Symptoms
- Water droplets on the inside of the skylight glass
- Dripping that looks like a leak but only happens in cold weather
- Worse in bathrooms, kitchens, or bedrooms with the door closed
- Fogging that clears once the room warms up
Likely causes
- CommonHigh indoor humidity meeting cold glassSkylights sit above rising warm, moist air and often run colder than wall windows.
- CommonPoor room ventilationBathrooms and kitchens without adequate exhaust fans push humid air upward to the skylight.
- PossibleSingle-glazed or older skylight unitLess insulated glazing runs colder, increasing condensation risk.
- Less commonBlocked or undersized skylight vent/shaft insulationPoorly insulated light shafts can make the glass colder than the surrounding ceiling.
What to do
- Rule out a roof leak first by checking if moisture appears only in cold weather without rain.
- Run exhaust fans in bathrooms and kitchens below or near the skylight, especially during and after showers or cooking.
- Use a dehumidifier in the room if whole-house humidity runs high, aiming for roughly 30–50%.
- Wipe condensation promptly to protect the frame and any wood trim from water damage.
- If the skylight has an operable vent, open it briefly on dry days to let moist air escape.
- Check that the light shaft (the tunnel between the skylight and ceiling) is insulated; add insulation if it's just bare drywall over metal.
- If the unit is older single glazing and condensation is chronic, consider upgrading to a double- or triple-glazed skylight.
Tools and parts
- Dehumidifier (optional)
When to call a pro
Call a roofer or skylight installer if you're unsure whether it's condensation or a leak, or if you want to upgrade the glazing.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.