STRUCTURAL GLASS FACADES - USC School of Architecture

used in overhead applications is generally required by code to be laminated, and depending
upon thermal requirements may be laminated insulated with the lower panel being
laminated. Many manufacturers limit the size of overhead panels to 35 ft² (3.25m²).
According to Joe Green, CEO of Glass Pro, a glass fabricator in Southern California that
does glass bending and provides glass fabrications for point-fixed applications, the company
can provide tempered glass up to 84 by 168 in (2134 by 4267mm), laminated glass up to
120 by 180 in (3048 by 4572mm) (narrower widths can be made longer), and 96 by 130
(2438 by 3302mm) for IGU’s (larger sizes can be produced by hand). Glass Pro also has a
CNC machine, used for notching, drilling, countersinking, and other glass machining
operations, the can handle sheet sizes up to 98 by 170 in (2489 by 4318mm). (J Green
2008, pers. comm., 18 Mar.)
Viracon publishes size guidelines that are available for download as an Acrobat (*.pdf) file;
Vircon size guidelines
2.4.3 Thermal and Acoustic Performance Issues
2.4.3.1 Thermal Performance vs. Transparency
As noted earlier, monolithic or laminated glass provides the highest level of transparency in
structural glass façade applications. While insulated glass units provide superior thermal
performance, and are often used for this most excellent reason, there is a price to pay in
relative transparency. The edges of the spacer in the IGU are sealed to the glass with a
black material, so there is a visible black band around the perimeter of an IGU that is the
thickness of the spacer; about 3/8”. An opaque sight line is formed between two glass
panels, spanning from the inner spacer edge of one panel, across the weather seal between
the panels, and to the inner spacer edge of the adjacent panel. The weather seal is typically
approximately equal to the overall thickness of the IGU. A common IGU makeup is two 1/4”
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