Glossary Terms

Glossary of Building Terms

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AAMA – American Architectural Manufacturers Association. A national trade association that establishes voluntary standards for the window and door industry.

Accelerated Aging – Laboratory conditions designed to recreate the normal aging process of IG units in a short period of time.

Acrylic (plastic) – A non-crystalline thermoplastic with good weather resistance, shatter resistance, and optical clarity; sometimes used for glazing.

Anodize – To provide an extremely hard non-corrosive oxide film on the surface of aluminum, by electrolytic action. Anodic coatings may be transparent, of varying shades of silver, gray, brown, or colors may be incorporated by the use of dyes.

Argon – An inert, colorless, and harmless gas used instead of air in sealed spaces between panes of glass in insulating glass units to increase insulation. Argon is less conductive to heat than air. It is injected in the airspace of an insulating unit, to improve energy efficiency.

ASTME 2189 – North American harmonized ASTM standard test method for insulated glass unit resistance to volatile fogging.

ASTME 2190 – North American harmonized ASTM standard specification for insulated glass unit performance and evaluation.

ASTME 773, E 774, E 1887 – Previous U.S. standards for insulated unit testing, performance and evaluation (replaced by harmonized E 2188, E 2189, E 2190).

Awning Window – A type of window with a top-hinged sash that swings out at the bottom, letting in fresh air while keeping rain out.

Balance – A mechanical device used in vertically operating windows that counter-balances the weight of the sash during opening and closing. Click for photo

Basement Window – A sash unit, usually of the in swinging awning type, used for basement or cellar sash openings. Products may include screens or storm sash and may include provisions for emergency evacuation from the basement area.

Bay Window – A type of window consisting of a central picture window flanked by a pair of narrow casement windows set at an angle – provides a panoramic view.

Bead – 1) A strip of metal, vinyl, or wood used around the periphery of a pane of glass to secure it in a frame or sash. 2) A strip of sealant, such as caulking or glazing compound.

Block – A small piece of lead, neoprene or other suitable material used to position the glass in a frame. Click for photo

Blocking – To shim, level and plumb windows in required position.

Bow Window – A type of window made of equal-sized casement/picture units in a gentle outward curve – allows for a wider view and more living space.

Casement Window – A type of window with a side-hinged sash that opens like a door – the best window for catching breezes and crosswinds. The sash are usually operated by means of roto-operators or a handles.

CGSB12.8 – Canadian standard specification for insulated glass unit testing, performance and evaluation. This standard was one of the predecessor standards in developing the ASTM E 2188, E 2189 and E 2190 standards, however, CGSB 12.8 remains an active standard in Canada and is the reference standard for insulating glass certification under the IGMAC certification program. Both ASTM E 2190 and CGSB 12.8 are referenced in the National Building Code of Canada.

Condensation – Formation of moisture on an insulated glass unit surface when the surface temperature is lower than the localized air dew point. Condensation occurs first around the window’s edge where surface temperatures are the coldest. Is a standard cold edge spacer exists and outside temperatures fall to 0o F/-17.78o Celsius, condensation will form on the glass edge even in homes with as little as 15% relative humidity.
Double Hung Window – A type of window that has an upper (outside) sash that slides down, and a lower (inside) sash that slides up. A vertical operating window consisting of two sashes of glass operating in a rectangular frame, both the upper and lower halves can be slid up and down and usually use a counter balance mechanism to hold the sash in place.

Drywall – Interior cladding with panels of gypsum board, fiber board or plywood, a dry operation as opposed to wet plaster.

Dual Seal Units – Insulating glass using two separate sealants for the edge seal system. Based on material characteristics, one sealant is used principally for the resistance of moisture into the insulating glass unit and to prevent leakage of insulating gases (argon, krypton). The second sealant primarily acts as a structural sealant/adhesive to maintain the integrity of the insulated glass unit.

Egress – A means of exiting. An egress window is one which is large enough to exit the room in case of an emergency. The size is defined by national or local building. CLICK HERE to view residential building codes.

Emissivity – A measure of an object’s ability to emit long-wave infrared radiation or room temperature radiant heat energy. Emissivity varies from 0 (no emitted infrared) to 1 (100% emitted infrared). The lower the emissivity, the lower the resultant U-value.

Enamel – A type of paint consisting of an intimate dispersion of pigments in a resin vehicle.

