There are 3 key benefits that installers look for when attaching Insulated Glass Units (IGUs) to buildings: speed of install, ease of use (ie replacing panes), and cost. Those needs, in combination with the architectural desire for clean and minimal sight lines, have led to the development of toggle systems, a facade system that is quickly gaining popularity among glaziers.
EVOLUTION OF FACADE SYSTEMS
Traditional framing, dry glazing with pressure plates and spider fittings, has been around for decades. With the desire to have a building envelope with a seamless image, Structural Sealant Glazing (SSG) was developed. However, it comes with challenges such as numerous steps for installation or replacement and quality control is very difficult to perform on site. As an alternative to SSG, facade system makers have found ways to use the IGU edges to allow mechanical connections between glass and the structure…. enter the toggle system.
With toggle systems, 100mm waterproof plastic pockets are embedded in the silicone joint and spaced apart from 200 to 600 mm, depending on wind load. Several types of pockets offer shallow or deeper retention area. The IGU is mechanically fixed back to the facade construction by means of the retractable tabs and a threaded restraint. The IGU assembly is done on a normal automatic line assembly. The self-centering plastic or composite pockets are pushed into the fresh silicone at the end of the line, expelling only the clip’s volume of sealant.
LOCATION. LOCATION. LOCATION.
Installing large (often oversized) glass units to luxury retailers and flagship retailers is no small feat. Most often, they are located in highly populated, downtown areas with many delivery hurdles such as lane closures, mid-night deliveries and tight access. We look at 2 retailers that used toggle systems to their advantage in their busy flagship locations.
1) H&M Flagship, Fifth Avenue
The H&M store consists of large format insulated units supported by structural glass fins. The triple laminated glass fins are spliced in two locations and carry the vertical load from the facade IGU panels. The architectural requirements to have minimal and clean sight lines with no discrete point or patch fittings or pressure caps suggested either a fully structural silicone approach or a toggle system. Beyond the typical drawbacks of a full-fledged SSG system, one of the biggest challenges of this project was lateral drift of the building under wind load.
Under this induced movement, the facade panels rotate about their support points, which causes differential vertical displacements in the joint between two adjacent panels. If the facade panels were attached to the fin directly with structural silicone, then the shear force generated in the silicone would be too high. For these reasons, the Skandinaviska clip system was used by Mistral Architectural Metal + Glass to laterally restrain the panels, meaning that all the silicone joints could be a low modulus weather-sealed type, capable of accommodating the required strain. Furthermore, the custom Skandinaviska channel could be structurally bonded to the glass fins in the factory under controlled conditions, ensuring a high-quality bond, and delivered to the site ready for the IGU panels simply to be mechanically fixed in place. This led to a very quick installation process and high-quality finish with minimal sight lines.
2) Samsung Experience Store, Toronto
Toggle systems offer many advantages including flexibility, simplicity, longevity which ultimately result in cost-efficiencies, ease of install and most importantly, an all-glass facade with minimal and clean sight lines.
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