The skylights themselves may not be the culprit!
If a skylight is mounted properly and sealed to its curb per the manufacturer’s instructions, it is very unlikely that it will leak.
Condensation—A drip, not a leak:
Lack of a thermal break
A common problem with older acrylic dome skylights is the lack of a thermal break—using an insulating material to physically separate the interior frame from the exterior. When rising warm, moist air meets the cold skylight it condenses and when conditions are met, it can certainly drip. It is usually perceived as a leak.
Solutions
If only the outer acrylic dome or glass is broken—your skylight may not leak until it can get repaired.
Reduce the humidity in your room. In the same way that you would use the bathroom exhaust fan to reduce condensation on the mirror, increase ventilation or even air circulation to lower the humidity. A dehumidifier is another option.
Plugged weep holes
A common problem with older acrylic dome skylights is the lack of a thermal break—using an insulating material to physically separate the interior frame from the exterior. When rising warm, moist air meets the cold skylight it condenses and when conditions are met, it can certainly drip. It is usually perceived as a leak.
Solution
Unplug any closed weep holes.
Flashing leaks:
A flashing leak is when water is penetrating the roof deck through the flashing around the skylight and not the skylight itself. It can usually be identified by damage at the ceiling level outside the skylight shaft.
Another way to pinpoint a flashing leak is to direct water from a hose onto the roof above the skylight so that the water flows around it. If you see a leak, it’s a flashing problem.
Solutions
Flashing leaks are roofing leaks. As such, a roofer with experience flashing skylights should be qualified to repair a flashing leak. We recommend an experienced skylight installer for consistent results.
Flashing repairs are somewhat labor intensive. Replacing a skylight while replacing the flashing would not incur additional labor, for example. It may be cost effective to replace the skylight, also. Our proposals will allow you to make the decision.
Skylight leaks:
Water is penetrating through a failed skylight seal. Improper repair is a more common problem. See Weep Holes above, for example. Evidenced by damage on the interior of the skylight shaft.
Drywall damage due to a skylight seal leak.
Solutions
If a poor skylight seal is causing a leak, a reseal may be a cost effective solution.
Since a seal often fails due to age, consider replacing the skylight with a more modern thermally efficient model. The energy savings can be significant and usually pay for the skylight and installation in a few years. Velux skylights are Energy Star rated and a venting skylight can further reduce cooling costs.
