a horizontally level raised terrace floor system for mounting over a non - level or irregular substructure that includes a plurality of spaced apart support pedestals that are fabricated of a heat shearable foam material . each pedestal is mounted upon the non - horizontally level substructure and the pedestals are heat sheared so that the top surface of each pedestal lies in a common horizontal plane above the substructure . a plurality of flat grates are placed directly upon the pedestals in an edge to edge relationship . a plurality of interlocking paving blocks are laid down over the grates to provide a tight deck over the grates .