This invention refers to a weight-lightening disc for making light reinforced concrete structures such as slabs, prefabricated slabs, foundation slabs, partition walls and beams; to a mesh, specifically designed for this invention and to the construction method to make such structures. The method allows manufacturing the components that make it possible to construct buildings with light reinforced concrete structures. The field of application of the invention is construction in general, such as houses, buildings and bridges.The invention provides a solution to the problem of lightening of the structures, including a construction method that comprises a set of weight-lightening discs in combination with electro-welded meshes (specially designed for the each specific thickness of the slab) and the hooks that hold together the meshes.The compound of elements and the method allow lightening minimum-thickness slabs.