GRP rooflights or Glass Reinforced Plastic is supplied in thicknesses from 6oz to 12 oz. And in over 500 separate box profiles. Class 1 fire grade normally used as an internal liner on a double skin or some external layouts composite fair or a double skin built up system. popular is 6oz.
Class 3 none fire grade used for external applications popular is 6 oz or 8 oz.