American Architectural Manufacturers Association (AAMA) - An organization made up of window and door manufacturers and their suppliers that establishes voluntary standards and specifications for the window and door industry, and certifies material and products that meet the specifications.
Active Panel - Operating portion of a sliding or swing door.
Air Exfiltration - Uncontrollable inside air exiting from a structure, a result of air pressure differences between the interior and exterior of a structure.
Air Infiltration - Uncontrollable outside air entering into a structure, a result of air pressure differences between the exterior and the interior of a structure. Glass surface temperature, by itself, is not an indication of air infiltration.
Air Infiltration / Exfiltration Testing - A test performed on windows and doors to measure the volume of air to pass through them at specific pressure differences between the exterior and the interior sides. Values are recorded at pressure differences equal to wind velocity of 25 and 50 MPH. Results are shown in Cubic Feet per Minute per Square Foot (CFM/SF).
Air Infiltration Barriers (House Wrap) - A flexible membrane which allows the moisture vapors inside the wall cavity to escape, while reducing outside air from entering the wall cavity. Air infiltration barriers come in two basic types: perforated and non-perforated. A perforated wrap is a membrane that starts as a material that does not allow the migration of moisture, once micro-perforated the migration of moisture is allowed. A non-perforated wrap is a spun bonded fiber-mesh; the structure of these materials allows the migration of moisture while inhibiting air infiltration.
Air Space - The space between adjacent layers of glass in a multi-layer insulating glazing unit.
Annealed Glass - Glass that has not been heat strengthened or tempered. Annealed glass, when broken, will fracture into large or small irregular shards.
Anodized - An electrochemical process that converts the aluminum surface into a durable, corrosion-resistant, anodic oxide finish. The anodic oxide finish originates from the aluminum substrate and is composed of aluminum oxide and is fully integrated with the underlying aluminum substrate, so it cannot chip or peel off of the surface. Dyes can be added to produce a variety of colors.
Argon Gas - A noble gas, a colorless, odorless, and inert gas used to fill the airspace in an insulated glazing unit to increase thermal efficiencies.
Astragal - The member that is attached to the meeting stile of one door out of a pair of doors in a double door system that stops the active panel and covers the meeting joint between the active panel and the inactive panel.
Awning Window - A window with one or more sashes, hinged at the top allowing the bottom of the sash to project outward from the plane of the frame.
Balances - A mechanical device used in hung windows as a means of counterbalancing the weight of the sash.
Bay Windows - Three windows assembled together to project out either 30 or 45 degrees from the face of the building.
Blind Stop - The part of the rough opening in which a window or door is to be anchored to that can not be seen after window or door is installed.
Bow Windows - Four or more windows assembled together at a 10 degree angle to each other to project out from the face of the building.
Brick Mold - A trim applied to the exterior perimeter of a window to cover the space between the window and the exterior siding or brick on a building.
Bronze Glass - A glare and heat reducing glass intended for applications where glare control and the reduction of solar heat are required or where tinted glass can add to the aesthetics of a building.
British Thermal Unit (BTU) - The amount of heat required to increase the temperature of one pound of water by one degree Fahrenheit.
Cubic Feet per Minute (CFM) - A unit of measure to determine the volume of air passing through a given area.
Cubic Feet per Minute per Square Foot (CFM/SF) - A unit of measure to determine the volume of air passing through one square foot of an area after the total volume of air has been divided by the square foot of the area.
Condensation Resistance Factor (CRF) - A rating number obtained under specified test conditions to allow a relative comparison of condensation resistance in products of the same size and configuration.
Cam Lock - A lever operated lock with a concealed pawl design used to secure the sash of a projected window to the frame.
Casing - A decorative interior trim that is applied to the inside edge of the jambs and to the rough opening in order to cover the joint between the window and the wall.
Casement - A window consisting of one or more sashes hinged to be opened from the side (adjacent to the jamb), which projects outward from the plane of the frame in the vertical plane.
Check Rails - See Meeting Rail.
Condensation - A natural accumulation of water droplets as the result of water vapor condensing into a liquid after coming in contact with a cold surface. Condensation may occur when a cold window glass or frame is exposed to humid, indoor air.
