Glossary
Air Leakage
An energy performance rating that measures the rate of which air moves through the fenestration system as the result of a pressure difference across the product. AL is expressed in cubic feet of air passing through a square foot of window area. The lower the AL, the less air will pass through cracks in the product. AL generally varies most by operator types within a single manufacturer's product line, with sliding units generally having a higher leakage rate than casement or awning windows with compression seals. AL generally has a smaller energy impact than U-factor and SHGC, but houses in windy of very harsh climate conditions may benefit from very low air leakage numbers. AL values may also change with time due to physical wear which changes the properties of the seals.
Air Space
The air space is the distance between the panes of glass in a sealed unit. The air space cavity is filled with an inert gas, like air or argon gas fills.
Argon Gas Fill
Argon is a colourless, odorless, nonflammable, non-reactive, inert gas. Argon gas fills are used to reduce heat loss in sealed units by slowing down convection in the air space. Argon gas is very cost efficient, and works in unison with Low E coated glazing.
Awning
A window similar to a casement except the sash is hinged at the top and always swings out.
Awning Sash
A frame in which the panes of a window are set. The frame is built in such a way that the bottom swings outward in a window frame.
Awning Window Unit
A combination of a frame, one or more awning sashes, weather-strip and an operating device assembled as a complete and properly operating unit; screens and/or storm sash are optional; the unit may contain one or more fixed or non-operative sashes in combination with the operative sash.
Awning Window
An operating style of window that uses a sash hinged on the sides that swings open at the bottom towards the exterior. Awning operators are especially suited for rooms that require a venting unit, even during rain or snow, like washrooms and kitchens.
Bay
A three (3) lite bay window using 45 or 90 degree angles.
Bay Window
A bay window is made up of three or more windows. The side or flanker units project out from the building, typically in 30, 45, or 90 degree angles. The center is parallel with the building wall and is made up of one or more windows. All the units can be stationary, operating, or any combination thereof.
Bench
A bay or bow with head and seat.
Brickmould
Outside casing around window to cover flanges.
Bottom Rail
A horizontal rail at the bottom of a sash or door.
Bow Window
A series of four or more adjoining window units, commonly five in number, installed on a radius (typically at 11-15?angles) from the wall of the building. Windows can be either operable or stationary.
Casement
A window sash that swings open on side hinges.
Casement Window
Casements are operating windows that have a sash hinged at the top and bottom which swings open at the side towards the exterior (like a door) to create a venting unit. Casement operators provide the most venting of all the operating windows, and are easy to clean from the inside of the room. Historically, casements were the first working windows. These windows were strategically placed throughout a house to capture breezes and direct them through the rooms. Screens were placed internally to prevent bugs and dirt from entering the house.
Casement Sash Unit
A combination of frame, casement sash, weather-strip and operating device assembled as a complete and properly operating unit; screens are optional.
Cladding
Aluminum material forms the exterior finish and is attached to the outside of a window creating a more durable, long-lasting window. Cladding is factory-applied in many colors and does not require painting.
Clearance
Recommended space between a window frame and the rough opening.
Condensation
Moisture or humidity in the air that forms on a cool surface such as a pane of glass. When moist air comes in contact with a cool surface it shrinks. If it shrinks enough to reach 100% humidity or the dew point, moisture will form on the cool surface. This is demonstrated when the outside of a glass of iced tea sweats.
Conduction
Conduction is a term used to describe heat loss through solid materials (frame, spacer bar). Each individual material has a different rate of conduction, which is measured by it's U-Value.
Convection
Convection is a term used to describe heat loss caused by circulating air currents. Different gases, like air and argon have different rates of convection depending on the size of air space between the glass panes.
Cripples
The short 2" x 4" members used to frame under the sill or above the header in a rough opening for a window in a frame wall.
Curb
A watertight wall or frame used to raise slope glazing above the surface of the roof as a preventive measure against water leakage from melting snow or rain run-off.
Drip Cap
A molding placed on the top of the head brickmold or casing of a window frame.
Dual Pane
A glass unit consisting of two panes of glass held together by a sealant and spacer bar, forming a sealed unit. This is the same as double glazing.
Due Date
Date the product was scheduled to be completed by the plant.
Emissivity
is a term used to describe a surface relative ability to absorb and reradiate heat. A surface with high emissivity will radiate heat faster that a surface with low emissivity. Emissivity is recorded on a scale of 0-1, where 0 would be the perfect white surface reflecting 100% of heat while 1 would be the perfect black surface that absorbs 100% of heat. Standard clear glass surfaces have an emissivity of 0.84, while low e glass surfaces have emissivity ratings of 0.08 to 0.04.
Energy Rating (ER)
Energy Rating is a value developed by the Canadian Standards Association to compare the overall thermal efficiency of windows. The higher the ER, the more efficient the overall window (frame, glass, spacer & air leakage).
Extrusion
A form produced by forcing material through a die. Metal and vinyl window frames and sashes are generally extruded material.
