by Michael C. Kerner, FASTM, CSI, CDT
With a history spanning more than a half-century in non-combustible commercial construction, cold-formed steel (CFS) is a popular material choice for framing non-structural interior walls, load-bearing interior and exterior walls, curtain walls, and floor joists. Its many performance-based characteristics and ‘green’ attributes have enabled architects to design safe, durable structures that are both dynamic and sustainable.
The material is:
- non-combustible;
- corrosion- and mold-resistant;
- termite-proof;
- made with high-recycled content; and
- reduces onsite construction waste as materials can be ordered to specified lengths.
Cold-formed steel framing products are completely recyclable, and can be locally or regionally sourced for most projects. New construction projects featuring cold-formed steel components can be eligible for up to 12 Leadership in Energy and Environmental Design (LEED) points in eight different categories, which include:
- Materials and Resources (MR) Credit 2, Construction Waste Management;
- MR Credit 4, Recycled Content; and
- MR Credit 5, Regional Materials.
The two primary CFS framing applications are structural and non-structural, with this article focusing on the latter. (For more on cold-formed steel, see “New Purposes for Cold-formed Steel.”) Non-structural steel studs are not designed for bearing any axial loads and are ideal for supporting the dead load typical of many wall finishes (e.g. gypsum board or tile) and providing resistance to limited interior transverse loads.
Accounting for the use of nearly 60 percent of all metal studs in the United States, interior, non-structural wall partitions are common applications for steel framing—specifically light-gauge steel studs. As specifiers, it is important to understand the material and manufacturing requirements set by ASTM C645, Standard Specification for Non-structural Steel Framing Members, the installation requirements set by ASTM C754, Standard Specification for Installation of Steel Framing Members to Receive Screw-attached Gypsum Panel Products, and the specification of fire-rated partitions.
The emergence of the new AISI S220, North American Standard for Cold-formed Steel Framing—Non-structural Members, is also critical. This standard will be adopted in the 2015 International Building Code (IBC), eventually replacing ASTM C645 as the universal industry standard for the specification of non-structural steel framing. Until then, guidelines and requirements of ASTM C645 and C754 should be followed.
ASTM C645
ASTM C645, Standard Specification for Non-structural Steel Framing Members, is the current industry standard for the manufacturing of non-structural steel studs. It is referenced in IBC to determine code compliance for non-structural studs.
The four key attributes for architects and specifiers to examine when evaluating non-structural steel stud products are thickness, shape or configuration, coating, and marking or identification. ASTM C645 addresses these attributes further in a series of sections, which includes “Materials and Manufacture,” “Dimensions and Permissible Variations,” and “Marking and Identification Requirements.”
