Roof insulation structure and method of making same

A roll of insulating material used for receipt on top of a roof and when unrolled received between a pair of adjacent and parallel metal roof purlins, the purlins having a vertical web and upper and lower horizontal flanges integrally formed into the top and bottom of the web forming a "Zee", "C", truss or bar joist type configuration, the insulating material comprising:

• a blanket of self-supporting medium density thermal insulation, the blanket having from end to end a substantially "U" shaped configuration, the blanket including:
• a pair of side portions opposite each other and adapted for receipt on top of the upper horizontal flanges of the adjacent purlins;
• a pair of intermediate portions adpated for receipt adjacent the web of the purlins, the intermediate portions divided from the side portions by a pair of elongated slits cut in the top of the blanket and along the length thereof, the slits allowing one of the side portions of the blanket to be folded outwardly away from the slit at an angle greater than 90 degrees from its adjacent intermediate portion, the other side portion of the blanket folded outwardly from the slit at an angle of approximately 90 degrees from its adjacent intermediate portion, the slits allowing the side portions to be positioned on top of the upper horizontal flanges and the intermediate portions tucked adjacent the vertical web of the purlins;
• and
• a horizontal center portion adapted for spanning the width between the adjacent purlins, the center portions divided from the intermediate portions by a pair of elongated notches cut in the top of the blanket and along the length thereof, the notches allowing one of the intermediate portions of the blanket to be folded inwardly toward the notch at an angle less than 90 degrees from the center portion with the other intermediate portion folded inwardly toward the notch at an angle approximately 90 degrees from the center portion;
• the blanket adapted for receiving a thick blanket of low density thermal insulation inside the substantially "U" shaped configuration.

A method of insulating the top of a roof having a pair of adjacent and parallel roof purlins, the purlins having a vertical web and upper and lower horizontal flanges integrally formed into the top and bottom of the web forming a "Zee", "C", truss or bar joinst type configuration, the steps comprising:

• forming a pair of elongated notches in the top of a blanket of self-supporting medium density thermal insulation and along the length thereof and forming a center portion of the blanket therebetween;
• forming a pair of elongated slits in the top of the blanket and along the length thereof, the slits spaced apart a greater distance than the notches and forming intermediate portions of the blanket therebetween and side portions between the slits and the edges of the length of the blanket;
• rolling the blanket into a roll for transportation to and onto the roof;
• unrolling the blanket on top of and between the adjacent purlins;
• folding inwardly the intermediate portion of the blanket at an angle up to 90 degrees from the center portion with the center portion spanning the width between the adjacent purlins and the intermediate portions tucked adjacent the vertical web of the purlins;
• and
• folding outwardly away from the slits the side portions of the blanket at an angle at least 90 degrees from the intermediate portions thereby allowing the side portions to be positioned on top of the upper horizontal flanges.