Why Do My Windows Sweat?

This is one of the more common questions related to home window maintenance. Window condensation occurs due to warm and cold air meeting on the inside and outside of your windows, combined with a humid environment.

The good news is that this is usually not a sign that your windows are in bad condition. Ironically, you may be experiencing window condensation due to how well your windows are doing their job. Modern windows do a wonderful job of insulating your home. So, cold or warm air doesn’t leave or enter your home, unless you mean for it to (such as opening windows or doors). With older windows, a draft may be created and condensation on either side is less likely.

Window Condensation in the Winter

In the winter, if it’s cold outside and you are heating your indoor environment, and if the relative humidity is not where it should be, condensation can occur on the inside of your windows.

Window Condensation in Warm Weather

Here in Florida, the issue more often arises in the summer, or any other time the temperatures and humidity are high… which is a regular occurrence in the Sunshine State. So, you’re more likely to experience condensation on the outside of your windows, due to the outside heat and humidity and the cool indoor air.

While low-E coated windows reduce the amount of heat that comes into your home, they may create just the right temperature difference that condensation occurs during warm weather.

How to Prevent Window Condensation

Since you can’t control the weather conditions outside your home, the easiest way to prevent window condensation during warm weather is to warm the window’s surface, which might be successful with just moving your thermostat a couple degrees higher.

Window condensation in hot weather often occurs due to unobstructed views. So, exterior shutters or shades that block direct sunlight might be a consideration.

In cooler winter months, if you are experiencing condensation on the inside of your windows, you likely need to adjust the relative humidity in your home, which should be below 40 percent to control condensation. Here are some ways you can control indoor humidity and/or prevent condensation.

• Run the bathroom vent while you shower or bathe, and for 10-15 minutes after you are finished.
• Use the overhead vent on your stove during and after moisture-producing cooking.
• Make sure your clothes dryer is properly ventilated.
• Occasionally open windows for a few minutes to ventilate your home.
• Try to minimize or prevent conditioned air from directly contacting your windows.
• Make sure your HVAC system is working properly.
• More challenging cases may require a dehumidifier.

Using a simple and very affordable hygrometer can help you monitor your indoor humidity and see if what you are doing to improve it is having a positive impact. If the problem persists, you may want to consult an HVAC professional.
However, if condensation is forming between two panes of a window, this is something entirely different. This means the seal, which is supposed to be airtight, has likely been broken. If seal failure has occurred, the glass will need to be replaced. If you have any questions about your windows, don’t hesitate to give us a call!