Foam envelope for sealing large volumes

A method for sealing an air gap between building interfaces, the method comprising the steps of:

• providing an article comprising a tube,
• wherein the tube has a length L, a width W and a height H, and the tube comprises an upper section, a lower section, an inner section, and an outer section, and the tube comprises a tube wall having an outer layer,
• wherein the outer layer is a semipermeable membrane formed from a material that is permeable to vapors but impermeable to liquids,
• wherein the tube has at least one inlet port integrated into the tube wall to permit the flow of fluid into the tube interior, and
• wherein the tube has a through-thickness Gurley air permeability of from 1 to 2,000 seconds, and a tensile modulus in the L direction of from 300 to 450 MPa and from 200 to 320 MPa in the W direction, and when tested by standard EN 12311-1:2000, exhibits a maximum tensile force of at least 100N/50 mm,
• the tube has a plurality of holes that penetrate through the outer layer of the upper section and/or the lower section of the tube;
• inserting the article into the air gap between the building interfaces;
• injecting an activated or activatable foamable composition into the tube via the at least one inlet port, and
• either activating the foam or allowing the foam to expand, thus expanding the tube,
• wherein the expanding foam exits the tube through the tube holes in the upper section and/or the lower section of the tube and, when present, between spaced apart flow restrictors that extend along the length of the tube, the expanding foam filling the air gap between the building interfaces and of the building structure and then cure in situ into a foam structure.