An interlocking rectangular sheet of simulated shakes for lock-up assembly upon a structure in an upwardly directed fashion having a thermo-formed base sheet with an exposure surface and a top and bottom surface. The bottom surface terminates in a cross-sectionally "U" shaped, clipping member. The top surface has a plurality of punched key portions, certain of which having apertured, flanged, assemblies thereon. All of the key portions allow for receiving securing members for attachment of the sheet to the structure, including the flanged portions. The apertured, flanged assemblies and the clipping members cooperate positively to interconnect in the upwardly directed fashion to provide, when secured to the structure by the securing members, a substantial inability to be removed or displaced by weather conditions. The flanged assemblies have an extended "S" shaped configuration. The front and back of each of the sheets have an upward and lower notched portion that provides for longitudinal engagement, one sheet against the other, by way of the front portion engaging the flange, and the rear portion engaging the "U" shaped clip.