Abstract: An improved roof insulation structure and method of making the structure for greatly increasing the insulation quality of a metal building roof. The structure includes a self-supporting low to medium density thermal insulation blanket having elongated lines of weakness in the top thereof. The blanket spans the width between a pair of adjacent and parallel roof purlins with one end of the blanket folded up one side of the purlin, folded across the top of the purlin and folded down the opposite side of the purlin, thereby enclosing the top and opposite sides of the purlin. The blanket provides means for receiving a thick blanket of low density thermal insulation inside thereof and between the purlins for increasing the insulation "R" factor of the insulated roof.

Abstract: A roof insulation structure and method of making the structure for greatly improving the insulation quality of a metal building roof. The structure includes a self-supporting medium density thermal insulation blanket having elongated slits and notches in the top thereof so that the blanket can be folded into a "U" shaped configuration. The "U" shaped blanket is received on the top and the sides of a pair of adjacent and parallel roof purlins and spans the width therebetween. The "U" shaped configuration of the blanket provides means for receiving a thick blanket of low density thermal insulation inside thereof and between the purlins for increasing the insulation "R" factor of the insulated roof.