Conduction - The transfer of heat or cold through a solid material (such as glass or wood).
Cottage Double Hung - A window with two vertically operating sashes in which the upper sash is shorter than the lower sash.
Cripples - The short 2" x 4" members used to frame under the sill or above the header in a rough opening for a window in a frame wall.
Custom Window - One-of-a-kind window designed to meet specific job requirements.
Custom Sizing - Refers to units that are sized for replacement purposes.
Daylight Opening (DLO) - The area of glass that is not covered by the window frame and that light can pass through.
Design Pressure (DP) - A rating that identifies the load, in pounds per square foot, induced by the wind and /or static snow, that a product is expected to withstand in its end-use application. Not to be confused with Performance Grade (PG) or Structural Test Pressure (STP).
Divider - A member that divides glazing into separate vision areas. Dividers are either structural or decorative. Other common terms are muntins, true divided lites (TDL), simulated divided lites (SDL), grilles, grids, or grilles between the glass (GBG).
Door Unit (Patio Door) - One or more panels contained within one master frame with a sill/threshold and with or without mullions or hardware. The operable panels are either hinged or sliding. The hinged panels can swing either inward or outward.
Double Glazing - The use of two panes of glass, which are individually glazed into a window, to increase energy efficiency and provide other performance benefits.
Double-Hung Window - A hung window with two sashes in which both sashes operate.
Drip Cap (Flashing) - A formed aluminum or vinyl piece which is installed across the head of a window or door, and sealed to the building in order to redirect water draining from above, off the face of the window or door.
Egress Hardware - Hardware specifically designed so that smaller windows may achieve clear opening dimensions that can meet building codes requirements.
Egress Window - A window big enough to have a clear opening large enough to meet the egress requirements, as defined by building codes, for exit or entry in case of an emergency. Typical egress opening requirements are 20" minimum width, 24" minimum height, and a minimum opening area of 5.7 square feet
Electric Operators - An electrically operated crank that will open the sash by use of a control switch. This is used in lieu of a manually operated roto crank with an extension pole.
ENERGY STAR® - A joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy to define standards and specifications of energy efficient consumer products. Products that meet ENERGY STAR® requirements for the end-use areas are consider ENERGY STAR® compliant.
Equal Leg Frame - A window frame with the exterior and interior perimeter legs having the same length.
Exterior Glaze - Glass that is set into a window or door from outside the building.
Extrusion - A product made from vinyl or aluminum by pushing material through a die to a desired cross-section shape. Extrusions are made to be window sill, head, jambs, and sash members.
Fenestration - Openings in the building envelope, such as windows, door, roof windows, Tubular Day-lighting Devices, and skylights, designed to permit the passage of air, light, or people.
Fixed Window - Windows that are designed to be non-operable and consist of a glazed frame or a non-operating sash within a frame.
Flanker - A term used to describe the glass or window that is the first and last window in a multi-window assembly.
Flashing Tape - A flexible waterproof membrane, with pressure-sensitive adhesive, used to seal the nailing flange of a window or door to the exterior waterproof membrane on the structure.
Frame - The enclosing structure of a window or a door which fits into or attaches to the wall opening and receives glazing, sash, panels, or vents.
Frame Depth - The overall depth of the window or door as measured from the front of the main frame to the back of the main frame.
Fusion-Welded - When materials are fused by heat to become one when cooled.
Gasket - A closed cell foam sheet applied to a frame member at a joint in order to create a seal to prevent water and air infiltration.
Glass - A hard, brittle substance, usually transparent, made by fusing materials such as soda ash, limestone, and sand under high temperatures.
Glass Size (GS) - The measurement of the actual glass dimension in width and height.
Glazing - (Noun) An infill material, such as glass or a decorative panel, that is installed into a prepared opening of a window or door.
Glazing - (Verb) The act of installing an infill material, such as glass or a decorative panel, into a prepared opening of a window or door.
Glazing Retainers - Also known as glazing beads, glazing stops, or glass stops, is the part of the window or door that can be removed from the frame to replace the glazing substrate.
Glazing Tape - A close cell foam material with pressure sensitive adhesive applied to both sides, used to glaze glass into a window or door.
