Condensation occurs when excessive moisture in the air comes in contact with a cold surface creating moisture droplets. When warm moist air and the cold surface meet, the excess moisture in the air converts from water vapor to a liquid, forming “condensation”. This is most common in the winter months because of the temperature difference between outside and inside air. During the cold weather, homes are sealed up tight not allowing moisture to escape through open skylights and windows, as in the warmer months. This helps explain why condensation is caused by the environment where the skylight is installed, not the skylight itself.
Determining If You Have a Leak or Condensation??
- Is it raining when you see the moisture develop? If yes, then it may be a leak. If not and it developed as the weather started dropping to temperatures near freezing, then it may be condensation.
- Is the moisture developing mainly on the inner glass surface then dripping or running down to the lower portion of the skylight? It is most likely condensation.
- Is there staining on the corners of the skylight? If the stain is on the wood curb and is at the top of the wood curb (or jamb), it may be condensation or a torn gasket. If the stain is below the wood curb, it is most likely a leak through or around the flashing and should be inspected by a roofing contractor.
Causes of Excess Moisture
- New spackle or paint (may require several weeks to completely dry)
- Humidifiers or heating systems with built in humidifier
- Large amounts of indoor plants
Steps You Can Take To Reduce Humidity in Your Home
Condensation is caused by excess moisture in the home that is unable to escape. Things you can do to decrease humidity and increase ventilation.
- Use exhaust fans in your kitchen, laundry and bathrooms.
- Vent gas burners, clothes dryers, etc. to the outdoors.
- Shut off furnace humidifiers and other humidifying devices in your home.
- Use ceiling fans to circulate the air in the home preventing the warm moist air from rising and settling on the glass surface.
- Run a dehumidifier in basements and during days with damp weather.
- Take shorter showers and use the exhaust fan in bathrooms when showering.
- Be sure that the ventilating louvers in your attic, basement or crawl spaces are open and are the correct size.
Below is a chart of recommended indoor humidity levels relative to outdoor temperatures to reduce the possibility of condensation.
Maximum Recommended Humidity Levels
|Outside Air Temperature
|Inside Relative Humidity
|-20° F or Below
|15% or Below
|-20° F to -10° F
|16 to 20%
|-10° F to 0° F
|21 to 25%
|0° F to 10° F
|26 to 30%
|10° F to 20° F
|31 to 35%
|20° F to 40° F
|Not over 40%
|*Information based on engineering studies at 70 degrees F
All Supreme Skylights come with an integral condensation gutter designed to handle typical condensation. The information above is meant to be used as a guide for owners of Supreme Skylights who may be experiencing condensation in their home. Supreme Skylights does not accept any responsibility for problems relating to condensation and is providing this information solely as an aid to understand and remedy the problem.