Corotherm 16mm Bronze Triplewall Polycarbonate Roof Sheet 2500mm x 2100mm x 16mmProperties Excellent protection: against hailstones, vandalism and accidental damage. Insulating glazing: which can achieve a sheet uValue of 2.4 W/mK. Light transmission: 18% which blends with dark coloured conservatories. Creates: a private internal environment. Provides: soft light quality. Up to "Class 1" fire rating: polycarbonate is a self-extinguishing material which will melt away from the flames, stopping as soon as the source is removed. Note: 6mm Twinwall does not have a Class 1 fire rating. High strength: weight ratio. Cost effective: as sheet weight is low, support structures can be lighter providing cost effective buildings.Corotherm provides high levels of insulation.