Steel As A Curtain Wall Framing Material

New forming methods advance material’s use in building construction



Photo of Charles Knickerbocker

Charles Knickerbocker

Curtain Wall Manager

Technical Glass Products



This paper will explore steel forming methods other than cold drawn or hot rolled processes, and how they allow steel to be utilized as the primary framing material for windows and curtain walls. Additionally, it will address how these forming methods eliminate the need to remediate steel for compliance with Architecturally Exposed Structural Steel (AESS) requirements. On the performance front, this paper will cover steel’s advantages over aluminum extrusions and its benefit in window and curtain wall applications. These include greater strength, smaller profiles, improved thermal conductivity, and use for life safety in the construction of fire-rated windows. It will also address specified performance criteria for deflection, air- and water-penetration resistance, as well as seismic, thermal, and dynamic movement, along with the strategies these steel systems use to enhance performance. Finally, this paper will review case studies of three projects where steel was used as the primary framing material, including a fire-rated application, a captured glazing system, and a structurally silicone glazing system.


In 1856, the Bessemer process allowed for the efficient, affordable mass production of steel, which benefited the building industry. By the late 1880s, architects were designing taller buildings utilizing steel

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With the advent of steel and concrete as the primary materials in building structures, it was no longer necessary for thick (usually masonry) exterior walls to carry the weight of

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The following section will overview current steel formation processes, and their impact on curtain wall and window design.

Hot-Rolling Process

Hot-rolled steel shapes are a commodity used for steel building structures, bridges

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Rolled and laser welded steel products are primarily sourced from European suppliers. Therefore, the raw material is usually produced from alloys meeting European standards, not ASTM International (formerly American Society

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Performance Outcomes

When designing a system for a window or curtain wall application, steel-based framing systems can meet the same typical set of specification criteria as their aluminum cousins for deflection, seismic

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Case Studies

The following case studies illustrate the use of modern-day steel forming in curtain wall and window applications.

Rolled Profiles / Fire-Rated Curtain Wall

This project overviews an interior fire-rated application, using rolled

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Conclusion and Future Work

Advanced manufacturing processes allow steel’s use for curtain wall and window applications in ways not previously envisioned, with an aesthetically acceptable visual quality. They can deliver excellent performance, are weather

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Rights and Permissions

Technical Glass Products, Snoqualmie, WA, for shop drawings and case study photographs.

Ipswich Bay Glass, Ipswich, MA, for case study #3 photographs.

Montanstahl for steel / laser fusion video.