Abstract: A door jamb comprising, a first sheet metal section having a flat portion for attachment to a vertical face of an aperture in a wall and a pair of channel-shaped portions on either side of said flat portion, an inner flank of one channel-shaped portion being connected by said flat portion to an inner flank of the other channel-shaped portion, a second sheet metal section for accommodating one edge of a door leaf, said second sheet metal section including a pair of longitudinal flange portions, each of which is slidably displaceable transversely of a respective one of the outer flanks of said channel-shaped portions, and fasteners for fastening each of said longitudinal flange portions in a selected transverse position on the respective one of said outer flanks.