STRUCTURAL GLASS FACADES - USC School of Architecture

2.4.1.6 Laminated Glass
Laminated glass consists of two or more pieces of glass
bonded together by a piece of plastic/vinyl called polyvinyl
butyral (PVB.) A minimum interlayer thickness of .030
(.76mm) meets the requirements of ANSI Z97.1 or CPSC
16 CFR 1201 safety glazing standards. (Viracon 2008)
Figure 2.26 Diagram of laminated
glass (Viracon 2006).
Laminated glass can utilize tinted glass, highperformance
coatings, silk-screened patterns and
pigmented interlayers together or alone.
The gluing or laminating of sheets of glass in layers evolved as a strategy for strengthening
the resulting panel and providing additional safety by eliminating the risk of injury from sharp
glass shards resulting from the breaking of monolithic glass; if one sheet breaks the broken
sheet will be held in place by the interlayer material. The process was invented and
developed by the French scientist Edouard Benedictus, who patented his new safety glass
under the name "Triplex" in 1910. (DuPont 1995)
Polyvinyl butyral (PVB) is the most common interlayer material. It is available in rolled sheet
form in various thicknesses. The thickness of the laminate, or interlayer, is usually a function
of the thickness of the glass pieces being laminated. In the glass grids used in structural
glass facades requiring pane thickness generally in the ¼ inch (6mm) to ½ inch (12mm)
range, 1/16 inch (1.5mm) thick PVC would be used. Overall thickness of the fabricated 2-ply
panel would then be 9/16 inch (13.5mm). The process involves compressing the
glass/PVB/glass sandwich and heating it in an autoclave. The translucent PVB becomes a
clear, tough material adhering to the glass surfaces and binding the two pieces of glass
firmly together. If one piece of glass breaks, the glass will remain stuck to the interlayer and
92