Glossary
Air Infiltration – The amount of air leaking in and out of a building through cracks in walls, windows and doors.
Airspace – This is a component placed at the perimeter of an insulting glass unit to separate lites – or single panes – of glass.
Aluminum Clad Window – A wood window covered with extruded aluminum to provide a durable, easy to maintain seal.
Argon – An inert, non-toxic gas used to insulate glass against the cold, and to reduce heat transfer to and from the interior of a home or building.
Astragal – An interior moulding attached to one of a pair of doors, or side-hinged windows to prevent swing. Astragal is also used on sliding doors to create a tight fit where the doors meet.
Awning Window – A top-hinged sash window that swings outwards from the bottom.
Balance – A spring loaded device used to counter-balance the sash of a hung window, thereby holding it in the ‘up’ position.
Bay Window – A three-window combination that projects out from a wall. Typically, bay windows feature a large center window with two flanking units, and are usually built at a 30 or 45 degree angle.
Bow Window – A combination window that projects out of the exterior, usually with four or more windows in a radial or bow formation.
Brickmould – A decorative border that runs along the entire perimeter of a window and is visible on the exterior.
Cam Locks – The hardware that locks the sash to the frame of the window.
Casement Window – A window with a side-hinge sash that swings outwards from one side.
Casing – Exposed moulding or framing around a window or door used to cover the space between the window frame or jamb and the wall. Casing is available in a variety of shapes and sizes.
Caulking – A compound used for filling joints and sealing cracks to prevent leakage of water and air.
Combination Window – A combination of two or more complete windows attached together to add architectural appeal to a home.
Condensation – Moisture that forms on glass surfaces due to cold temperatures, high humidity, or poor air flow. Please read our Maintenance Guide for more information.
Dew Point Temperature – The temperature at which water vapour in the air starts to condense in the form of liquid, or as frost.
Dual Pane – An insulted glass unit, comprised to two panes of glass built together using a sealant and a spacer bar.
Egress – This refers to the size of open space in certain windows. To be safe, the egress must be large enough for a person to climb through in an emergency.
Extrusion – A process by which a heated material is forced through a die to produce aluminum, PVC and other profiles or components used in the production of windows and doors.
Finger-joint – A toothed joint used to connect two pieces of wood end to end.
Fixed Sash Window – A picture window with an non-operable sash used to create matching sightlines in a operable window.
Flashing – Sheet metal used during the window installation process to facilitate water drainage, and to prevent water from leaking into a home or building.
Glazing – The installation of glass in a window opening.
Glazing Stop - A removable trim that holds the glass in place.
Grilles (Muntin Bars) – Dividing bars inserted between panes of glass to add a decorative flair.
Header – A supporting member or beam above a window opening used to shift the weight of the building to the supporting walls on each side of a window. The term “header” generally refers to a wood beam. A “lintel” is a steel beam.
Hinge – A movable joint that enables a window to swing open.
Inside Casing (Interior Trim) - The inside visible moulding that surrounds the interior of the window frame.
Jamb Extension – A board (wood or PVC) used to increase the depth of window frame jambs to fit any thicknesses of wall.
Lite – A single pane of glass.
Low-Emissivity Coating (Low-E) – Coating for glass surfaces that reflects radiant heat energy away from the glass. The lower the emissivity of the glass, the lower the heat transfer co-efficient.
Nailing Fin - A pre-punched fin that is part of the extrusion which allows for easy installation.
Natural Convection – A heat transfer process involving motion in a fluid (such as air) caused by difference in density of the fluid and the action of gravity. This is an important part of heat transfer from the glass surface to room air.
Obscure Glass - Any textured glass (frosted, etched, fluted, ground, etc.) used for privacy, light diffusion or decoration.
Operator – Crank-operated device for opening and closing casement awning windows.
Pane – A sheet of glass used for glazing a window. After installation, the pane is referred to as a lite.
Picture Window – A non-operational window without a sash.
PVC (Polyvinylchloride) – An extruded or moulded plastic material used for window framing. Also known as “vinyl.”
Relative Humidity – Weight of water vapour in air divided by the weight of water vapour in completely saturated air at the same temperature, expressed as a percentage.
Rough Opening – The framed opening in a wall into which a window or door is to be installed.
R-Value (Thermal Resistance) – A measure of resistance to heat flow of a material or construction; a higher value indicates a better heat insulating property. The R-value of an ordinary single-pane sash with a 15 mph wind on one side is approximately 0.9.
Sash – A sub-frame component that surrounds a sealed unit. A sash can be operational or fixed.
Screen – A close-mesh woven screening material of metal, plastic or fibreglass used to block out insects and debris, while allowing light and fresh air into a home or building.
Sealant – A compressible plastic material used to seal any opening or junction of two parts, such as between glass and a metal sash. It is usually made of silicone, butyl tape or polysulfide.
Sealed Unit – A combination of two or more lutes of glass separated by a sealed space.
Sidelite – An often narrow window unit jointed to the side of a door frame.
Silicone – An enduring sealing agent that resists water.
Sill – The horizontal members at the bottom of the window or door frame.
Simulated Divided Lites – A decorative bar mounted on the exterior and interior of a sealed window unit, giving the illusion of multiple sealed units.
Single Hung Window – A window where the top portion is stationary and the bottom sash moves up and down.
Super Spacer – The linear object that separates and maintains the space between the glass surfaces of sealed units.
Single Strength Glass – Glass with thickness between 0.085 to 0.100" (2.16 mm to 2.57 mm).
Stained Glass Window – A window with a painted scene or pattern that has been fired into the glass. Windows with plain coloured glass set in lead are also called stained glass.
Thermal Resistance (R-value) – A property of a substance or construction which slows the flow of heat; one measure of this property is R-value.
Transom – A window set in the top of a window or door.
Triple Glazing – Three panes of glass with two air spaces between.
Vinyl – See PVC.
Weather Strip – A strip of resilient material used to cover the joint between the window sash and frame to reduce air leaks and prevent water from entering the structure.