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What Causes Window Condensation and How Do I Get Rid of It?


on November 3, 2022


Like a cold glass of lemonade on a summer’s day, window condensation occurs when the surface temperature of glass is below the dew point of the air. While condensation on your windows can look bad, it’s typically not concerning. And the good news is, you can minimize or prevent condensation on windows with a few easy fixes — here’s how.

Common Causes of Window Condensation

Although it might look like an issue, moisture on your windows doesn’t necessarily indicate a problem. In fact, window condensation can be a sign that your windows are forming an airtight seal, reducing air leakage and keeping the moisture inside your home.

Most of the time, moisture on your windows is a matter of temperature and humidity. In the summer, when there’s hot, humid air on one side of the glass and refreshing AC cooling the other, condensation is likely to form on the window’s exterior glass. In winter, condensation is more prone to forming on the interior of your windows because the cold outside temperatures cool window glass below the dewpoint of the warm and humid air inside.

If you can’t easily remove window condensation by wiping the glass — and be sure to do this using a soft cloth or towel to avoid leaving fingerprints and streaks — the moisture is likely between the panes, and that’s a sign of a bigger issue.

Dangers of Window Condensation

While condensation on your window glass alone won’t harm anything, excess amounts of it can trickle down elsewhere, may cause blistering, cracking or peeling paint on your frames, or even warping and water damage. Eventually, this wear and tear can require you to replace your window frames. 

Condensation in Windows

If the condensation is on the inside of the windows — as in, between the pieces of insulated glass on dual-pane or triple-pane windows — it’s indicative of glass seal failure. The only way to get condensation out of windows is to replace the faulty piece. In some cases, this might just be the panes, but it could also mean replacing the whole window.

Moisture Throughout Your Home

Regular indoor condensation on your windows means the moisture is elsewhere in your home. Over time, this can damage insulation, leave stains on the walls and ceiling, and in extreme cases, lead to structural damage in your home.

The important thing to remember is that your windows are often the first indication your indoor humidity levels are elevated. Reduce the source of the humidity before it has the chance to cause hidden, costly problems elsewhere.

How to Stop Condensation on Windows

Before we discuss prevention, let’s talk about how you can stop condensation on windows once it’s started to accumulate. Here are a few troubleshooting steps to help eliminate existing condensation so you can focus on preventing it in the future:

Open up the windows. Letting fresh air circulate through the window’s components by opening it up can minimize and sometimes even eliminate the buildup of condensation you see. 

Use a moisture absorber. These come in lots of shapes and sizes, with varying designs to suit your sensibilities, and when placed near a window will absorb condensation-causing moisture before it has a chance to settle in. Some moisture absorbers are refillable as well, so when the gel inside has reached its maximum absorption capacity, replacing it is simple and straightforward. 

Get a dehumidifier. For those in humid climates, especially homeowners with basements, a dehumidifier is likely not a new concept. However, this machine, which sucks moisture from the air at a slow, consistent pace, can also be used to stop and get rid of window condensation. While most homeowners keep their dehumidifiers in the basement, consider placing a smaller unit on the floor where your window condensation problems are the worst. 

Pull back the curtains. While we all love a good window treatment and the stylish accent it provides, sometimes those window treatments trap moist air against your windows, making condensation issues worse. Simply pulling back the curtains to keep them away from the window pane and frame can allow better air circulation against the window, which can stop condensation before it gets out of control. 

How to Prevent Condensation on Windows

Inside and outside window condensation each have their own approaches for prevention. Your first step is to figure out where the moisture is coming from. Once you identify this, use the following tips to stop condensation from forming on your windows.

Interior Window Condensation

When you have condensation on the inside of a window, or roomside condensation, it’s It's a sign that the humidity levels inside your home are elevated. This can be caused by a number of things, including cooking, showering, houseplants and even laundry.

The humidity level inside of a home varies depending on your climate and the time of year. Too low, and you may see warping of your woodwork or static electricity build-up that causes you to get a small “zap” when you run your feet across the carpet before touching metal. Too high and you may risk dust mite infestation, air quality issues and condensation on walls, windows and other surfaces. 

According to the Environmental Protection Agency (EPA), the relative humidity in your home should always be below 60 percent. Ideally, you want it somewhere between 30 and 50 percent. It’s normal to be on the lower end of the range (or slightly below) during winter months.

Preventing Window Condensation on the Inside

Stopping condensation on the inside of your windows starts with measuring the relative humidity. The EPA recommends picking up a hygrometer — a small, inexpensive humidity meter you can find at your local home improvement store or big-box retailers. Some home thermostats, like smart thermostats, have a humidity meter built-in. 

Once you know how humid it is inside your house, you can take measures to bring the levels down and help prevent condensation:

  • Open window treatments. Condensation is more likely to occur when drapes are closed or shades are pulled down. Try drawing your window treatments so the heat isn’t trapped on your window pane. 
  • Circulate the air. The same way a gentle breeze can take the edge off the humidity outside, some air circulation can do wonders indoors. You can use ceiling fans in a clockwise direction — even during the winter — to move warm air from the top of your room down. 
  • Turn down the humidifier. If you’re using a humidifier — in a nursery, to treat a cold or as part of your furnace — turn it down or off until the relative humidity decreases.
  • Ensure proper ventilation in your home. Some areas are more prone to moisture, like your kitchen, bathroom and laundry area. Make sure to run exhaust fans when cooking and showering. Also make sure those exhaust fans, as well as the clothes dryer vent, are in good working order. If your home doesn’t have exhaust fans, try opening your window just a bit for a few minutes to dry the air out. 
  • Keep firewood outside. Plants bring moisture into the air, even if that plant is now kindling for a fire. If you have a wood-burning fireplace, store firewood outside to help control the humidity.

Exterior Window Condensation

Condensation on the outside of your windows occurs when the exterior surface temperature of the glass falls below the dew point of the air. This type of condensation is more likely to occur when outside humidity levels are higher, like in the spring, summer and fall when cool nights follow warm days.

Exterior window condensation happens more in the summer months when the days are hotter and sunnier. It’s caused by three main conditions: high outdoor humidity, little or no wind and a clear night sky. 

Getting Rid of Window Condensation on the Outside

Because it’s seasonal and climate-related, condensation on the outside of windows is quite common. It isn’t indicative of problems with your windows or the humidity inside your home. You can simply wait for the sun to come out and dry up all the moisture. 

Combat the Effects of Window Condensation With Help From the Pros

If you’re in need of condensation-related window repairs, get in touch with your local Pella window professional today. Our team of experts will inspect the window, determine what needs replacing and—if a replacement is required— help you find the most suitable window material, style and functionality for your home’s needs.

Schedule a free consultation to find windows and doors for your home.