Glider - See Horizontal Sliding Window.
Grilles - See Dividers or Muntins.
Grilles Between the Glass (GBG) - See Dividers or Muntins.
Gusset - A concealed, strong, right-angle shape used to assemble mitered corners in tubular aluminum extrusions.
Head Board - A flat board used at the top of a bay or bow window and cut to fit the contour of a bay or bow window.
Header - A structural member of the building that spans across the top of the rough opening to prevent the building weight from above the opening from resting on the window frame.
Head - The main horizontal member forming the top of the window or door frame.
Heat Strengthened Glass - Glass that has been heat treated to a specific surface and/or edge compression range to meet the requirements of ASTM C 1048 (kind HS). Note: heat-strengthened glass is approximately two times as strong as annealed glass. Heat-strengthened glass is not considered safety glass. When broken, heat strengthened glass will fracture into large or small irregular shards.
Hinging - A term used to describe the side which the swinging panel is attached to the frame of a window or door as viewed from the exterior side.
Historical - A term used to define window or door products that meet the requirements of historical renovation standards.
Hopper Window - A window with one or more sashes, hinged at the bottom allowing the top of the sash to project inward from the plane of the frame.
Horizontal Sliding Window - A window that consists of one or more sashes that slide horizontally within a common frame and can also contain fixed lites. Note: Typically, operating sashes are identified with an (X) and fixed lites are identified with an (O).
Hung Window - A window consisting of one or more vertically sliding sashes which utilize counterbalancing devices to allow the sash to be opened to any variable position between its fully open and fully closed.
Insulating Glass Certification Council (IGCC) - Directs a program of periodic accelerated laboratory testing and unannounced plant inspections to ensure sealed insulating glass performance in conformance with ASTM E 774-88.
Impact Resistant Glass - Glass that can withstand the impact by windborne debris and stay intact without falling out of the window or door frame.
Inactive Panel - The secondary portion of a sliding or swing door that is either non-operating or cannot operate until the primary portion of the door is operated.
Inside Snap Trim - Interior finishing trim used to trim a window to the interior wall.
Insulating Glass Unit (IG unit or IGU) - Two or more panes of glass separated by a spacer and hermetically sealed to form a single unit with an air or gas filled space between each lite.
Insulating Spray Foam - A two part material that when combined, will swell up to fill a void. It can be used around the perimeter of a window during installation. It is used in lieu of or in conjunction with fiberglass insulation.
Integral Lift Rail - A handle extruded into the frame of the sash that is used to operate the sash.
Integral Mullion - A frame member within a common window frame to separate two or more operating sashes.
Integral Nailing Flange - An anchoring fin extruded into the window frame and is not an added or slide-on piece of material.
Interior Casing - Trim used on the interior perimeter of the window or door to cover the joint between the window and the rough opening.
Interior Glaze - Glass that is set into a window or door from inside the building.
Interlock - A leg on the meeting rail of a sash and frame that when the two members come together one leg slides behind the other leg so the two members cannot separate.
J-Channel - An exterior trim used around the perimeter of the window to cover the joint between the window and siding.
Jack Stud - Building framing members which run from the header to the sole plate and create the jambs of the rough opening. It also carries most of the load from the header.
Jamb Depth w/Flange - The point from the backside of the nailing fin to the interior side of the frame including added on extension jambs.
Jamb Depth w/o Flange - The point from the face of the window to the interior side of the frame including added on extension jambs.
Jamb - The upright or vertical members forming the sides of the frame.
Jamb Extension - An add-on part, either wood or an extruded part, which increases or extends the depth of the window or door frame to the interior side.
Keeper - The part of the locking mechanism that the throw of the lock engages to hold the sash tight to the frame in the closed position.
Keyed Cylinder Lock - Locking device that can be operated from the exterior with the use of a key.
Laminated Glass - Two or more lites of glass permanently bonded together with one or more polymer interlayers.
Leaf - A part of a side-hinge door system, glazed or unglazed, surrounded by a frame. Leaves can be fixed in place (non-operable) or movable (operable).
