:: Glossary

Aluminum
A malleable metallic element of the earth’s crust that is silver and white with a hint of blue tones. It is not easily tarnished or corroded and has very good thermal and electric conductivity.
Aluminum Cladding
Provides a protective shell for exterior surfaces. It is available in a variety of colors and does not scratch, crack, flake, or blister easily. Common uses for aluminum cladding include patio door or wood window surfaces.
Annealed Glass
Not to be mistaken for safety glazing, annealed glass is standard float glass before it is treated for tempering or heat strengthening.
Extruded Nailing Fin
An extruded metal or plastic flange that is inserted in the head, jambs and sill of window units.
Arch Top Window
Commonly referred to as a radius window, the arch top window is curved. It may include components such as full round, half-round, quarter-round, or arch top products. It also may be available in operating or fixed configurations.
Argon
Used to improve efficiency, the colorless gas argon is injected into the airspace of an insulating glass.
Astragal
Used to provide weather and overswing protection, astragal is the vertical trim that is attached to one of the sashes of a French casement window or one of the panels of a French door. Astragal is used to bridge the gap between the sash/panels when closed.
Awning Window
A window that has a sash that is hinged at the top but opens from the bottom.
Constant Force Balance System
A balance system that features an interlocking spring system to fit various window designs.
Ball Bearing Hinge
Hinges that reduce friction of the hinge flange, commonly used when doors are expected to receive high traffic
Basement Window
Used to provide ventilation for basements or similar spaces. Basement windows are sash units that swing from the top or bottom and consist of one to three glass lites. They may also include screens and/or storm panels.
Bay window
A set of three or more windows projecting out from a structure at 30, 45 or 90 degree angles. The center window is parallel with the structure.
Bow Window
Four or more (commonly five) window units that adjoin together and project 10”-20” from a building wall forming a radius.
Brickmould
A type of exterior casing for doors and windows that are used as an aesthetic boundary between the frame and the siding.
Bulb seal Weatherstrip
A form of weatherseal that has a rounded and closed profile.
Cable Support Kit
Typically used in a large or bay window, this set of hardware is designed to tie a window to the structure. It prevents window sagging and supports the projecting portion of the assembly.
Cam Lock
Used to form a tight weather seal, this single-point locking mechanism uses a “cam” action to lock and pull the window sash against the frame. Large windows may need more than one cam lock.
Cam Pivot
Allowing the sash to “pivot” for easy reinstallation or removal, the cam pivot are pins on the bottom corners of single and double-hung sashes.
Caming
Pieces of metal that hold individual pieces of glass together in a sidelight, transom, or decorative glass insert. Commonly used metals are lead, brass, zinc or nickel.
Casement window
Hinged on either side allowing the sash to open outward, to the right or left, in a swinging motion. Casement windows offer maximum ventilation.
Caulking
A compound used for sealing cracks and filling joints, this prevents any possible leakage of air or water.
Meeting rail
In a double-hung window, this is the bottom rail of the upper sash (upper checkrail) and the upper rail of the lower sash, where the lock is mounted (lower checkrail). It is also known as a checkrail.
Circle top window
A type of window featuring curved components such as full round, half-round, quarter-round, arch top and springline products. Circle top windows may be available in either operating or fixed configurations.
Condesation
When excess humidity in warm air is released as water droplets onto a cold surface such as a pane of glass.
Cottage window
A single-hung or double-hung window that has an unequal bottom and top sash; the bottom is greater in height than the upper sash.
Crank handle
A handle that has a knob and arm assembly, commonly used for a casement or awning window.
Design pressure ratings
A way to specify the performance of windows based on structural, air, and water ratings. The ratings measure a product’s ability to withstand forces in both negative and positive directions, while the window or door is closed or locked.
Dessicant
A dying agent that is used in manufacturing insulated glass to prevent fogging of the insulated unit. The porous crystalline substance is used to absorb any moisture present.
Diamond lite
Used for divided lites, this is a diamond grille pattern.
Divided lite
An opening in a window that is divided into small sections using a grid system on the exterior, interior, or in between glass panes.
Door frame
Used to fasten the door system to the structure with structural members (head, jambs, sill).
Door jamb
The two vertical frame members as well as the upper horizontal that house the door panel, classified as side or head jambs.
