A method for installing light-weight panels, according to which method the light-weight panel is mounted in its place on the wall or ceiling of a building and fastened there by a fastening member resting on or attachable to the edge portion of the light-weight panel. The light-weight panel installation apparatus incorporates a fastening device, such as a nail gun, by means of which the fastening member, resting on or attached to the edge of the light-weight panel, is fastened to a building frame. The panel fastening member incorporates a part resting on the edge of the light-weight panel, which part can, directly or by means of an intermediate member, be fastened to a base, such as a building frame.