Definition of Terms

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AAMA (American Architectural Manufacturers Association)A national trade association that establishes voluntary standards for the window, door, storefront, curtain wall, and skylight industries.

Adjustment Clip – Hardware on hung window jambs to align jamb after window installation.

Air Infiltration – The amount of air leaking in and out of a building through cracks in walls, windows, and doors.

Ambient Temperature – The outdoor temperature.

Annealed Glass – This glass is created in molten form in a long oven where the glass is heated and then slowly cooled under controlled conditions, emerging as a flat and “fire polished” glass product. When annealed glass is broken, it commonly breaks into large, jagged shards producing razor-sharp pieces of glass, which can be dangerous. Building codes in many parts of the world restrict the used of annealed glass because of this breakage effect. Solar Innovations® does not incorporate annealed glass in any of our products because of the nature of the glass.

Anodize – The process that provides a hard, durable oxide film on the surface of aluminum by electrolytic action.

ANSI (American National Standards Institute) - A clearinghouse organization for all type of standards and product specifications.

Apron – Interior flat trim piece which is used under the stool at the bottom of the window.

Argon – An inert, nontoxic gas used in insulating glass to improve the insulating value of the sealed glass units.

ASHRAE - American Society of Heating, Air-conditioning, and Refrigeration Engineer

ASTM International – Formerly, the American Society for Testing and Material, is an organization that establishes material standards (including glass) and test methods. It has also produced a window installation standard.

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

Awning Window – A window with the sash swinging outward from the bottom.

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Back Bedding – The process of adhering and sealing.

Balance - A mechanical device, normally spring loaded, used in hung windows to counterbalance the weight of the sash during opening and closing.

Balance Shoe – Nylon hardware in a hung window jamb that connects the balance with the sash.

Bay -The section of a structure from one post to the next extending from the sill to the ridge.

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.

Bay Width – The distance from the centerline of a rafter or post to the center of the next one.

Base Wall – A short wall below the glazing on all or some of the exterior walls. Also see Knee Wall. (Base wall is by other.)

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

Billet – The cylindrical form of aluminum just prior to the extruding process.

Bite – A glazing term referring to the dimension of the glazing leg which overlaps the edge of the glass.

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.

Brickmold – A type of external casing which frames windows and doors. Exterior casing around window to cover jambs and provide means for nailing during installation.

BTU – The heat required to increase the temperature of one pound of water one degree Fahrenheit.

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Casement Window – A projecting window hinged at the sides and usually opening outward like a door.

Casing - Molding of various widths, thickness, and shapes applied to the framework of window and door units. Interior casing is a flat, decorative molding which covers the inside edge of the jambs and the rough opening between the window unit and the wall. Exterior casing (or brick mold) serves the same purpose, while it also is an installation device through which nails are driven to install the window unit into the wall.

Caulking – A compound for filling joints and sealing cracks to prevent leakage of water and air.

Center of Glass - All glass area of window except that within 2.5” (10 cm) 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) – A unit of measurement used in air infiltration testing, e.g., “maximum 0.10 cfm per foot of sash perimeter.”

Check Rail - On a double-hung window, the bottom rail of the upper sash and the upper rail of the lower sash where the lock is mounted. The top rail of the lower sash and the bottom rail of the upper sash meet when a double-hung window is closed. Both pieces should be weather stripped for maximum weather ability.

Circlehead - A generic term referring to any of a variety of window units with one or more curved frame members, often used over another window or door opening.

Cladding – Material placed on the exterior of a frame and sash components.

Clerestory – The part of a building rising clear of the roofs or other parts and whose walls contain glass for lighting of the interior.

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 inches from the frame sill to CMR.”

Collection - The act of trapping solar radiation and converting it to heat.

Comfort Engineering - Optimizing glazing selections on a window-by-window basis to fulfill a prioritized set of objectives; e.g., comfort, energy efficiency (both summer and winter), UV protection, natural lighting, desired aesthetics, views, and budget.

Condensation - The change of water from vapor to liquid when warm, moisture-laden air comes in contact with a cold surface.

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 and between two panes of glass.

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

Countersink – The placement of screw or nail in wood or metal so that the top of either is flush with or below the surrounding material.

