Patent ID: 8438810

Claim:
A roof structure comprising: a plurality of parallel, spaced-apart purlins, wherein bays are defined between each successive pair of said purlins; a vapor retarder system comprising: a vapor retarder sheet draped over a plurality of said purlins so as to span multiple bays, said vapor retarder sheet comprising a tie-strap located adjacent an inner surface of said sheet, said tie-strap connected to said sheet at multiple connection locations that are spaced from each other along a length of the tie-strap, wherein the sheet comprises drape regions that are disconnected from the tie-strap between successive connection locations, said connection locations located adjacent respective ones of said purlins and said drape regions located in respective bays between successive ones of said purlins, wherein said tie-strap is severed between connection locations along the length of the tie-strap such that said tie-strap is interrupted in the region of a corresponding one of said bays; a roof deck supported on said purlins, wherein said inner surface of said vapor retarder sheet is oriented toward said roof deck; insulation located in each of said bays and supported on said inner surface of said vapor retarder sheet.