Cold-formed steel trapezoidal sheeting has a very significant decrease of its bending resistance in fire. The bending resistance is generally reached within 10 minutes of a fire. However, the failure in bending is followed by transitions from bending behaviour to a catenary action. The catenary action can form only if a horizontal support is provided by fasteners to the supporting structure. The fasteners are therefore a critical component of the structural design and usually determine the load capacity of the sheeting in fire. In this study, connections tests at both normal and elevated temperature are conducted using three different types of fasteners: self-drilling screws with washers, shot nails and concrete anchor screws. For each tested temperature (20, 350, 500, 600 and 700 °C) and sheet thickness (0.75 and 1.5 mm), 4 tests are conducted. The results provide insights into the behaviour of these connections at both normal and elevated temperatures. The behaviour is also used to define the connection parameters in a numerical model. This paper also describes two large-scale fire tests of lightweight roofs with trapezoidal sheeting. In both tests, fastening with self-drilling screws is used. The first fire test consists of two simple beams with a span of 2x4 m and focuses on the behaviour of a roof above an internal support. The second fire test primarily focuses on fastening and consists of a simple beam with a span of 6 m. Both fire tests resulted in a failure of the sheeting connection. A finite element model of the trapezoidal sheeting is created in Abaqus software to predict the behaviour of the sheeting in fire and validated on the fire tests. The primary outcome of the numerical model is the horizontal reaction force on the fasteners.