Attic Condensation

Jan 08, 2018

The weather has finally warmed up and some of you are seeing water spots on your ceiling. Fear of a roof leak could actually be condensation built up in your attic space.

Moisture in your attic is never a good thing. It can lead to rotting wood, mold and ice damming Frost in atticon the roof. In the freezing temperatures of winter, the attic moisture will turn to frost and ice. The sudden warm weather has caused this moisture to melt and run down to ceiling surfaces.

What causes moisture in the attic?

The primary cause of attic moisture is when it travels from your heated portion of the building up to the attic space. If your home has too much humidity , from a furnace humidifier or other sources, it can rise to the attic. Venting of your kitchen or bathroom  into the attic will also cause Improperly vented bathroom fan.jpgmoisture. Improper ventilation can also lead to ice damming which can result in water coming into the home when temperatures rise and damage to your roof.

How to prevent it

A report from Cornell University lists a number of ways to prevent this problem with removing excess moisture in the home and proper ventilation in high moisture areas. Click here for the complete report.

  • Clothes dryers should always be vented to the outdoors, even in the coldest weather.
  • Never store large volumes of firewood within the heated area of the home.  Even firewood that appears dry can contain significant amounts of water that can evaporate into the house as it dries.
  • It is not necessary to use a humidifier to maintain comfortable levels of indoor relative humidity in a well insulated and properly weatherized house. 
  • Unvented heaters release tremendous amounts of water vapor into a house.  If you will be purchasing a kerosene or gas space heater, spend a little extra money and get one that is vented to the outdoors.
  • If you do not have exhaust fans in bathroom and kitchen areas consider having them installed.  If that is not possible, then open a window slightly during periods of high moisture generation to allow excess water vapor to escape. 
  • Bathroom fans should remain on during showering, and for at least 15 minutes afterwards.
  • Exhaust fans must be vented to the outdoors, not into attics, overhangs, crawl-spaces, etc.

In addition to these steps, proper insulation and ventilation is key.  As stated in the Cornell report: “The United States Department of Energy (DOE) recommends that ceilings have insulation levels of R-49. Doing so can significantly reduce home heating bills. Combining proper levels of insulation with air-sealing will prevent both attic condensation and ice damming problems…Even with sufficient insulation levels and a good air seal between the attic and heated spaces below, some heat may escape.  Attic ventilation is suggested because it can draw this heat from the attic before it can accumulate and begin to melt roof snow.  It also keeps the roof cooler in summer.“

“These extreme weather conditions, with it being -10 one day and almost 40 the next, makes it hard to control the attic temperature,” says Ledegar Roofing Vice President Alex Koonce. “Accumulated frost will normally evaporate through the vents but with these big temperature swings a large amount of thawing will need to find a place to go.”

If you are experiencing water spots on your ceilings, schedule our service department for an inspection. Controlling attic moisture levels are important for a healthy home.



Category: Leak Detection


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