David Bareuther, Associated Press Building editor, sums up the problem of reducing humidity by saying there are only three ways to do so:
1. CONTROLLING SOURCES OF HUMIDITY:
For instance, venting all gas burners, clothes dryers, etc., to the outdoors. Use of kitchen or bathroom exhaust fans.
2. WINTER VENTILATION:
Because outside air usually contains less water vapor, it will “dilute” the humidity of inside air. This takes place automatically in older houses through constant infiltration of outside air.
3. HEAT:
The process of heating your home will reduce the relative humidity, providing its dry heat. It will counter-balance most of all the moisture produced by modern living.
Now before we summarize specific steps for reducing humidity in your home, let’s include some basic data about recommended moisture. You can refer to it if you are inclined to test the moisture levels in your own home. The table below is the result of long and careful experiments at the University of Minnesota Engineering laboratories. It shows the maximum safe humidities for your home, not only for the windows, but even more for your paint, insulation, and structural members. In most cases, reducing moisture to these humidities will cure troublesome condensation on windows; if not, you can reduce humidity further without discomfort to you or your family.
If you test humidity in your home, be sure to use an accurate instrument, preferably a good sling psychrometer. Remember, too, that these relative humidities are for 70 degrees Fahrenheit. For higher temperatures, lower humidities are required.