Glossary of Window Terms
Air Chambers - Small honeycomb spaces within the sash and frame which help to insulate and strengthen the window.
Air Infiltration - 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.
Angled Welding - Shaped windows of angles greater or less than 90 degrees are all fusion welded for strength, weatherseal, and durability.
Aluminium Clad Sill - Heavy extruded aluminum over wood that provides a long lasting, weatherproof sill for StrongArm II Entry Doors.
Arctic Vinyl Threshold - Provides the ultimate long lasting thermal break for both the inswing and outswing sills.
Argon Gas - An odorless, colorless, tasteless, non-toxic gas which is six times denser than air. It is used to replace air between the glass panes to reduce temperature transfer. The optimal spacing for an argon- filled unit is the same as for air, about 1/2 -1 inch.
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.
Balance System - 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.
Bay Window - 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.
Bow Window - 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.
Brickmould - Decorative perimeter or border that encases the entire window and is visible from the outside of the house
Camlock - Locks sash to frame for air tightness and security. (One or two per slider or hung, depending on height or width).
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.
Cladding - An aluminium material 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.
Condensation Resistance Factor - 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.
Conduction - A process of heat transfer whereby heat moves directly through a material by molecule agitation.
Convection - Heat transfer by currents that flow from a warm surface to a colder one.
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.
Double Hung Window - A window that has two operable sash which slide vertically.
Double-strength Glass - Glass with a thickness of approximately 1/8".
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.
ENERGY STAR - Is an independent U.S. government program establishing a standard set of guidelines to recognize the energy efficiency of various products. ENERGY STAR guidelines are used in conjunction with a variety of building materials, including windows and patio doors. Over the past ten years, ENERGY STAR guidelines have helped double the efficiency of windows they endorse.
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. (61/4 or other special widths)
Extended Half Round and Elliptical window - The sides extend to various heights beyond the curvature of the top.
Exterior Glazed - Glass installed from the exterior side of the window.
Finseal Weatherstripping - A brush type weatherstripping that has a plastic mylar fin centered 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.
Fusion Welded Corners (PVC) - Equal to the extruded frame. 100% air and water tight. All frames and sash are constructed in this fashion in automated machines to produce a perfectly square frame every time.
Garden Door - Available two or three-wide, One panel operates as a door while the other panel opens window-style and comes complete with screen. On three-wide units the third panel is fixed.
Glazing - The process of sealing the glass to the sash.
Glazing Stopper - Bar that holds glass inside the frame.
Grills (Muntin bars) - Dividing bars or muntins, used either on the surface or between panes of glass for a decorative appearance.
Glider - An operating style of window that has a sash which slides horizontally to open. Also known as a Slider Window.
Grids - Decorative horizontal or vertical bars installed between the glass panes to create the appearance of the sash being dividing into smaller lites of glass.
Half Round window - True half round where the arch comes right down to the sill. The height is half the width.
Head - The horizontal top portion of the main 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 - A window unit in which the top of the sash swings inward.
I.G. Unit (Insulating Glass Unit) - Today, quality windows are built around what's called an insulated glass (IG) unit. An insulated glass unit starts out as two or three individual panes of glass that are chemically bonded by a sealant to spacer bars. When comparing vinyl replacement windows, always ask about the IG unit. Because not all windows or glass are alike, you should require the highest quality and performance standards.
Jamb - Vertical sections of the main frame.
Integral Nailing Fin - A prepunched fin that is part of the extrusion which allows for easy installation.
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.
Krypton Gas - 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. Used when a higher performance is desired than that produced with Argon gas. Krypton has better thermal performance, but is more expensive to produce. Krypton is particularly useful when the space between glazings must be thinner than normally desired, for example, 1/4-inch. A mixture of krypton and argon gases is also used as a compromise between thermal performance and cost.
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.
Lift Handle - A handhold for raising and lowering the sash. Handle implies that the handhold is not continuous across the sash.
Lift Rail - A handhold for raising and lowering the sash. Rail implies that the handhold is continuous across the sash.
Lite - A unit of glass in a window.
Low E (Emissivity) Glass - Low-emittance (Low-E) coating are thin, metal or metallic oxide layers deposited on a window surface primarily to reduce the U-factor by suppressing the heat flow through the glazed window unit. Coating the inner glass surface with a low-emittance material between the glass layers, blocks a significant amount of this radiant heat transfer, which lowers the heat flow through the window. Low-E coatings are transparent to visible light. Different types of Low-E coatings have been designed to allow for high solar gain, moderate solar gain, or low solar gain. We usually only recommend Low-E for the south side of homes if any in our region where the sun shines throughout the day. One thing to remember is the windows have a slightly tinted appearance.