Crack Length – Total outside perimeter of window sash/vent; used when defining the AAMA air infiltration rate.

CRF (Condensation Resistance Factor) – An indication of a window’s ability to resist condensation. The higher the CRF, the less likely condensation is to occur. Based on AAMA standard.

Curb – Watertight wall or frame used to raise slope glazing above the surface of the roof as a preventative measure against water leakage from melting snow or rain run off.

Curb Appeal - The visual attractiveness of a home as seen from the street; often the first impression. Realtors see curb appeal as an influential factor in evaluating and selling homes.

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

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Dade County – Florida county, including Miami, that has set numerous standards and requirements for hurricane-resistant windows and doors.

Daylight Transmittance - The percentage of visible light that glazing transmits through a window; a standard clear dual pane has a daylight transmittance of 82%.

Debridge - The process of cutting away the metal on the bottom of an aluminum thermal break cavity once the two-part polyurethane has reached full strength, thus creating a thermally broken extrusion.

Desiccant - A porous crystalline substance used to absorb moisture and/or sealant solvents 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, e.g., “the project design load shall be 38.7 psf, both positive and negative.”

Designation Number - Prescribed by AAMA. One for each window style. It provides a code for architectural selection, e.g., TR-5000=DH-C45=Double Hung-Commercial Grade-45 psf Design Pressure.

Dew Point – The temperature at which water vapor will condense as warm, moist air is cooled.

Die – A perforated steel block through which aluminum or vinyl is extruded.

Direct Gain – A direct gain passive solar system utilizes south-facing windows to open a house to the sun; a large window area accepts direct sunlight while thermal mass serves as storage.

Dormer – An area that protrudes from the roof of a structure.

Double Glazing – Use of two panes of glass in a window to increase energy efficiency and provide other performance benefits.

Double Glazing Panel (DGP) – A removable interior glass panel which creates an air space between the exterior glazing and itself. It provides improved insulation and condensation control and allows for between-glass shading options such as muntins, blinds, and pleated shades.

Double Strength Glass – (DSB) 1/8” thickness.

Double-Hung Window – A window unit with two operable sashes which move vertically in the frame. Two vertically sliding sashes which bypass each other in a single frame. Sashes typically fit within vinyl balances and tilt out and remove for safe, easy cleaning.

Drip Cap – A molding placed on the top of the head brickmold or casing of a window frame.

Dry Glazing – A method of securing glass in a window frame with a dry, preformed, resilient gasket, without the use of a glazing compound.

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

Dual Durometer Bead – A vinyl bead with a softer flap against glass and a harder section inserted into sash member.

Dual Glazed – Two single lites glazed into a split sash with an airspace, not hermetically sealed, between the two single lites.

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

Dual Pane – Two panes of glass with a single airspace, held together by an edge spacer; the most economical IGU.

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Eave – The area of the structure where the front wall meets the roof.

Eave Height – The vertical dimension from finished floor to the eave.

Edge of Glass – The glass area within 2 ½ inches (10cm) of the edge of a window.

Egress Window – A window with specific release hardware and minimum clear opening size to allow occupants to escape through the window in case of a fire.

Electrostatic – 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.

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

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

EPDM (Ethylene Propylene Diene Monomer) – A weather resistant synthetic rubber from which many flexible gaskets for windows are made.

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

Escutcheon Plate - Hardware for handles, etc.

Etch – To alter the surface of glass with hydrofluoric acid or other caustic agents. Unintentional permanent etching of glass may occur from alkali and other runoff from surrounding building materials.

Expansion Mullion – Self mulling window frame jambs that, when slipped together, permit expansion/contraction while preserving strength and water tightness.

Extension Jambs – Flat wood parts which are nailed to the interior edges of the window jamb to extend it in width and adapt to a thicker wall. The inside edge of extension jambs should be flush with the finished wall surface. Interior casing is then nailed into it.

Exterior Glazed – Glass glazed from the exterior of the building.

Extrude – The process of shaping aluminum or vinyl by forcing it through a die.

Extrusion – The process, in which a heated material is forced through a die, used to produce aluminum, vinyl (PVC) and other profiles or components.

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Fenestration – The arrangement and design of openings in a building for the admission of light.

Fin Seal - A form of pile weatherstrip with a plastic mylar fin centered in the pile. This fin reduces air infiltration and ensures weatherstrip contact throughout the window’s life.

