Air infiltration – The amount of air leaking in and out of a building through cracks in walls, windows, and doors.
Argon – A colourless, odourless, non-flammable, non-reactive, insert gas that acts as an insulator between the panes of glass in a sealed unit.
Astragal – The center member of a double door, which is attached to the fixed or inactive door panel.
Awning window – An operating style of window with a sash hinged on the sides, and swings open at the bottom towards the exterior.
Balance – A mechanical device, normally spring loaded, used in hung windows to counterbalance the weight of the sash during opening and closing.
Bay window – A three-unit combination window consisting of a central picture or fixed window and flanked by a pair of windows set at an angle (usually 45o).
Brickmould – Decorative perimeter or border that encases the entire window and is visible from the outside of the house.
Bow window – A type of window consisting of four or more window units attached at an angle to give the impression of a curve.
Casement window – An operating style of window with a side-hinged sash that opens from the side towards the exterior.
Casing – Molding of various widths, thicknesses and shapes applied to the framework of window and door units.
Caulking – A sealant used to seal construction joints, in order to prevent water and air infiltration.
Cladding – A material—usually aluminum—locked to the outside faces of many products to provide a durable, low-maintenance exterior surface.
Combination window – A combination of two or more complete window assemblies of the same or different types that are mulled together.
Condensation – Moisture formation on surfaces due to cold temperatures, high humidity levels and poor air flow.
Conduction – A process of heat transfer whereby heat moves directly through a material by molecule agitation.
Dew point – The temperature at which water vapour will condense as warm, moist air is cooled.
Double hung window – An operating style of window with an upper sash that slides down and a lower sash that slides up.
Drip cap – A moulding placed on the top of the head brickmould or casing of a window frame.
Dry glazing – A method of securing glass in a window frame with a dry, preformed, resilient gasket, without the use of a glazing component.
Double pane (Double glazed) – An insulated glass unit consisting of two panes of glass held together by a sealant and a spacer bar.
Edge of glass – The area within 10 cm (2.5 in) of the edge surrounding the perimeter of the glass.
Egress – The space in which the operating part of the window requires clearance for fire regulations.
Elliptical window – Curved top window that does not form a half circle, since the curvature is less. The arch doesn’t come down to the sill, but meets with vertical sides.
Emissivity – The rate at which a surface of a material radiates long-wave heat energy, usually referring to glass surface properties. Low emissivity results in less overall heat loss.
Extension jambs – Flat wood or vinyl parts that are applied to the inside of the frame to extend it in width, which allows the frame to adapt to a thicker wall.
Exterior glazed – Glass installed from the exterior side of the window.
Fixed unit – A stationary window or door unit that does not open.
Flashing – A thin strip of metal or synthetic material that diverts water away from a window or skylight.
Frame – The enclosing box of a window or door that surrounds a sash or sealed unit, consisting of a head, sill and two jambs.
French door (Garden door) – A hinged door often available in one, two, three, or four-wide combinations with some fixed and some operating panels.
Garden door (French door) – A hinged door often available in one, two, three, or four-wide combinations with some fixed and some operating panels.
Glazing (1) – The generic term for the transparent, or sometimes translucent, material in a window or a door. It is most often glass.
Glazing/glazed (2) – The process of installing a sealed unit into a frame or sash using stops. Also refers to the type of glass used to make the sealed unit.
Glazing stop – Used to hold the glass into the frame.
Glider window (Slider) – An operating style of window that has a sash that slides horizontally to open.
Grille (Muntin bar) – Dividing bars or muntins used either on the surface or between panes of glass for a decorative appearance.
Half round window – True half round where the arch comes right down to the sill. The height is half the width.
Head – The top portion of a window or door frame.
Head and seat – Attached to the top and bottom of a bay or bow window as an option where the wall is not framed to follow the angle of the window.
Hopper window – A window unit in which the top of the sash swings inward.
Inside casing (Trim) – The moldings that surround the window and cover the frame on inside of the building.
Insulating glass unit (IG or IGU) – A combination of two or more panes of glass factory sealed using a spacer bar. Also known as a sealed unit.
Integral nailing fin – A pre-punched fin that is part of the extrusion, allowing for easy installation.