Lever Lock - See Cam Lock
Lift Handle - An add-on hardware installed on a rail of the sash to make it easier to raise or lower the sash.
Limit Stop - An add-on hardware that limits how far a sash in a window can open.
Lite (light) - A pane of glass or an insulating glass unit (IGU) used in a window or a door. Industry literature will frequently spell it "Lite" to avoid confusion with visible light.
Load - Pressure differences between the exterior and interior sides of a window or door.
Lock Handle - A mechanism to operate the tie bar on a multi-point locking system.
Lockset - A complete door lock system comprised of the lock mechanism together with knobs, keys, plates, strikes, and other accessories.
Lock Strike - See Strike Plate.
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. There are two basic types of Low E glass. The first, vacuum or sputter coated Low E, is referred to as soft-coat. The second is pyrolytic Low E, commonly referred to as hard-coat.
Main Frame - The enclosing structure of a window or door which fits into or attaches to the wall opening and receives glazing, sashes, panels, leaves, or vents.
Meeting Rail, Check Rail or Meeting Stile - The member of the window that is created when two adjacent horizontal or vertical leaf or sash members come together when in the closed position.
Masonry Opening - Brick, stone, or a CMU block opening into which a window or door unit is to be installed.
Molding - An ornamental exterior trim around the perimeter of a frame.
Mulling - The act of combining two or more windows or doors together to create different and larger window or door configurations.
Mullion or Mull - Vertical or horizontal members that allow the assembly of two or more windows or doors together for a multiple window or door configuration.
Multi-Point Lock - A system that secures the sash to the frame at two or more points by the operation of one handle.
Muntins - A fabricated product that is placed into the air space of an IGU to simulate the appearance of a divided lite. They do not provide structure to the glass.
National Fenestration Rating Council® (NFRC) - A non-profit organization that provides fair, accurate and credible energy performance ratings for windows and doors.
Nailing Flange - A leg protruding out from around the perimeter of the frame which overlaps the edge of the rough opening in which the window can be anchored to the rough opening.
Negative Indoor Pressure - The air is being removed from inside the building faster than it is being replaced, which causes uncontrollable outside air to replace it through any opening in the building envelope.
Negative Pressure - Load acting in the outward direction on a window or door.
Non-Keyed Cylinder - Locking device that cannot be operated from the exterior with the use of a key.
Outdoor / Indoor Transmission Class (OITC) - Testing is done to measure the effectiveness of a window or door at reducing the transmission of exterior sounds, aircraft, trains, automobiles, and other low to mid frequency noise sources - 80 to 4000 hertz, from passing into the interior of a building. The OITC rating is calculated in accordance with ASTM E1332. The higher the rating value is the better the window will reduce the transmission of sound.
Obscure Glass - See Patterned Glass
Panel - The members of a sliding door or sliding door side lites within a frame which are designed to accommodate the glazing.
Panning - A window installation system design to cover up an old window frame in an existing opening and is ready to receive the installation of a new window without removing the old window frame.
Patterned Glass - Glass that has been rolled to create a distinct pattern on one or both surfaces that will obscure the vision through the glass but allows light to pass through. It is also known as obscure glass.
Pivot Bar - A metal part used to connect the bottom of a sash to the counterbalancing system on a tilt-in double hung or single hung window.
Pocket Depth - A dimension in a rough opening, starting at a point in which the front part of the window is to align with, face of window or back of flange, ending at a point in which the back side of the window is to butt up against.
Pole Crank - An extension pole used to open or close windows that would be inaccessible because of the height of the operator off the floor.
Positive Pressure - Load acting in the inward direction on a window or door.
Performance Grade (Grade or PG) - A numeric designator that defines the performance of a product in accordance with AAMA/WDMA/CSA Standard/Specification. Performance grade (PG) is achieved only upon successful completion of all applicable tests specified in Clause 5 of the AAMA/WDMA/CSA Standard/Specification. Not to be confused with Design Pressure (DP) or Structural Test Pressure (STP).
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 or center point of a spring line to the arc or circumference of a circle.
Rafter - Structural members of a roof that support the roof load and run from the ridge to the eaves.
Rails - The horizontal members of the framework of a sash, door or other panel assembly.
