What may appear to be a leak in a skylight might actually be condensation from warm room air contacting a skylight’s cold surfaces in winter. A key frame improvement over early models has been the addition of condensation gutters. Nearly all major manufacturers now make these special channels, which collect condensation and channel it outside or retain it until it evaporates. To eliminate condensation problems, Velux makes a fixed skylight with an operable ventilation flap that lets warm, moist air escape.

Nearly all skylights also now come with special integral flashings that allow for easy installation and virtually eliminate leaks.

Before buying a skylight, be sure it’s rated for your roof’s pitch. Many skylights are not meant for nearly flat roof slopes, and those installed on steep roofs may require a special splash guard. As a rule, skylights are made to mount on a curb about 4 inches above the roof. CeeFlow offers an unusual unit, designed to improve a roof’s ventilation system, that is installed slightly below the roof surface yet remains watertight.