Review of the NRC Canada studies on fire resistance of floor assemblies: Results, design guidelines and research gaps

Abstract

The National Research Council Canada conducted two major fire resistance studies on floor assemblies over the past two decades. Despite the publication of the experimental results, there is a lack of suggested guidelines for design practitioners and gaps for future research. Thus, this paper comprehensively reviews the fire resistance results of 85 full-scale floor tests, suggests design guidelines, and identifies research gaps. These efforts aim to enhance the understanding and support the potential improvement of the fire performance of floor assemblies. The review of the results covers the impact of various design parameters on the fire resistance of floor assemblies, such as framing type and spacing, insulation type, subfloor configuration, resilient channel spacing, number of gypsum board layers, and screw spacing from the board edge. Although the interaction of these factors is complex, some of them play significant roles in determining the overall fire resistance of floor assemblies. For instance, rock and cellulose insulation outperformed glass fibre, a wider resilient channel spacing lowered fire resistance, whilst an increased distance of screws from the board edge improved the fire resistance. More importantly, detailed explanations are provided for the influences these parameters exert on fire resistance. Following this detailed examination of the results, design guidelines are provided for practitioners' consideration. A comparison is made between the experimental results and predictions from the component additive methods in the Canadian and Euro Codes, demonstrating that both methods yield conservative results. Finally, this paper concludes by identifying research gaps and providing recommendations for future investigations, including the necessity of experimental studies on floor assemblies with new design configurations and the promising role of machine learning in fire resistance evaluation.