A little fog on the lower corners of your windows now and then probably doesn't bother you. By the time you've thought about it a second time it has usually gone away. But what we're talking about is EXCESSIVE condensation. Troublesome condensation. Condensation that blocks whole windows with fog or frost. Water that runs off windows to stain woodwork... or in serious cases even damage the wallpaper or plaster. If you have this kind of condensation on your windows, you have good reasons to worry. And good reasons to act. Don't worry so much about the windows... where you can SEE the effect of excess humidity. You should worry more about what excess moisture may be doing elsewhere in your home. It may be freezing in the insulation in your attic where it will melt and damage your plaster exactly like a roof leak when warm weather comes. Or it may be forcing its way out through siding to form blisters under your exterior paint. That means the most expensive kind of paint job. It's natural and easy in such cases to blame the paint, or the insulation, or the windows. But it's wrong to blame them. The real villain is invisible. It's water vapor... too MUCH water vapor. The best — usually the ONLY way to prevent this trouble is to get rid of excess water vapor. Once you’ve equipped your home with quality insulated windows, there isn’t very much more you can do window-wise to lick condensation.