AAMA
American Architectural Manufacturers Association is a national trade association that establishes voluntary standards for the window, door, skylight, curtain wall and storefront manufacturers.

Air Infiltration
The amount of air leaking in and out of a building through cracks in walls, windows and doors.

Argon Gas
An inert, nontoxic gas used in insulating glass units to reduce heat transfer.

ASTM
American Society for Testing and Materials. An organization that develops methods for testing of materials.

Awning Window
A type of window that when the handle is cranked, the window will open out away from the house pivoting from the top of the unit.

Balance
Used to offset the weight of a sash in a double or single hung window. Permits the sash to stay at the height to which it is opened. There are various types used including spiral, block and tackle, constant force also known as true force.

Balance Cover
A thin piece of vinyl used to cover the balance for aesthetic reasons only.

Balance Shoe
This is the part that connects the balance to the sash through the use of the pivot bar. The shoe also allows the sash to lock in place when the sash is being tilted in for cleaning. It also allows the sash to be removed from the window when necessary. 

Bay Window
A window that incorporates the use of 30° or 45° angle mullions when connecting
the windows to each other. There is usually only three windows used on a Bay window.

Block and Tackle Balance System
The block and tackle system utilizes a high-density nylon cord pulley action which is attached to a moveable block that travels up and down within a metal chamber. Tension from a heavy duty coil spring at the top of the block creates the proper resistance necessary for smooth operation of the window sash.

Bow Window
AA window that incorporates the use of small angle mullions usually 15° or less to connect anywhere from 3 to 7 windows together. Gives a rounded affect to the unit.

Box Bay
A window that uses 90° mullion to connect the windows together. There is usually only three windows used in a unit of this type.

Butyl
A rubber material that seals the glass to the spacer, creating an airtight and water-tight insulated glass unit.

Cable Support
Used to support the weight of a Bay or Bow window when installed in a house. If cable supports are not used, knee braces are recommended.

Call Size
Usually a four digit code used to describe the rough opening size of a window. The first two digits indicate the width in feet and inches and the second two digits indicate the height in feet and inches. (2/0 x 3/0= two feet, zero inches by three feet, zero inches)

Cam-action Lock and Keeper
The mechanisms, which pull and secure the sashes together when placed in the locked position.

Casement Window
A window with a side-hinged sash that opens and closes outward by a crank handle mechanism. Available in continuous mainframe, with multi-lite configurations.

Condensation
The deposit of water vapor from the air on any cold surface whose temperature is below the dew point, such as a cold window glass or frame that is exposed to humid indoor air.

Cottage Window
A single hung or double hung window where the lower sash is taller than the upper sash (or IG unit). Usually a 40/60 or one third two thirds ratio.

CRF (Condensation Resistance Factor)
A measurement that determines at what interior humidity level condensation will occur. The higher the number the better. A low CRF number would be 25 - 30, while a high number would be 60 - 65. The test is done per AAMA guidelines.

Coved Glazing Beads
A contoured piece of vinyl that holds the glass in place within the sash and adds an elegant, finished look.

Crank
A mechanism used in awning and casement windows to operate the sash.

Desiccant
A chemical put onto the spacer of an insulated glass unit to help absorb moisture from inside the IG unit.

Double-Hung Window
A window that has two vertical operating sashes.

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, times, the space between the jambs of the opening. Most building codes require a minimum opening of 5.7 square feet when the sash is opened for emergency exit.

ENERGY STAR®
The ENERGY STAR program is a joint venture between the US Environmental Protection Agency (EPA) and the US Department of Energy (DOE) designed to encourage homeowners to purchase energy-efficient products. Using less energy in our homes reduces the amount of CO2 emissions released into the atmosphere from burning fossil fuels such as coal, oil and natural gas. The advanced components and design in the ClimaTech™ insulated glass package exceed all performance criteria required by the ENERGY STAR program.

Extension Jamb
Snap on pieces that attach to the inside of the window allowing the interior surface of the window to reach to the drywall. Sometimes made of wood that is screwed or stapled to the window. Common sizes allow for 4 9/16 and 6 9/16 walls.

Fenestration
The placement of window 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 Lite
A pane of glass installed directly into non-operating framing members; also, the opening or space for a pane of glass in a non-operating frame.

Fixed Panel
An inoperable panel of a sliding glass door or slider window.

Fixed Window
A window with no operating sashes.

Flankers
Are the windows that are at the opposite ends of a mulled unit. In a five lite bow, the first and fifth windows are called the flankers. In a picture window combo unit, the windows on each side of the picture window are called the flankers.

French Patio Doors
A two panel glass door where both panels operate and swing either inward or outward.

Full Screen
A screen that covers the entire area of a window that has the possibility of opening.

Fusion-welded
The process of joining materials by melting them together with extreme heat (in most cases over 500ºF), resulting in the materials combining into a one-piece unit.

