Definition:         A - E     •     F - H     •     I - N     •     O - S     •     S - Z

AAMA - American Architectural Manufacturers Association is a trade association of firms engaged in the manufacturing and sale of architectural building components and related products.

Absorptance - The ratio of radiant energy absorbed to total incident radiant energy in a glazing system.

Acoustic Windows - Windows used to help reduce the amount of sound that enters the home.

Acrylic - A general purpose glazing material with excellent optical clarity, weather durability, good chemical resistance and thermoformability.

Active Leaf - Usually the first operating leaf in a door having a pair of leaves; the leaf to which the latching or locking mechanism is attached.

ADA Threshold - A wheelchair-accessible door threshold. This type of threshold is not to exceed 3/4" in height for exterior sliding doors or 1/2" for other types of doors.

Aerogel - A microporous, transparent silicate foam used as a glazing cavity fill material, offering possible U-values below 0.10 BTU/(h-sq ft-°F) or 0.56 W/(sq m-°C).

AIA - American Institute of Architects.

AIF - Acoustic Insulation Factor, a sound-transmission measure used in Canada.

Air Infiltration - The amount doors (the lower, the better) of air leaking in and out of a building through cracks in walls, windows.

Air Leakage - The volume of air which flows through a closed window or door in a given length of time as a result of the difference in air pressure on its opposite faces.

Allowable Stress - The maximum unit stress permitted under working loads by codes and specifications.

Alloy - A composition of two or more metals to obtain a desired property.

Ambient Temperature - Temperature at a given set of environmental conditions. Typically, the surrounding localized air temperature.

Anchor - Any device used to secure a building part or component to adjoining construction or to a supporting member.

Anneal - To soften a metal piece and remove internal stresses by heating the piece to its critical temperature and allowing it to cool very slowly.

Annealed Glass - Glass that has not been heat-treated and is essentially strain free; often referred to as " float glass."

Annealing - Heating above the critical or recrystallization temperature, then controlled cooling of metal, glass, or other materials to eliminate the effects of cold-working, relieving internal stresses, ductility, or other properties.

Anodic Coating - The surface finish resulting from anodizing. Coatings may be produced by clear, integral color or electrolytically deposited color processes. Also see Anodize.

Anodize - A process that provides a hard durable oxide film on the surface of aluminum. This coating can produce coloring and finishing that both protects and beautifies the aluminum.

ANSI - American National Standards Institute is an independent association of trade organizations, technical societies, professional groups and consumer organizations which establishes and publishes standards at the national level.

Apron - The finished board placed against the wall surface immediately below a window stool.

Arch Window - Half-circle picture window.

Argon - An inert, non-toxic gas used in insulating glass units to reduce heat transfer.

ASCE - American Society of Civil Engineers.

ASHRAE - American Society of Heating, Refrigeration and Air Conditioning Engineers.

ASTM - American Society for Testing and Materials. A nonprofit organization that establishes standard tests and specifications for construction materials; such tests and specifications usually are referred to by the abbreviation ASTM followed by a numerical designation.

Astragal - The center member of a double door, which is attached to the fixed or inactive door panel.

Attenuation - Reduction in strength of sound measured in decibels (dBs).

Automatic Operator - Power-operated, door-activated device and control, actuated by approaching traffic or remote switch.

Awning Window - A type of window with a top-hinged sash that swings out at the bottom.

Back Bedding - The process of adhering and sealing glass to a frame or sash.

Backer Rod - A round, compressible material, either open or closed cell, that’s placed into voids between materials to insulate and allow a backing for the application of sealant.

Baffle - A material used in windows and doors to impede the flow of water or air into the framing system through weep slots.

Balance - A mechanical device (normally spring-loaded) used in single- and double-hung windows as a means of counterbalancing the weight of the sash during operation.

Balance Shoe - Nylon hardware that slides in hung window jambs and connects the balance with the sash.

Bay Window - A composite of three windows, usually made up of a large center unit and two flanking units at 30- or 45-degree angles to the wall. A bay projects from the wall of the structure.

Bead - A molding or stop placed around a window frame to hold the glass in place by pressure.

Bearing Wall - A wall that supports loads in addition to its own weight.

