A fluidtight and thermally insulating tank wall comprises:a multi-layer structure comprising a fluidtight barrier (5) and a thermally insulating barrier (4), retaining rods (22) attached to the bearing wall (7) between the insulating elements and extending in the direction of the thickness of the multi-layer structure to hold the multi-layer structure on the bearing wall, in which crossmembers (30) are attached to the retaining rods (22) such that in each instance a crossmember extends between two retaining rods at the interface between two insulating elements, the cover panels (11) of the insulating elements being connected to the crossmembers (30) so as to be held against the bearing wall via the crossmembers, and the fluidtight barrier (5) being connected to the crossmembers (30) so as to be held against the cover panels of the insulating elements via the crossmembers.