Abstract: The roofing module of the present invention is comprised of a sheet of thermoplastic material which has opposed side margins that are bent upwardly at 90.degree. with respect to the body of the sheet to provide joinder tabs. The module is formed by transporting a flat sheet of the material between a pair of inwardly-facing radiant heaters which are focused on a line which the sheet will be bent about in order to soften the sheet along that line. After the sheet is softened along the fold line it is transported through a bending section comprised of a series of die rollers which cause the margin to progressively be bent upwardly to the desired orientation.