Why Are My Windows Sweating?

Do some of the windows in your home “sweat?” This phenomenon occurs when condensation forms on the glass. Learn common causes for sweaty windows and how to prevent the problem.

Why Do My Windows Sweat?

  • Condensation on the outside: Indianapolis summers get quite hot and humid. To stay comfortable, you probably blast the A/C, which removes heat and humidity from the air. The windows in your home are cooled by this air, and when hot, humid outdoor air comes in contact with it, the sudden change in temperature makes water vapor condense on the glass. This forms condensation on the outside of the glass.
  • Condensation on the inside: Dropping temperatures and dry air that come with winter have you running the furnace and humidifier all day and night. Higher indoor relative humidity causes water is to condense on cold surfaces, including the interior of your windows. In fact, window sweating on the inside of the glass can occur anytime indoor relative humidity gets too high.
  • Condensation between the panes of glass: Fogging and condensation occur between insulated window panes when the seal breaks. This is most likely to occur in older windows installed on the south or west sides of your home, since heat from direct sunlight often accelerates window seal failure.

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Why Does It Matter?

Now that you know why windows sweat, you might wonder why it matters. Condensation on glass doesn’t do any harm (unless it’s constant and excessive), but when the moisture drips down onto the windowsill or seeps into the wall, that’s when you face trouble. Standing water can damage window frames, especially those made of wood. Even if you have rot-resistant windows, water can still dampen building materials in the wall, allowing mold and mildew to grow.

How to Stop Windows from Sweating

The key is to keep humidity levels fairly consistent between the inside and outside. To reduce indoor humidity in the summer, you can do things like run exhaust fans when cooking and cleaning, ventilate the attic, and avoid hanging laundry inside to dry. To reduce the impact of your humidifier in the winter, keep indoor relative humidity below 50% and cover your windows with curtains to reduce their contact with the warm, moist air. If your windows are always sweating and the condensation is excessive, you may need repair or replacement.

If your window frames have been damaged by condensation or you determine the window seals have broken, contact the team at Overhead Door Co. of Indianapolis & Muncie!