Finger-Jointing - A means of joining individual pieces of wood together to form longer lengths. The ends of the pieces are machined to form a set of interlocking fingers, which are then coated with adhesive and meshed together under pressure.

Fixed Lite – Non-venting or non-operable window.

Fixed Panel – Non-operable door, usually combined with operable door units.

Fixed Window - Non-operable window applications.

Flange Frame - A window frame with the head, jamb, and sill exterior perimeter leg longer than the interior perimeter leg.

Flanges – Aluminum edges used in attaching fenestrations to a structure.

Flashing – Metal used to prevent water penetration and/or provide water drainage, especially between a roof and wall, and over exterior door openings and windows.

Float Glass - Transparent glass with flat, parallel surfaces formed on the surface of a pool of molten tin.

Foam Spacer - Foam material placed in the airspace of the insulating glass windows to enhance the appearance and improve the performance of the window.

Foundation – The wall that supports the structure of a building. Can be poured concrete, block, stone, or break.

Frame - The enclosure in which window sash or door panels are mounted. Outside members of a window unit which enclose the sashes. Composed of side jambs, head jamb, and sill.

French Door – Generally refers to a pair of hinged doors that open from the middle.

French Sliding Door - A sliding door which has wider panel members around the glass, giving the appearance of a French hinged door.

Front Wall – Wall of a structure running the length of a building between the two gable ends.

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Gable – A vertical surface commonly situated at the end of a building, usually adjoining a pitched roof.

Gable End – A wall of a structure with a gable at its end.

Gas-filled Glass – A gas, other than air, placed between insulated glass to reduce the U-factor by suppressing conduction and convection. (Usually Argon, Krypton, or Carbon Dioxide.)

Gasket – A rubber or plastic pliable material used to separate glazed glass and aluminum or vinyl.

Glazing – The glass or polycarbonate panes in a structure. Also the act of installing panels of glass in a structure.

Glazing Bead – A molding or stop around a window frame to hold the glass in place by pressure. A vinyl or wood strip, applied around the perimeter of the glass on the exterior of the window sash, for holding the glass in place.

Glazing Stop – The part of the sash or door panel which holds the glass in place.

Green Building – A movement in architectural and building circles aimed at creating occupant and environmentally friendly structures. Criteria such as sustainability, energy efficiency, and healthfulness are considered.

Greenhouse Effect – The property of glass that permits the transmission of short-wave solar radiation but is opaque to long-wave thermal radiation. The interior of a car heating up direct sun illustrates the greenhouse effect.

Grille – A term referring to windowpane dividers or muntins, usually a type of assembly which may be detached for cleaning.

Gusset – A concealed, strong, right-angled shape used to reinforce mitered corners in tubular aluminum extrusions.

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Heat-Strengthened Glass – This glass is produced by heating the glass to temperatures approaching 1300º F, then rapidly cooling it with air, similar to tempered glazing. The glass results in a thermally strengthened glass that is approximately two times stronger than a piece of annealed glass. In general, the benefit of using heat-strengthened glass is reduced breakage from thermal and bending stress, which allows the use of larger pieces without increasing the thickness.

Head Board - A flat board, cut to fit the contour of a bow or bay window, for installing between the head jambs and the flat wall surface to finish off the area which would normally be ceiling.

Head Expander - A u-shaped extrusion slipped over the frame head that, when pushed up, closes the gap above the window after window installation.

Header – A heavy beam extended across the top of the rough opening to prevent the weight of wall or roof from resting on the frame.

Heat Fusion - Welding method to join PVC frame and/or sash members by heating the cut-ends, squeezing them together, and allowing the assembly to cool.

Heat Treating - The process where glass or aluminum extrusions are heated and cooled, so they become harder and stronger.

Hermetically Sealed Unit - An insulating glass unit that is sealed against moisture. The unit is made up of two lites of glass, separated by a roll-formed metal spacer tube (at the full perimeter) which contains a moisture and/or solvent absorbing material. The unit is then completely sealed, creating a moisture free air space.

Hollow Extrusion – An extrusion having an enclosed cavity within it.

Hopper - A window unit in which the top of the sash swings inward.

