A fire door has a box-shaped panel (1) with two door leaves (2, 3) and a frame (4) which includes two mineral fibre plates (5). The frame (4) which forms a bridge between the ends (6) of the angle strips (7) has a groove (8), open on top. This groove is filled with a strap (10) which foams when exposed to heat, and a filler block (11) of gypsum, both wrapped in a plastic foil (9) of PVC. Beads (12) on the foil (9) and matching recesses (13) on the inside surfaces of the groove (8) hold it fn position.
