Skylight Leak Repair

A skylight sits on a raised curb that penetrates the roof membrane, with a seal or gasket around the glazing itself and flashing where the curb meets the roof surface. Any of these three elements — the glazing seal, the curb flashing, or the gasket — can fail independently, which is why skylight leaks sometimes get misdiagnosed as “the skylight is broken” when the actual problem is the roof flashing around it.

One useful diagnostic distinction: a leak that only appears during or right after rain is more likely a flashing or seal failure. Moisture that appears consistently regardless of weather, especially with fogging on the glass, is more often condensation — a different problem with a different fix (usually ventilation, not roofing repair).

Repair depends on which element failed: reglazing or resealing the skylight unit itself for glazing failures, or removing and properly reflashing the curb transition for flashing failures — the same flashing-repair principles that apply to any other roof penetration.

Ruling Out Condensation Before Assuming It’s a Leak

Not all moisture around a skylight is a roof leak. Condensation forms when warm, humid interior air meets the cooler surface of the skylight glazing, especially in bathrooms, kitchens, or poorly ventilated rooms. Condensation-related moisture tends to appear consistently regardless of weather and is often accompanied by fogging on the interior glass surface.

A true leak, by contrast, correlates with rain events and doesn’t require warm, humid interior conditions to appear. If you’re not sure which you’re dealing with, noting whether the moisture shows up specifically during or after rain (leak) versus more randomly tied to indoor humidity (condensation) helps narrow it down before a service call.