Garden Window
Designed much like a bay or bow window, a garden also extends from the wall to the exterior of the home. It is built in a square or rectangular shape at right angles. The two side lights often operate for added ventilation.

Gas Fill
A gas other than air, usually argon or krypton, placed between window or skylight glazing panes to reduce the U-factor by suppressing conduction and convection.

Glazing
The glass or plastic panes in a window, door or skylight.

Glazing Bead
A molding or stop around the inside of a window frame to hold the glass in place.

Grids
Optional horizontal or vertical lineals installed between the glass panes help to create the appearance of a divided window design.

Half Screen
A screen that is only large enough to cover the opening of one sash on a double hung or single hung window. (Single hung windows only have this type of screen)

Head Expander
Used for replacement windows only. It is a “C” shaped piece of vinyl that attaches to head of the window in the rough opening. (Not used on casement windows)

Headboard
The top wooden board used in a bay or bow to connect all the windows together in
a fixed location.

Header
The top part of the master frame.

Hinged Patio Doors
A two panel glass door where one panel is stationary or fixed, while the other operates and swings either inward or outward.

Hopper Window
A bottom-hinged sash window that opens inward for ventilation.

Insulated Glass Unit (IG)
The same as thermal glass. Usually two pieces of glass separated by a spacer, and sealed as a unit to trap air in between the two pieces of glass for insulation purposes. For better insulation values, clear Argon gas can be used to fill the IG.

Insulated Head and Seat Board
A special type of lumber that can be used when making a Bay or Bow Window that has 1/2” of insulation laminated inside the board to provide better insulation.

Intercept Spacer
A roll formed “U” shaped spacer that offers much better thermal resistance in the IG unit than ordinary rectangular spacer. (Also known as “Warm edge technology”).

Interlock
A section of the window or patio door where two sashes meet, and one part of the
first sash slips into a channel or groove on the second sash.

Internal Sloped Sill
Where one of the inner walls of the sill is sloped towards the outside of the house to enable water to flow toward the exterior side of the window.

Jamb
The side of the master frame. It attaches to the head and the sill of the window.

Jamb Adjuster
Used to adjust the fit of the window in the rough opening. Helps align the jambs in relation to the sashes and the framing of the opening.

Keeper
The device the lock latches into when it is in the locked position.

Knee Braces
An inert, nontoxic gas used in insulating windows to reduce heat transfer.

Krypton Gas
An inert, nontoxic gas used in insulating windows to reduce heat transfer.

Lift Rail
The part of the sash, the operator uses to raise or lower the window.

Lite
A unit of glass in a window.

Lock
Used to secure a window or patio door when in the closed position.

Lock Rail
The part of the sash the lock or keeper is attached to.

Low-E  
A special coating that can be applied to one side of the glass to help reduce heat
transference. Helps to reduce heating and cooling energy bills for the homeowner.

Low-E Argon
The same as Low-E, except that there is clear Argon gas in the insulated glass
unit instead of air providing for a better R-Value.

Masterframe
The part of the window in which the sashes operate.

Mechanical Window
A window that is screwed together rather than welded.

Meeting Rail
Used in single hung windows, it is a rail that connects both jambs at the middle
of the window.

Miter
To make a diagonal cut, beveled to a specific angle (usually 45°). Sometimes miter cuts are made into an overlapping siding or soffit panel surface, to provide a neater appearance.

Mullions
Used to join two or more windows. Some types are: snap mullion, “U” mullion and “H” mullion.

Muntins
The decorative bars used in a window to make the criss cross or diamond patterns in the glass. Also known as Grids or Grills. Internal Muntins go in between the two pieces of glass in an IG unit. Snap on, or add on grids, are applied to the outside of the glass.e.

Nailing Fin
Used to attach windows to a house in new construction applications.

NFRC
National Fenestration Rating Council.

Night Latch
A small device that is on the upper sash of a double hung window. When placed in the out position it will only allow the lower sash to open a few inches. When placed in the closed position the lower sash can operate completely.

Obscure Glass
Also known as frosted glass. A person can not see through the glass, however, the glass allows light to pass through it. It is translucent but not transparent.

Oriel Window
A single hung or double hung window where the upper sash (or IG unit) is taller than the lower sash. Usually a 60/40 or one third two thirds ratio.

Overall Projection
The greatest distance from the outside of the window to the inner most part of a bay or bow.

Panel
A major component of a sliding glass door, consisting of a light of glass in a frame installed within the main (or outer) frame of the door. A panel may be sliding or fixed.

Picture Window
A picture window that does not move or operate.

Pivot Bar
Connects the sash to the balance shoe. Allows the sash to tilt (pivot) in for cleaning.

Pocket Sill
The bottom part of the window where the sill has no slope or angle to it. The water
drains to the exterior of the window through a series of weep holes. A pocket sill window
sometimes uses the same profile for the sill as it does for the head and jambs.

