Abstract: Vertical and horizontal sliding sash windows have two parallel but spaced leaves which slide in respective portions of the window opening. The portions are separated by a parting bead which extends around the window opening. Draught between the parting bead and the window leaves is reduced by the provision of seals between the parting bead and the window surfaces. These are formed by pile weatherstrips carried either on a replacement parting bead formed in one or two pieces. The remainder of the window is also sealed for the reduction of draughts.