Abstract: A masonry block system is disclosed incorporating a plurality of courses of masonry block, each block of which is formed with minimum webbing to minimize heat flow therethrough. The wall system is formed into a unitary structure through the utilization of post-tensioning rods tied to reinforcing rods in the wall footer and extending through the voids in the respective blocks to a top plate positioned on top of the wall. The rods are threaded and are post-tensioned; the voids contain a polyurethane foam.