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Window Condensation: Why It’s There and How to Stop It

Have you ever woken up to foggy windows or noticed beads of water on your window panes after taking a shower or cooking a meal? Condensation on windows is a common problem faced by many homeowners. Not only is it unsightly, but it can also lead to a host of other issues such as mold growth, peeling paint, and wood rot.

In this blog, Thomas & Galbraith Heating, Cooling & Plumbing will explore why window condensation occurs and how you can stop condensation from becoming a persistent problem.

What Causes Window Condensation?

Before we delve into the causes of condensation on windows, it’s important to understand that not all window condensation is bad. In fact, some condensation on windows is a normal occurrence resulting from changes in temperature and humidity. However, excessive condensation can be a sign of a bigger problem.

The primary cause of window condensation is a high level of humidity in your home. When the humidity level is high, excess water vapor in the air can come into contact with cool surfaces, such as your window glass. The dew point causes the water to condense and collect as droplets on the surface of your house windows.

A variety of factors can contribute to high humidity levels in your home, such as:

Inadequate ventilation

Poorly ventilated homes cannot get rid of excessive moisture, leading to high indoor humidity. Inadequate ventilation creates a favorable environment for mold and mildew growth, which can cause structural damage, respiratory problems and produce unpleasant musty odors.

Activities that generate moisture

Certain daily activities like cooking, showering, doing laundry, and other household chores can lead to high humidity in the home. Boiling water for cooking, showering, or running a hot bath can produce up to a pint of moisture each time. Running a dishwasher or washing and drying clothes inside the house can also create a significant amount of moisture.


The outdoor temperatures, weather conditions, and seasonal changes play an essential role in indoor humidity levels. In humid regions, high outdoor humidity levels are a common problem due to an excess of moisture in the air. In winter, condensation forms on any cold surface like windows, window frames, and walls due to colder temperatures, leading to high indoor humidity. On the other hand, air conditioning systems can also lead to high humidity in summer if they are not well-maintained.

Building materials

The materials used in constructing a home can affect indoor humidity levels. Poorly sealed windows, doors, and roofs can allow moisture to seep in, leading to high indoor humidity. Older homes are often constructed with materials that trap moisture, such as plaster and brick walls, making them more prone to high indoor humidity levels. Poor insulation can cause sweating walls and window panes when the temperature fluctuates, leading to high humidity.

Plumbing leaks

Plumbing leaks can lead to high indoor humidity, causing structural damage, increasing the risk of mold and mildew growth. Leaks in walls or crawl spaces are often easy to miss, leading to ongoing humidity problems in the home.

How to Stop Window Condensation

Now that we know the primary cause of window condensation, the next step is to take action to stop it. If you notice condensation on your window glass, here are some effective solutions to reduce window condensation in your home:

Control the Humidity Level

The first and most important step in preventing window condensation is to control the humidity level in your home. Use a dehumidifier to reduce excess moisture in your home and maintain a relative humidity level between 30-50%.

Installing a whole home dehumidifier not only reduces the amount of humidity in the air and makes it more comfortable to breathe, but it can also help prevent condensation on your windows. A whole home dehumidifier works by drawing in humid air through the HVAC and removing the excess moisture, releasing the dry air back into your home. Investing in a high-quality, durable whole home dehumidifier can save you money and lead to a healthier, more comfortable home environment.

Improve Ventilation

Installing a whole home ventilator can go a long way in helping you control humidity levels in your home. A whole home ventilator is designed to exchange air between indoor and outdoor environments while maintaining a constant temperature, reducing humidity levels and keeping your home properly ventilated. By reducing moisture in the indoor air, a whole home ventilator also helps in minimizing condensation on windows.

You can also increase the ventilation and air circulation in your home by opening windows and turning on ceiling fans, as well as opening interior doors. Also, use kitchen and bathroom exhaust fans to allow excess moisture to escape when performing activities that produce moist air and excessive moisture inside, such as cooking or showering. Close the bathroom door and run the bathroom fan while taking a hot shower or bathing.

Upgrade Your Windows

If you have single window pane glass, consider upgrading old windows to double-pane or triple-pane windows to minimize condensation. These types of energy efficient windows have insulating properties that can help prevent the glass surface from becoming too cold, reducing the likelihood of condensation inside. Additionally, new windows with low-emissivity (Low-E) coatings and double glazed windows can help prevent heat loss and reduce condensation.

Installing storm windows is another option to help reduce the likelihood of interior window condensation. Storm windows create an additional layer of insulation that helps to keep the surface temperature of the glass warmer, reducing the likelihood of condensation.

Use Weatherstripping

Weatherstripping is a cost-effective solution to prevent drafty windows and doors, and reduce the amount of cold air coming in contact with your windows. This helps to regulate the surface temperature of the cold glass and reduces the likelihood of condensation.

Install Window Films

Window films are a cost-effective solution to prevent condensation. These films work by creating a barrier that helps to regulate the surface temperature of the glass and reduce the likelihood of condensation. Additionally, some window films have insulation properties that can help your home better retain warm air during the winter months.

End Condensation Issues with Help from Thomas & Galbraith

Window condensation can be a persistent and frustrating problem for homeowners, but it’s not something that you have to live with. By controlling the excess humidity levels in your home, you can reduce the likelihood of condensation and enjoy clear, unobstructed views from your windows.

For more information about installing indoor air quality products such as whole home dehumidifiers and ventilators to control the humidity of interior air in your home, schedule a consultation from Thomas & Galbraith today.

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