Fenestration jargon takes some getting used to!
See below for an attempt to capture the majority of relevant terms and definitions to make this process as smooth as possible.
Industry test that measures the amount of air leakage through a window or door (the lower the number the better).
Decorative trim positioned directly underneath a window stool and installed flush against the wall.
4-sided unit with a curve at the top.
Colorless, odorless gas used in the air space of double pane Low-E glass to increase the insulating performance.
Decorative glass in a variety of colors/shapes/patterns used to accent a window or door.
The center post between two swinging doors.
Unit with hinged sash that swings outward from the bottom; allows ventilation at the bottom.
Counter-weight mechanism to assist raising or lowering of a double-hung or single hung sash
Window consisting of three or more units that angle out beyond the wall; often configured with a large center unit and two flanking units.
Window consisting of three or more units projecting out from wall to form a radius
High Altitude Capillary Breather Tubes:
Very small diameter tubes placed within the unit that allows equalization of the air space due to high elevation pressure differences.
Exterior trim around the window frame traditionally used to attach the window to the wall
Unit with hinged sash that opens to the side; allows top to bottom ventilation.
Flat, decorative molding used on the interior perimeter of a window or door that covers the space between the unit and rough opening or between units.
Located on double-hung windows where the bottom sash and top sash meet, and the lock/keeper is mounted.
Circle Top™ (Half Round) window:
Half circle unit consisting of a curved top and linear bottom.
Low maintenance covering, or coating attached to the unit exterior.
The size of the opening created when a unit is in a fully open position.
Window located up high on wall; typically, unreachable from ground level.
Roll aluminum that is bent into shape to form a transition piece between the unit exterior and siding/trim.
Storm window and insect screen contained in a single frame.
Water that collects as droplets on the glass/sash/panel interior or exterior under certain conditions (typically cold services when exposed to humidity).
An ornamental molding at the top of the window positioned above the exterior trim.
Double-hung window where the upper sash is shorter than the bottom sash
Percent of the Ultra-Violet (UV) and Visible Light energy from the sun that can cause fabric fading. The lower the number, the less potential for fabric fading. Preferred over just looking at UV transmission.
Visible glass area.
Decorative drip cap:
An ornamental trim piece positioned at the top of the window above the exterior trim that directs water away from the top of the window.
Pressure (measured in pounds per square foot-psf) required by building codes to meet wind load requirements. Our product “PG” -Performance Grade rating is used to determine compliance.
Direct glazed/ direct set:
Glass is directly glazed into frame; stationary unit.
Venting upper and lower sash in a single frame that slide vertically past one another.
A corner joint created by precisely boring matching holes into a door rail and style and joining them together with a dowel pin.
One piece aluminum or vinyl cover installed above windows/doors that directs water away from the top of the unit.
Dual pane/Double pane glass:
Two panes of uncoated (non-Low-E) glass with an air-filled cavity (not argon-blend gas-filled)
A venting window required by building codes for emergency escape and rescue, which are typically required in bedrooms, and which are required to meet certain minimum opening dimensions.
A motorized device that provides for remote operation of an awning window
A government-backed program to help consumers identify energy efficient products.
Window or door with equal spaced grille bars
Decorative door handle plate that conceals the locking mechanism
Wood component fastened to the interior of the window/door that extends the window frame out to the wall depth
A decorative trim positioned around the exterior perimeter of a window or door
Aluminum that is shaped by running it through a dye, typically more durable than roll-formed material
Refers to an opening in a structure such as windows, doors, and skylights. Can also refer to the placement of windows and doors in a building
Removable, semi-transparent material that adheres to and helps protect the glass during construction
non-venting or non-operable
Water resistant material that directs water to a drainage plane or to the exterior surface of a building.
Door unit with multiple hinging panels that can be folded together to create an large, unobstructed opening
Auxiliary lock used on gliding doors to secure the operating panel to the sill
Outer structure of a window or door that holds the sash or panel in position
Hinged door(s) with large glass area surrounded by a wide wood side stiles and a tall bottom rail
Full divided light:
Grille intended to replicate the look of a True Divided Light unit; consists of an interior grille, exterior grille, and spacer between the glass panes
Frame intended for installation direct to the rough opening; opposite of insert window
Glass in a window sash or door panel; the act of installing glass in a window sash or door panel
Wood or vinyl pieces around the perimeter of the glass that covers the space between the glass edge and sash/panel
Gliding door/sliding door:
Door with two or more panels where one panel slides horizontally past another
Gliding window/sliding window:
Window with two sashes, where one sash slides horizontally past the other
Components used to simulate individual pieces of glass within a sash/panel
Metal plate attached to a window or door to strengthen a window or door joint
Half insect screen:
Insect screen that covers the opening area of the operating sash in hung and gliding windows
Opening direction of hinging windows and doors; direction is determined by location of hinge on unit as viewed from exterior
Stain grade wood shaped to the angles of a bay or bow window that form the finished upper and lower interior surfaces
Heavy beam extended across the top of the rough opening to prevent the weight of the wall or roof from resting on the window frame
Impact Resistant glass:
Laminated glass frequently used in hurricane-prone areas for protection from wind-borne debris
Panel/sash that will open only after active panel/sash is opened
A tightly woven mesh attached to a frame; allows outside air ventilation while keeping insects out
A new window unit intended to be installed inside the frame pocket of an existing window
Insulating glass unit:
Two or more glass panes that are sealed together to increase energy efficiency
Window or door frame members that form the top and sides of a unit
Metal brackets used to secure a unit to the rough opening from the interior
Interior frame cover surface where the sash slide on double-hung window
Receiver components that surrounds a window intended to hide the seam between the window and siding
Receiver on a sash that the lock engages
Patio door lock that enables locking and unlocking from the home’s exterior
Layered glass that resists breakage and holds together when broken
Laminated Veneer Lumber (LVL):
Engineered wood consisting of multiple layers of thin wood bonded together
Handle on the bottom of a double hung window that makes it easier to raise/lower the sash
Individual glass panes within a window sash or door panelLock: Mechanism used to secure windows and doors into a closed position
Glass with a low-emissivity coating that restricts heat loss
Step-by-step tool to help in determining the dimensions of replacement windows
Central location on a gliding window or door where the sash/panel overlap
Strong wood joint made by fitting together a slot (mortise) in one board and the matching projecting member (tenon) on the adjoining board
Joining of two or more window or door units together; joint can run vertically, horizontally, or both
The vertical or horizontal joint between individual window or door units that form a combination
Lock that engages the sash or panel in multiple locations; activated by a single motion
Nailing flange / Installation flange:
Narrow attachment strip on the window perimeter that typically used to secure the window to the rough opening
National Fenestration Rating Council is a non-profit organization that provides for fair, accurate and credible energy performance ratings for windows, doors & skylights.
