Glossary of Terms

A

AAMA (American Architectural Manufacturers Association)

A professional organization that developed performance standards, testing methods, and certification programs for windows, doors, skylights, curtain walls, and other fenestration products.

Air Infiltration (AI)
A measurement of how much air passes through a closed and locked window. Lower numbers indicate better performance.

Argon Gas
A colorless and odorless gas used to fill the airspace between insulating Low E glass. The addition of argon greatly increases the insulating performance of the Low E glass.

Astragal
A permanently attached fixed divider bar that creates the appearance of divided lites by visually separating the glass into smaller sections.

ASTM International (America Society for Testing and Materials)

A globally recognized organization that develops voluntary standards for testing the quality, safety, and performance of products and materials.

B

Balancers
A block and tackle system used in the jamb liner of double hung or single hung units.

Balance System
A mechanism inside the window frame that helps the sash open, close, and stay in position.

BlackCore^TM

Elevate’s true black vinyl window technology features a reinforced frame that is black through and through, paired with a black laminate designed to maintain its bold appearance in demanding climates.

Breathing Tube

A small vent tube installed in an insulated glass (IG) unit that equalizes air pressure between the sealed air space and the surrounding atmosphere during shipping or installation at different elevations. The tube is sealed after installation to maintain the insulating glass unit’s performance.

C

Cam Lock
A lever operated lock which is used to prevent intrusion through the sash.

Capillary Tubes
A tube inserted into the insulating glass spacer that allows the inside and outside air pressure to equalize in higher elevations.

Casement Window
A combination of frame, sash, weather-strip, concealed hinges and operating device assembled as a complete and properly operating unit. Operating casements have a crank handle for smooth operation.

Condensation
Moisture that forms on glass surfaces when warm, humid air comes into contact with a cooler surface.

D

Design Pressure (DP) Rating
A performance rating that indicates a window’s ability to withstand wind pressure, water penetration, and structural loads. Higher DP ratings generally indicate stronger performance.

Divided Light

A window style featuring a pattern of muntin bars that divides the glass into the appearance of multiple lites (panes).

Double Hung
Double hung windows have two movable sash which operate vertically. Double hung sash are held in an open position with the use of coil spring block and tackle balancing devices.

Double-Pane Glass
Two panes of glass separated by an insulating airspace to improve energy efficiency. Also see IGU.

Double-Strength Glass

Double-Strength Glass (DSB) is glass that is thicker and more durable than standard single-strength glass. In residential windows, double-strength glass is commonly used to provide improved strength, durability, and resistance to everyday impacts.

E

Egress Window

A window that meets building code requirements for emergency escape and rescue openings, typically used in bedrooms and basements.

Extrusion
An article or product of vinyl or metal-made by the process of extruding. Extrusions include vinyl sill and head jamb tracks, vinyl jamb liners and aluminum used on the exterior of units.

F

Fenestration

Fenestration refers to the arrangement, design, manufacture, and installation of openings in a building envelope, including windows, doors, skylights, and other glazed openings.

Flashing Tape

Flashing is a weather-resistant material installed around windows, doors, and other building openings to help direct water away from the structure and prevent moisture intrusion.

Frame
The stationary portion of a window that encloses either the glass (direct glaze) or the sash (operating or stationary) and consists of the head jamb (top), sill (bottom), side jambs and jamb extension.

G

Glass Size (GS)
The measurement of the actual glass, not the visible glass.

Glazing
Installing glass into windows and doors. INSULATING GLASS: two panes of glass separated by a spacer and hermetically sealed together with dead air space between the panes.

Glazing Bead
Strips of profiled vinyl used to hold the glass in position in the sash. A vinyl bead is held in place by extruded barbs positioned in the kerf. Aluminum caps may be used over the vinyl bead in some cases.

Glazing Tape
A two-sided adhesive tape placed between the glass rabbet and the glass and/or the glazing bead and glass of some unit types.

Grey Glass

Gray-tinted glass that is designed to reduce glare, heat, and sunlight entering the home.

Grey 31 Glass

A gray-tinted glass that reduces glare, solar heat gain, and UV exposure while allowing approximately 31% of visible light to pass through, helping improve occupant comfort and energy efficiency. This provides the most privacy during both daylight and nighttime hours.

Grilles Between Glass (GBG)

Aluminum flat or contour bars divide the glass visually. Because the grille is between the glass, grilles do not become misplaced or damaged. Cleaning is easy without small panes of individual lites.

H

Head Jamb

The top member of a frame.

Horizontal Slider
A window with one or more operable sashes that slide horizontally for ventilation.

I

Inspire Series

An all-encompassing vinyl window system engineered to deliver durability, energy efficiency, contemporary design, and dependable performance for both new construction and replacement applications.

Impact Series

A storm-rated window specifically designed and tested to withstand severe weather conditions, including high winds, wind-driven rain, and, in some cases, impact from flying debris.

Insulated Glass Unit (IGU)
Two or more panes of glass sealed together with an insulating space between them.

J

Jamb Extension
A jamb-like member, usually surfaced on four sides, which increases or extends the depth of the exterior or interior window or door frame; jamb extensions imply a larger depth than “wood jamb liners.”

Jamb Liner
Thin strips of wood attached to the head jamb, side jambs and sill to accommodate various wall thicknesses.

K

Keeper
The keeper is the part of the window that the lock hooks onto when you lock the window.

