Schedule a Free Consultation
Posted on Nov 17, 2017 by Sam Heer

Everything You Need to Know about Window Condensation – Part 1: Window Condensation – What Causes It?

Many homeowners think fog on the glass means their windows are already compromised. They’re probably not–or at least, not yet. Over time, however, condensation can influence the way your windows perform, and not in a good way. You have to take a closer look at your home’s humidity levels first. In fact, condensation is a telltale sign of excessive indoor moisture in your home as window glass provides the perfect cold surface on which humidity can visibly condense.

Window Condensation - What Causes It?

Identifying High Humidity in the Home

Notice how a glass of iced tea “sweats” outside during summer, or how bathroom mirrors fog up after a hot shower? It’s the same with your windows. High levels of humidity don’t just affect the overall thermal comfort of your living spaces, but your family’s health, as well. Aside from window condensation, other warning signs that humidity levels inside your home are high include:

    • General feeling of dampness inside the home
    • Growth of mold and mildew
    • Cracks, peels or blisters on exterior or interior paint
    • Warping on wooden surfaces
    • Musty smells
    • Sweating pipelines
    • Staining or discoloration on interior surfaces
  • Stale warmth inside the home even on cold days

What Causes Excessive Indoor Moisture in the First Place?

There are a couple of things that generate high levels of humidity in your home, and in turn, create condensation on your windows. In fact, any activity which involves using water can lead to copious amounts of indoor moisture. Cooking, hot showers, laundry, dishwashing, mopping floors clothes drying–all of these add moisture to the air. Too much water vapor in your home means higher indoor humidity, which then comes into contact with a cold surface, like your window’s glass, to produce condensation.

How Does Excessive Indoor Moisture Affect Your Windows?

When left unattended, too much indoor humidity can damage your windows. Constant exposure to moisture can give rise to gaps and penetrations in the frame, weakening the windows’ build while allowing significant energy loss. If you want to keep your windows looking good and performing well, make sure to deal promptly with high moisture levels. Opening windows, running bathroom fans and using a dehumidifier will help.

Stay tuned for the second installment of this three-part blog series, where we will be discussing more about how window condensation affects your home and quality of life.


"I would recommend RBA of Central Illinois for QUALITY windows and doors. Compared to our old cheap, thin vinyl windows, Andersen blows them away. You can easily tell by how well the sliding doors fit and close, and how heavy duty they are. We also cannot hear the wind rushing through the house in inclement weather anymore! And the black window frames we went with are amazing to look at. Aaron, Al, Darrell, and Cory all were professional and went all out to finish the job, given the weather they had to deal with. I would definitely recommend. They were also on top of communicating with me given the weather delays, and what I could expect for them coming out. Five stars!"

Eric L.

View All Reviews