Abstract: A fiberglass railcar roof that includes a fiberglass surface with a central portion and plural elongate fiberglass ribs extending transverse to the longitudinal axis of the fiberglass surface. In a first embodiment, the central portion has a cross-sectional configuration that defines a first arc, and the ribs each have broad widths and each extend above the central portion to define a second arc that intersects the first arc. In a second embodiment, the ribs have arcuate cross-sections and extend downward from the lower face of the central portion. Also disclosed are embodiments of the previously described roofs that are configured for use on refrigerated and cryogenic railcars.