Abstract: A plane, hollow, reinforced concrete floor slabs with two-dimensional structure and method for their production. Constructions developed by this technic will vary widely and with considerable profit replace conventional floor structures. The technique makes it possible to choose higher strength and stiffness, less volume of materials, greater flexibility, better economy or an arbitrary combination of these gains. The technique makes it possible to create a total balance between bending forces, shear forces and stiffness (deformations)--so that all design conditions can be fully optimized at the same time. The technique presents a distinct minimized construction--characterized by the ability that concrete can be placed exactly where it yields maximum capacity. The technique offers material and cost savings compared with the conventional compact two-way reinforced slab structure. The technique is suitable for both in situ works and for prefabrication.