Double glazing
Two glass panes separated by air to form insulating glass; may also be accomplished by adding a storm panel.
Double hung window
A window that has both an upper and lower sash and slides vertically.
Double strength glass
Refers to the thickness of the glass. Nominal thickness is 0.117, MM Designation is 3.0, and the Traditional Designation is 1/8 inch.
Dual durometer weatherstripping
Designed with two different materials providing above average performance.
Dual seal
Used in sealing dual-pane windows where the primary seal is polyisobutylene and the secondary seal is silicone.
Egress opening
The space between the top of the sill of the frame of an open window and the bottom part of the raised sash, multiplied by the space between the jambs of the opening.
Energy Star
An independent U.S. government program established designation to recognize energy efficient products based on a set of guidelines.
Extension Jambs
Wood or other material that is fastened to the inside edges of a door or window to increase width that allows adaptation to a thicker wall.
Extrusion
Formed when material is forced through a die.
Eyebrow Top
A door with a top that slopes down from the center and up on either end.
Fabricator
The person or business that assembles all the component parts into a completed door, window, or sash unit.
Factory Mulled
Two ore more window units that have been attached together at a manufacturing plant.
Fenestration
The arrangement and design of doors and windows on the exterior of a building.
Fixed
A door or window that is inoperable or non-venting.
Fixed Sash
A window sash or door panel, often used in combination with other types of window and sash units, that is fixed to the frame and intended primarily for viewing purposes and for admitting light.
Flanker Unit
An outside door or window that is inoperable or non-venting.
Flashing
Sheet metal that is overlapped to provide protection against water leakage.
Float Glass
A quality of glass that is made by taking a ribbon of molten glass and feeding it across a bath of heated liquid such as molten tin.
Fogging
A deposit of film left on the interior surface of an insulated sealed glass unit. Fogging occurs when extreme conditions are present or when seals fail.
Folding Crank Handle
A type of hardware that is used to operate casement windows. The handle has the ability to easily fold away when not in use.
Frame
The assembly of structural members such as the sill, head or jam that is used to fasten a door panel or window sash to a building or structure.
French Door
A style of door where two panels open completely making a space equal to approximately twice the width of the panel.
Full Round
A type of geometric shape and radius that is available specifically for vinyl and aluminum windows.
Full Screen
A screen that fills the entire window opening of a double-hung window.
Fusion Welding
When vinyl windows, door frames, or sashes are joined together. Each piece is heated and bonded together to reduce water and air infiltration.
Gable top
A five sided geometric shape available in a vinyl and aluminum picture windowframe bar.
Garden window
Popular in greenhouses for plants, a garden window projects out from the side of a structure. The slanted glass roof allows heat and light to enter.
GBG (Grilles Between the Glass)
A divided lite option for patio doors or windows. These grilles are placed between the panes of insulating glass and are maintenance-free.
Geometric Window
Specialty geometric shaped windows, available in triangle, rectangle, octagons, trapezoids, half-rounds, pentagons, quarter-rounds, sectors, full rounds, and ellipse shapes.
Glassstop
Trim that covers the edge of the glass.
Glazing
Glazing is used as a process to mount glass into doors and windows. The purpose of glazing is to retain the glass adequately under the design load, provide an effective weather seal, 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. Glazing also refers to the lowest quality of plate glass.
Grille
A decorative removable or non-removable grid on the exterior or interior of the glass, between the glass panes, or in any combination of these locations that divides a window opening into smaller openings to create simulated divided lite or true divided lite.
Grilles between the glass
Placed between the panes of insulating glass, grilles are divided lite options for patio doors or windows. They are also maintenance-free.
Half screen
A screen that only covers one sash and fills half of the opening of a double-hung, single-hung or half-slide window.
Half-round
A half-round window has the 180 arc of a halved circle.
Handle set
Components that attach to the face of a sliding door panel that allow the door to open and close.
Heat gain
Transfer of heat from outside to inside by means of convection, conduction, and radiation.
Heat loss
Heat loss is the transfer of heat from inside to outside by means of convection, conduction, and radiation.
Hopper Window
A sash unit that typically swings from the top or bottom is used to provide ventilation to basements or cellars. Hopper windows usually have one, two or three glass lites. They also sometimes include screens or storm panels.
