Joint closure system for foamboards

An insulating assembly comprising a plurality of insulating structures lying in abutting relationship for forming an envelope to cover a wall or roof of a building, each structure comprising:

• a generally rectangular board of insulating material having two major surfaces and a first facing sheet on one of the surfaces, and a second facing sheet on the other of the surfaces, first and second side edges, and top and bottom edges;
• and
• a generally rectangular closure strip having two equal and integral rectangular side portions comprising a first side portion extending over the first facing sheet from the top edge to the bottom edge and inwardly a short distance from the first side edge of the board, the first side portion being bonded to the first facing sheet, and a second side portion extending outwardly away from the board a short distance from the first side edge,
• the second side portion extending over the second side edge of the adjacent insulating structure and being bonded to the first facing sheet of the adjacent insulating structure wherein the insulating structures form an envelope to cover a wall or roof of a metal building, the first facing sheet of each insulating structure facing to the interior of the building, the second facing sheet of each insulating structure facing the exterior of the building, and each second facing sheet being covered by metal sheeting.