Improving the fire resistance of light steel floor–ceiling systems through enhanced materials and construction methods

• Investigated the fire resistance of three new light steel floor systems using good materials and construction methods. • Three new systems achieved FRL exceeding 130 min, outperforming conventional two-layer plasterboard systems (90 min). • Semi-rigid cavity insulation supported by furring channels was effective even after ceiling fall-off. • External rigid insulation was also effective beyond ceiling fall-off, and the AAC panel system achieved the highest FRL. • Delaying ceiling fall-off and ensuring effective joint bonding were identified as key strategies for improving FRL. Light gauge steel framed (LSF) floor–ceiling systems, composed of cold-formed steel (CFS) joists and plasterboard ceilings, are increasingly used in modern construction for their strength-to-weight efficiency and cost benefits. However, conventional two-layer plasterboard ceiling systems typically provide only about 90 min of fire resistance level (FRL), limiting their applications when higher fire-ratings are required. This study presents four short-span, load-bearing fire tests on LSF floor–ceiling systems, including three innovative configurations: external rigid stone wool insulation (C1), a single 37 mm autoclaved aerated concrete (AAC) panel (C2), and semi-rigid cavity insulation supported by furring channels (C3) and a conventional three-layer plasterboard ceiling system (C4) commonly used to enhance the FRL. All three new systems achieved FRLs exceeding 130 min, representing more than a 40% improvement over typical two-layer plasterboard systems. Among them, the AAC panel (C2) reached the highest FRL of 158 min, followed by C3 (145 min) and C1 (138 min). The findings confirm that the proposed floor systems, incorporating alternative ceiling configurations or high-performance insulation materials, can substantially enhance the fire resistance of LSF floor systems. The proposed solutions also offer practical advantages in terms of constructability and acoustic performance, making them suitable for adoption in diverse building applications.