A method for producing a sealed and thermally insulating wall for a fluid storage tank includes attaching plural anchoring elements to a support structure; installing modular formwork elements on the support structure, the modular formwork elements having a shape that protrudes relative to the support structure and that defines, with the support structure and the plurality of anchoring parts, compartments having an open side opposite the support structure; spraying insulating foam into the compartments through the open side to form plural insulating sectors made from sprayed insulating foam; arranging insulating junction elements in a stressed position in which they are stressed between the insulating sectors and capable of expanding when the insulating sectors contract, to ensure continuity of the thermal insulation; and attaching a sealing membrane to the anchoring elements.