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Steel Compares Well to the Trusty 2x4 | |||||||||||
Cold-formed steel (CFS) is durable, strong, and recyclable, points out the Partnership for Advancing Technology in Housing (PATH), a public/private program managed and supported by the U.S. Department of Housing and Urban Development, in a September 2002 report. Moreover, CFS-supported floor/ceiling, wall, and roof systems can be designed to be at least as fire and sound resistant as traditional wood-supported components in house construction, the report states. A 30-minute fire-resistant rating (per manufacturers ASTM E119 testing) is readily achievable using one layer of ½-inch (12.8 mm) gypsum wallboard, and 60 minutes is achieved using multiple layers of gypsum wallboard, Residential Steel Framing: Fire and Acoustic Details reports. Board materials such as gypsum boards, cementitious boards, or gypsum fiberboards for walls and ceilings, and timber-based boards for floors can readily provide up to 120 minutes of fire protection. CFS has a tendency to lose strength markedly at 740 degrees F (390 degrees C), which is why the report advises fire protection, including mineral wool insulation. [W]hen multiple layers of boards are used, their joints should be staggered to maximize integrity in fire, the authors add. Gypsum makes it quiet,
too Because any stud-wall system is lightweight, such
systems require special design considerations to minimize air- and impact-transmitted
sound. Increasing the mass with additional layers of gypsum board and
filling the space between the gypsum-board leaves are typical ways to
increase the STC of a stud wall. The report suggests three more strategies
for CFS-supported walls. Copyright 2002 The American Institute of Architects. All rights reserved. |
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