Abstract: The invention relates to a system for mounting a flat wall covering on an uneven existing surface or studs. A screw is provided with a threaded portion and a non-threaded portion near the head. At one end of the threaded portion is a flat annular plateau, perpendicular to the axis of the screw. A support nut, with an attached bearing surface, is threaded onto the screw, up to the flat plateau, at which point the bearing surface will contact the wall covering. The screw can then be rotated without axial displacement of the support nut or the wall covering with respect to the screw. However, the screw and the wall covering will move axially with respect to the existing surface. A plurality of these devices can be used and adjusted independently to create a flat surface.