Skylights consist of metal-framed units, Roof Windows, and Sloped Glazing Systems. They are a great way to introduce to light and solar heat gain to a building interior in the winter. They’re also a great way to beautify a room with more visuals of the outdoors. The downsides of skylights are their tendency to allow solar heat gain in summer and their heightened vulnerability for leakage. Also, brightness and glare must be addressed and controlled with louvers, shades, reflector panels, or tinting. Skylight glazing is most commonly acrylic, polycarbonate plastic, wired glass, laminated glass, heat strengthened glass, or tempered glass, or a combination therof. Some have claimed that plastic skylights, while often less expensive, are more prone to leakage, are less energy efficient, and allow excessive UV light to penetrate which can discolor items in the room. Building codes will commonly govern a maximum square footage allowed for skylights for safety purposes.