Billet - A cylindrical-shaped section of aluminum alloy used as the starting stock in an extrusion.

Bite - Distance by which the inner edge of the aluminum frame glazing pocket or stop overlaps the glass. Also termed purchase, edge cover or engagement.

Bituminous Paint - A low-cost paint containing asphalt or coal tar used to isolate aluminum from mortar, concrete or masonry.

Block Frame - Non-finned frame that can be used as new or retrofit installation in a block (concrete) wall application or as a wood window replacement frame.

BOCA National Codes - A series of performance-oriented model A series of performance-oriented model codes responsive to the latest advancements in construction technology. Building Officials and Code Administrators (BOCA) International, Inc. was founded in 1915. Area of influence: Northeast region of the U.S. Replaced by ICC codes.

Bond - The joining together of building materials to ensure solidity.

Bond Breaker - A release type of material used to prevent adhesion of the sealant to the back-up material.

Bottom Rail - The bottom horizontal member of a window sash.

Bow Window - A composite of four or more window units in a radial or bow formation gently curved contour. Bow windows also project from the walls of the structure.

Brake Metal Shape - Aluminum sheet stock bent or "broken" to desired shape, as required by specific job conditions, on a power or manual press brake. This shape is often used to cover conditions which cannot be covered by a stock extruded aluminum shape.

Brick Molding - A standard trim piece that covers the gap between the window frame and masonry.

Btu (B.T.U.) - An abbreviation for British Thermal Unit, the heat required to increase the temperature of one pound of water one-degree Fahrenheit.

Bull Nose - Convex rounding of a member, such as an extruded aluminum snap-on radius face cover used on aluminum-curtain walls.

Butt Hinge - A hinge designed for application to the edge of a door consisting of two rectangular metal plates joined together with a pin.

Butt Hung Door - A door hung on butt hinges.

Butt Joint - A meeting of two members squarely.

Butyl - A synthetic rubber formed by the co-polymerization of isobutylene with isoprene. It is used as a sealant and as an architectural glazing tape.

Cantilever - A beam, girder or truss overhanging one or more supports.

Casement handing - Side that the hinge in on. For residential windows, the hinge side is looking from the outside. For commercial windows, the hinge side is looking from the inside.

Casement Window - The whole sash swings in or out from the jamb of the window and it either uses a crank-out system or a friction system of operation. It’s the best window choice for catching breezes and providing cross-ventilation.

Casing - Exposed molding or framing around a window or door, on either the inside or outside to cover the space between the window frame or jamb and the wall.

Caulking - Sealants used to seal fixed and movable construction joints to prevent infiltration.

Center of Glass - All-glass area of a window except that within 2.5" (10cm) from the edge of the glass – used in measuring and calculating glazing performance such as R-values and U-values.

CFM - Cubic Feet per Minute.

Chamfer - To bevel a sharp external edge. A beveled edge.

Check Rail - The bottom horizontal member of the upper sash and the top horizontal member of the lower sash which meet at the middle of a double-hung window.

Cladding - An exterior covering or skin applied to framing or a structure for aesthetic or protective purposes.

Clerestory Window - A window placed vertically in a wall above one's line of vision to provide natural light -- often at the intersection of two offset roof planes.

CMR - Centerline of Meeting Rail – a reference line used to locate integral mullions and/or size oriel (unequal) sash, e.g., "the height of the lower sash shall be 22" from the frame sill to CMR."

Column - A structural vertical compression member. It is usually a long and slender post or pillar.

Compatibility - The ability of two or more materials to exist in close and permanent association for an indefinite period with no adverse effect on one another.

Composite Frame - A frame consisting of two or more materials; For example, a white interior with a beige exterior.

Compression Gasket - A method of securing the glass into the aluminum frame glazing pocket by using a soft gasket on one side of the glass and a firm, dense gasket called a wedge on the other. Also see Wedge Glazing.

Condensation - The change of a gas to a liquid state. Because warm air can hold more water vapor than cold air, as warm air cools, its ability to hold water vapor is reduced. Excess moisture condenses on the warm side of glass. E.g., condensation on the outside of a glass of ice water.

