It’s one of those niggling little things that you tell yourself you’ll get to when you have a moment; your windows are sweating, which in and of itself isn’t such a bad thing. What is, is when that water drips down your windows and then leaps over the pane edge and down onto the sill, which is more often than not made of wood; which means standing water which will cause your sill to rot.
Windows sweat when there is a temperature and humidity level difference between what is on one side of the window and the other. Window sweating occurs most often when the weather cools outside and the heat is turned on inside and the heat is not the dry kind, which means the humidity level in the house is a little high.
There are two basic ways to stop windows from sweating. The first is by lowering the humidity level in the house. If you have electric heat, this may be a problem as it doesn’t do much to take moisture out of the air. A drastic action would be to replace the electric heat with gas heat, which actually burns the water right out of the air and sends it outside with the rest of the exhaust. Though, be warned, this may not completely fix your window sweat problem because it won’t take out all the moisture, just most of it. A more logical approach would be to buy a de-humidifier, which pulls the water out of the air and deposits it in a little bucket. But again, this approach will like help but not completely solve your problem because there will always be some moisture in the air or you’d feel uncomfortable in your home because it would feel uncomfortable and would dry out your skin and furniture.
Thus, it’s best to go another route, and that is to buy a transparent plastic window cover. They work by completely sealing off the window from the rest of the house. It looks an awful lot like saran wrap, and functions in much the say way. What you do is put a piece of this material over your window; one that is big enough to cover the whole thing, then you pull it as tight as you can and tape it to the sill. And then, the magic starts. You get out your hair dryer, turn it on and aim it at the cover and slowly move it around continually blowing hot air on it. Soon, the cover material will start to shrink slightly, which will pull it tight against the window, effectively sealing it so no air can get in or out. Doing this will not only keep moisture off your window, but will help reduce heating bills by keeping cold air out.