A method for realising a floor which comprises a second plurality of planks and a first plurality of planks fixed to the second plurality of planks, comprising steps of: providing a plurality of blocks of lightening material; providing a first plurality of planks; providing a second plurality of planks; positioning the planks of the second plurality of planks distanced from one another, before positioning the first plurality of planks and the plurality of blocks of lightening material; positioning the first plurality of planks and the plurality of blocks of lightening material resting on the second plurality of planks in such a way that: they are flanked with one another; they are in contact with one another; and are aligned with respect to a same horizontal plane; each block of lightening material of the plurality of blocks of lightening material can be held still by at least two planks of the first plurality of planks which are opposite one another; a containing surface is defined for a casting of concrete; fixing the first plurality of planks to one another and/or to a frame; arranging a plurality of reinforcing elements above the first plurality of planks and fixing the plurality of reinforcing elements to the first plurality of planks; arranging a plurality of containing walls for a casting of concrete, which emerge from the horizontal plane and which surround the containing surface to define, with the containing surface, a containing volume; casting concrete into the containing volume so as to fix the plurality of blocks of lightening material and the plurality of reinforcing elements to one another; wherein the steps of positioning the first plurality of planks and the plurality of blocks of lightening material and of fixing the first plurality of planks comprise a first plurality of cycles, each cycle comprising steps of: placing a first block of lightening material of the plurality of blocks of lightening material in contact with a first plank of the first plurality of planks, that has already been fixed to the planks of the second plurality of planks, placing a second plank of the first plurality of planks in contact with the first block of lightening material of the plurality of blocks of lightening material and fixing the second plank of the first plurality of planks to the second plurality of planks. providing a plurality of blocks of lightening material; providing a first plurality of planks; providing a second plurality of planks; positioning the planks of the second plurality of planks distanced from one another, before positioning the first plurality of planks and the plurality of blocks of lightening material; positioning the first plurality of planks and the plurality of blocks of lightening material resting on the second plurality of planks in such a way that: they are flanked with one another; they are in contact with one another; and are aligned with respect to a same horizontal plane; each block of lightening material of the plurality of blocks of lightening material can be held still by at least two planks of the first plurality of planks which are opposite one another; a containing surface is defined for a casting of concrete; fixing the first plurality of planks to one another and/or to a frame; arranging a plurality of reinforcing elements above the first plurality of planks and fixing the plurality of reinforcing elements to the first plurality of planks; arranging a plurality of containing walls for a casting of concrete, which emerge from the horizontal plane and which surround the containing surface to define, with the containing surface, a containing volume; casting concrete into the containing volume so as to fix the plurality of blocks of lightening material and the plurality of reinforcing elements to one another; wherein the steps of positioning the first plurality of planks and the plurality of blocks of lightening material and of fixing the first plurality of planks comprise a first plurality of cycles, each cycle comprising steps of: placing a first block of lightening material of the plurality of blocks of lightening material in contact with a first plank of the first plurality of planks, that has already been fixed to the planks of the second plurality of planks, placing a second plank of the first plurality of planks in contact with the first block of lightening material of the plurality of blocks of lightening material and fixing the second plank of the first plurality of planks to the second plurality of planks.