Glass with a texture of pattern of various degrees of opacity that limits visibility through a window or door (see also patterned glass)
Metal arm, gear and handle used to open and close hinged windows
Outdoor/Indoor Transmission Class (OITC):
Measurement standard used to indicate the rate of sound transmission between indoors and outdoors (see also STC)
OX / XO:
“OX” or XO” are used to identify the opening direction of gliding windows/doors; “X” stands for operating while “O” stands for stationary
Refers to the rail, stile, and glass assembly on a door; similar to a window sash
Narrow groove on the exterior outer frame edge of a unit typically used to accept trim or aluminum coil stock
A narrow frame molding that holds a sash or panel in position
Glass that lets in light while obscuring vision (see also Obscure glass)
Performance Grade (PG):
An industry rating for a unit that has been tested for air, water, structural and force entry performance. Used to determine compliance with code required design pressures.
A door panel that can be concealed by a wall; panels slide into wall
Factory painted or stained unit that is ready for installation; no finish coat required
A casement with no crank handle; window is opened by releasing sash lock and pushing the sash outward
Horizontal components of a window sash or door panel framework
Mull that uses a structural material (wood, aluminum, steel, LVL) to provide a stronger joint
Removable Interior grille:
Interior grille that can be readily removed for cleaning
Opening in a wall for the installation of a window or door. The rough opening is larger than the actual unit to allow for shimming and insulating.
Rail, stile and glass components joined together the form the venting capability of a window
Sash glazed /Sash set:
Fixed window with a separate sash and frame intended to replicate the look of nearby venting windows
A tightly woven mesh attached to a frame; allows outside air ventilation while keeping insects out
A compressible surface that inhibits air and water passage
A wedge often made of wood used to plumb and/or level a window or door in the rough opening
Tall, narrow unit placed alongside a window or door
Horizontal member that forms the bottom of a window or door frame
Traditional exterior trim component that attaches underneath and extends out beyond the sill
Simulated divided light:Use of interior and exterior grille with no spacer between the glass panes; used to simulate the look of a window with multiple glass lites
Double-hung styled window in which the top sash is inoperable
Solar Heat Gain Coefficient (SHGC):
A measurement of the sun’s heat energy that passes through the window/door. The lower the value the less heat gain thru the product.
Sound Transmission Class (STC):
Rating system used to measure how much sound is transferred through windows/doors (see also OITC)
The vertical components of a window sash or door panel
Flat, interior trim member located at the sill of a window or door, typically extending into the room and horizontally beyond the extension jambs
A trim member attached to the window or door intended to hold, position or separate components
Sustainable Forest Initiative (SFI):
Forest certification standard dedicated to promoting sustainable forest management
Safety glass that is stronger than annealed glass and breaks into small pieces
Decorative wood component used as a transition door sill to the interior flooring
Top hung insect screen:
Insect screen used on patio door units that are secured from the top; results in smoother operation
A decorative wood piece used to cover the joint between extension jambs or casings
Window positioned directly above another window/door
Glass construction consisting of three distinct layers of glass and two air-spaces
True Divided Light (TDL):
Windows and doors in which multiple smaller glass lites are framed in a single sash or pane
U.S. Green Building Council (USGBC):
Non-profit trade organization that promotes sustainability in how buildings are designed, built, and operatedU-
Commonly used measurement of heat transmission through a window/door. The lower the U-Factor, the better the insulating value.
Unobstructed glass opening:
Visible glass area
Percentage of Ultra-Violet (UV) transmission from the sun’s energy. The lower the number, the potential for reduced fabric fading. (See Damage Function)
Watertight material used to prevent moisture migration around windows and doors
Device that restricts window operation and cannot be disengaged without tools or special effort.
Window or door that opens; operates
Polyvinyl chloride (PVC) material that is very durable and resistant to corrosion.
Visible light transmission:
The fraction of the light allowed to enter through a window
Compressible material designed to seal the sash or panel to the frame
Small holes placed on the exterior of a window or door that allows for water drainage
Window Opening Control Device (WOCD):
Device intended to restrict the opening dimension of a window when first activated to less than 4 inches but can be disengaged to allow full opening of the sash for escape and rescue, but reengages when the sash is closed such that the sash will open to a less than 4 inch dimension when opened again.