TRUCTURAL glazing is a way to bond glass to a metal window frame or curtain wall system. It uses a high-strength, high-performance silicone sealant, without an external cover bead. With a less obtrusive, more attractive finish, structural glazing is popular in commercial applications, such as multi-level buildings, suburban office complexes and in factories. Structural glazing offers several advantages:
It allows architects and building designers more design freedom. Glass facades are popular because they are versatile, look good, allow natural daylight, and offer occupants a sense of well being.
It increases the thermal efficiency of glass building facades. Heat travels through conventional metal window frames, but structural glazing means that any metal framing or fitting exposed to the outside is minimal.
It reduces the potential for thermal breakage of the glass installed.
It can reduce or eliminate air and water infiltration.
There are two types of structural glazing systems:
Two-sided joint system. This is where the glass pane has the head and sill contained in a conventional glazing rebate. The two remaining sides are bonded either to a metal mullion or to a glass fin, using structural sealant.
Four-sided system. This is where you bond all four sides of the glass pane to the framing system using structural sealant.
The main components of structural glazing systems are structural framing, the glass, silicone sealant, spacers and setting blocks. Each of these components must be compatible, and able to perform its proper functions. Preparation and testing is very important. In particular, great care in the surface preparation of all the components to be bonded is essential. The glazing types used in structural glazing can include monolithic glass; heat strengthened laminated glass, and energy saving options, such as insulated glass units (IGU). For years, IGUs in commercial buildings have helped to meet energy efficiency regulations. IGUs have also helped to reduce of the cost of heating and cooling by improving the thermal insulation performance of windows and glass facades.
Continuous sampling of the structural sealant for strength tests and surface preparation is essential to ensure consistent quality. Sealants: Weatherseal the exterior of the building; Anchor the glass to the structural framing; Transfer structural loads, such as positive/ negative winds and seismic activity, from the exterior glass to the structural framing located inside the building. Thermotech IGUs, by Viridian (formerly Pilkington and DMS Glass), use a butyl-based thermo plastic spacer as the primary seal between the glass panels, and structural silicon as the secondary seal.
Gerard McCluskey is Director, DMS Glass.
Source: Construction Contractor