Skylights often are a desired enhancement for low- and steep-slope roof systems. As such, skylights often are installed as part of remodeling or upgrading an existing interior space, especially for residential construction. Skylights allow sunlight into a building's interior and can be designed to increase ventilation or release smoke.
Although there are several skylight types with different features, skylights share many commonalities regarding design and installation. And there are issues that should be understood about what skylight installation does to a roof system, such as flashing concerns, especially for reroofing projects; insulation concerns; and potential vapor retarder and condensation concerns.
Types of skylights
A typical skylight consists of a translucent or clear lens and extruded metal frame. Lenses are made from acrylic or polycarbonate (for impact resistance) and available in single configurations or double configurations (for added insulation). Skylight lenses and frames can be manufactured with an integral curb or installed on top of a site-built curb. Site-built curbs provide greater flexibility for installation height. However, skylights with integral curbs are available in various heights, such as 4 inches, 9 inches and 12 inches (100 mm, 225 mm and 310 mm).