Interior glazed – Glass installed from the interior of the building.
Jamb – The side components of a window or door frame.
Jamb wrap – Applied on the jamb between the brickmould and weatherstrip of a door frame. It is usually painted metal.
Krypton gas – A rare atmospheric gas that is odorless, colorless, tasteless, nontoxic, monatomic and chemically inert. It is a better insulator than even argon gas.
Lite – Single pane of glass.
Low-E glass – A type of glass consisting of a low emissivity coating on one side. A low emissivity coating significantly reduces heat loss in glazing combinations.
Mortise – A slot or rectangular cavity cut into a piece of wood to receive another part.
Mortise and tenon joint – Used at the corner of a wood sash to give strength and prevent sagging. Glued and machine squared for perfect fit in frame.
Mullion – An extrusion that joins windows. A sealant is applied between the units to prevent air and water leakage. A bullnose or profiled moulding is used on the inside and outside to cover this joint.
Multi-lock – One cam lock lever at the bottom operates multiple locking points to secure the sash to the frame.
Muntin bar (Grille) – Dividing bars or muntins used either on the surface or between panes of glass for a decorative appearance.
Nailing fin – A vinyl or metal flange attached to the perimeter of a window frame for insulation onto the rough opening header, jack studs and rough sill.
Operator – Refers to a door or a window that has an operable sash or panel that opens to allow passage or ventilation.
Patio door – A sliding door comprising of a panel fitted with an insulated sealed unit, with one operating panel sliding horizontally to provide passage. Sometimes available in three- and four-wide units.
Picture window – A type of window in which a sealed unit is glazed directly into window frame, without a sash.
Polyurethane core – Doors are foam injected for higher insulating value.
R-value – A term used to express the insulating values of a material or unit. A higher R-value indicates better insulating properties.
Reinforced steel – Comes in flat or tubular form that is completely enclosed in the vinyl frame for very large window combinations to structurally enhance the window.
Relative humidity – Humidity expressed as a percentage of the maximum possible humidity at a given temperature.
Rough opening – The opening built into a frame wall to receive a window or door unit.
Sash – A sub-frame component that surrounds a sealed unit. A sash can be either fixed (non-operating) or operating.
Sash balance – A coiled spring or spiral system integrated into the jamb liners to allow double hung or single hung sashes to open and close.
Sealed unit – A combination of two or more panes of glass factory sealed using a spacer bar. Also known as an insulating glass unit (IGU).
Shims – Rubber setting blocks used to position the glass into the window to ensure it is level, square and plumb.
Sidelite – A narrow fixed or operating unit joined to the side of a door frame combination.
Sill – The bottom component of a door or window frame.
Simulated dividing lites (SDL) – A decorative bar mounted on the exterior and interior of a sealed unit to provide the visual affect of dividing the glass into smaller units.
Single hung window – < An operating style of window with a fixed top panel and a lower sash that slides up vertically.
Skylight – A window designed for roof installation, usually to provide natural light to interior building areas.
Slider window (Glider) – A type of window with one fixed sash and one or two units that slide sideways.
Solar heat gain coefficient – A measurement of how much solar energy a glass combination will allow to pass through. A higher coefficient allows more potential solar heat gain than a lower coefficient.
Solar transmittance – The percentage of total solar energy that glazing transmits through a window.
Sound transmission class – Rates the ability of glazing to block out sound from outside sources.
Spacer bar – The strip of material that maintains uniform separation between the layers of glass in the sealed unit of the window.
Stops – A window component that holds the sealed unit into a frame or sash.
Thermal break – A space or insulating material used to break highly conductive materials, to reduce heat transfer.
Transom – A window unit combined to the top of a window or door frame.
Triple pane (Triple glazed)- A sealed unit consisting of three panes of glass separated by two spacer bars.
U-value – A measurement of heat transmission.
Visible light transmittance – The percentage of visible light that is transmitted through a glazing combination. The type of sealed unit, coatings and tints will affect the percentage of visible light transmittance.
Weather stripping – A material used to create an air or water seal between operating components of a window or door.
Wind load – The amount of pressure exerted by the wind on a window or door generally expressed in pounds per square foot.