Condensation Gutter - A trough for carrying off condensed or infiltrated water; this may be drained to the exterior or allowed to evaporate.

Condensation Resistance F - Condensation Resistance Factor (CRF) measures the ability of a product to resist the formation of condensation on the interior surface of the product.

Conduction - A process of heat transfer whereby heat moves directly through a material by molecular agitation. The handle of a cast-iron frying pan becomes hot due to conduction.

Conductivity - The transfer of heat through a given material – see U-value which is the measure of conductivity, the inverse of R-value.

Convection - A heat-transfer process involving motion in a fluid (such as air) caused by the difference in density of the fluid and the action of gravity. Convection affects heat transfer from the glass surface to room air as well as between two panes of glass.

Cope - To notch an aluminum-framing member such as a channel, etc. so that another member may be fitted against it.

Coped Joint - A joint between two aluminum-framing members where one extrusion is cut to the profile of the second.

Cottage Double-Hung - A double-hung window in which the upper sash is shorter than the lower sash.

Counter bore - To enlarge a hole to a given depth.

Countersink - To form a depression to fit the conic head of a screw or the thickness of a plate so that the face will be level with the surface.

CR - Condensation factor determined using NFRC 500-2004. A relative indicator of a fenestration product's ability to resist the formation of condensation at a specific set of environmental conditions.

Crack Length - Total outside perimeter of a window sash/vent; no longer used to define the AAMA air-infiltration rate.

Crazing - Minute cracks in a surface or coating caused by force bending a material, such as aluminum, beyond the recommended minimum radius.

CRF - Condensation Resistance Factor is a rating number obtained under standard-test conditions which allows a prediction, within reasonable accuracy, of the ability of a window, door or glazed wall to resist the formation of condensation on interior surfaces (Higher CRF value indicates better performance).

Cripple - A short stud located under the rough sill or above the header.

CSI - Construction Specifications Institute.

Curing - The process of allowing sealants to dry and harden over a given period of time.

Curtain Wall (Aluminum) - An exterior building wall which carries no roof or floor loads and consists of a combination of aluminum, glass and other surfacing materials supported by the aluminum framework.

Custodial Lock - Window hardware only operable with a tool or key.

Cylinder - The cylindrical mechanism has a keyhole which receives the key used to operate a locking mechanism.

Cylinder Cam - Usually refers to the flat metal plate on the end of a mortise type cylinder which actuates the lock mechanism when rotated by the key.

Cylinder Guard - Hardened protective shield designed to prevent unlawful entry by forcefully twisting and removing the cylinder.

Cylinder Ring - Spacing collar to accommodate longer cylinders.

Daylight Transmittance - The percentage of visible light that glazing transmits through a window – a standard clear dual pane without considering whether a window frame has a daylight transmittance of 82%.

De-bridging - The process whereby the aluminum-bridge web connecting the exterior and interior portions of the extruded thermal-break cavity is removed either by milling or sawing after the polyurethane has cured.

Dead Latch - A latch bolt having an auxiliary feature which prevents its retraction by end pressure when in a projected position.

Dead Lock and Latch - A hardware item containing both a deadbolt and latch bolt.

Deadload - A static applied load. A load without movement.

Decibel - Unit used to measure sound. The human ear can normally detect a decibel change of 1 to 3. Normal conversation is around 60 dB while a 747 jet at takeoff is around 125 dB.

Decibel Loss - A measure of reduction of sound.

Deflection - The measure of movement of a member from its static position when subjected to loads.

Degree Day - A unit that represents a one-degree Fahrenheit deviation from some fixed reference point (usually 65° F) in the mean, daily outdoor temperature. See also heating degree day.

Desiccant - An extremely porous crystalline substance used to absorb moisture from within the sealed air space of an insulating glass unit.

Design Load - The project wind load to be determined by the architect and expressed in psf. Windows ratings are determined using AAMA 101/I.S.2/A440-05.

Designation Number - Prescribed by AAMA. One for each window style. It provides a code for architectural selection, e.g., a single hung 6220 = H-R20 = Single Hung - Residential Grade - 20 psf Design Pressure.

Dewpoint - The temperature at which water vapor in air will condense at a given state of humidity and pressure.

