Improving the Fire Performance of LSF Wall and Floor Systems Using External Insulation

Abstract

The load-bearing light-gauge steel-framed (LSF) wall systems used in buildings are protected against fire by attaching fire-resistant gypsum plasterboard layers on both sides. They are also provided with cavity insulation to improve the thermal comfort of buildings during severe hot and cold weather conditions. However, recent research studies have shown that cavity insulation reduces the fire performance of load-bearing LSF walls. Therefore, researchers at the Queensland University of Technology proposed the use of externally insulated LSF walls and floors where insulation is sandwiched between the inner and outer layers of plasterboard instead of being placed inside the cavity. This article reviews and evaluates the results from the small- and full-scale fire tests and numerical studies performed on such externally insulated wall and floor systems exposed to standard and code-prescribed parametric fire curves. Comparison of the fire-resistance ratings and time–temperature profiles of the cavity-insulated and externally insulated wall and floor systems confirmed the superior fire performance of externally insulated load-bearing LSF walls and floors compared with cavity-insulated systems. The reasons for the superior fire performance are discussed in this article. This research also found that placing the plasterboard joints along the studs had minimum detrimental effects on the fire performance of externally insulated LSF wall systems. Overall, this research recommends the use of externally insulated wall and floor systems instead of cavity-insulated systems because of their thermal comfort and superior fire performance. This article includes the details of an efficient LSF wall construction process based on the use of composite panels consisting of two plasterboard layers with insulation sandwiched between them.