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The Evolution of Glass in the Operable Wall Industry


Glass is all around us wherever we look and look through. The most common applications are windows of all sorts as well as eating and cooking accessories, jewellery and ornamental items. It has been with us since the 3500s BC when the Egyptians made vessels, small artifacts and amulets. Fast forward over 3000 years to when the Romans began to use glass for Architectural purposes as they discovered techniques to produce glass in window form and then the first mirrors. By the 8th Century Venice was the glass making capital of the world producing stained glass windows for churches and cathedrals. In the 18th Century the British Plate Glass Company was producing window glass for commercial and home use. Then in 1950 the big breakthrough: Alastair Pilkington created and patented “float glass” (floating molten glass on a bed of molten tin)  allowing it to be mass produced in much larger sizes and types for use as a primary building component. And now in the 21st Century with all Pilkington patents having expired there are glass manufacturing plants all over the world with new applications being introduced on a regular basis.

Interior Glass Wall systems as a manufactured product, were common in Europe long before they became popular in North America. In N.A. operable glass systems were extensively used but typically assembled by local glass distributors using fittings purchased from a myriad of hardware suppliers. And even then, most required floor tracks in order to ensure stability. It wasn’t until the need for acoustic glass walls became a need that operable wall manufacturers like Moderco combined features such as operable seals, astragals, closure methods etc. with their knowledge of acoustics to create the present day operable  glass wall systems. Moderco was one of the first to introduce, test and bring to market their “Crystal STC 44 “ wall system. Introduced in 2003 it remains to this day the leader in the acoustical operable wall market.

There are four basic types of Glass Operable Wall Systems.

  • Frameless Panels – Patch Fittings (non-acoustical). Moderco does not offer a Patch Fitting product.
  • Frameless Panels – Horizontal Rails (non-acoustical) Moderco Vision
  • Framed Panels – In a traditional solid operable wall panel design (untested acoustics). Available in Moderco Excel and Signature Operable Walls.
  • Framed Panels – Aluminum Frame (tested acoustics). Moderco STC 44 Crystal.

There are four main types or strengths of glass:

  • Annealed Glass (float glass that is slowly cooled): Annealed glass is the basic product typically used in windows, weak, breaks into large jagged pieces, least expensive and should never be used in an operable wall. ...
  • Heat Strengthened Glass. Annealed glass cooled at a specific rate, semi tempered, more tolerable to temperature change, twice as strong as annealed, breaks into large jagged pieces similar to annealed and should never be used in an operable wall..
  • Tempered Glass: Annealed glass that is heated to very high temperatures and then rapidly cooled (quenching). Shatters into cube shapes when broken. 5 times stronger than annealed..
  • Laminated Glass: A sandwich of two layers of glass (usually tempered but not necessarily) separated by a vinyl interlayer (polyvinyl butyral PVB). When it breaks the particles adhere to the interlayer thus the name “safety glass’ as used in car windshields.. Offers additional UV protection as well as a potential increase in tested STC values. A possibility for operable walls but probably not worth the extra cost.

Tempered is the most common choice for operable walls. One Operable wall manufacturer is using the term “High STC Glass” as a way to describe the glass used in one of their products. There is no such glass as “High STC Glass”: it is created terminology. In fact the manufacturer uses “tempered glass” like the rest of the industry.

Moderco uses Tempered Glass in all Glass Wall systems.

Glass Thicknesses, weights & heights.

The most common glass thicknesses that might be used in Architectural Products are: 4 mm (5/32”or 0.16, 2.10#/sq. ft.), 6 mm (1/4” or 0.25, 3.27#/sq. ft.)), 8 mm (5/16” or 0.31, 4.07#/sq. ft.), 10 mm (3/8” or 0.375, 4.91 #/sq. ft.), 12 mm (1/2” or 0.50, 6.54#/sq. ft.), 16 mm (5/8” or 0.625, 8.19#/sq. ft.), 19 mm, ( ¾” or 0.75, 9.84#/sq. ft.), 22 mm, (7/8” or .875, 11.47#/sq. ft.), 25 mm, (1” or 1.00, 13.11 #/sq. ft.).

You can calculate the weight of any glass area & thickness by multiplying the area (length in feet X width in feet) X thickness of glass in inches (decimel) X 13.11. For example a piece of ½” glass 4’ X 8’ would weigh 4’ X 8’ X .5 X13.11 = 209#. The most common thickness used in operable walls is ½” (0.5”) for Frameless Panels (Moderco Vision) and combinations of two thicknesses for Framed acoustically rated walls: more on this in a future article on glass wall acoustics.

The typical maximum height for glass, especially for single pane non acoustic product, is 10’ however Moderco offers both Crystal and Vision glass wall systems in standard heights of 12’. Above 12’ glass begins to flex creating potential safety hazards. Also height is limited due to limitations as to what an installer can manage in the field or a manufacturer can safely produce. There are exceptions from Moderco to the published maximum height of 12’especially with the framed Crystal product so please contact us with special needs.

Moderco Glass Wall Systems are:

-      Crystal: Acoustically Rated, STC 44, Aluminum Framed. Click here for more information.

-      Vision: Non Rated, Frameless Panels with horizontal Rails. Click here for more information.