Divided Light - A window whose glass is separated by true divided lite (see TDL), simulated divided lite (see SDL) or by muntins.

Door Backset - Dimension from the face plane of door to the face plane of frame.

Door Clearance - The margin of clearance around the edge of a door, between door and frame.

Door Closer - A device or mechanism to control a door during its opening and closing cycle; may be overhead or floor mounted and either exposed or concealed.

Door Frame - An assembly of members, consisting of jambs and a header, into which a door or doors fit when closed. The door frame may also include transom lights and adjacent sidelights. Also see Threshold.

Door Handing - Determined by placing your back to the hinge jamb. If the door swings to your left it is a left-handed door.

Door Holder - A hardware device designed to limit the swing of a door and hold it in an open position.

Door Jamb - One of two vertical members of a door frame. The hinge jamb is the jamb to which the hinges or pivots are mounted; the lock jamb is the jamb at the leading edge of the door where a lock bolt may be engaged.

Door Light - The glass area in a door.

Door Opening - The opening dimension of a doorway is measured from inside of jambs and from floor line to underside of frame header. The opening size is usually the nominal door size and is equal to the actual door size plus clearances and threshold height.

Door Size (Actual) - The actual width and height of the swing door leaf.

Door Size (Nominal) - See Door Opening.

Door Stop - a) A molding or projecting element on a door frame which overlaps the edge of a door, causing it to stop in its closed position. b) A bumper mounted on the floor or wall to limit the extent of the door opening. c) An accessory feature of a door holder.

Dormer - A space which protrudes from the roof of a house, usually including one or more windows.

Double Glazing - In general, two thicknesses of glass separated by an air space within an opening to improve insulation against heat transfer and/or sound transmission. In factory-made double-glazing units, the air between the glass sheets is thoroughly dried and the space is sealed airtight, eliminating possible condensation and providing superior insulating properties.

Double-Acting Door - A door equipped with hardware that permits it to swing in both directions from the plane of its frame.

Double-Hung Window - A window consisting of two sashes operating in a rectangular frame, in which both the upper and lower halves can be slid up and down. A counterbalance mechanism usually holds the sash in place.

Double-Strength Glass - Sheet glass between 0.115" and 0.133" (3­3.38 mm) thick.

Drip Mold - An exterior molding (extrusion or brake shape) contoured for controlling or deflecting dripping water.

Dry Glazing - A method of securing glass in a frame that uses pre-formed resilient gaskets instead of a wet sealant or glazing compound.

Dual Durometer - A material that has two or more levels of flexibility.

Dual Window - Two windows joined together, one in front of the other, to provide superior sound control.

Durometer - An instrument with a blunt probe used to measure the hardness of elastomeric glazing gaskets and setting blocks on a scale of 0 to 100. Also see Shore A.

E E.P.D.M - (Ethylene Propylene Diene Monomer) is a type of elastomeric material which has excellent resistance to ozone, sunlight, and severe weather conditions and is ideal for outdoor service.

Edge Blocks - Short lengths of elastomeric materials located at one or both sides of a glass light to limit lateral movement ("walking") caused by horizontal expansion/contraction, minimal building sway or other factors.

Edge Clearance - The dimension between the edge of the glass or panel and its surrounding frame which is measured in the plane of the glass or panel.

Edge Cover - The dimension by which the inner edge of the frame or stop overlaps the edge of the glass or panel.

Edge Effects - Two-dimensional heat transfer at the edge of a glazing unit due to the thermal properties of spacers and sealants.

Edge of Glass - The glass area within 2 1/2" (10cm) of the edge of a window.

Egress - Exit or way out.

Egress Window - A window meeting certain size requirements for egress. The size is determined by national or local building codes. Typically, the rule is 5.7 sq. ft. of clear opening, 20" minimum clear width and 24" minimum clear height.

Elasticity - The condition or property of being elastic; flexibility.

Elastomeric Material - A term often used for rubber and polymers that have properties similar to those of rubber. Thermal break polymers having the elastic properties of natural rubber.

Electrochromics - Glazing with optical properties can vary continuously from clear to dark with a low-voltage signal. Ions are reversibly injected or removed from an electrochromic material, causing the optical density to change.

