A securing cap, for use in fixing a wall with a floor or ceiling mounting, is snap fit within the space between the wall and a floor or ceiling mounting thereby fixing each component in position. The securing cap, in conjunction with other such caps, holds a wall assembly in a desired position in a building or shed where wall panels are positioned relative to each other to form a wall. The securing cap also serves to prevent the accumulation of dust and debris within the space formed by the wall and the floor or ceiling mountings.