L

Laminate

Heat-reflective exterior laminate used to reduce heat absorption and preserve color integrity over time.

Laminated Glass
Glass composed of two sheets of glass fused together with a sheet of transparent plastic between the sheets. When broken laminated glass will generally not leave the opening.

Lever Lock
A lever handle and lever arm operator available as an option on awning units.

Low E Glass
Low E stands for low emissivity. The lower the emissivity the higher the percentage of long-wave radiation blocked thereby improving thermal performance. Low E glass is coated with a thin microscopic, virtually invisible, metal or metallic oxide layer. The primary function is to reduce the U-value by suppressing radiative heat flow. A secondary feature is the blocking of short-wave radiation to impede heat gain.

M

Meeting Rail
The horizontal portion of a sash where two operable sashes meet when closed.

Mulling
The act of attaching two or more window or door units together. The joint is then finished with a mullion center cap or mull trim.

Mullion
The vertical member of a sash, window or door frame between openings in a multiple opening frame. 

N

NFRC (National Fenestration Rating Council)

A non-profit organization that provides standardized energy performance ratings for windows, doors, and skylights.

Nailing Fin
A flange attached to the exterior of a window frame used to secure the window to the wall during new construction installation.

O

Obscure Glass
Glass formed by running molten glass through special rollers. These rollers have a pattern on them causing the glass to become patterned and thus obscure.

Operation
Our drawings always illustrate the window sash or door panels as if you are looking at it from the exterior. X means operating, O means stationary.

OX
The letters OX or XO identify the operation of window or door units as viewed from the exterior. The letter O stands for stationary while the letter X stands for operating.

P

Panel
Either the stationary or operator frame with glass used on door products.

Picture Window
A fixed, non-operable window designed to maximize views and natural light.

R

R-Value
The resistance a material has to heat flow. Higher numbers indicate greater insulating capabilities.

Radius
The length of an imaginary line from the center point of a circle to the arc or circumference of a circle.

Rails
The cross or horizontal members of the framework of a sash, door, or other panel assembly.

Rain Glass

A textured privacy glass that resembles falling rain while allowing natural light into the home.

Replacement Glass

Replacement glass is a new glass unit installed into an existing window sash or frame to replace glass that has been damaged, broken, or has experienced seal failure, without replacing the entire window.

Retro-Sizing
Refers to units which are sized for replacement purposes.

Rough Opening
The opening in the wall where a window or door unit is to be installed. Openings are larger than the size of the unit to allow room for insulation and to shim the unit square.

S

Sash
A sash is the portion of a window that holds the glass and is typically the part that moves when the window is opened or closed. Depending on the window style, a sash may be operable (movable) or fixed (non-operable).

Sash Lock
A locking device which holds a window shut, such as a lock at the check rails of a double hung unit. Larger units utilize two locks.

Sash Opening (SO)
The opening between wood frame members for both height and width (disregarding any jamb hardware tracks).

Sash Width
Horizontal measurement across the face of a sash.

Screens
A mesh barrier that allows ventilation while helping keep insects and debris outside.

Simulated Divided Lites (SDLs)

Muntins permanently adhered to the interior and exterior of the glass.

Side Jamb
The side (vertical) member of a frame.

Sill
The horizontal member forming the bottom of a window or exterior door frame; the lowest member of the frame of a structure, resting on the foundation and supporting the frame.

Single Hung
A window very similar to a double hung window, except that the top sash is stationary or non-operable.

Solar Heat Gain Coefficient (SHGC)
A measurement of how much solar heat passes through a window. Lower numbers generally help keep homes cooler in warmer climates.

Spacer
Used to separate the two pieces of glass in an insulating glass panel.

STC (Sound Transmission Class)
STC is a rating that measures how effectively a window reduces the transmission of airborne sound from outside to inside a building. The higher the STC rating, the greater the window’s ability to block noise.

Square Foot
For measuring the area of a unit. RO width (in inches) x RO height (in inches) divided by 144 equals the area in square feet of a unit.

Stationary
A non-operating sash, panel or unit.

Stiles
The upright or vertical perimeter pieces of a sash, panel or screen.

T

Tempered Glass
Tempered glass is safety glass that has been heat-treated to make it significantly stronger than standard glass. If broken, it shatters into small, pebble-like fragments rather than large, sharp shards.

Tilt Latch
A mechanism that allows certain window sashes to tilt inward for cleaning.

U

U-Factor
A measure of total heat flow through a window or door barrier from room air to outside air. Lower numbers indicate greater insulating capabilities.

Unit
One single product such as a one-wide casement.

V

Vinyl Glazing Bead
A vinyl extrusion used on clad units which serves the same purpose as a wood glazing bead for wood units.

Vinyl Window
A window manufactured primarily from PVC (polyvinyl chloride), valued for durability, energy efficiency, and low maintenance.

Visible Transmittance (VT)

A measurement of how much visible light passes through a window. Higher numbers allow more natural daylight into a home.

W

Weatherstripping
A strip of resilient material designed to seal the sash and frame members in order to reduce air and water infiltration.

Weep Holes

Weep holes are small openings designed into a window frame that allow water that enters the window’s drainage system to exit safely to the exterior.

Window Opening Control Device (WOCD)
A safety device that limits how far a window can open to help reduce the risk of falls, particularly in homes with young children.

X

XO

The letters OX or XO identify the operation of window or door units as viewed from the exterior. The letter O stands for stationary while the letter X stands for operating.