Electrolysis - Chemical decomposition of a metal surface by the action of dissimilar metals and moisture.

Electromagnetic Spectrum - Radiant energy over a broad range of wavelengths.

Electrostatic Painting - A painting process by which the aluminum is grounded and the paint carries a positive electric current. This creates a magnetic attraction between the paint and the aluminum, allowing for uniform paint coverage on all exposed extrusion surfaces.

Emergency Exit Window - Fire escape window (egress window) large enough for a person to climb out. In U.S. building codes, each bedroom must be provided with an exit window. The exact width, area, and height from the floor are specified in the building codes.

Emergency Release - A safety device other than panic hardware which permits egress through an entrance door under emergency conditions.

Emissivity - Emission, or the ability to radiate heat in the form of long-wave radiation.

Emittance - The ratio of the radiant flux emitted by a specimen to that emitted by a black body at the same temperature and under the same conditions.

End Dam - Used to close the ends of a subsill, so water will not leak out of the ends. It makes the subsill a complete water trough allowing it to collect excess water and drain it to the exterior.

Entrance - The doorway, vestibule or lobby through which one enters a building.

ER Rating - Energy rating number developed by the CSA (Canadian Standards Association) to compare the thermal performance of windows. Measured in watts per square meter (W/m2).

Escutcheon Plate - Back plate for handles and deadbolts.

Exterior Glazing - A method in which glass is secured in an opening from the exterior of the building.

Extrudability - This term is used to compare the relative resistance of different alloys and/or shapes to deformation in the extrusion process and is usually based on pressure required and attainable extrusion speed.

Extrudability Limits - A set of guidelines established by the Aluminum Association which provides limits on the production of extrusions. Dimensional tolerances, gap-width ratios, extrusion factor and circumscribing circle are examples of these limits.

Extruded Aluminum Shapes - There are two basic types of extruded shapes: Solid Extrusion - Any extruded shape other than a hollow or semi-hollow shape. Semi-Hollow Extrusion - An extruded shape where any part of the cross section partially encloses a void. The area of the void bears a fixed ratio to the square of the gap as shown in published tables developed by the Aluminum Association.

Extrusion - The metal-fabricating process by which a heated aluminum billet is forced to flow through a hole in a steel die of the desired shape. Also see Extrusion Press.

Extrusion Circle Size - This is represented by the diameter of the smallest circle that will completely enclose the aluminum extrusion. For a die with two or more holes, the diameter of the smallest circle that will enclose all the holes in the die is designated as the layout circle. Also see Extrusion Side Wall Clearance.

Extrusion Die - A steel plate or forging having a hole of the desired extrusion shape through which the aluminum is forced to flow. The die is specially machined to control the flow of metal.

Extrusion Die Support Too - These include the steel die ring, die backer, bolster and sub-bolster and have the purpose of supporting the die against the very high pressures of extrusion and transferring these forces to the head of the press.

Extrusion Factor - The numeral representing this term is the ratio of the perimeter of an aluminum extrusion to its weight per foot. It is a measure of the complexity of an extruded shape represented on the die drawing. Thin wall sections have high factor numbers and are more difficult to extrude. A solid round section has the lowest factor and would require less extrusion pressure than a more complicated shape with a high factor but an equivalent weight per foot.

Extrusion Press - A hydraulic press used for forcing heated aluminum ingots (billets) through a hole in a steel die of the desired shape.

Extrusion Pressure - The pressure available for aluminum extrusion is determined by dividing the press capacity in pounds by the cross-sectional area of the bore of the container in square inches.

Extrusion Ratio - This is determined by dividing the cross-sectional area of the bore of the container by the sum of the cross-sectional areas of the holes in the die. It is the measure of the deformation required to reduce the aluminum billet size to the extrusion size.

Extrusion Side Wall Clear - One-half the difference between the container diameter and the layout circle. This clearance is necessary to avoid feed-in of the liquated outer surface of the extrusion billet or of the skull that may adhere to the wall of the container. Greater side wall clearances are specified for extrusions with very critical surface requirements. Also see Extrusion Circle Size.

Eyebrow Windows - Picture windows that are segments of circles rather than arch windows which are half circles.