A z-clip has a back side member that is angled relative to the front face. A wedge is designed to be used with the z-clip, where the wedge has an angle that matches the angle of the back side member of the z-clip. Thus, the wedge can be slid under the z-clip at a desired position to angle the z-clip in its use position, while allowing the z-clip to be horizontally offset from the wall. The system provided by the z-clip and wedge can quickly and easily set z-clips on a wall to a vertical reference plane, thus providing an easy fit for a wall panel to be subsequently attached thereto. Further provided are quick offset blocks that can attach to ends of each row of z-clips to provide a way for spanning a string therebetween, thus providing a vertical reference line for aligning z-clips along the vertical reference line.