We install new supreme skylight with copper flashing with high quality and we do repair to. Have many reason why the skylight leaking. The way it can be installed. Degradation of the roof by years, broken or cracked glass, change of temperatures can degrade the safety parts of the skylights. Also, leak can be from the flashing when is damages or from not easily apparent reasons.
In some cases the skylight can be repaired, can sealing with 4 season silicone, or when the damage is severe, we recommended to completely replace it. In our team we have the best installers for the skylight and we includes up to 10 years on labor and up to 30 years on material depending on the manufacturer description.
The cost of replacing the skylight depends on the size of the skylight, also if the skylight is fixed, vented or with electric motor.