Reinforcement - The material added to individual sash, leaf, panel, frame members, or mulled assembly to increase strength and/or stiffness.
Rolled Aluminum - Flat stock aluminum that is ran through a series of rollers to produce a desired profile.
Roto Operator - Manually operated device for opening and closing casement or awning windows. Also known as Roto-Cranks.
Rough Opening - A hole in the building envelope used for the installation of a window or door.
Round Top Window - A window with a frame that has a radius head.
Sash - The members of a window within a frame which are designed to accommodate the glazing and operate as intended with the window.
Sash Balance - See Balances
Sash Cord - In double-hung windows, the rope or chain that attaches the sash to the counter balance.
Sash Lock - A hardware device designed to hold the sash securely to the frame in the closed position.
Sash Dimension - Horizontal and vertical measurement across the face of the sash.
Screens - A product that is used with a window or a door, consisting of a loosely woven mesh of metal or fiberglass stretched over and fastened to a frame, used to keep out insects but allow ventilation when the sash is opened. It is not for the purpose of providing security or retention of objects or persons from the interior.
Seat Board (Sill Board) - A flat board used at the bottom of a bay or bow window and cut to fit the contour of a bay or bow window.
Shaped Window - A window with one or more frame members that are either radius or the corners are not at right angles to each other.
Shims - A tapered or flat material used to separate a window or a door frame from the rough opening and to maintain a sealant joint after installation.
Side Lite - An operable or non-operable product that is designed to be a companion product installed on one or both sides of an operable door or a fixed door. Side lites often have their own separate frame or are contained within the frame of a composite assembly.
Sill - The horizontal member forming the bottom of a window or door frame.
Sill Plate - A framing member used to form the bottom of a rough opening in a building envelope.
Simulated Divided Lite - Grilles adhered to the interior and exterior surfaces of the glass in a window, sometimes with or without internal muntin bars, this is to simulate the look and provide the illusion of a True Divided Lite.
Single Glazing - The use of one pane of glass in a window or a door.
Single Hung - A hung window with one operating sash and one non-operating sash.
Slide Latch - See Tilt Latch
Slope - The measure of rise over run on an angled surface.
Snap-in Glazing - Usually a vinyl or aluminum material that holds glass in the sash or frame.
Solar Heat Gain Coefficient (SHGC) - The fraction of the heat from the sun that enters through a window. SHGC is expressed as a number between 0 and 1. The lower a window's SGHC, the less solar heat it transmits.
Spandrel Glass - An insulated glass unit consisting of one pane of clear heat-strength glass seal to one pane of glass that transmits no light whatsoever.
Spacer - The material used to separate two pieces of glass to create an air chamber in an insulated glass unit.
Special Shapes - See Shaped Window.
Specification - A written document often accompanying architectural drawings, giving such details as scope of work, materials to be used, installation method, required performance, and quality for work under contract.
Square Feet - A unit of measurement to describe the area of a surface. Width of an area (in feet) multiplied by the height of an area (in feet).
Stationary Panel - A non-operating sash, or frame on a window or door.
Structural Test Pressure (STP) - The pressure differential applied to a window or door. In AAMA/WDMA/CSA Standard/Specification, the STP is 150% of design pressure (DP) for windows and doors. Not to be confused with Performance Grade (PG) or Design Pressure(DP).
Strike Plate - A metal plate with or without a curved edge fabricated with one or more slots or holes used to receive the latch and dead bolt on the locking hardware of a swing door.
Storm Door - A supplemental door installed on the outside or inside of an exterior door.
Sound Transmission Class (STC) - Testing is done to measure the effectiveness of windows, doors, and partitions at reducing transmission of interior noises from speech, television, radio, office equipment and other mid to high frequency noise sources (125 to 4000 hertz). The STC rating is calculated in accordance with ASTM E413. The higher the rating value the better the window will reduce the transmission of sound.
Stiles - The upright or vertical member of a sash or panel on a window or a door.
Stool - Horizontal trim at the sill of the rough opening that butts up to the back of the window sill and extends beyond the interior casing.
Strap Anchors - An installation bracket that is used to reposition the anchor point of a window or door, from anchoring through the frame to anchoring behind the frame of the window or door.
