Influence of cavity insulation on the fire resistance of light gauge steel framed walls

•Investigated the effect of cavity insulation on the fire resistance of LSF walls.•Results from full scale fire tests and finite element analyses of LSF walls are presented.•Cavity insulation significantly reduced the fire resistance of load bearing LSF walls.•Cavity insulation increased the fire resistance of non-load bearing LSF walls.•Highlighted both the beneficial and detrimental effects of cavity insulation. Light gauge steel framed (LSF) walls are used in fire compartmentation to prevent the spread of fire, smoke and toxic gases. The fire behavioural characteristics of non-load bearing LSF walls are different from those of load bearing walls. In non-load bearing LSF walls, fire penetration to the ambient side is to be prevented for insulation and integrity criteria whereas in load bearing walls, steel studs need to be protected from heat for structural adequacy also. This paper investigates the fire resistance of non-load bearing and load bearing LSF walls with and without cavity insulation. It presents the details of a series of standard fire tests conducted to investigate the effect of cavity insulation in both load bearing and non-load bearing LSF walls. The use of cavity insulation increased the fire resistance level (FRL) of non-load bearing walls, while it significantly reduced the FRL of load bearing walls. A finite element parametric study was then conducted for LSF walls lined with both single and double layers of plasterboards. Both thermal and structural fire performance results of LSF walls from finite element analyses are presented and compared in this paper. These results showed that FRL of cavity insulated non-load bearing LSF walls increases by 10–20 min, while it is significantly reduced for load bearing LSF walls with load ratios below 0.7. This study highlights both the beneficial and detrimental effects of cavity insulated LSF walls exposed to fire.