Fiber-reinforced molded plastic roofing unit and method of making the same

A roofing unit for securing to a roof of a structure to cover and protect the roof of the structure, wherein said roofing unit extends longitudinally from an upper end to a lower butt end and comprises:

• a top side intended to face outwardly of the roof when secured to the roof,
• an underside intended to face inwardly resting in abutting engagement with the roof when secured to the roof, the distance between said top side and said underside being the thickness of the unit at any given location along a length of said unit;
• a solid upper tab section extending from the upper end of the unit to a lower tab end, wherein the thickness of the upper tab section decreases from the upper end to the lower tab end to define a downwardly sloping top side of the unit within the upper tab section;
• a top panel extending from said lower tab end to the butt end of the unit, to form a lower exposed section said top panel having a top surface, a bottom surface and side edges;
• a plurality of longitudinal ridges and valleys formed within the top panel of the unit;
• edge sidewalls extending downwardly from the side edges of the panel to a bottom edge of the sidewalls, wherein a height of said edge sidewalls increases from said lower tab end to said butt end of the unit;
• an end wall extending downwardly from the panel along the butt end of the unit to a bottom edge of the end wall;
• a cavity on the underside of the unit within the lower exposed section;
• a first set of ribs extending parallel to said edge sidewalls within said cavity;
• a second set of ribs extending parallel to said end wall within said cavity such that said first and second sets of ribs form a grid of intersecting ribs within said cavity, wherein a bottom edge of each of said ribs, the bottom edge of each of said edge sidewalls and the bottom edge of the end wall are in the same plane so as to rest flush against the roof of the building when the roofing unit is secured to the roof;
• a camber formed along the length of said unit such that the unit is arched along a midsection of the unit;
• and
• an index line extending transversely across said unit adjacent said lower tab end.