Transparent, fire-rated glazing has allowed designers to plan open, bright, and code-compliant interior spaces in almost every area of a building, including stairwells. This has shifted the demands placed on today’s stairwell enclosures, turning these architectural necessities from purely functional parts of a building into features that contribute to a project’s overarching design aesthetic.
While fire-resistive glass supports many design possibilities that were previously unattainable, it is not the only part of a fire-rated assembly. From the frames to the component parts, fire-resistive framing systems rely on each member to ensure a glazing system is both code-compliant and design forward.
For example, narrow-profile steel framing systems are inherently strong and can allow larger spans of fire-resistant glass while also providing a close visual match to adjacent non-rated systems. This helps maintain an aesthetically pleasing design when both rated and non-rated systems are in proximity to each other.
Although stairwell design no longer faces the same constraints it did 15 or 20 years ago, its success often hinges on building professionals’ knowledge of applicable codes and standards as well as the appropriate use of fire-rated materials.
Stairwells balance several fire and life safety requirements
The demands building codes place on stairwells can vary significantly depending on the building type, the context of the stairwell, and the local codes that are in use. For this reason, it is encouraged that designers and specifiers consult local building codes and contact an authority having jurisdiction (AHJ) to answer any remaining questions.
That said, in general, egress stairwells often need to be surrounded by fire-resistive materials and systems. These create a barrier to fire, smoke, and radiant heat to maintain free egress during a fire. For larger projects, fire-resistive materials may also be needed to contribute to compartmentalization strategies to limit the spread of smoke and fire.
In addition to the walls around a stairwell, doors, sidelites, and windows will also need all component parts, including frames, to have a fire rating that is appropriately matched with the fire-rated wall that surrounds them. Depending on opening size and local code requirements, specifiers may have multiple options for achieving code compliance, so it is encouraged that these professionals consult local codes and, if necessary, discuss options with an AHJ.
Planning for code-compliance is crucial for occupant safety, but creating interiors that support occupant experience is also important. This can include providing access to daylight and using systems that support navigability by increasing visual connection between spaces. Narrow-profile fire-rated steel framing can contribute to
these goals.
Framing systems make the previously impossible, possible
Often, fire-resistant rated glazing is heavier than non-rated glass. As such, its use also impacts framing beyond the need for fire ratings. In the past, the increased weight of rated glazing often necessitated bulkier framing systems. Thicker frames limited the amount of glazing possible, both in terms of free spans and the amount of glazing visible after installation. They also made it more difficult to achieve a cohesive design aesthetic with non-rated systems. Creating a close visual match between systems can receive added emphasis in stairwell design, where assemblies can be in view simultaneously.
For example, the external stairwell at 419 Occidental Avenue in Seattle, Wash., required fire-rated doors and windows in its north and south walls. The east and west walls were designed with full wall panels of transparent, non-rated glass. This had the potential to create disharmony between the framing profiles. SHED Architecture & Design, the firm behind the project, turned to narrow-profile, fire-rated steel frames to solve this challenge. These systems supported visual unity between glazing systems while also meeting the performance requirements needed for the assemblies within the north and south walls.
Greg Shiffler, senior architect and partner at SHED, says, “This design would not have worked if it were just a tiny window in a brick wall.” The strength of fire-rated, steel framing allowed larger glazing sizes without compromising code compliance and design intent. Steel’s inherent strength helped open the stairwell, providing sprawling views of downtown Seattle and flooding the enclosure with daylight—all without compromising a cohesive look.
419 Occidental Avenue is only one example of the design benefits narrow-profile fire-rated frames provide. Building professionals have used these systems to achieve code compliance and visual cohesion in projects across the country, including high-profile structures like New York City’s Fulton Center. This project utilizes narrow-profile, fire-rated steel frames for its elevator enclosure and upper level. These systems maximize the glazing area and provide a close visual match to non-rated glazing assemblies throughout the bustling transit hub.
Narrow-profiles support cover caps
to fit a variety of aesthetics
On their own, narrow-profile, fire-rated frames deliver value by allowing a closer visual match to adjacent, non-rated assemblies than traditional hollow-metal frames. This helps specifiers maintain a cohesive design aesthetic without compromising fire and life safety. However, this is not their only benefit.
If a framing system needs to be fire-resistive to achieve code compliance, steel sub-frames can be designed to provide fire-resistance ratings without needing an inner core with insulative materials, depending on the glazing materials paired with them. This results in framing components that are thinner than traditional hollow-metal frames. As such, even with cover caps, these framing systems can achieve profiles that more closely resemble non-rated assemblies.
Further, cover caps can help maintain visual consistency with surrounding windows and curtain walls. Cover caps can also be custom wet painted, anodized, or powder coated in nearly any color. For instance, the designers of Mill Brook Elementary School in Concord, N.H., covered slender, fire-rated steel sub-frames with aluminum caps that were powder coated in a bright purple to match the school’s interior color scheme.
Using thin sub-frames can also mean leveraging materials other than metal. This allows building professionals to use the strength and fire-resistant qualities of steel frames without limiting their design choices. As an example, the stairwell at La Crema Estate at Saralee’s Vineyard needed to meet fire-resistance requirements while also fitting in with the estate’s extensive use of wood framing and hardwood flooring. To solve this challenge, the specifiers chose a fire-rated framing system that pairs a high-strength steel sub-frame with a real-wood veneered metal cover cap. The result was a code-compliant glazing system that maintained the warm allure of the estate’s wood aesthetic.
Designing stairwells without compromise
Although glass often takes center stage when discussing fire-rated glazing assemblies, the frames are equally important. These systems not only ensure curtain walls, windows, and doors meet fire- and life-safety code requirements, but also contribute to a project’s design aesthetic.
Capable of meeting a wide range of performance requirements, slender, fire-rated steel frames allow building professionals to take stairwell designs a step further. These framing systems minimize obstructions to sightlines and support a visual cohesion between rated and non-rated systems, both in terms of material and profile size.
As a result, designers can solve multiple challenges without compromising their aesthetic vision. Not only does this create more freedom within a design, but it also helps ensure occupant well-being stays central.
Devin Bowman is general manager of Technical Glass Products (TGP) and AD Systems. With more than 20 years of industry experience, Bowman is actively involved in advancing fire- and life-safety codes and sits on the Glazing Industry Code Committee (GICC). He can be contacted at devin.bowman@allegion.com.