Exterior Casing
A casing (brickmould) that trims the exterior of a window or door frame and serves as the boundary molding for the siding material.
Fenestration
An architectural term referring to the placement of openings in a building wall, one of the important elements in controlling the exterior appearance of a building. Also, a window, door, or skylight and its associated interior or exterior elements, such as shades or blinds.
Fixed
Refers to windows with sashes that are non-venting or inoperable.
Fixed Window
A fixed window is a non-venting style of window that contains a fixed sash. Fixed windows are typically used when joined beside an operating window to keep a more balanced appearance.
Flashing
A metal or plastic strip attached to the outside of the head or side jambs to provide a weather barrier, preventing leakage between the frame and the wall.
Frame
The perimeter material of a window or door that consists of a head at top, sill at bottom and two jambs at the sides.
French sliding door
A sliding door which has wider panel members around the glass, giving the appearance of a French hinged door.
Garden Window
A box-shaped window that hangs outside the house and can be used as a greenhouse for plants. It has a slanted glass roof that pulls in heat and light from the sun.
Glazing
The insertion of glass into sashes and doors. Glazing also refers to the lowest quality of plate glass. The purpose of glazing is to retain the glass adequately under the design load, provide effective weathering sealing, prevent loads or pressure points on the glass resulting from building movement, prevent glass-to-metal contact, and minimize glass breakage from mechanical or thermal stress. The glass panes or lights in the sash of a window.
Glazing bead
A metal, vinyl or wood strip applied to the window sash around the perimeter of the glass.
Grills
A term referring to windowpane dividers or muntins. An applied style of divided lites, or decorative metal bars mounted between the glass panes inside a sealed unit. Grills are available in varying widths and colours.
Half Round
A 1/2 circular window.
Hand
A term describing the opening portion of a window or sliding door when viewed from the exterior.
Head
The main horizontal member forming the top of the window or door frame.
Head Plate
Plywood in fill panel of a bench bay or bow: as in c/w head and seat.
Hinged
Windows (casement and awing) with an operating sash that has hinges on one side.
Horizontal-Gliding Window
See horizontal slider
Horizontal Slider
A window with a moveable panel that slides horizontally.
Insulating Glass (IG)
Insulated glass units (IG or IGU) are a combination of two or more panes of glass sealed together using a spacer bar in a factory controlled environment. The sealed unit has an optimum air space which is filled with a gas fill such as air or argon gas, and produces a higher insulating glass panel.
Jamb
The main vertical members forming the sides of a window or door frame.
Jamb extension or liner
Wood or vinyl lining the inside surface and head jambs of sliding windows, bringing widows flush with the interior surface of the walls.
Keeper
The protruding, hook-shaped part of a casement window lock, which is mounted on the inside surface of the sash stile.
Laminated Glass
Laminate glass is a type of safety glass comprising of two pieces of glass with a clear vinyl interlay. This glass may break under impact, but typically remains integral. Splinters and sharp fragments adhere to the interlay. Laminated glass is ideal for area's where someone might fall against the glass, or to prevent forced entry.
Lite
Sections of glass separated by mullion or muntin bars.
Low-E glass
Low Emissivity coated glass, either soft-coat or hard-coat, sputtered or pyrolitically applied silver oxide coatings, to enhance thermal performance. A term used to indicate glass which has low emissivity due to a film or metallic coating on the glass to restrict the passage of radiant heat.
Low-Emissivity (low-e) Coatings
Microscopically thin, virtually invisible, metal or metallic oxide layers deposited on a glazing surface primarily to reduce a products U-factor by suppressing radioactive heat flow. A typical low-e coating is transparent to the solar spectrum (visible light and short-wave infrared radiation) and reflective of long-wave infrared radiation.
Moulding
A relatively narrow strip of wood, usually shaped to a curved profile throughout its length; used to accent and emphasize the ornamentation of a structure and to conceal surface or angle joints.
Mullion
The vertical or horizontal divisions or joints between single windows in a multiple window unit.
Multi-point lock
A casement locking system, which secures the window at two or more locking points by operation of one handle. Also known as unison locking.
Muntin
A short bar used to separate glass in a sash into multiple lights. Also called a windowpane divider or a grille.
Nominal Size
A rounded off approximation of the window's dimension, eg. nominal size 4060 is 47 l/2"x 70 7/8" approx. 4' x 6'.
Open
No glass in window, that is, a frame only.
Operator
The operating hardware of a window unit, often metal arm and gear which allows for easy opening or closing of projecting (casement or awning) windows.
Operating Unit
An operating unit (or operator) is a window or door that has an opening sash or slab. Operators typically include hardware, locks and insect screens to create a venting unit.
Patio Door
A patio door is a sliding entryway comprising of at least one operating sash panel and one fixed panel which hold sealed units. Patio doors are also available in three or four wide units.
Picture Window
Picture windows are non-operating windows with a sealed unit set directly into the frame (no sash). Picture windows provide a maximum glass viewing area and can be combined with other operating windows.
