A method for producing a thermal insulation barrier (2, 5) for a wall of a fluid-tight and thermally insulative tank integrated into a support structure, said method including the following steps: - anchoring a plurality of insulative panels (16, 65, 66) directly or indirectly to the support structure by means of anchor devices (38, 54, 69); said plurality of insulative panels (16, 65, 66) defining an internal support surface of a sealing membrane (4, 6) and including at least one opening (43, 55) opening at the level of said internal surface; - procuring a polymer foam insulative blocking member (44, 57, 58, 59, 60, 95, 96) intended to ensure continuity of thermal insulation at the level of said opening (43, 55), said insulative blocking member (44, 57, 58, 59, 60, 95, 96) having an internal end (48, 61); - inserting said insulative blocking member (44, 57, 58, 59, 60, 95, 96) in said opening (43, 55) and pushing it in the direction of the support structure until the insulative blocking member comes to bear in the direction of the support structure against a bearing member (15, 82, 91) housed in said opening (43, 55); - the said process being characterized in that it further comprises the step of: - pushing the insulative blocking member (44, 57, 58, 59, 60) in the direction of the support structure against the bearing member (15, 82, 91) so as to damage irreversibly the insulative blocking member (44, 57, 58, 59, 60, 95, 96) where it bears against the bearing member (15, 82, 91) and so as to reduce irreversibly the dimension of the insulative blocking member (44, 57, 58, 59, 60, 95, 96) between the internal end (48, 61) of the insulative blocking member (44, 57, 58, 59, 60, 95, 96) and where the insulative blocking member (44, 57, 58, 59, 60, 95, 96) bears against the bearing member (15, 82, 91) until the internal end (48, 61) of the insulative blocking member (44, 57, 58, 59, 60, 95, 96) reaches a predetermined position in said opening (43, 55). - anchoring a plurality of insulative panels (16, 65, 66) directly or indirectly to the support structure by means of anchor devices (38, 54, 69); said plurality of insulative panels (16, 65, 66) defining an internal support surface of a sealing membrane (4, 6) and including at least one opening (43, 55) opening at the level of said internal surface; - procuring a polymer foam insulative blocking member (44, 57, 58, 59, 60, 95, 96) intended to ensure continuity of thermal insulation at the level of said opening (43, 55), said insulative blocking member (44, 57, 58, 59, 60, 95, 96) having an internal end (48, 61); - inserting said insulative blocking member (44, 57, 58, 59, 60, 95, 96) in said opening (43, 55) and pushing it in the direction of the support structure until the insulative blocking member comes to bear in the direction of the support structure against a bearing member (15, 82, 91) housed in said opening (43, 55); - the said process being characterized in that it further comprises the step of: - pushing the insulative blocking member (44, 57, 58, 59, 60) in the direction of the support structure against the bearing member (15, 82, 91) so as to damage irreversibly the insulative blocking member (44, 57, 58, 59, 60, 95, 96) where it bears against the bearing member (15, 82, 91) and so as to reduce irreversibly the dimension of the insulative blocking member (44, 57, 58, 59, 60, 95, 96) between the internal end (48, 61) of the insulative blocking member (44, 57, 58, 59, 60, 95, 96) and where the insulative blocking member (44, 57, 58, 59, 60, 95, 96) bears against the bearing member (15, 82, 91) until the internal end (48, 61) of the insulative blocking member (44, 57, 58, 59, 60, 95, 96) reaches a predetermined position in said opening (43, 55).