What causes window condensation?

posted on in Global Blogs

What causes window condensation?Water on your windows - what causes it and what should you do about it?

Although it might look like an issue, condensation on your windows does not necessarily indicate that your windows are not performing as intended. In fact, condensation forming on your windows can be a sign that your windows are forming an airtight seal, reducing air leakage and keeping the moisture inside your home.

Just like a cold glass of lemonade on a hot day, condensation occurs when the temperature on one side of glass is drastically different from the temperature on the other side of the glass. While it can be concerning or frustrating, the good news is you can minimize or prevent condensation by controlling the humidity inside your home.

What Causes Window Condensation?

Condensation on the inside of a window, or roomside condensation, is a sign of higher humidity inside the home than outside. Humidity levels inside a home can be impacted by a number of things, including cooking, showering, houseplants, and even laundry.

Roomside condensation

Roomside window condensation

A comfortable humidity level inside 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 causing you to get a small “zap” when you run your feet across carpeting before touching metal. Too high and you may risk dust mite infestation, air quality issues, and condensation on windows or other surfaces, in addition to other issues. According to the Environmental Protection Agency, the ideal relative humidity in a home should be below 60 percent and ideally somewhere around 30-50% - it’s normal to be on the lower end of the range (or slightly below) during winter months.

Other types of Window Condensation

Exterior Condensation

Outside condensation happens 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. It typically occurs in the spring and fall when cool nights follow warm days.

What causes condensation on the outside of windows? Exterior condensation generally occurs in the summer months. It is caused by three main conditions: high outdoor humidity, little or no wind and a clear night sky. It occurs mostly during times of the year when days are warm but cool off at night.

Condensation on the outside of windows is quite common, and not indicative of problems with the windows or home.

Condensation between the glass

Condensation between the glass

Condensation between two pieces of Insulated Glass is not controllable and is an indication of glass seal failure. Contact your window manufacturer for this situation.

Reduce or prevent roomside window condensation

Condensation is more likely to occur when drapes are closed and shades are pulled down. Try drawing your window treatments and circulating the air inside your home. You can use ceiling fans in a clockwise direction - even during the winter - to move warm air from the top of your room down. If you’re using a humidifier, in a nursery or as part of your furnace, turn it down or off for a while

Ensure proper ventilation in your home - especially areas that are more prone to moisture. This includes kitchen, bathroom, and laundry area. Make sure to run your exhaust fans when cooking and showering. Make sure your exhaust fans and clothes dryer vent outside the home and are in good working order. If your home does not have exhaust fans, you could try opening your window just a bit for a few minutes to dry the air out. Also, make sure to not store firewood inside - it can bring unwanted moisture into the home.

Reduce or prevent window condensation

When should I be concerned about condensation?

Not necessarily, and it’s not an indication of an issue with the window, either. Start by looking at the humidity level inside your home. This can be accomplished with a humidity meter (hygrometer) which can be purchased at home improvement or big-box stores. Some home thermostats have a humidity meter built-in. Problems like window condensation and musty odors are nuisances while others can be more serious such as blistering or peeling paint, damage to insulation, stains on walls and ceiling or structural damage to the home. The important thing to remember is that your windows are trying to tell you to reduce indoor humidity before it causes hidden, costly problems elsewhere in your home.

Condensation or frost on windows can cause issues over time. Prolonged exposure to moisture can discolor or crack paint and varnish or warp wood windows or trim. If possible, try to wipe away moisture before it pools or puddles around woodwork.

Overall, condensation on windows does not necessarily mean you have an issue with the way your windows are functioning. Make sure to address the situation by regulating the humidity inside the home to avoid potential future humidity-related problems.

What experiences or questions do you have about window condensation?

Sarah Mueller

About The Author

Sarah is a professional writer by trade and passion. She specializes in writing about windows, doors, home design and decor, and learning all she can about the home improvement industry. Sarah spends her time away from the office cleaning up stray socks and pokemon cards strewn about by her two little boys. She is an avid reader, runner, and gardener who is known for her atomic salsa.

More posts from this author.

  Call Now
  • Energy Star Partner logo
  • AAMA logo
  • Pella Limited Lifetime Warranty logo
  • Property Brothers Buying + Selling logo

Inspired Design. Exceptional Detail.

Get inspiration and upcoming local offers...