Horizontal Gliding Window
Two or more sashes that slide horizontally past each other; one or more of the sashes may be fixed or inoperative or all the sashes may operate. In a closed position, the sashes come together to form a vertical meeting rail.
Insulated glass
Two panes of glass with material between the two panes making it difficult for heat or cold to pass through.
In-Swing
Patio doors that swing to the interior of a home.
Insulating Glass Unit
Two or more panes of glass separated by a spacer.
Interlock
Provides hooking action on a window or door between the sash rail and the sill or jam. Interlocking provides security and reduces air infiltration.
J-Channel
A space that allows siding on a home to slip between the nailing fin and the trim. This feature also allows for easy installation and provides a clean appearance.
Jalousie
Several small horizontal glass slats held together by a metal end frame and then attached to the face of a window frame, side jams, door rails or stiles.
Jamb
The vertical frame components of a door or window assembly.
Jamb Adjuster
Used to ensure that a product is installed squarely, these are adjustable screws designed for mounting door and window frames into rough openings.
Jamb Extension
Extends the depth of a door or window frame and usually has a larger depth than a jamb liner.
Keeper
A bracket used as a latching point.
Lift Rail
A rail on a single or double hung window designed with an integrated method of lifting the operating sash.
Lite
A framed opening in the glass within a door panel or sash used in reference to glass divided by a grid into multiple smaller openings.
Lock Rail
The intermediate rail of a door at lock height.
Low-E Glass
A type of insulating glass that blocks harmful ultraviolent rays as well as the sun’s infrared heat so homes stay cooler in the summer. Low-E glass also keeps homes warmer in the winter and reduces the level of condensation.
Mulled Unit
Two or more window units joined together.
Multi Point Lock
A locking system with more than one lock.
Muntin
The individual pieces of a decorative grid that work to divide a window opening into smaller sections.
Nailing Fin
A plastic or metal flange that is inserted into a point on the head, jambs and sill of window units. Nailing fins are commonly used to secure windows or doors to an opening in new construction installations.
National Fenestration Rating Council
An independent third party certification organization with accepted standards for evaluating and certifying energy performance.
New Construction Window
A window installed during the original construction of a building.
Obscure Glass
A type of decorative textured glass that partially or fully obscures the view. Obscure glass allows for privacy while allowing light to enter a home.
Operating Sash
An assembly that consists of stiles (vertical pieces), rails (horizontal pieces), and a window’s glass that opens and closes.
Operator
Hardware (excluding hinges) used to open and close windows.
Oriel Window
Either a double or single-hung window that have unequal top and bottom sashes. The bottom sash is greater in height than the upper sash.
Out Swing Door
Refers to a door than swings outward rather than inward on a home.
Palladian
A large arch top window that is flanked by smaller windows on either side.
Pane
Refers to one piece of glass.
Patio Door
A door made of mostly glass that opens onto a patio, deck, or backyard of a home.
Picture Window
A fixed large window with smaller adjacent windows.
Pile Weatherstripping
A type of weatherstrip that has a pile, also known as fuzz, that helps reduce dust around a window sash or door panel.
Prairie Grills
A type of divided lite grille pattern that borders the glass on the outside of the sash or frame, sometimes referred to as Queen Anne grilles.
PVC
Polyvinyl Chloride (PVC) is an extruded or molded plastic material framing as well as a thermal barrier.
Quarter Round
A radius and geometric shape used for vinyl and aluminum windows.
R-Value
The amount of resistance a window has to heat flow or thermal transfer. The higher R-Value, the better the insulation.
Radius Window
A window available in operating or fixed configurations with curved components that may include full round, half-round, quarter-round, arch top and springline products.
Reinforcement Bar
Reinforcement bars have a steel or aluminum profile and is used to reinforce patio doors and vinyl windows.
Relative Humidity
The ratio of the amount of water vapor in the air compared to the maximum amount that could be present. 100 percent is when the air is totally saturated with moisture.
Round Top
A 180-degree top curve feature on a window or door, also known as a true radius top.
Sash
Stiles and rails that are put together to form a frame for holding glass in a window.
Seal Failure
When the hermetic seal around the perimeter if insulated glass unit is lost which results in fogging between panes.
Shading Coefficient:
The measure of a window’s ability to transmit solar heat relative to the ability for a 1/8” clear glass pane. The higher a unit’s SC, the more heat it transmits, and the less shading ability it has.
