Abstract: A fire resistant door leaf (30, 32) comprises a core (42) and a lipping (50, 52) extending along at least one edge (40) of the core (42). The lipping (50, 52) is of plastic material (60) and is bonded to the edge (40) of the core, and comprises at least one strip of intumescent material (62) extending parallel to the edge (40) of the core. The at least one strip of intumescent material (62) is covered by the plastic material (60) of the lipping, and the plastic material (60) is cast or moulded against the at least one strip of intumescent material (62). The fire resistant door leaf (30, 32) may be formed by locating the at least one strip of intumescent material (62) along the edge (40) of the core and subsequently forming the lipping (50, 52) by casting or moulding the plastic material (60) of the lipping to the core in a liquid or semi-liquid state to cover the at least one strip of intumescent material (62) and curing the plastic material in situ (60).