1 Leaks!

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.

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.

Weep Holes. Skylights, even modern acrylic domes, often have channels that collect condensation and empty it to the exterior to prevent drips. Roofers, or others with little experience with skylights, often see these holes as a source for leaks. By closing them with caulk or sealant, they may actually create a condensation drip.

SolutionsReduce 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.

Replace the skylight with a more thermally efficient model. Velux LuxGuard polycarbonate domes are 100% thermally broken and Velux skylights are Energy Star rated. If high humidity is a common condition, consider a venting skylight.

Unplug any closed weep holes.


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.

Leak damage at bottom outside shaft indicates flashing issues.

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.

SolutionsFlashing 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.


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.

Drywall damage due to a skylight seal leak.
SolutionsIf 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.

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