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The world of contract glazing is extremely technologically advanced and, as a result, can sometimes be confusing. We’ve taken the time to craft an industry glossary in order to assist designers, project architects, fellow glaziers, architecture students, engineers and anyone else interested in learning more about some industry terminology including Pilkington Planar™ structural glass systems. We’d like our readers to fully understand our featured content and projects and truly hope this glossary assists on that front.


901 Fitting: A Pilkington Planar™ countersunk bolt fitting designed to transfer glass loads. It can be connected to spring plates or spider fittings without access the back of the fitting. Also known as a “blind” fitting.


902 Fitting: A Pilkington Planar™ bolt fitting with a countersunk, flush head designed to transfer glass loads. It directly fixes to a back-up structure by means of stainless steel spring plate bracket or a spider casting. In addition to vertical walls, this fitting can accommodate any slope making it the perfect choice for use on roofs, canopies, and skylights.


905 Fitting: A Pilkington Planar™ bolt fitting with a countersunk, flush head designed to transfer glass loads. It attaches to a stainless steel rod connected to a back-up structure. This fitting can be articulated to create faceted facades. This fitting can be used on vertical and sloped walls, canopies, roofs, and skylights.


Adjustable Jaw Turnbuckle: A termination assembly that can be used on the end of tension cable or rod that had a telescoping end concealing threads. Aside from adjustability, this provides an aesthetically pleasing machined termination for vision areas in lieu of a much larger steel assembly.


Bow: The amount of curve over the length of glass to greatest deviation of flatness.


Cable Net Wall: A tension facade system that uses both vertical and horizontal cables or one-way vertical stainless steel tension cables or rods that are pre-tensioned from the boundary structure to act as support for bolted glass panels to be be hung off of. A simplistic way of thinking of this is that of stringing a tennis racket. A surrounding frame is built with cables brought across it and those cables are pulled tight and locked in place.


Clevis: See spelter, swage stud, adjustable jaw turnbuckle, and fixed jaw assembly.


Component Warranty: A manufacturer’s warranty on a specific product that is used in an assembly only. This is not the same as a single source “system” warranty.  


Edge-Dip: The amount of deviation at the edge of the glass from the tempering process.


Fixed Jaw Assembly: A termination assembly that can be used on the end of tension cable or rod that is fixed in place. This provides an aesthetically pleasing machined termination for vision areas in lieu of a much larger steel assembly.


Glass Fin Wall: A type of point-supported structural glass system that uses vertical, tempered glass mullions also know as “fins” as a structural support. These glass fins can be ¾-inch (19mm) tempered or multi-ply laminated glass make-ups. Fins are generally suspended from structure above in most applications above 26-feet or in high seismic zones.


Gusset: A steel plate with that is bolted or welded to steel to accept a Pilkington Planar™ fitting or spring plate.


Heat Soaking: A process of reheating fully tempered glass in a chamber and holding it at a constant temperature for a duration of time then cooling back down. This process can be 2-8 hours depending on the manufacturer and standard. It helps to reduce the probability of spontaneous breakage due to a nickel sulfide inclusion. Glass that may have inclusions has more of a propensity to break in the heat soak chamber than in service from this process. See Spontaneous Breakage.


Hybrid Tension Structure Facade: A kind of tension facade system that often utilizes 1”-2” thick horizontal steel plate beams, that can vary in depth, to brace the system for wind load behind the horizontal joints. These plates beams are combined with vertical stainless steel sag rods/cables to support the dead load of the glass and pick up some of weight of the beam between attachment points at the building columns. The resulting structure helps to spread out the forces put on the building into both the columns and the head of the wall, while keeping the sightlines very clean inside and out. 


Infill: A type of material glazed directly into unitized curtain panels. Infill materials can be any material that is inserted into the curtain wall panel between extruded aluminum support mullions. Traditionally, they have typically been composed of vision glass or spandrel glass, but can also be made of metal, terracotta, and stone. Infills can also be operable and automated. 


Iridescence/Leopard Spots: When heat strengthened or tempered glass is viewed in polarized light, stress patterns called “leopard spots” or “iridescence” may become visible. This phenomenon is unavoidable and can be present from the tempering process.


Longhorn Fitting: A custom machined Pilkington Planar™ 905 rod fitting that is clamped to a cable or rod. 


Mullion: A support member anchored vertically or horizontally to be a rigid support to transfer loads of a material back to structure. See Stick-built System,  Structural Glazing System, and Unitized Curtain Wall.


Patch Fitting: A fitting that clamps face glass to a structural element to hold it in place. This can be connected to another piece of glass, a tension cable/rod, or a steel mullion.


Point-Supported Structural Glass System: A structural glass system that consists of tempered glass with holes allowing for attachment to a structural member by using bolted or clamped fittings. The structural glass is hung off of a back-up support structure in most cases. These structures can be tempered glass fins, steel members, or stainless steel tension cable structures. See The Pilkington Planar™ System.


Portal Frame: An entrance frame constructed to separate a suspended structural glass wall from the base loaded entrance doors. These frames can be made of hollow tube steel sections clad in stainless steel or painted steel/stainless steel custom fabricated plate beams or shapes. Depths will vary on each application.