Positive Lock
Area below the nailing hem that the buttlock locks into.

R-value
The resistance of conductive heat transfer in one hour through a one square foot area of a specific IG Unit, for each degree Fahrenheit temperature difference, between the indoor and outdoor air. (How well an item can insulate. The higher the number the better.)

Radiation
The transfer of heat in the form of electromagnetic waves from one separate surface to another. Energy from the sun reaches the earth by radiation and a person’s body can lose heat to a cold window or skylight surface in a similar way.

Rough Opening
The dimensions of the opening in the house where a window will go.

Sash
The part of a window or patio door that moves up and down, left or right, or in and out. In some cases, such as a patio door or single hung window, one sash may be fixed. (designed not to move or operate.)

Sash Stop
A piece of vinyl used to stop the travel of the sash at the top and bottom of the
window.

Screen Plunger
A type of spring loaded device used to hold the screen in place on a window.

Seatboard
The bottom board used in a bay or bow to connect all the windows together in a
fixed location.

Shading coefficient
TThe ratio of the rate of solar heat gain through a specific IG Unit, to the rate of solar heat gain through a single piece of 1/8” clear glass in the same situation. The lower the number the better.

Sill
The horizontal, bottom section of the masterframe.

Sill Adapter
A snap on piece that provides a slope sill effect and appearance to a pocket sill window.

Sill Angle
A piece of vinyl that fills in the gap between the bottom of a window and the rough opening sill to help finish off the installation job.

Single Hung
A window that only has a lower sash. In place of the upper sash, is a insulated glass unit glazed to the master frame.

Slider Window
A window where the sashes move left and right.

Sliding Patio Doors
A combination of fixed and sliding glass door panels that operate solid brass roller trucks. Available in 2-, 3- or 4- lite configurations with the operable panel available in any position.

Solar Heat Gain Coefficient (SHGC)
The fraction of solar radiation admitted through a window or skylight, both directly transmitted and absorbed and subsequently released inward. The solar heat gain coefficient has replaced the shading coefficient as the standard indicator of a window’s shading ability. It is expressed as a number between 0 and 1. The lower a window’s solar heat gain coefficient, the less solar heat it transmits and the greater its shading ability. SHGC can be expressed in terms of the glass alone or can refer to the entire window assembly.

Spacer
An object placed between two or more pieces of glass which helps to maintain a uniform width between the glass, and prevent sealant distortion.

Stile
The side part of a sash that connects the lock rail and the lift rail.

Structural PSF
A structural load test performed per ASTM guidelines and standards measured
in pounds per square feet.

Tandem Locks
Usually used in casement applications, where multiple locks are operated simultaneously from a single lever.

Tempered Glass
The same as safety glass. Used in patio doors and other window applications. When the glass breaks, it does not create sharp shards of glass. Instead it breaks into many small glass cubes or chunks.

Tilt Latch
A device at the top of the sash that prevents the sash from falling into the room until the latches are disengaged. When the latches are disengaged, the sash can be tilted in or pivoted in for cleaning.

Transom
A picture window that is usually located or mulled above another window.

True Sloped Sill
The bottom of the master frame, which by design is sloped toward the exterior of the house.

United Inch (U.I.)
The measurement of the width of the window plus the height of the window. (A 24” x 36” window would have a U.I. of 24” + 36”. The U.I. would be 60”.)

United Window and Door Mfg
A leader in the vinyl window industry.

Utility Window
A window where the sash pulls into the house pivoting from the sill or from the header. (Dual positioning)

UV (Ultraviolet light)
The invisible rays of the spectrum that are outside of the visible spectrum at its short-wavelength violet end. Ultraviolet rays are found in everyday sunlight and can cause fading of paint finishes, carpets and fabrics.

UV reflection
The percentage of ultraviolet rays being blocked rather than being transmitted through the window’s glass unit. The higher the number, the lower the percentage of ultraviolet rays being transmitted through the window.

U-value (U-factor)
A measure of the rate of non-solar heat loss or gain through a material or assembly. It is expressed in units of Btu/hr-sq ft-ºF (W/sq m-ºC). Values are normally given for NFRC/ASHRAE winter conditions of 0ºF (18º C) outdoor temperature, 70º F (21º C) indoor temperature, 15 mph wind and no solar load. The U-factor may be expressed for the glass alone or the entire window, which includes the effect of the frame and the spacer materials. The lower the U-factor, the greater a window’s resistance to heat flow and the better its insulating value.

Warm-Edge Technology
The use of low-conductance spacers to reduce heat transfer near the edge of insulated glazing.

Weatherstripping
Material used to form a weather-resistant seal around operable sash.

Weep Holes
Openings cut into siding or accessories to allow for water runoff.

Welded Window
A window that has the ends of the master frame parts heated to several hundred degrees and pressed together during cooling so as to fuse the parts into one continuous piece. The same can also be done for the sashes.