Polycarbonate plastics with their lightweight, impact-resistant nature, offer a viable alternative to glass for skylight applications. These plastic sheets are layered with thin coatings that render them resistant to ultraviolet radiation, along with a recyclable nature, makes polycarbonate sheets a "green" component of your building. The sheets have a light-diffusing property that renders dirt undetectable; however, they can easily be cleaned by a simple pressurized jet of water. To choose the right polycarbonate sheet, you will have to consider the specific location and characteristics of your skylight.