Water on your interior window sill is not always a sign of water intrusion originating from the exterior side of your home.  Sometimes, condensation on your windows is the direct result of moisture that is generated from inside the home. 

Within every home there are many interior sources of water vapor. These sources include toilets, sinks, showers, baths, dishwashers, people, pets, cooking (especially when steaming or boiling food), as well as washers and dryers.  When this vapor comes in contact with cooler services such as window glazing, it condenses. 

Over the decades, increased energy-efficiency codes have led to “tighter” homes that, when not properly designed, can lead to excess moisture vapor inside the home and increased condensation.

Fortunately, there are some simple ways to reduce such excess humidity. Listed below are some action steps that will likely alleviate this challenge:

• Keep all rooms at a consistent warm temperature.  Maintaining a constant, even temperature in your home, even while you are away, will reduce the ability of cold humid air to accumulate. 
  
  
• Turn on the bath fan when showering. During showers, keep the bathroom door closed and run the bathroom fan both during the shower and after for an extra 15 - 20 minutes.  When you close the door, you force the fan to draw air from a smaller source (i.e. the gap under your bathroom door) at a greater velocity resulting in better ventilation.  Bathroom doors should have a minimum of a ½” gap between the top of the floor finish and the bottom of the door.  You should also confirm that the air is being vented to the outside. 
  
  
• Attempt to reduce the times that you boil or steam water for cooking during the winter (colder) months and, if you are steaming or boiling food, open a window slightly or if you have a fan over the stove that vents to the exterior of the home, make certain it is running when cooking. 
  
  
• Open windows for a few minutes each day. Doing so will allow humid air to escape and drier air to replace it (especially after cooking or showers).  
  
  
• Acquire a temperature and humidity meter. This will allow you to gauge what the current humidity is in your home at any given time.  When the humidity remains above 70%, condensation is increased.
  
  
• Acquire a dehumidifier. Be certain that it has enough capacity to handle the air volume in your home (qualified retailers who sell dehumidifiers should be able help you define your capacity needs).

By performing the above action items consistently, homeowners who are currently experiencing condensation at their windows should be able to significantly reduce the challenge of excess moisture originating from the interior of the home.   

As always, if you have any questions regarding your home or building, our seasoned team of professionals is prepared to assist you with your questions and/or needs.  

Charter Construction has built and repaired buildings for 34 years.  Our Disaster Solutions and Reconstruction Team also provides emergency services for water, fire, and storm damage.  

Please contact our Team at 206-382-1900 in Seattle or 503-546-2600 in Portland.   Very Truly Yours,    

Eric Jackson   Vice President