Hurricane Impact Resistant Glazing – Used in coastal regions that are subjected to hurricane winds and flying debris. Specially designed, laminated glass products can fulfill these requirements – the multiple layers of glass may break from an impact, but the plastic interlayer and the structural bonding of the glass to the window frame allows the panel to remain in place, protecting the interior of the building. The test method for compliance involves impacting the window in multiple locations and then subjecting the assembly to cycles of positive and negative pressures to replicate the exposure seen during a hurricane.

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ICC (International Code Council) - A national organization that publishes model codes for adoption by states and other agencies. Codes include the International Building Code (IBC) and the International Energy Conservation Code (IECC).

IGCC (Insulating Glass Certification Council) - Directs a certifications program of periodic accelerated laboratory testing and unannounced plant inspections to ensure sealed, insulating glass performance is in conformance with ASTM E 774-88.

Impact-resistant – Term used to describe window and door products that have passed established tests for resistance to wind-borne debris. Such products are typically used in coastal areas that are prone to hurricanes.

Infiltration – The seepage or flow of air into a room or space through cracks around windows, under doors, etc.

Inside Snap Trim – Used in retrofit work to cover the inside gap between the new window and the existing opening.

Insolation – Incident solar radiation; the total radiation striking an exposed surface.

Insulated Glass (IG) – IG glass is made up of two discrete pieces of glass with an airspace interlayer. The added insulation will isolate the room from the outdoor temperatures. Insulating values can be improved by adding a Low-E coating or inert gas fills, such as argon. Variations, such as heat-treated and laminated glass, can be incorporated where additional strength and security may be desired. The thickness of the glass used will depend on window size and building design requirements (e.g. windload). Solar Innovations® standard glazing thickness for insulated glass is 1”.

Insulation – A material with high resistance (high R-value or low U-value) that is used to retard heat flow. Air, Argon, or Krypton gas spaces between panes of glass provide insulation in IGUs.

Insulating Value – See U-factor.

Integral Mullion – A frame member trapped within the master frame to separate vents or fixed glass.

Interior Glazed – Glass glazed from the interior of the building.

Interlock – A design feature which enables sash to become engaged with one another when closed.

Internal Gain – The heat produced in the interior of a dwelling from the operation of lights, appliances, etc.

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Jack Stud – Vertical framing members, generally 2×4’s, which form the inside of the window or door rough opening. They support the header and run down to the sole plate.

Jamb – A vertical member at the side of a window frame, or the horizontal member at the top of the window frame, as in head jamb.

Jamb Liner – In a modern double-hung window, the tracker installed inside the jambs on which the window sashes slide. Vinyl or metal covering applied to the side jambs of double hung and single hung windows. They are generally formed to include an integral balance system and stops for the exterior and interior surfaces of the sash.

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K.D. (Knocked Down) – Product components that are shipped unassembled, e.g., the frame for a sliding glass door.

Keeper - A hardware device into which a window locking latch engages for security. The receiving portion of a lock that interlocks with the lock arm. It’s mounted to the upper sash check rail on a double hung or single hung window and the inside surface of the sash stile on a casement window.

Kitchen Bay Window - A small bay window used above counter-height in kitchens; allows for a wider view and an inside sill for herbs and flowers.

Knee Wall – A short wall below the glazing on all or some of the exterior walls. Also see Base Wall. (Knee wall is by other.)

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Laminated Glass – Consists of a plastic interlayer material, polyvinyl butyral, that keeps the glass in place should it break. The pieces are retained within the frame and do not “fall off” after impact. Laminated glass can qualify as a safety glazing with any combination of annealed, heat strengthened, or tempered glass as layers.

Left or Right - Location information, always outside looking in, that can be used to specify direction, e.g., “the operating sash slides to the right.”

Lift - A handle or grip installed or routed into the bottom rail of the lower sash of a double hung or single hung window.

Lite – A pane of glass, a window, or a compartment of a window. Sometimes spelled “light.”

Low-Emittance (LowE) Coating - Microscopically thin, virtually invisible, metal or metallic oxide layers deposited on a glazing surface primarily to reduce the U-factor by suppressing radioactive heat flow through the glass. Solar Innovations® utilizes Sol-I-Guard 240 as our high performance glass LowE and Sol-I-Guard 272 as our standard LowE glass.

