Photo courtesy Technical Glass Products
Rather than resorting to a solid gypsum board enclosure around the stairs, architects opted for fire-resistive transparent glass panels. This enabled them to incorporate an unrestricted amount of glazing that would allow the staircase to remain visible. They paired this glazing with a fire-rated system overlaying a high-strength, steel sub-frame with a domestic white oak-veneered metal cover cap. The result is a stairwell that enables clean sightlines, capturing the warmth of wood and acting as a barrier to fire, smoke, and heat.
In previous decades, the choice in doors for such a stairwell would have been restricted to a solid metal fire door with a small vision kit. However, the architects were able to take full advantage of the latest material offerings and specify a fire-rated glass door in framing that maintains the same visual esthetic as the surrounding fire-rated system.
Further, the design team incorporated another breakthrough: they lined the perimeter of the main staircase with fire-rated glass flooring segments. The advanced fire-rated glass floor system consists of heat barrier glass, a tempered, laminated walking surface, and a steel framing grid. This configuration allows the system to draw light from the upper level down to the ground floor while providing critical fire resistance. It can support loads of up to 732kg/m2 (150 psf) and is fire-rated for up to 120 minutes.
The next frontier
In recent years, the trend has been toward glossy spans of uninterrupted glass in prominent applications, such as storefronts, partitions, and visible curtain walls. Until recently, it was impossible to achieve this clean, modern look in areas subject to fire-rated criteria. Now, two systems offer this functionality.
The first is a structural, silicone-glazed, fire-rated curtain wall system. It emulates the smooth, monolithic appearance of its non-rated counterpart and does not require pressure plates or caps. Its toggle retention system anchors the glazed lites and becomes completely hidden once installed. The resultant effect is a seamless, uninterrupted surface appearance. The system is available with up to 120-minute fire-resistance-ratings and can accommodate full-lite doors for a complete curtain wall entrance solution. In application, it can help ensure smooth visual transitions at junctions between the rated and non-rated systems while providing critical protection against the spread of fire.
The second development to capture the continuous glass esthetic is butt-glazed, fire-rated glass walls. Currently available systems comprise fire-rated glass wall panels with butt-glazed joints in a heat-resistive perimeter frame. To further improve sightlines, some assemblies have vertical butt-glazed joints as narrow as 5 mm (197 mils). Offerings with a solid, multi-laminate glass makeup (i.e. those that have colourless, wireless, low-iron float glass and clear intumescent interlayers) eliminate the need for coloured internal spacers or vertical mullions between adjoining pieces of glass.
Adding an element of customization, some systems are now available with perimeter framing options. For these products, the perimeter of each butt-glazed elevation can be held in place by the designer’s choice of fire-rated framing.
With near imperceptible sightlines, butt-glazed, fire-rated glass walls are suitable for interior applications where it is crucial to match the look of neighbouring non-rated systems or improve views and light transmission.
Conclusion
Once an inhibitor to design freedom, fire-rated glass and framing now serve as inspiration, turning possibilities into realities that were inconceivable in the past. There is no longer a need to sacrifice form for the sake of function—buildings can be both safe and beautiful. The creative opportunities continue to expand and the ongoing product development happening in the field of fire-rated glazing only promises even greater potential for the future.
If the proposition of modern, high-performance fire-rated glass appears to be cost prohibitive, one can consider the benefits of bringing esthetics in line with function. Opening up a wall or adding fire-rated curtain walls throughout interiors can enhance daylighting and occupant well-being. Characteristics such as larger glass sizes, increased clarity, higher impact ratings and compliance with energy codes can also improve the user experience and add to the longevity of the building.
Connor Martin represents Technical Glass Products (TGP) in Canada, supporting design and construction activities. TGP is a supplier of fire-rated and specialty glass and framing solutions for the architectural and commercial building industry.