Projection
Distance a Bay or Bow window protrudes from the wall, measured from like point, i.e.: sheathing to sheathing.
R-Value
R-value is a term used to indicate an objects ability to resist heat loss. The higher the R-value, the better an objects ability to resist heat loss. R-values are determined by inverting the U-value (R=1/U).
Rakehead
Specialty windows of various design (anything non-rectangular or octagon shaped).
Rails
The cross or horizontal members on the framework of a sash or door.
Reglaze
Replacing the sealed unit or glass in a frame that has previously contained glass.
Rough opening (or Rough Stud Opening)
The opening left in a frame wall to receive a window or door unit.
S.D.L.
Abbreviation for Simulated Divided Lites.
Safety Glass
Glass less prone to breakage and designed to break in a manner less conducive to personal injury, such as tempered, laminated, or Georgian Polished Wire (GPW).
Sash
A single assembly of stiles and rails in a frame for holding glass, with or without dividing bars or muntins, to fill a given opening; it may be either open or glazed. The portion of a window that includes the glass and the framing sections directly attached to the glass, not to be confused with the complete frame into which the sash sections are fitted.
Sash balance
Coiled spring assemblies which assist in raising single-hung sashes and tend to keep the sash in any placed position by counterbalancing the weight of the sash.
Sealed Unit (SU) (See insulated glass unit)
Two pieces of glass hermetically sealed to form one insulating unit.
Seat board
A flat board cut to fit the contour of a bow or bay window and installed between the sills and the flat wall surface, providing a seat or shelf space.
Seat Plate
Opposite of head plate.
Shims
Wedges (often wood shingles) used to secure the window or door unit in the rough or masonry opening in a square, level and plumb position during and after installation.
Sill
The main horizontal member forming the bottom of the frame of a window or door.
Simulated divided lites
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. S.D.L.s can be affixed to the inside and outside of a panel of insulating glass to simulate the look of true divided lights.
Skylight
A window installed in a roof and assuming the same slope. Depending on which direction they face, skylights can bring in more light and heat than windows. For example, in the summer months, an unshaded south-facing skylight will bring in more direct sunlight and heat than a window. In a cold climate, a north-facing skylight gives almost five times more light than a north-facing window with almost the same amount of heat loss.
Stationary Sash
A fixed or inoperative sash, often used in combination with other types of window and sash units; intended primarily for viewing purposes and for admitting light.
Stop
A wood, vinyl, or metal trim member nailed to the window frame to hold, position or separate window parts. The stop is often moulded into the jamb liners on sliding windows.
Tempered glass
Glass manufactured through heat strengthening in a tempering furnace to withstand over three times greater than normal forces on its surface. When it breaks, it shatters into small pieces to reduce hazard. A type of safety glazing, in the same category as laminated glass.
Thermal Break
The addition of a thermal insulating material between two thermally conductive materials. Thermal breaks are used to break up a highly conductive material by joining them together with a low conduction material. Typically, aluminum frames have thermal breaks from made from vinyl, fiberglass or some other insulated material, to prevent massive heat loss from conducting to the outside.
Transom
A smaller window above a door or another window. A transom joint is also the horizontal joining area between two window units which are stacked one on top of the other.
Tri-pane
A glass unit consisting of three panes of glass held together by a sealant and spacer bar, forming a sealed unit.
Trim
Millwork, primarily moldings and/or trim, that finishes off window and door openings, fireplaces, walls and other members.
Triple glazing
A sash glazed with three lights of glass, enclosing two separate air spaces.
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. Windows that contain individual panes of glass and are assembled in the sash using muntins.
U-Factor
A measure of heat transmission through a wall or window. The rate of heat flow value through the complete heat barrier, from room air to outside air. The lower the U-factor, the better the insulating value. U-Factor is given in BTU/ft20F (Imperial) or W/m20K (metric), and takes into account conductive, convective and radiative heat transfer. The lower the U-Factor, the greater a product’s resistance to heat flow and the better its insulating value.
Vent Unit
A window or door unit that opens or operates.
Weather-strip
Cold air entering the house in winter can account for up to 35% of the heating load. Weather-stripping can reduce the load to 20%.
Window Frame
A group of wood parts machined and assembled to form an enclosure and support for a window or sash.
Window Jamb
The part of the window frame that surrounds and contacts the window or sash that the frame is intended to support.
Window Unit
A combination of the frame, window, weather-stripping, sash activation device and, at the option of the manufacturer, screens assembled as a complete and properly operating unit.
Windowpane Divider
A short bar used to separate glass in a sash into multiple lights. Also called a muntin or a grille.
Windows
A wall opening in a building added for the purpose of letting in light and air, usually sealed from the elements in some way, using a frame and sash containing glass or another type of transparent material, and usually able to be opened and shut. Windows containing glass began being heavily used in the late nineteenth century with advances in glass technology and frame construction. Windows gave building occupants options about views, ventilation, and exterior design.
