Abstract: An apparatus for providing a roof structure of the type having a plurality of purlins spaced apart from one another in a parallel arrangement is disclosed. The purlins have a generally vertical portion. The space between the vertical portions of adjacent purlins defines an insulation cavity which is generally rectangular in cross-sectional shape. The apparatus includes a carriage which is movable along the length of the purlins for dispensing a support sheet from a roll for support of insulation material. As the carriage travels along the length of the purlins, the support sheet is dispensed so that the support sheet depends from the top portion of adjacent purlins. The apparatus further includes a first bar having a curvilinear shape which is mounted on the carriage and extends across the width of the support sheet. The first bar is positioned so that the support sheet contacts and is guided by the first bar as the support sheet is dispensed.