What Causes Condensation on Windows and How to Prevent It.

Oct 31, 2023 | News

Condensation on windows can be a frustrating issue for homeowners, but it’s also a sign that something deeper may be at play in your home.

Window condensation is a natural occurrence that happens whenever warm air meets a cold surface or when the humidity level in a home is too high. This phenomenon is especially common during the winter months, when central heating systems are turned on to keep homes warm. Warmer air is able to hold more moisture and in the center of the room the temperature will naturally be higher compared to the exterior walls with windows. As that warmer air, if containing a larger percentage of water or humidity moves towards the cooler wall with a large enough temperature difference it can no longer hold that moisture at the lower temperature. This can cause the moisture to transform into water droplets and other forms of condensation on the glass and frames of windows. This is often more noticeable and frequent during the winter season because of the extreme differences in the indoor and outdoor temperatures. If you are looking to avoid condensation when the temperature drops to 35 degrees or less, maintaining a 25-30 degree relative indoor humidity is recommended. Windows are not the cause of condensation. That is why if you are experiencing condensation, installing new windows most likely will not correct that issue. Homes constructed with improved insulation standards and energy conservation measures may be more likely to experience visible condensation as they are designed to be more airtight and don’t have as much built-in ventilation than older buildings with less insulation or single paned windows.

The good news is that by understanding what causes condensation on windows and taking appropriate measures with a resource you can trust, families can ensure that their homes will remain energy-efficient, comfortable, and reduce condensation occurrences.

What Causes Window Condensation?

What causes condensation on windows? In a nutshell, window condensation is caused by a combination of factors, including temperature differentials, humidity levels, and the quality of insulation around windows. When the inside of your home is warm and humid, and the outside temperature is cold, your windows act as a barrier that can lead to condensation forming on the inside of the glass. This issue can be exacerbated by poor insulation around the window frames.


  • Temperature And Humidity: When the temperature outside drops, indoor air tends to hold more moisture. As such, indoor humidity levels increase, and, if there is no proper ventilation, the moisture finds its way to the windows and other cold surfaces causing condensation. Conversely, when indoor temperatures rise the air can hold more moisture, and as a result, indoor humidity levels drop which is another culprit of window condensation. Even minor everyday activities can add moisture that can contribute to condensation inside your home or business including:
    • Cooking
    • Taking a hot shower or bath
    • Humidifiers or vaporizers
    • Construction projects
    • Dish washing
    • Heavy breathing
    • Fish Tanks
    • Even house plants
  • Poor Ventilation: When a home's ventilation system is insufficient, moisture is trapped indoors, and that can lead to high humidity. Again, high humidity levels facilitate the condensation process, causing an overabundance of moisture to form on windows. Proper ventilation is critical in reducing condensation on windows. An effective ventilation system helps to control humidity levels indoors, reducing the amount of moisture in the air and ultimately reducing the chance of condensation on windows.
  • Condensation In Between Windowpanes: If you are noticing moisture on your windows but cannot rub it off on the inside or the outside, the moisture may be between the windowpanes. If that is the case, a seal has failed and should be repaired or replaced.

Preventing Window Condensation

All that said, several steps can be taken to prevent window condensation from occurring in the first place. By taking these preventative actions, homeowners can maintain a comfortable and healthy indoor environment while avoiding the potential risks of excess moisture buildup. Condensation is a natural process that cannot always be completely avoided. Therefore, when you see it on the outside of your windows or doors, there is not much you can do.

  • Controlling Indoor Humidity: Homeowners should aim to maintain an indoor humidity level falling between 30 to 50%. If your home is particularly humid, then consider investing in a dehumidifier to help remove excess moisture from the air.
  • Improving Ventilation: Proper ventilation helps to circulate air and reduce humidity levels, which can discourage excess moisture and prevent condensation. You can improve ventilation by using exhaust fans in your kitchen and bathroom, opening windows strategically, and ensuring good airflow throughout your home.
  • Insulation: oper insulation and installation can help to create a barrier between the indoor and outdoor environments by retaining heat and blocking cold outdoor temperatures. This makes it harder for moisture to collect on your windows and reduces the risk of condensation.
  • Window Treatments: Window treatments, such as thermal curtains or shades, can help insulate your windows and reduce condensation. They provide an additional barrier between the interior and exterior of your home, helping to reduce any heat loss and prevent condensation from forming on your windows.

Fixing Window Condensation

Fortunately, fixing window condensation is relatively simple and can be achieved through several steps. The first step in fixing window condensation is to identify the underlying cause. This may begin with inspecting the windows for cracks or leaks, which can allow moisture to seep in. Additionally, using exhaust fans in kitchens and bathrooms and opening windows occasionally to allow fresh air in can alleviate humidity levels.

Other solutions include switching to double-pane or energy-efficient windows to reduce temperature differences or using dehumidifiers to extract excess moisture from the air.

Replacement Windows

When it comes to a comfortable home environment, having functional windows is key. Over time, windows can become damaged or outdated, leading to increased utility costs and decreased efficiency. Therefore, it's important to consider replacement windows in certain situations. These include windows that are difficult to open or close, have cracked or broken glass, show signs of rotting or warping, etc.

In short, replacement windows are necessary when your current windows are outdated, damaged, drafty, or unable to provide the right level of insulation. If you are already looking, make sure to choose windows with low-e coatings. These coatings help to reduce the amount of heat transferred through the glass and prevent the window from getting too hot – thus why they are far less prone to condensation.

All that said, choosing the right replacement windows that fit your style, budget, and energy-saving needs can be challenging. However, Vector Windows offers a diverse collection of energy-efficient windows that help eliminate condensation and improve insulation. In addition, we are home to a devoted team committed to providing high-quality services and window products.


In conclusion, condensation on windows is a common occurrence that can signify deeper issues in your home's humidity and energy efficiency levels. That's why having quality windows installed by a trusted resource like Vector Windows is essential for maintaining a comfortable, safe, and energy-efficient home.

With Vector Windows, you can be confident that their window selections will provide a long-lasting, reliable solution. In the end, when it comes to your home's windows, don't settle for less than the best. Contact Vector Windows today to learn more about their installation services and quality products, and visit www.vectorwindows.com/windows/ to get started.

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