Fenestration – The placement and arrangement of the windows and doors of a building.

Frame – Consists of a head, jambs, and sill to form an opening into which sash or door panels fit. An assembly of structural members which surrounds and supports the sash, ventilators, doors, panels or glazing which is installed into an opening in the building envelope or wall.

Frost Point – Temperature within an insulated glass unit at which moisture condenses and/or freezes on the interior glazing surface(s). To pass the requirements of ASTM E 2190, an insulated glass unit must have frost point equal to or less than -40o
Fahrenheit or -40o Celsius, Dry ice with thermocouples and digital indicators are used to determine the frost point in an insulated glass unit.

Glazing – The installation of glass into a window or door sash.

Glazing Bead – A molding or stop along the inside perimeter of the frame that assists in holding glass in place.  Click for photo

Grilles/Grids – Decorative inserts for windows or door glazing that adds a traditional touch – available in fixed or removable inserts.   Click for photo

Head – The main horizontal member forming the top of the window or door frame.

Hinge – A device on which doors or windows may turn or swing, to open and close.

Horizontal Sliding Window – A window where the movable panels slide horizontally. These windows consist of one or more horizontally operable sash in a sealing frame.
Insulating Glass – Insulating glass refers to two or more pieces of glass spaced apart and sealed to form a single-glazed unit with an air space between. Heat transmission through this type of glass may be as low as half that without such an air space.

Insulation – Construction materials used for the protection from sound, heat, cold, or fire. A material with high resistance that is used to retard heat flow. Air, argon, or krypton gas spaces between panes of glass provide insulation.

Interlock – A set of meeting rails or meeting stiles which contains a provision for each of rails or stiles to physically engage one another over their entire length.

Jambs – Vertical, or side members of the window’s or door’s main frame.

Keeper – The part of a window lock, mounted on an opposing surface of the window that the lock arm locks under or into to pull the sash into a locked position and fully releases it when opened.

Laminated Glass – Two or more sheets with an inner layer of transparent plastic to which the glass adheres if broken. This process produces glass four times more impact resistant than non-tempered glass. Used for overhead, safety glazing, and sound reduction.

Lift Rail – A rail in a vertical window provided with an operator to raise and lower the operable sash.

Lock – The device on a window or door that secures it in a closed position. Click for photo

LoE2 – Sputtered Low E glazing.  Click for photo

Low E Glass – Low-emissivity glass with a transparent coating which acts as a thermal mirror – used to increase a window’s insulating value, block or increase heat flow, and reduce fading.  Click for photo

Marine Type Glazing – A glazing system which begins by wrapping the full perimeter of the glass unit with a soft vinyl channel which serves to cushion the glass, as well as provide positive protection from water. Marine type glazing is typically round on high quality window products.

Meeting Rail – A rail which overlaps another rail. The part of a sliding glass door or a sliding window where two panels meet and create a weather barrier. Click for photo

Mullion – An intermediate-connecting member used as a means to “join” two or more window products together in a single rough opening.

Muntin Bar – A small bar that divides window or door glass.

Nailing Fin – An integral extension of a window frame which generally laps over the conventional stud construction and through which nails are driven to secure the frame in place.

NRFC – National Fenestration Rating Council, measures and compares the energy component of windows and doors.

Obscure Glass – Mainly used for decoration, diffusion, or privacy. The design is pressed into the glass during the rolling process. There are many patterns available.

Operator – A component or means of gripping that is used to move, pivot or to adjust the position of an operable sash, ventilator, or panel in a window or door assembly. Click for photo

P-1 TEST –  Insulated glass units are tested and evaluated under extreme temperatures, humidity and ultraviolet (UV) light exposure. Test specimens are fully and continuously exposed to conditions of 140o Fahrenheit or 60o Celsius, 95% RH and 100% ultra violet. Many engineers consider P-1 the world’s toughest accelerated aging and durability test. One week of testing is considered by industry experts to be equivalent to approximately one year in the field.

Pane – A framed sheet of glass.

Panel – A part of fenestration product, composed of a light of glass and surrounded by a frame. Panels can be fixed in place or be movable.

Panning – Used in replacement window work. Panning refers to the outside aluminum trim that can extend around the complete perimeter of the window opening. It is used to cover up the old window material, such as wood or steel.

