Answers · Materials and upkeep
Why is my skylight leaking?
The short answer
Most skylight leaks are at the flashing where the unit meets the roof rather than through the unit itself. A meaningful share are not leaks at all but condensation, which shows on cold mornings with no rain and needs ventilation rather than sealant.
Leak or condensation
- Water after rain, especially heavy or wind-driven rain: a leak at the flashing or the unit.
- Water on cold mornings after a warm humid evening, with no rain: condensation on a cold surface.
- Staining at the top of the shaft: usually flashing.
- Staining lower down the shaft with a dry top: often condensation running.
Replace the flashing kit, not just the sealant
Manufacturers make flashing kits specific to the unit and the roof covering. A skylight flashed with sealant instead of the proper kit is a leak on a timer. If a contractor proposes to reseal it, ask whether a proper flashing kit exists for it and what the difference costs.
Also asked
- Should I remove the skylight instead of fixing it?
- It is a legitimate option if you do not value the light, and the cost is decking, insulation and repairing the ceiling below, which is not trivial. Weigh it properly rather than as a default, because daylight is hard to get back.
General information about roofs and about hiring, not advice about your building. Roofing contractor licensing, permits, insurance practice and deductible rules are set state by state and province by province across the United States and Canada, so your own authority is the current answer.