Stud - Vertical framing members that form a frame wall of a structure.
Sub-Sill - An additional member placed under the sill of a window that is used to anchor the window sill to a rough opening without placing an anchor through the window sill itself.
Tempered Glass - Glass that has been reheated to just below the softening point, about 1300 degrees Fahrenheit, and then rapidly cooled. Note: Tempered glass, if broken, will fracture into many small pieces (dice) which are more or less cubical. Tempered glass is approximately four times as strong as annealed glass.
Template - A pattern or of a window, glass, or rough opening from which dimensions and measurements can be determined.
Thermal Break - A material with a low thermal conductance used to separate the exterior side from the interior side of a high thermal conductance material. This is intended to reduce or stop the transfer of heat or cold from the exterior to the interior.
Three-Wide (3W) - Refers to a product or unit when three separate frames are mulled together in a multiple window unit.
Threshold Ramp - A ramp designed to create a gradual slope from the main frame sill of a door to the interior/exterior surface.
Tilt Latch - Lock mechanism embedded or attached to the top of a hung sash in which the throw of the lock engages the jambs of the frame to keep the sash parallel to the frame on a tilt-in sash option.
Transom - An operable or non-operable product that is designed to be a companion product installed above a window or door.
Triple Glaze - An insulated glass unit with three panes of glass, enclosing two separate air spaces.
True Divided Lite - Multiple lites in a single frame separated by a true muntin.
True Muntin - A structural frame member used to divide glass lites in a single frame.
Two-Wide (2W) - Refers to a product or unit when two separate frames are mulled together in a multiple window unit.
U-value - The amount of conductive heat energy (BTU's) transferred through 1 square foot of a window or door for each 1 degree Fahrenheit temperature difference between the indoor and outdoor air. In the USA, values are normally given for winter conditions of 0° F (-18°C) outdoor temperature, 70°F (21°C) indoor temperature, 15 mph wind (with no air infiltration), and no solar heat gain. It is the inverse of the R-Value (U=1/R).
Unit - One single complete product, ready for installation that can either be an individual window or door product or an assembly of multiple windows or doors.
Vapor Barrier - A watertight material, installed between the insulation and the interior drywall, used to prevent the passage of moisture from inside the building into the insulation in the floors, walls and ceilings.
Venting Unit - A window or door that consists of a frame with a sash that operates as intended by design.
Visible Transmittance (VT) - Is the percentage of visible light that is directly transmitted through a window or a door. Visible transmittance is usually expressed as a number between 0 and 1. The higher the VT, the greater the amount of light that will be transmitted through.
Wall Depth - A measurement in the rough opening that is from the face of the exterior sheathing to the face of the interior drywall of a structure.
Weatherstripping - A flexible component used to reduce air leakage, water penetration or both between the sash, leaf, panel, and/or frame. Comes in various types.
Weather-Strip (Fin-seal) - Polypropylene threads piles are woven, or extruded, into a plastic backer with a thin plastic fin that runs down the center of the threads piles.
Weather-Strip (Hollow Bulb Seal) - A flexible hollow tube extruded onto a rigid plastic backing.
Weather-Strip (Foam Bulb Seal) - A foam filled flexible tube extruded onto a rigid plastic backing.
Weep Hole (Weeps) - An opening provided in the sill of the window or door to allow water to drain.
Wicket Screen - A product that is used on a projected window with no operating hardware, consisting of a loosely woven mesh of metal or fiberglass stretched over and fastened to a frame which has a operable leaf that is opened to manually operate the sash, used to keep out insects, but allow ventilation when the sash is opened. It is not for the purpose of providing security or retention of objects or persons from the interior.
Wind Load - Force exerted on a surface by the velocity of moving air.
Window Dimension - The outside horizontal and vertical measurement of the window, not including nailing flanges.
Wire Glass - Glass with a layer of wire mesh completely embedded into the glass.
Wrap Around Glazing - The perimeter edge of the glass is wrapped with a flexible gasket, then a U-channel is placed over the gasket and pressed onto the gasket and the glass. This is done on all four sides of the glass and the corners are fastened together to complete the assembly.