Pivot Bar – Part mounted on or in the end of the sash that fits into balance shoe and from which the sash may be tilted or pivoted in.
R-Value – A measure of the resistance to heat loss: a measure of conductivity. R-Value is the inverse of U-Value.

Radiation – The direct process of heat transfer through space by means of electromagnetic waves. Energy in the form of rays of light is transferred from body to body without heating the intermediate air.

Rail – A horizontal surrounding edge member of a sash, ventilator, or panel.

Receptor – Framing system consisting of one or two aluminum extrusions used to contain a window or door frame, head and/or jambs in a masonry type opening. Allows for deflection and inconsistencies in the openings.

Shoe – Part attached to bottom of balance that attaches balance to sash. A bar or pin on the sash sash fits in a “slot” in the shoe.

Single Seal Units – Insulating glass using a single sealant for the edge seal system. Based on material characteristics, the single sealant is used for the resistance of moisture into the insulated glass unit to prevent the leakage of insulating gases (argon, krypton) out of the unit and as a structural sealant/adhesive to maintain the integrity of the insulated glass unit.

Spark Emission Spectrograph – Equipment used to measure argon gas concentration in an insulated glass through non-destructive emission of an electrical spark within the insulated glass unit.

Sash – The portion of a window which includes the glass and the framing sections which are directly attached to the glass. Normally the moving segment of a window, although sash are sometimes fixed. Not to be confused with the main frame into which the sash sections are fitted.

Screen – A product used with a window or door, consisting of a four- sided frame surrounding a mesh of wire or plastic material used to keep out insects. The screen can be fixed in place or it can be rolled side-to-side as on a sliding glass door.

Sill – The main horizontal member forming the bottom of the frame of a window or door.

Single Glazing – The use of single thickness of glass in a window or door.

Single Hung Window– Single hung windows are vertically operating windows in which the sash weight if offset by a counterbalancing mechanism mounted in the window. The single hung window features a stationary top and a movable bottom half. One or more locking devices are furnished to secure the sash in the closed position.

Slider Window – A slider window may have one or two movable panes of glass. Whatever the type, the windows slide horizontally in the frame.

Sliding Glass Door – Sliding glass doors consist of one or more pieces of glass contained in panels, which are contained within an overall frame designed so that one or more panels are movable in a horizontal direction. Panels shall be all sliding or some sliding and some fixed. Panels shall lock or interlock with each other or shall contact a jamb member where the panel is capable of being securely locked. Doors shall be designed and assembled so that panel to panel contact between horizontal members moving relative to each other does not occur.

Super Spacers – In glazing, small blocks of neoprene, nylon, or other material placed on both sides of the edges of glass, during its installation, to center it in the glazing channel to maintain uniform width of sealant bands and prevent excessive sealant distortion under lateral loading. Click for photo

Stile –The upright or vertical surrounding edge members of any sash, ventilator, or panel.
Tempered Glass – The glass is reheated to right below the melting point then suddenly cooled. When shattered, it breaks into small pieces. It is approximately five times stronger than standard annealed glass. It cannot be re-cut after tempering.

Tilt Latch – A device that holds the sash in place while allowing it to tilt in or pivot in for easy cleaning or removable.

Tinted Glass – A mineral Admixture is incorporated in the glass, resulting in a degree of tinting. Any tinting reduces both visual and radiant transmittance.

U-value or U-factor – A measure of how well heat is transferred by the entire window-the frame, sash and glass-either into or out of the building. U-Value is the reverse of R-Value.

Ultraviolet – The invisible rays of the spectrum which are outside of the visible spectrum at its violet end. UV rays are found in everyday sunlight and can cause fading or chalking of dark paint finishes.

Vinyl – Polyvinylchloride (PVC) material that can be either rigid or flexible, used in glazing channels and weathering of both windows and doors.

Volatile Fog – Condensation of chemicals or other impurities within an insulated glass unit on the interior glazing surface(s) that result in permanent haze or “fog”.

Warm Edge Spacers – Insulating spacers used to seal panes of glass in the manufacture of insulated glass units – edge conductivity is lessened for improved window energy performance and reduced condensation problems.

Weather-stripping – Thin sections of material used to prevent air leakage around operable windows and doors – usually foam gasketing, metal strips, or vinyl.

Window – An opening constructed in a wall or roof and functioning to admit light or air to an enclosure, usually framed and spanned with glass mounted to permit opening and closing.