The Pilkington Planar™ System: A type of custom point-supported structural glass system developed by Pilkington Architectural that is manufactured in St. Helens, United Kingdom. W&W Glass, LLC is the exclusive distributor for Pilkington Planar™ structural glass systems throughout North America. This product comes with a system warranty for twelve years from date of production/shipment on design, engineering, materials, and installation. It also features one of best roller-wave flatness tolerances on tempered glass in the industry at 0.0007-inches per foot or 0.02-millimeters per meter peak to valley.


Roller-wave Distortion: The deformation of glass on the rollers due to the tempering process where the glass is heated and cooled. It is measured from peak to valley per foot or meter taking the average of the high and low point deviations using a zebra board or electronic scanning device. There is no industry standard to quantify roller-wave distortion tolerance, just a general recommendation of no more than .006” peak to valley per foot. However, this deformation can be specified and controlled with better processing techniques and equipment. The Pilkington Planar™ System has an average peak to valley roller-wave distortion of 0.0007” per foot (.02mm per meter) on all tempered glass, which is the best in the structural glass industry.  


Single Source System Warranty: A comprehensive single source manufacturer warranty on the design, engineering, components, and installation by a single product manufacturer. This is not the same as a component warranty. See Pilkington Planar™ System.


Sloped (Overhead) Glazing: A type glazing that is horizontal or sloped to form a skylight or canopy. These must use laminated glass or insulated laminated glass units with the laminated glass facing the occupant side for fallout protection. Sloped or overhead glazing is subject to permanent gravity load from its self-weight and depending on the location, long-term gravity load from snow drift.


Sotawall® HYBRID-WALL®: A versatile, proprietary curtain wall system developed by Sotawall®. These HYBRID-WALL® systems can have integrated vision and spandrel materials combined inside a single unitized panel, which may be a preferred choice over window wall and slab edge cover systems due to better air and water penetration performance and less potential for leaks between systems on mid to high-rise construction.


Spelter: A termination for tension cables that may be closed or open depending on connection details. These are generally used in applications for larger diameter cables where the cable termination can be hidden from view.


Spider Fittings: A cast stainless steel fitting with armatures to accept bolt fittings to connect back to a back-up structure. These fittings can accept Pilkington Planar™ 902 or 901 fittings. See 902 Fitting and 901 Fitting.


Spontaneous Breakage: A phenomenon that causes fully tempered glass to break spontaneously due to the expansion of a nickel sulfide (NiS) stone (particle inclusion) trapped inside the tension layer of glass. When the stone expands due to a phase transformation from in-service temperature exposure (from alpha to beta phase), the glass can spontaneously break. See Heat Soaking. 


Spring Plate: A stainless steel angle that is connected to a back-up structure to accept fittings. These are most often used with Pilkington Planar™ 902 or 901 fittings.


Stainless Steel Cable: A tension cable comprised of stainless steel strands in a wire rope or structural strand configuration. 


Stick-built System: A curtain wall where long vertical pieces of aluminum (hence the name stick) are anchored between floors and horizontal mullions are set between vertical members to support and transfer the loads of the glass or infill material back to structure. Most of the erection and glazing for a stick-built system is done on site.


Structural Glazing System: A structural glazing system, in its simplest form, is a type of curtain wall system that consists of glass that is bonded or anchored back to a structure without the use of continuously gasketed aluminum pressure plates or caps.


Swage Stud: A threaded stud termination at the end of a cable. This allows for locking the cable in place with a nut on the end using mechanical engagement.


Tension Box Assembly: A galvanized steel box that a cable end will pass through and be locked in place. A hydraulic jack tensioning device will then pull the cable tight against the tension box assembly.


Tension Cable: A cable constructed of wire strands twisted around a core that is used in tension in structural applications. Cables can be constructed of stainless steel or galvanized steel with wire rope, structural strand, or fully locked configurations depending on the application. For structural elements, structural strand and fully locked are the most commonly used. Since each construction has it’s specific uses and limitations, it is recommend that a system supplier is consulted for selection. 


Tension Facade System: A point-supported system that uses high tension cables or stainless steel rods to impose the loads of the facade onto main structure. This decreases the amount of solid structural elements visible on the project and in many cases depth of the support structure, therefore increasing the transparency of the facade.


Unitized Curtain Wall: A curtain wall system that is composed of large panel assemblies that are fabricated into aluminum frames and pre-glazed within a factory with infill materials (fixed glass, operable windows, metal panels, terracotta, etc.) and then sent to the construction site for weathertight installation. Once on site, the units can then be hoisted onto anchors connected to the building.


Vertical Glazing: Any curtain wall/structural glass panel that is oriented vertically on the facade. This glazing may be comprised of monolithic, laminated, insulating glass units, or insulated laminated units. The glass can be tinted, annealed, heat-strengthened, tempered, low-e coated or even painted with colored silk-screened ceramic frit patterns. 


Vestibule: A vestibule is a small space or entranceway most often employed in all commercial and institutional buildings to provide a passage to connect the exterior and interior environments. These entryways serve to act as a transitional barrier from the weather outside.


Warp: The amount of twist or curve diagonally from corner to corner.


Do you have any questions about any of the included terms? Do you have a term you’d like to see added to the list?


Please comment below and we’ll respond as soon as we can.

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