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Marine Glazing – A u-channel of soft PVC, which is wrapped around the edge of the glass, cushioning the glass against the aluminum or vinyl. This process allows for unrestricted expansion and contraction and water tightness.

Masonry Opening – The space in a masonry wall left open for windows or a door. The opening in a masonry wall to accept a window or door unit, the same as a rough opening in a frame wall. The header (or lintel) in a masonry opening is usually a steel beam.

Meeting Rail – The part of a hung window where the two sashes meet and create a weather barrier.

Mill – Unfinished and unpainted aluminum material.

Miter Joint – A joint formed by fitting together two pieces cut at an angle to form a corner.

Monolithic Glazing – Consists of a single sheet of glass formed using the float glass manufacturing process. From this development, the monolithic glass is modified for increased strength, improved insulating capability, and safety glazing requirements. Installed as a single pane, the glass can be annealed, heat-treated, or bonded to another piece of glass with a plastic interlayer to form laminated glass. Monolithic glass allows the heat and cold from the outside to penetrate the structure and greatly affect the inside temperature.

Mortise Lock – A lock fitting a rectangular-shaped cavity in the edge of a door.

Mullion - A horizontal or vertical member that supports and holds such items as panels, glass, sash, or sections of a curtain wall.

Muntin – Horizontal or vertical bars that divide the sash frame into smaller lites of glass. Muntins are smaller in dimensions and weight than mullions.

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Nailing Fin – A vinyl or metal flange integrated into (or attached to) the perimeter of a window frame for installation on the rough opening’s header, jack studs, and rough sill. A continuous nailing fin may surround the frame as with an all-vinyl window or a nailing fin may be affixed to the head and side jambs as with a vinyl ultraviolet stability.

Neoprene – A synthetic rubber having physical properties closely resembling those of natural rubber. It has extremely good weather and temperature resistance, bother heat and cold, with ultraviolet stability.

Nite Latch – Hardware which, when extended, restricts the sash opening to a predetermined dimension.

Non-Tempered GlassSee annealed glass.

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Obscure Glass – See patterned glass.

Operator – A metal arm and gear device which allows for easy opening and closing of projecting windows; e.g. casement and awning windows.

Orientation – The compass direction that a structure faces. To optimize heat-gain, the major facade of a building should face South (a variation as much as 30 degrees east or west of south will not seriously affect performance).

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Patterned Glass – One type of rolled glass having a pattern impressed on one or both sides. Used extensively for light control, bath enclosures and decorative glazing. Sometimes called “rolled”, “figured,” or “obscure” glass.

Palladian Window – A large, arch-top window flanked by smaller windows on each side.

Pane – A framed sheet of glass.

Panel – Usually refers to the separate panel or panels in a door frame.

Panning – A set of extrusions which are fastened to a new window to cover the exterior perimeter of an existing opening in a retrofit application.

Parting Stop – A strip of wood applied to the jamb to separate the sash in a double-hung window.

Passive Solar – A solar heating system which operates on natural thermal processes and uses no external mechanical power to move the collected heat. Generally, the building’s structure itself forms the solar system.

Patio Doors – Sliding glass doors, often used for access to a deck or terrace.

Picture Frame Casing – The use of casing on all four sides of the interior of a window. The stool and apron at the sill are replaced with casing.

Picture Window – A large stationary (non-ventilating) window which is designed for a maximum view without obstruction.

Pitch – The degree of the inclination upward from horizontal or flat. It may be expressed in degrees or as the ratio of the number of inches it rises in each 12″ of horizontal span (e.g. 3/12 means the roof rises 3″ in every foot of horizontal span).

Pleated Shade – A shade of folded fabric which can be installed like regular shades or between the panes of glass of a window.

Polycarbonate – Strong, semi-transparent plastic used in place of glass. Polycarbonate is a less expensive infill selection when compared to glass. Polycarbonate is available in many thicknesses.

Prime Frame – A window frame which has an extended perimeter leg 1” back from the window exterior plane, which becomes a nailing fin for new construction installation.

Projected Window – A window in which the sash opens on hinges or pivots. Refers to casements and awning windows.

Projection - The distance of a structure from the point of attachment to an existing structure to the farthest point outward of the structure.

