Abstract: The method includes: filling and levelling of a heat insulation layer on a cathode shell bottom; its coverage from above with a refractory layer; installation of the cathode bottom and side blocks with subsequent sealing of joints or seams between them with cold ramming paste and further monolithic baking; wherein: the levelled heat insulation layer is covered with a lower barrier layer of graphite foil placed between layers of fiberboard sheets; at least one refractory layer is formed; an upper barrier layer of graphite foil is placed between the layers of fiberboard sheets; all formed layers are simultaneously compacted to achieve alignment of the uppermost layer surface with a lower edge plane of the ports in the cathode shell; and the refractory layer of 20-30 mm thick is formed above the upper layer, according to some embodiments.