Glossary of Terms

The glossary below will help you understand some of the window and door terminology used in the industry

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, inert gas which 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, normal spring loaded, used in hung windows to counterbalance the width of the sash during opening and closing.

Bay Window - A three-unit combination window consisting of central picture or fixed window and flanked by a pair 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 4 or more window units attached at an angle to give an impression of a curve.

Camlocks – Locks sash to frame for air tightness and security. (One or two per casement, depending on height; two per awning).

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, thickness 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.

Centre of Glass Area (COG) - The central area of a sealed unit making up 80 % of the glass area.

Cladding – An aluminium material locked to the outside faces of many products to provide a durable, low-maintenance exterior surface.

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 or Flashing - A molding 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, performed, resilient gasket, without the use of a glazing component.

Dual Pane – An insulated glass unit consisting of two panes of glass held together by a sealant and a spacer bar.

Egress - The space in which the operating part of the window requires clearance for fire regulations.

Elliptical Window – Curved top window which does not form a half circle since the curvature is less. Nor does the arch 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.

Extended Half Round and Elliptical Window – The sides extend to various heights beyond the curvature of the top.

Extension Jambs - Flat wood or PVC 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. (6 ½” or other special widths)

Exterior Glazed – Glass installed from the exterior side of the window.

Finseal Weatherstripping – A brush type weatherstripping that has a plastic mylar fin centred in the pile. Mainly used with sliders.

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.

Flushbolts and Astrigal - Where a double door is desired that will have no restricting post when both doors are open. This movable, weather-
stripped post is attached to one door and locked to the head and sill with flush bolts.

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 – Hinged door available in one, two, three, or four-wide combinations with up to two panels operating.

Glazing Stop – Used to hold the glass into the frame.

Glider – An operating style of window that has a sash which slides horizontally to open.

Grilles (Muntin bars) – 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.

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.

Interior Glazed – Glass installed from the interior of the building.

Interlocking Mullion and Sash – Where the sash joins the centre of the fixed mullion the two are drawn together by a beveled interlock that is double weather-stripped.

Jamb – The side components of a window or door frame.

Jamb Wrap (painted metal) - Applied on the jamb between the Brickmould and weatherstrip of a door frame.

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.

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.

Mullion Cover – An extrusion that joins panning perimeter legs that extend over existing mullions.

Multi-lock – One cam lock lever at the bottom operates multiple locking points to secure the sash to the frame.

Nailing Fin – A vinyl or metal flange integrated into (or 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. Available in two, 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 high insulating value – R15
R-Value – A term used to express the insulating values of a material or unit. A higher R-value results in a better insulating properties. R-value is the inverse of the materials U-value. (R=1/U).
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 a 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 (Vertical) - An operating style of window, with fixed top panel and a lower sash that slides up vertically.
Skylight – A window designed specially for roof installation, usually to provide natural light to interior building areas.
Slider – A type of window with one fixed sash, and one or two that slides sideways. Also known as a glider.
Solar Heat Gain Coefficient (SHGC) -The measure of how much solar heat gain energy a glass combination will allow to pass through. A higher SHGC allows more potential solar heat gain than a lower SHGC. (See SunStopä)
Solar Transmittance – The percentage of total solar energy that glazing transmits through a window.
Sound Transmission Class (STC) – A rating measure for 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.
Tripane – A sealed unit consisting of three panes of glass separated with two spacer bars.
U-Value – A measurement of heat transmission.(See R-Value)
Visible Light Transmittance - Is 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.