Do you have frost on the inside of your windows? Are you forever wiping up water from your windowsills? If you answer yes, chances are the problem is not with your window, but rather you have excess moisture in your home. Understanding the problem is the solution unto itself. The problem moisture and ultimately the frost that forms on doors and windows, is a result of too high of an indoor humidity. High humidity can also cause woodwork to swell, drawers to stick, and create mold and mildew. You can monitor the humidity with an instrument called a Hygrometer, which can be purchased for just a few dollars. The chart below indicates proper indoor humidity levels when the indoor temperature is 70 degrees Fahrenheit.
|Outside Temperature||Recommended Indoor Relative Humidity|
|-20 d F||15% or less|
|-20 d F to –10 d||20% or less|
|-10 d F to 0 d||25% or less|
|0 d F to 10 d||35% or less|
|Above 10 d F||40% or less|
When levels of indoor humidity exceed the chart above, dehumidifying should be done, or eliminate if possible, the source of the excessive humidity. Sources of humidity include: dryers not properly vented to the outside; not running the fan when cooking and bathing, improperly vented crawlspace areas, and improperly vented gas burners. Just to give you an idea of some of the normal everyday sources of humidity, normal perspiration and breathing of a family of four adds about ½ pint of water into the air every hour. Cooking three meals a day adds 5 pints of water into the air. In fact, the daily living of a family of four can add up to 18 gallons of water in a given week.
New homeowners today wonder why their brand new home has moisture problems and their friend's older home does not. And their friend's house has single glazed windows and the attic isn't even insulated. Newer homes are built tightly, to save energy, and have little or no air-infiltration, thus they require ventilation. The older home has natural ventilation through its excessive air-infiltration. This eliminates the excessive humidity.
In summary, monitor the humidity in your home and resolve any problems through dehumidification and/or eliminate the problem source if possible. For additional information you can contact many local universities, housing agencies, building research centers or a qualified home inspection company. Any of these individuals should be able to assist you in remedying the problem.