A fire barrier is provided for a structure including a substantially planar member (1) having secured thereto an elongate substantially C-shaped member (3) having a longitudinal slot (5) formed therein, the C-shaped member having longitudinally-extending flanges (7) protruding laterally therefrom in a plane substantially parallel to the planar member. The fire barrier includes a plurality of panels (9) of fire-resistant material supported adjacent to the planar member (1) and extending between the planar member and one of the lateral flanges (7). A sheet of intumescent material (13) covers the elongate slot (5) of the C- shaped member (3), and resilient retaining means (15) extends partially around the C-shaped member (3) and engages behind the flanges (7) thereof so as to support the sheet of intumescent material (13) and the panels (9) of fire-resistant material.