Low Conductive Gas Filled Units - An improvement that has been made to the insulating performance by the use of argon or krypton gas between the panes of glass. Normally, the space is filled with air or dry nitrogen prior to sealing the window panes together. In a sealed glass insulated window unit, air currents between the two panes of glazing carry heat to the top of the unit and settle into cold pools at the bottom. Filling the space with a less conductive gas minimizes this and the overall transfer of heat between the inside and outside is reduced.
Main Frame - The head, sill and jambs sections of a window.
Mortise - A slot or rectangular cavity cut into a piece of wood to receive another part.
Mortise & 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 - A vertical or horizontal connecting unit between two or more windows.
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.
Obscure Glass - Glass that has been made translucent instead of transparent.
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 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.
Picture Window - A type of window in which a sealed unit is glazed directly into window frame, without a sash.
Peakhead - A window with two equal sides and a peaked top
Polyurethane Core - Doors are foam injected for high insulating value - R15
Rakehead - A triangular window with only 1 side perpendicular to the base
R-value - Resistance a material has to heat flow. The higher the R-value, the greater the resistance, the better the insulation. R-values are the reciprocal of U-values (R-value of 4 is equal to U-value of 0.25)
Radiation - Wave energy transmitted directly from one object to another through the atmosphere or through transparent or translucent materials. The energy radiated is either transmitted, absorbed, reflected or a combination of all three.
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.
Sealant - Hot melt butyl between glass and sash for air and water tight seal every time.
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).
Shading Coefficient - 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 gains.
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 horizontal, bottom section of the main frame.
Sill Track - Snap-in extruded vinyl, covers drain holes and provides platform for sash rollers to roll on.
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 - An operating style of window, with fixed top panel and a lower sash that slides up vertically.
Single-strength Glass - Glass with a thickness of approximately 3/32".
Skylight - A window designed specially for roof installation, usually to provide natural light to interior building areas.
Slider Window - 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.
Solar Heat Gain (SHGC Factor) - 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. Solar Heat Gain indicates the total amount of solar energy that passes through glass relative to a 1/8" (3mm) thick clear glass under the same design conditions. It includes both solar energy transmitted directly plus any absorbed solar energy subsequently re-radiated into the room. Lower values indicate better performance in reducing summer heat gain and, in turn, air conditioning loads. Your average single paned wood framed window has a SHGC of 0.98 whereas a quality replacement window will have ratings from 0.91 - 0.39 depending upon glazing options.
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 - Material placed between two or more pieces of glass in order to maintain a uniform width between the glass, and prevent sealant distortion.
Stile - The vertical sections of the sash.
Stopper - A window component that holds the sealed unit into a frame or sash.
Tempered Glass - Glass with a surface compression of not less than 10,000 psi, or an edge compression of not less than 9,700 psi. When broken, the glass breaks into pebbles instead of shards.
Thermal Break - A space or insulating material used to break highly conductive materials, to reduce heat transfer.
Tilt Latch - Mechanism that unlocks the sash and allows it to tilt in from the main frame.
Total Unit U- and R-values - The U- and R-values of the window calculated from the average U and R-values from the center of glass, edge of glass, and frame.
Transom - A window unit combined to the top of a window or door frame.
Triple pane glass - A sealed unit consisting of three panes of glass separated with two spacer bars.
VT-Visible Light Transmission - The visible transmittance (VT) is an optical property that indicates the amount of visible light transmitted. The VT is a whole window rating and includes the impact of the frame which does not transmit any visible light. While VT theoretically varies between 0 and 1, most values are between 0.3 and 0.8. The higher the VT, the more light is transmitted. A high VT is desirable to maximize daylight.
U-factor - The rate of heat loss is indicated in terms of the U-factor (U-value) of a window assembly. The lower the U-value, the greater a window's resistance to heat flow and the better its insulating value. Winter nighttime U-values are calculated using an outdoor air temperature of 0 degrees F and outdoor air velocity of 15 mph, indoor air temperature of 70 degrees F, and air velocity of 0 mph. This is similar to the R-value that you think of when choosing insulation except a low U-factor is better, unlike R- value which the larger the number the better.
It is calculated as 1 divided by the R-value = U-factor. If you used this calculation R-13 insulation would have a U-factor of 0.077.
To convert U-factor to R-value you take 1 divide by the U-factor. If you used this calculation for the average aluminum framed window with a U-factor of 1.125, your R-value would be 0.89.
Good replacement windows depending upon the glazing options and low conductive gas fills range between 0.5 and .1 for the U-factor.
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.
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