During the process of purchasing windows you're going to come across some terms that you may have never heard before. To help we've collected some of them together and provided an explanation for each.
Air infiltration: Industry test that measures the amount of air leakage through a window or door (the lower the number the better).
Apron: Decorative trim positioned directly underneath a window stool and installed flush against the wall
Arch window: 4 sided unit with a curve at the top
Art glass: Decorative glass in a variety of colors/shapes/patterns used to accent a window or door
Astragal: Center post of a double door attached to the fixed or inactive door panel
Awning window: A window hinged at the top the sash swings outward from the bottom.
Balancer: Counter-weight mechanism to assist raising or lowering of a double-hung or single-hung sash
Bay window: Window consisting of three or more units that angle out beyond the wall; often configured with a large center unit and two flanking units
Bow window: 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.
Brick mould: Exterior trim around the window frame traditionally used to attached the window to the wall
Casement window: A window hinged on either side the sash opens horizontally opposite the hinge.
Casing: 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
Check rail: 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
Cladding: Low maintenance covering or coating attached to the unit exterior to protect it from the elements
Clear opening area: The size of the opening created when a unit is in a full open position
Clerestory: Window located up high on wall; typically unreachable from ground level
Coil stock: Roll aluminum that is bent into shape to form a transition piece between the unit exterior and siding/trim
Condensation Resistance: Condensation Resistance (CR) measures how well a window resists the formation of interior condensation. CR is expressed as a number between 1 and 100. The higher the number, the more resistant to condensation formation. Condensation Resistance ratings are determined under specific laboratory conditions. Actual condensation performance is a function of temperature, humidity and air movement as well as other uncontrolled, site specific factors.
Combination unit: Storm window and insect screen contained in a single frame
Condensation: Water that collects as droplets on the glass/sash/panel interior or exterior under certain conditions (typically cold surfaces when exposed to humidity).
Conversion kit: Retrofit kit to add tilting capability to 1968 and newer Andersen® Perma-Shield® Narroline® windows
Cornice: An ornamental molding at the top of the window positioned above the exterior trim
Cottage window: Double-hung window where the upper sash is shorter than the bottom sash
Design Pressure: Pressure (measured in pounds per square foot-psf) required by building codes to meet windload requirements. Our product "PG" -Performance Grade rating is used to determine compliance.
Direct glazed/ direct set: Glass is directly glazed into frame; stationary unit
Double-hung: Venting upper and lower sash in a single frame that slide vertically past one another
Dowel joint: A corner joint created by precisely boring matching holes into a door rail and style and joining them together with a dowel pin
Drip cap: 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)
Egress window: A venting window large enough to be used as an emergency exit. Check local codes for egress requirements in your area.
ENERGY STAR®: A government-backed program to help consumers identify energy efficient products.
Equal lite: Window or door with equal spaced grille bars
Escutcheon plate: Decorative door handle plate that conceals the locking mechanism
Extension jamb: Wood component fastened to the interior of the window/door that extends the window frame out to the wall depth
Exterior trim: A decorative trim positioned around the exterior perimeter of a window or door
Extruded aluminum: Aluminum that is shaped by running it through a die, typically more durable than roll-formed material
Fenestration: Refers to any opening in a structure filled with a window, door or skylight.
Fibrex® material: Exclusive to Andersen, its a composite of wood fiber and PVC polymer thats 2x stronger than vinyl.
Fixed/Stationary: Non-venting or non-operable
Flashing: Water resistant material that directs water away from your windows
Flexiframe®: Andersen brand name for fixed geometric windows shapes (octagon, pentagon, trapezoid)
Folding door: Door unit with multiple hinging panels that can be folded together to create an large, unobstructed opening
Foot lock: Auxiliary lock used on gliding doors to secure the operating panel to the sill
Frame: Outer structure of a window or door that holds the sash or panel in position
French casement window: Unit with two venting sash that open outward to provide a large center opening with no center post
French door: 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
Full frame: Frame intended for installation direct to the rough opening; opposite of insert window
Glazing: Glass in a window sash or door panel; the act of installing glass in a window sash or door panel
Glazing bead: 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 sash, where one sash slides horizontally past the other
Grilles/Muntins/Dividers/Bars/Grids: Components used to simulate individual pieces of glass within a sash/panel
Grilles-Between-the-Glass (GBG's)/Finelight™: Grille bars that are placed between the glass panes; allows for easy cleaning
Gusset plate: Metal plate attached to a window or door to strengthen a window or door joint
Half insect screen: Insect screen that only covers the lower sash area of a double-hung windows
Handing: Opening direction of hinging windows and doors; direction is determined by location of hinge on unit as viewed from exterior
Head board/Seat board: Stain grade wood shaped to the angles of a bay or bow window that form the finished upper and lower interior surfaces
Header: Heavy beam extended across the top of the rough opening to divert the weight of the wall or roof around the window
Impact Resistant glass: Laminated glass frequently used in hurricane-prone areas for protection from wind-borne debris
Insect screen: A tightly woven mesh attached to a frame; allows outside air ventilation while keeping insects out
Insert window: 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
Jalousie window: Louvered window with multiple horizontal glass sections that rotate open or closed
Jamb: Window or door frame members that form the top and sides of a unit
Jamb clips: Metal brackets used to secure a unit to the rough opening from the interior
Jamb liner: Interior frame cover surface where the sash slide on double-hung window
J-channel: Receiver components that surrounds a window intended to hide the seam between the window and siding
Joining: Two or more window or door units joined together with mull materials or Andersen’s Easy Connect joining system; joint can run vertically, horizontally or both.
