A sealed and thermally insulating tank incorporated into a bearing structure, said tank comprising a tank wall fixed to a bearing wall (1, 3, 203) of the bearing structure, in which the tank wall comprises: a thermally insulating barrier fixed to the bearing wall and a sealed membrane (12, 204) borne by said thermally insulating barrier, the thermally insulating barrier comprising a plurality of rectangular parallelepipedal insulating blocks (8, 202) juxtaposed in a regular rectangular grid pattern, each insulating block comprising an insulating filling and a cover panel (119, 210) facing toward the inside of the tank, an upper face of the cover panel on the opposite side to the insulating filling bearing a metal anchor piece (14, 217, 218), the sealed membrane (12, 204) being made up of a corrugated metal membrane comprising a first series of parallel corrugations and flat portions (101, 102) situated between the parallel corrugations and resting on the upper face of the cover panels, the parallel corrugations being arranged parallel to a first direction of the parallelepipedal insulating blocks and spaced by a first corrugations pitch, characterized in that the pitch of the rectangular grid pattern in a second direction perpendicular to the first direction, which is substantially equal to a dimension of the insulating blocks (8, 202) in the second direction, is equal to twice the first corrugations pitch, so that the first series of corrugations comprises two corrugations situated in line with each of the insulating blocks (8, 202), in that a flat portion of the sealed membrane situated between the two corrugations is arranged in line with an internal zone of the cover panel that is situated some distance from the edges of the cover panel that are parallel to the first direction, so that the two corrugations of the first series of corrugations are situated in line with a marginal zone of the cover panel which zone is situated between the internal zone and the edges of the cover panel (119, 210) that are parallel to the first direction, and in that the metal anchor piece (14, 217, 218) of each insulating block is arranged at least in the internal zone of the cover panel, the sealed membrane being fixed to the thermally insulating barrier by the fixing of said flat portions of the sealed membrane to said anchor pieces (14, 217, 218) of a plurality of the insulating blocks only in the internal zone of the cover panels (119, 210), so that the sealed membrane is not fixed to the thermally insulating barrier in said marginal zone of the cover panels. a thermally insulating barrier fixed to the bearing wall and a sealed membrane (12, 204) borne by said thermally insulating barrier, the thermally insulating barrier comprising a plurality of rectangular parallelepipedal insulating blocks (8, 202) juxtaposed in a regular rectangular grid pattern, each insulating block comprising an insulating filling and a cover panel (119, 210) facing toward the inside of the tank, an upper face of the cover panel on the opposite side to the insulating filling bearing a metal anchor piece (14, 217, 218), the sealed membrane (12, 204) being made up of a corrugated metal membrane comprising a first series of parallel corrugations and flat portions (101, 102) situated between the parallel corrugations and resting on the upper face of the cover panels, the parallel corrugations being arranged parallel to a first direction of the parallelepipedal insulating blocks and spaced by a first corrugations pitch, characterized in that the pitch of the rectangular grid pattern in a second direction perpendicular to the first direction, which is substantially equal to a dimension of the insulating blocks (8, 202) in the second direction, is equal to twice the first corrugations pitch, so that the first series of corrugations comprises two corrugations situated in line with each of the insulating blocks (8, 202), in that a flat portion of the sealed membrane situated between the two corrugations is arranged in line with an internal zone of the cover panel that is situated some distance from the edges of the cover panel that are parallel to the first direction, so that the two corrugations of the first series of corrugations are situated in line with a marginal zone of the cover panel which zone is situated between the internal zone and the edges of the cover panel (119, 210) that are parallel to the first direction, and in that the metal anchor piece (14, 217, 218) of each insulating block is arranged at least in the internal zone of the cover panel, the sealed membrane being fixed to the thermally insulating barrier by the fixing of said flat portions of the sealed membrane to said anchor pieces (14, 217, 218) of a plurality of the insulating blocks only in the internal zone of the cover panels (119, 210), so that the sealed membrane is not fixed to the thermally insulating barrier in said marginal zone of the cover panels.