Solar Heat Gain Coefficient (SHGC) Rating
A measurement of the amount of solar radiation present throughout a piece of glass or door material. The lower the SHGC, the fewer UV rays that cause heat gain will come through the window.
Sill:
The main horizontal member that forms the bottom of the frame of a door or window.
Sill expander
An extrusion that is attached to the bottom of the window to cover the gap between the sill and the rough opening.
Sliding patio Door
A door with one or more panels that slide horizontally past each other, very commonly used in areas with minimal space.
Sliding Window
Includes one stationary sash and another sash that moves to the left or right in groves or tracks.
Soft Coat LowE Glass
A thin layer of materials offering low emissivity or solar control benefits are applied to glass in a manufacturing center.
Solar Heat Gain Coefficient
A measurement of how much solar radiation is present through a piece of glass or door material. The lower the SHGC, the fewer UV rays that cause heat gain come through the glass.
Spacer
A component that is typically metal that separates panes of glass to create airspace in an insulating glass unit.
Sputter Coating
A thin layer of materials offering low emissivity or solar control benefits are applied to glass in a manufacturing center.
Stationary Sash or Panel
A door panel or window sash that is typically used in combination with other types of window and/or sash units, fixed to the frame, and is used primarily for viewing and admitting light.
Storm Door or Window
A door or window that is meant to cover, protect, and insulate an exterior door or window. Typically contains glass and screening material.
Stress Crack
Resulting from a stress condition on the edge of glass, a stress crack is a defect in an insulated glass unit.
SuperSpacer
A polymer foam, no metal WarmEdge spacing system.
Tempered Glass
Extra strength heat-treated glass that withstands abnormal pressure and force on the surface, will not break into sharp pieces.
Thermal break
A low conductivity element that is placed between higher conductivity elements to reduce the flow of heat or cold, often used in aluminum windows.
Tilt Latch
A latch at the end of a window checkrail allowing the sash to easily release from the jamb liners and tilt into the structure.
Transom
Often a rectangular window placed over a door or another window.
Trapezoid
A four sided geometric shape available specifically for an aluminum or vinyl picture window frame bars.
Tilt Window
A double-hung window where the sashes tilt inward to allow for easy cleaning of the exterior glass.
Tinted Glass
Colored glass that protects a home from harsh direct sunlight.
Triangle
A three-sided geometric shape used for an aluminum or vinyl picture window frame bar.
Triple Pane
Three panes of glass offering optimal thermal performance and insulation.
True Radius Top
A 180-degree top curved feature on a door or window.
Twin Vent Slider
A vinyl horizontal slider where the center lite is generally equal to the width of both vents together.
U-factor/u-Value
A number representing the rate of heat loss through a door or window; the lower the number, the greater a window can handle the transfer of heat.
Ultraviolet (UV)
The type of rays that exist outside the visible spectrum. Too much exposure can cause plastic metals to change shape and dark paint finishes to chalk or fade.
V-Groove
A specialized process where a decorative pattern is grooved into glass, V-Groove is available in standard as well as grid patterns and can be created in various polishes and shadows.
Veneer
A thin layer of wood that is typically rotary-cut, sliced or sawn from a log, bolt or flitch.
Vent
The operating sash in a window
Vinyl
Either rigid or flexible, this polyvinyl chloride material is used in glazing channels and weathering of doors and windows.
Virgin Extrusion
The original vinyl extrusions that do not have any regrind added.
Visible Transmittance
How much light actually comes through a product expressed as a percentage. The higher the VT, the more light transmitted.
Warm Edge Technology:
A way to create insulated glass using a non-thermal conductive spacer bar.
Weatherstrip
Metal, plastic, or vinyl fiber strips that fit tightly against the window or door frame to prevent air infiltration.
Weep Hole
Used to drain water out of a window or patio door, a weep hole is visible exit or entry point of a drainage system.
Wind Load
Force on a surface caused by air.
Window
An opening in a building designed to let in air and light with the ability to block outside elements and can be opened and shut. Windows are created using a frame and sash containing a transparent material such as glass.
Window & Door Manufacturer’s Association
An association that researches, tests and provides certification for windows and doors.
Window Unit
Some combination of the frame, sash, weatherstrip, sash opening mechanism, screens and stormsash assembled as a complete operating unit.