Keeper: Receiver on a sash that the lock engages
Keyed lock: Patio door lock that enables locking and unlocking from the home's exterior
Laminated glass: 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
Lift: Handle on the bottom of a double hung window that makes it easier to raise/lower the sash
Light/Lite: Individual glass panes within a window sash or door panel
Lock: Mechanism used to secure windows and doors into a closed position
Low-E glass: Glass with a low-emissivity coating that restricts heat loss
Masonry opening: Opening in a brick, stone or stucco wall where a window or door is installed
Measurement guide: Step-by-step tool to help in determining the dimensions of replacement windows
Meeting stile: Central location on a gliding window or door where the sash/panel overlap
Monolithic glass: Laminated glass that has no air space; used in specific situations such as some coastal applications
Mortise-and-tenon: Strong wood joint made by fitting together a slot (mortise) in one board and the matching projecting member (tenon) on the adjoining board
Mullion: The vertical or horizontal joint between individual window or door units that form a combination
Multi-point lock: 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 and provide added protection from water infiltration
NFRC: National Fenestration Rating Council is an non-profit organization that provides for fair, accurate and credible energy performance ratings for windows, doors & skylights.
Obscure glass: Glass with a texture of pattern of various degrees of opacity that limits visibility through a window or door (see also patterned glass)
Operator: 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
Palladian window: Large, arch-top window flanked by smaller windows on each side
Panel: Refers to the rail, stile and glass assembly on a door; similar to a window sash
Panning kerf: Narrow groove on the exterior outer frame edge of a unit typically used to accept trim or aluminum coil stock
Parting stop: A narrow frame molding that holds a sash or panel in position
PassiveSun™ glass: Andersen brand name for a glass type ideal for situations where solar heat gain is desired, typically in passive solar building designs.
Passive panel/sash: Panel/sash that will open only after active panel/sash is opened
Patterned glass: Glass than 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.
Perma-Shield®: Andersen brand name for low-maintenance exterior cladding
Plinth block: Decorative wood block typically found at the top corners of the unit that creates a transition from vertical to horizontal interior trim
Pocket door: A door panel that can be concealed by a wall; panels slide into wall
Pre-finished: Factory painted or stained unit that is ready for installation; no finish coat required
Pultrusion: Strong, stiff composite material, in profile form, made from polymeric resin and glass fiber. Also used to refer to the process for producing these profiles
Push-out casement: A casement with no crank handle; window is opened by releasing sash lock and pushing the sash outward
Rail: Horizontal components of a window sash or door panel framework
Reinforced mull: 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
Reverse Cottage/Oriel window: Double-hung window where the upper sash is larger than the bottom sash
Rough opening: 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.
Sash: 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
Seal: A compressible surface that inhibits air and water passage
Segmented arch: Multiple arch windows mulled horizontally to provide a single continuous arch
Shim: A wedge often made of wood used to plumb and/or level a window or door in the rough opening
Sidelight: Tall, narrow unit placed alongside a window or door
Sill: Horizontal member that forms the bottom of a window or door frame
Sill Nose: 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
Single-hung: Double-hung styled window in which the top sash is inoperable
SmartSun™ glass: Andersen brand of a glass option that reduces solar heating but allows high visible light transmission
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)
Springline™ windows: Round top picture windows
Stile: The vertical components of a window sash or door panel
Stool: Flat, interior trim member located at the sill of a window or door, typically extending into the room and horizontally beyond the extension jambs
Stop: A trim member attached to the window or door intended to hold, position or separate components
Stormwatch® protection: An Andersen brand name for a series of upgrades you can specify to meet increased code performance in coastal areas. Check your local codes for performance requirements in your area
Sun glass: Tinted glass that reduces heat gain
Sustainable Forest Initiative (SFI): Forest certification standard dedicated to promoting sustainable forest management
Tempered glass: Safety glass that is stronger than annealed glass and breaks into small pieces
Threshold: Decorative wood component used as a transition door sill to the interior flooring
Top hung insect screen: Insect screen used on patio door and are secured from the top; results in smoother operation
Transition block: A decorative wood piece used to cover the joint between extension jambs or casings
Transom: Window positioned directly above another window/door
Triple pane: 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 panel
TruScene® insect screens: Unique to Andersen this patented micro-fine stainless steel mesh provides 50% more clarity than typical Andersen insect screen cloth
U.S. Green Building Council (USGBC): Non-profit trade organization that promotes sustainability in how buildings are designed, built and operated
U-Factor: 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
UV protection: Percentage of Ultra-Violet (UV) transmission from the sun's energy. The lower the number, the potential for reduced fabric fading. (See Damage Function)
Vapor barrier: Watertight material used to prevent moisture migration around windows and doors
Vent Limiter: Device that restricts window operation and cannot be disengaged without tools or special effort.
Venting unit: Window or door that opens; operates
Vinyl: 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
Weatherstrip: Compressible material designed to seal the sash or panel to the frame
Weep holes: 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.