Where do most skylights usually leak?

Most skylights typically leak at the flashing system—the metal components designed to divert water away from the junction where the skylight curb meets the roof deck. Specifically, water infiltration frequently occurs at the corners of the step flashing, where individual metal pieces interlock with the roof shingles, or at the head flashing located at the top of the skylight if debris builds up and blocks proper drainage. Another common leak point is the seal where the glass pane meets the frame, especially as rubber gaskets dry out, shrink, or crack under constant ultraviolet exposure and extreme temperature fluctuations. Additionally, condensation buildup inside the frame due to poor indoor ventilation or inadequate insulation around the skylight shaft is often mistaken for an exterior roof leak, highlighting the importance of inspecting both the flashing and interior frame joints.