PSF (Pounds Per Square Foot) – A measurement of air pressure used in window testing, e.g., 1.56 psf (25 mph) or 6.24 psf (50 mph).

Purlins – The horizontal components of a roof structure used to support and attach roof panels.

PVC (Polyvinylchloride) – An extruded material used for window and door framing.

Pyrolytic Coating – A special coating “sprayed” directly onto glass while it is still in a molten state, resulting in a permanently embedded surface coating.

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Radiation – The transmission of heat through space by means of electromagnetic waves or particles from one surface to another.

Rafter – Structural members of a roof that support the roof load and run from the ridge to the eaves.

Rail – The top and bottom horizontal members of the framework of a window sash or door panel; a horizontal sash member.

Receptor – Framing system consisting of two snap-together extrusions used to contain a window frame head and jambs in a masonry-type opening. It allows for deflection and inconsistencies in the openings.

Reflectance Back – A measurement in percentage of the visible light reflected back into a room.  For ease of seeing to outside, a lower rating is better.

Reflected Radiation - Solar radiation that strikes an exposed surface (like a window) after being reflected from the ground, trees, buildings, snow, etc. Reflected radiation can provide a significant amount of heat when vertical windows are used.

Reflective Glass – Glass with a metallic coating to reduce solar heat gain.

Relative Heat Gain – A measurement of the total heat gain through glazing for a specific set of conditions.

Relative Humidity – Humidity expressed as a percentage of the maximum possible humidity at a given temperature.

Removable Grilles – Ornamental or simulated muntins and bars designed to provide a divided light appearance. Generally made of wood, they are applied to the inside of the sash against the glass surface for easy removal.

Ridge Height – The vertical dimension from finished floor to the ridge.

Rough Opening – An opening in a wall or the frame work of a building, where a door frame, window frame, or sub frame is fitted.

Rough Sill – The horizontal framing piece, usually a 2×4, which forms the bottom of the rough opening. It is toe-nailed into the jack studs and supported by cripples.

R-value – The measure of resistance to heat gain or loss (insulated ability). R-values, rather than thickness, can be compared for different materials. The higher the R-value, the greater the glass’s resistance to heat flow and the higher the insulating value. The R-value is the inverse of the U-value.

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Safety Glass – A strengthened or reinforced glass that is less subject to breakage or splintering.

Sash – Framework holding the glass in a window unit. Composed of stile (sides) and rails (top and bottom).

Sash Balance – A coiled spring or spiral system integrated into the jamb liners to allow double hung or single hung sashes to open and close. They also allow the sashes to remain open in varied positions.

Sash Cord – In double-hung windows, the rope or chain which attaches the sash to the counter balance.

Sash Lift – a protruding handle screwed to the inside bottom rail  of the lower sash on a double-hung window.

Screw Channel – The threaded channel centered in the glazing track.

Sealant – A compressible plastic material used to seal any opening or junction of two parts, such as between the glass and a metal sash, commonly made of silicone, butyl tape, or polysulfide.

Seismic Load – The force produced on a structural system due to the action of an earthquake.

Self-cleaning Glass – Glass treated with a special coating. Currently, commercially available products feature a coating that uses the sun’s UV rays to break down organic dirt through what is called a photocatalytic effect. The coating also provides a hydrophilic effect, which reduces the surface tension of water to cause it to sheet down the surface easily and wash away dirt.

Setting Block – A piece of rubber on which a piece of glazing is set.

Shading Coefficient (SC) – The total amount of solar energy that passes through a glass relative to a 1/8″ (3mm) thick clear glass under the same design conditions; included both solar energy transmitted directly plus any absorbed solar energy subsequently re-radiated or convected into a room; lower values indicate better performance in reducing summer heat gain and therefore air-conditioning loads.

Sidelights – A fixed frame of glass beside a window or door.

Sill – The lowest horizontal member in a door, window, or sash frame. Generally slanted down to the outside to shed standing water.

Simulated Divided Lites (SDLs) – Glass that has the appearance of a number of smaller panes of glass separated by muntins but actually is a larger glazing unit with the muntins placed between or on the surfaces of the glass layers.

Single Glazing – A single layer of glazing used to enclose a structure, usually glass or plastic.

