Fenestration Forum – December 2017
Bricks of glass
November 29, 2017 By Brian Burton
Glass block usage, traditionally a popular glazing option to diffuse light in industrial applications, is on the upswing. With proper detailing it can be enhanced for various applications including daylighting, security, fire separation and blast resistance, while adding more colours and textures as well.
Glass blocks (or bricks, as they are often referred to in Europe) should only be relied on to support their own weight, whether in a wall, roof or a below-grade location, and the potential for differential movement should always be considered. Rainwater run-off may also need consideration as run-off patterns at some exterior locations may require design detailing. Wind loads also need to be considered and there may be size limitation to the wall as a result.
Increasingly, as designers consider improving sustainability, glass blocks are used to maximize available sunlight and reduce energy consumption. This approach depends heavily on building orientation and location.
Glass blocks provide designers with numerous options that can be very attractive in addition to their long-standing role in accenting entrances and doorways and creating privacy. In the past, solid glass components were used for what were known as “vaulting” applications and sidewalks at grade level. Both Vancouver and Toronto have excellent examples of heritage glass pavements, a unique feature these two cities share with Paris, London and Berlin. These solid glass prisms in Vancouver slowly turned deep purple as a result of exposure to UV radiation, adding to their lustre.
Designers often take advantage of the unique diffused light and wide range of shapes and textures provided by blocks to create well-lit and attractive spaces that can add special design interest. These attributes and the fact that block sizes have finally been standardized have enabled glass blocks to enlarge their share of the fenestration component market.
The technology used to manufacture glass blocks has seen tremendous advances over the past two decades. In the past, fabrication involved production by hand: fusing two solid glass block halves together at high temperature in a time-consuming process. Today, the process is automated for the most part and much like other glass fabrication techniques is highly efficient.
With new products like solar-powered in-ground glass pavement blocks and blocks with stunning metallic finishes entering the market, even more interest is being shown.The ability of blocks to add a sense of openness while maintaining an impression of stability is often used to great effect in government buildings and institutional structures where designers are creating prominent buildings with strong visual appeal.
Other specialized applications have made glass blocks a popular choice when it comes to combining modernistic style with functional energy efficiency. For example, commercial or institutional owners often want to create welcoming entrances for their businesses or perhaps waiting areas or partitions that are attractive and bright. Many adaptive re-use and remediation projects have also used blocks effectively in stairwell areas that were formally quite dark and had a very industrial look or feel. Glass blocks were used with great success in upscale conversions such as Tip Top Tailors and a number of well-known distillery condo conversions in Toronto, Vancouver and elsewhere. When design professionals use glass blocks to effectively contrast with other materials or textures, the overall visual effect or impression is greatly amplified.
Blocks can be used virtually anywhere, however the complexity of modern buildings is such that block installations typically need input from structural and safety professionals to ensure adequate long-term performance and durability.
Brian is a construction writer from Ottawa Ontario who served on the CSA’s Fenestration Installation Technician Certification Program Personnel Committee. You can contact Brian at Blueblade49@gmail.com or learn more by visiting burton’s-pen.com
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