Condensation is quite a normal thing.


Usually, it occurs in winter, and it's caused by humidity in your home.Humidity comes from everyday activities like cooking, bathing, and doing laundry. Even breathing increases humidity so, there's no getting 'round it.


Humid air + cool glass = condensation

When your home's warm, humid air meets the cool glass of a winter window, the warm air is cooled. And cool air can't hold as much moisture as warm air that's basic physics.

So where does the moisture go? It turns to water and clings to the glass. Voila, condensation.


Weather-tightness and interior humidity

Replacing old windows with energy-efficient Wallside Windows typically makes a home more snug and weather-tight a good thing! But the more snug the home, the more easily humidity can build up inside.

So, condensation is normal... but, it's not so desirable. Who wants a window with an obscured view?


Simple steps can make a difference

There are many things you can do to reduce the humidity in your home.

Sometimes it's as simple as opening a window briefly to release humidity from a room, or running the bathroom exhaust fan during and after a shower. Other steps involve more permanent and substantial fixes.


Monitor your home's humidity levels

An inexpensive humidity gauge from the hardware store can help you monitor humidity in your home. Below are suggested ideal humidity levels, based on an indoor temperature of 70 degrees Fahrenheit.

Outside Air Temp.Inside Relative Humidity
-20 F15-20%
-10 F20-25%
0 F25-30%
10 F30-35%
20 F35-40%

When it's colder outside, regulate for a lower relative humidity inside, in order to minimize condensation. (Relative humidity is a percentage of the total moisture air can hold at a given temperature.)



Reducing Condensation

  • Vent your clothes dryer, exhaust fans and gas appliances to the outside.
  • Leave exhaust fans in your bathrooms and kitchen running for 10-15 minutes after bathing or cooking. (Running them constantly can be a fire hazard.)
  • Turn off humidifiers, including the one on your furnace.
  • Circulate fresh air in your home, and increase air's movement over window surfaces, with portable or ceiling fans.
  • Cover bare earth in a crawl space with a vapor barrier.
  • Open your fireplace damper to let moist air escape.
  • Make sure your attic and crawl space are ventilated well and the vents are open.
  • Air out your home briefly when necessary.
  • Cover aquariums and consider restricting houseplants to limited areas.
  • Wrap sweating pipes with pipe insulation to soak up the moisture.
  • Do laundry in the morning or evening, when the house is cooler.
  • Open window shades and drapes to allow a room's warm air to circulate over the window glass.
  • Invite a heating and cooling expert to your home for an analysis.