We have an issue with moisture on the inside of our Anderson Windows. The home is about 20 years old and this has been happening for about the last 10 years.

We want to replace the siding & windows, but my
contractor suggest I found a solution to this problem before installing all new windows.
My contractor is familiar with the house, but can not find out why this is happening. He recommended we turn up the heat at night to about 62 degrees. We have done this, it does help, but it is too warm to sleep and Oil costs too much.

This situation is causing us to get mold on the wood framing.

Please, does anyone have any ideas on this problem.

Thank you.

Did you really say turn UP the heat to 62 degrees at night? What temperature are you keeping it at now? There is really only one thing that causes windows to sweat. The surface of the glass reaches a temperature below dew point for the amount of moisture in the air. There are two ways to approach the problem. One is to raise the temperature of the glass to above dew point. The other is to lower the available humidity in the air. The first could be as simple as leaving the curtains and blinds open so that warm air can reach the glass, or as expensive as replacing the windows with units that have a much higher insulating value. You mentioned Andersen windows, so I am assuming that they already have insulated glass. If any of the windows do not have insulated glass, you will likely never solve the problem except MAYBE by installing a really good quality storm window. I would be pretty skeptical of any window company that promises to completely eliminate condensation. In other words, if you plan to replace your windows, make them back up thier claims at their expense first. The second attempt at a solution is to lower the amount of moisture in the air. Every day activities such as showering, cooking and even breathing add moisture to the air. If you have exhaust fans in bathrooms, use them. If you have an exhaust hood above a kitchen range, use it. If you have an excess of moisture in your home from some other source,such as an unvented crawl space, remove it. In a worst case scenario, run a dehumidifier, but be careful not to over dry your home to the point where it becomes uncomfortable. If you are keeping the temperature in your home overly cool, however, you may never solve the problem.

Maintenance 6 has a lot of good ideas about your issues.
Moisture within a home plays a very important roll in providing comfort in a home. If its to high it also can cause a lot of concern due to health issues.
I assume that because the house is fairly new your heating with forced warm air heat?
If that is the case I would check with the humidifier that most likely was installed on the furnace. These units can put out a lot of moisture within a home in a very short time. With better construction of homes being tighter they do not loose their humidity as fast as older homes do. You may have set the control for this to high.
If you do not have a humidifier installed on the furnace. Be sure to check that the chimney is working correctly. Poor vent systems can lead to CO2 and excessive moisture in a home.
You must find the source of the moisture and get it under control. Excessive moisture within a home as shown on the windows can result in hidden mold within the walls causing all kinds of issues.

Thank you for you help , we will try your suggestions.

For the Home Care Club - We have baseboard heat not forced air, doe this make a difference?

First of all it is important to know where you are located because the climate zones are different throughout the U.S. and different methods have to be used. I am in a Hot, Humid, climate and if you were also, I would suggest installing a dehumidifier. One like you can purchase at Lowes or Home Depot will work just fine and keep the condensation from forming on the inside of your windows. There are so many factors that contribute to this that a more detailed analysis would have to be done, but in my climate the humidity levels should be 50 - 55.
TD

If your keeping your moisture levels at that point, You must be very careful not to develop mold in the walls. High humidity levels such as this over extended periods of time will allow for fungal development. Ideally you should be keeping your moisture down to levels of at around 45% or less. Regardless of what part of the country you reside.

You cannot say "regardless of what part of the country you reside" because the environments are totally different and methods and procedures of moisture control should differ just as much. Houses should be designed to suit their environments. In the home-building industry, we have accepted that design and construction must be responsive to varying seismic risks, wind loads and snow loads. We also consider soil conditions, frost depth, orientation and solar radiation. Yet we typically ignore the variances in temperature, rainfall, exterior and interior humidity and their interaction.

There is an article on this site that talks about indoor relative humidity levels. They recommend between 30-60%. In a hot, humid climate you could never get the RH down to 30%.
Here is the article link. TDMaintaining Indoor Relative Humidity

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