Single Hung – A double-hung type of window in which the top sash is fixed or inoperable.

Sliding Door – Door in which a vent panel moves horizontally on a track system past a fixed panel.

Sloped Glazing – Any installation of glass that is at a slope of 15 degrees or more from vertical.

Span – The distance between any two consecutive structural supports.

SolarCool Bronze Glass – In extremely hot regions, SolarCool bronze can help keep your area cooler. It does this with a special light and heat reflective coating, which is fused permanently to the outside surface of the glass. This coating reduces the amount of sunlight entering your sunroom by 75% and reflects much of the infrared heat waves radiating from the ground or nearby buildings.

Solar Heat Gain Coefficient (SHGC) – The solar heat gain coefficient, also called a shading coefficient, is a measure of how well a window absorbs or reflects heat from the sun. The lower the coefficient, the better the window is at blocking the sun’s heat. Windows in hot or temperate climates should have a low SHGC; south-facing windows in cold climates should have a high SHGC.

Sound Transmission Class (STC) Rating – Measures the amount of noise reduction that can be achieved with a given product. A noise reduction of 10 decibels represents cutting the noise level in half, as interpreted by the human ear. So, a rating of 25 means the product reduces the outside noise by approximately 25 decibels, cutting the noise in half 2-1/2 times, or cutting it by over 80%.

Stile – The vertical members of a window sash or door panel.

Stool – An interior trim piece on a window which extends the sill and acts as a narrow shelf.

Stop – A molding used to hold, position, or separate window parts.

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Tempered Glass – This glass is manufactured by heating annealed float glass to its softening point (1300º F), then rapidly cooling it with air. The resulting compression layer increases the glass strength to four times that of common annealed glass. Tempered glass will break into small particles. The pieces of broken glass are sufficiently smaller in size, allowing it to be classified as a “break safe” glass. Note: For skylight applications in commercial situations, laminated glass may be required. Please review the local and state building codes in your area.

Thermal Barrier – A stop of non-conducting material, such as wood, vinyl, or foam rubber, that is used to separate the inside and outside surfaces of a metal frame to stop the conduction of heat to the outside which results in a cold inside surface.

Thermal Break – An element of low conductance placed between elements of higher conductance to reduce the flow of heat. Often used in aluminum windows.

Tinted Glass – Glass with colorants added to the basic glass batch that gives the glass color, as well as, light and heat-reducing capabilities.

Transmittance – The ability of the glass to pass light and/or heat, usually expressed in percentages (visible transmittance, thermal transmittance, etc.).

Transom – A horizontal transverse beam or bar in a frame; a crosspiece separating a door or the like from a window or fanlight above it. Also, a window above a door or other window built on and commonly hinged to a transom.

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uPVC – Unplasticized polyvinyl chloride, a rigid, chemically resistant form of PVC used for piping, window frames, and other structures.

U-value (U-Factor) – The measure of ability of different structural components to conduct heat. The U-value of glass is measured by the number of BTUs that will pass through each square foot area, per degree of temperature difference, from one side of the glass to the other. Y-values indicate how well the glass will hold the heated or cooled air. The lower the U-value, the greater the glass’s resistance to heat flow and the higher the insulating value. The U-value is the inverse of the R-Value.

Ultraviolet Light (UV) – Invisible rays of solar radiation at the short-wavelength violet end of the spectrum. Ultraviolet rays can cause fading of paint finishes, carpets, and fabrics, as well as deterioration of some materials. Back to Top


Vent Panel – The panel that moves horizontally on a sliding door.

Vent Unit – A window unit that opens and closes.

Visible Transmittance (VT) – The percentage of visible light striking the glass that penetrates to the interior, expressed as a number between 0 and 1.

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Weatherstrip – A material of device used to seal the openings, gaps, or cracks of venting windows and doors to minimize water and air infiltration.

Weep Hole - Holes in the sill of the glazing system to prevent accumulation of condensation and water.

Windload – The force of wind against the exposed surfaces of the structure. Expressed in pounds per square foot (psf).

Wire Glass – Rolled glass with a layer of meshed or stranded wire completely imbedded. Available as polished glass and patterned glass. Approved polished wired glass is used as transparent or translucent fire protection rated glazing. The wire restrains the fragments from falling out of the frame when broken.

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