[A sealed and thermally insulating tank comprising a tank wall, the tank wall comprising, successively from the exterior of the tank to the interior of the tank in a thickness direction of the tank wall, a secondary insulating barrier intended to be anchored on a support wall, a secondary sealed membrane resting on the secondary insulating barrier, a primary insulating barrier resting on the secondary sealed membrane and a primary sealed membrane resting on the primary insulating barrier and intended to be in contact with a product contained inside the tank, the primary insulating barrier comprising a plurality of juxtaposed primary insulating panels, the tank further comprising a plurality of primary anchoring members intended to be retained, directly or indirectly, on the support wall, each of said primary anchoring members interacting with at least one primary insulating panel of the plurality of primary insulating panels in such a way as to retain said at least one primary insulating panel on the secondary sealed membrane, in which a said primary anchoring member comprises: - a base intended to be retained, directly or indirectly, on the support wall, - a stem extending in the thickness direction of the tank wall from said base toward the primary sealed membrane, said stem passing through an opening in the secondary sealed membrane, - a bearing element (16, 54) mounted on the stem, said bearing element (16, 54) bearing on a primary insulating panel in such a way as to retain said primary insulating panel on the secondary sealed membrane, - a sealing washer engaged on the stem between the bearing element and the opening in the secondary sealed membrane, the sealing washer having a central opening through which the stem passes, the sealing washer being secured sealingly to the secondary sealed membrane around the opening in said secondary sealed membrane, characterized by the fact that said primary anchoring members includes - a deformable seal sealingly connecting said sealing washer and the stem in such a way as to allow a relative movement between the sealing washer and the stem. the primary insulating barrier comprising a plurality of juxtaposed primary insulating panels, the tank further comprising a plurality of primary anchoring members intended to be retained, directly or indirectly, on the support wall, each of said primary anchoring members interacting with at least one primary insulating panel of the plurality of primary insulating panels in such a way as to retain said at least one primary insulating panel on the secondary sealed membrane, in which a said primary anchoring member comprises: - a base intended to be retained, directly or indirectly, on the support wall, - a stem extending in the thickness direction of the tank wall from said base toward the primary sealed membrane, said stem passing through an opening in the secondary sealed membrane, - a bearing element (16, 54) mounted on the stem, said bearing element (16, 54) bearing on a primary insulating panel in such a way as to retain said primary insulating panel on the secondary sealed membrane, - a sealing washer engaged on the stem between the bearing element and the opening in the secondary sealed membrane, the sealing washer having a central opening through which the stem passes, the sealing washer being secured sealingly to the secondary sealed membrane around the opening in said secondary sealed membrane, characterized by the fact that said primary anchoring members includes - a deformable seal sealingly connecting said sealing washer and the stem in such a way as to allow a relative movement between the sealing washer and the stem. - a base intended to be retained, directly or indirectly, on the support wall, - a stem extending in the thickness direction of the tank wall from said base toward the primary sealed membrane, said stem passing through an opening in the secondary sealed membrane, - a bearing element (16, 54) mounted on the stem, said bearing element (16, 54) bearing on a primary insulating panel in such a way as to retain said primary insulating panel on the secondary sealed membrane, - a sealing washer engaged on the stem between the bearing element and the opening in the secondary sealed membrane, the sealing washer having a central opening through which the stem passes, the sealing washer being secured sealingly to the secondary sealed membrane around the opening in said secondary sealed membrane, characterized by the fact that said primary anchoring members includes - a deformable seal sealingly connecting said sealing washer and the stem in such a way as to allow a relative movement between the sealing washer and the stem.