Skylights: Installing, Flashing and Fixing Them Properly

A skylight is a hole in the roof with glass in it, so it is only as good as the framing around the hole and the flashing around the frame. The glass rarely fails first. The leaks come from a rough opening that was cut wrong, a flashing kit that was changed or skipped, or a curb that sits too low to shed water. Start with the skylight types so you know which kind of unit you are dealing with, then work through the install that matches it.

The two main installs are a deck-mounted skylight, which sits directly on the roof deck, and a curb-mounted skylight, which sits on a built-up frame. Both depend on the flashing, and on flat roofs the curb, the upstands and the cricket behind it decide whether the skylight is still dry in ten years.

Many skylight complaints are not leaks at all. In a long, wet Fraser Valley winter, cold glass collects condensation that looks exactly like a drip. The guide on fixing a leaking skylight shows how to tell the difference before anyone pulls the flashing apart. And when a roof is already being replaced, replacing the skylight at the same time is almost always cheaper than doing it later.