The placement and arrangement of the windows and doors of a building. From the Latin word, "fenestra," meaning window

Finger-jointing

A means of joining individual pieces of wood together to form longer lengths. The ends of the pieces are machined to form a set of interlocking fingers, which are then coated with adhesive and meshed together under pressure.

Fixed window

Non-opening portion of a window.

Flashing

 Window flashing is material installed around windows designed to prevent water from entering between gaps in adjoining building surfaces.

Glazing

Glass in a window or door; the act or process of fitting with glass.

Glazing bead

 A molding or stop along the inside perimeter of the frame that assists in holding glass in place

Head

The main horizontal member forming the top of the window or door frame.

Header

A horizontal framing member placed over the rough opening of a window to prevent the weight of wall or roof from resting on the window frame.

Horizontal Sliding Window

A window where the movable panels slide horizontally.

Hopper

A window unit in which the top of the sash swings inward.

Insulating glass (IG)

Refers to two or more pieces of glass spaced apart and sealed to form a single-glazed unit with an air space between. Heat transmission through this type of glass may be as low as half that without such an air space. This space may or may not be filled with an inert gas, such as argon.

Jamb

The main vertical members forming the sides of a window or door frame.

Laminated Glass

Two or more sheets of glass with an inner layer of transparent plastic to which the glass adheres if broken. This process produces glass four times more impact resistant than non-tempered glass. Used for safety glazing and sound reduction.

Light

A separately framed piece of glass in a window or door. A traditional double-hung window, for instance, often has several lights divided by muntins in each sash. Such windows are described as six-over-six, eight-over-one, twelve-over-twelve, etc., to indicate the number of lights in each sash. Sometimes spelled 'lite'.

Low-emissivity (Low-E) glass

A special type of glass having a transparent material fused into its surface which acts as a thermal mirror.

Mullion

A wood or metal part used to structurally join two window or door units.

Muntin

Applies to any short or light bar, either vertical or horizontal, used to separate glass in a sash into multiple lights. Also called a window pane divider or a grille.

Nailing Fin

 An integral extension of a window frame which generally laps over the conventional stud construction and through which nails are driven to secure the frame in place

Palladium window

A large, arch-top window flanked by smaller windows on each side.

Rail

The top and bottom horizontal members of the framework of a window sash.

RainScreen Wall System

This system is a form of double-wall construction that uses an outer layer to keep out the rain and an inner layer to provide thermal insulation, prevent excessive air leakage and carry wind loading. The outer layer breathes like a skin while the inner layer reduces energy losses. The structural frame of the building is kept absolutely dry, as water never reaches it or the thermal insulation. Evaporation and drainage in the cavity removes water that penetrates between panel joints.

Roto-operator

A window opening device that has a handle to crank open a window

Rough opening

The framed opening in a wall into which a window or door unit is to be installed.

R-Value

Resistance to thermal transfer or heat flow. Higher R-value numbers indicate greater insulating value.

Sash

The portion of a window which includes the glass and the framing sections which are directly attached to the glass. Normally the moving segment of a window, although sash are sometimes fixed. Not to be confused with the main frame into which the sash sections are fitted.

Sidelights

Narrow fixed units mulled or joined to door units to give a more open appearance.

Sill

The main horizontal member forming the bottom of the frame of a window or door.

Simulated divided light

A method of constructing windows in which muntins are affixed to the inside and outside of a panel of insulating glass to simulate the look of true divided light.

Single glazing

Use of single panes of glass in a window. Not as energy-efficient as double glazing.

Spacers

In glazing, small blocks of neoprene, nylon, or other material placed on both sides of the edges of glass, during its installation, to center it in the glazing channel to maintain uniform width of sealant bands and prevent excessive sealant distortion under lateral loading

Single-hung

Vertically operating windows in which the sash weight is offset by a counterbalancing mechanism mounted in the window. The single hung window features a stationary top and a movable bottom half.

Stile

The main vertical members of the framework of a sash.

Stool

An interior trim piece on a window which extends the sill and acts as a narrow shelf.

Stop

A molding used to hold, position or separate window parts.

Tempered glass

The glass is reheated to right below the melting point then suddenly cooled. When shattered, it breaks into small pieces. It is approximately five times stronger than standard annealed glass. It cannot be re-cut after tempering.

Thermal break

The addition of a thermal insulating material between two thermally conductive materials.

Transom

A small window that fits over the top of a door or window, primarily for additional light and aesthetic value.

True divided light

A term which refers to windows in which multiple individual panes of glass or lights are assembled in the sash using muntins.

U-value

Rate of heat flow-value through the complete heat barrier, from room air to outside air. The lower the U-value, the better the insulating value.

Vent Unit

A window or door unit that opens or operates.

Vinyl

A plastic material used for cladding of entire window units.

Weatherstripping

A material or device used to seal the openings, gaps or cracks of venting window and door units to prevent water and air infiltration.

Windload

Force exerted on a surface by moving air.