Question

How do you stop windows from getting condensation?

Asked by Sharon
Flemington, NJ

Our windows have condensation during the cold months and there seems to be too much humidity in the house. We have even tried opening the windows a little but still get the condensation. How do you stop it, or is it the windows themselve?

Answer

Michael Holcomb

Answered by Michael Holcomb

Byron Center, MI

Alliance for Environmental Sustainability (Headquarters)

November 12, 2012

Moisture control is the key to reducing/eliminating window condensation.

  • Almost all new construction, in cold weather states, experiences some window condensation in the first year because moisture in new paint, lumber and concrete must evaporate as these components cure.
  • In older homes the moisture is introduced by the occupants.
  • Even the finest replacement window on the market will not eliminate condensation if you don't reduce moisture in the air.

Sweating is normal

The average family of four produces 8 - 12 quarts of moisture daily through cooking, cleaning, perspiration, respiration, plants and pets.

Tightly constructed homes without mechanical may build up moisture levels that are high enough to condense when warm interior air contacts colder surfaces. Windows are normally the coldest component in the thermal envelop so sweating in colder weather is normal when humidity levels are high.

Moisture reduction

Reduce moisture in interior air by:

  • running a dehumidifier and bathroom and kitchen exhaust vents for longer periods of time after showering or cooking.
  • Bathroom exhaust vents should be controlled by a timer or humidistat that allows for longer run times for greater moisture removal.

Turn off a furnace humidifier

Older homes used to have humidifiers installed on HVAC systems to provide needed moisture during cold weather months. Moisture was needed because older houses leaked so badly that they dried out too much in winter months. As home construction tightened up over the decades the need for additional humidification decreased.

If you have a furnace humidifier you should turn it off.

  • Whole house humidification is used when the interior humidity level drops due to excessive air changes with the outdoors.
  • If your home leaks excessively causing the air to dry out in the winter you should hire a contractor to seal your home to stop the air leaks, reduce energy loss and improve comfort levels in the home.

Folks that have medical reasons requiring additional humidification should invest in a room humidifier which can be easily controlled and properly cleaned weekly.

 

For more information:

Read "What can we do about condensation on our windows during the winter?" a Q&A answered by Danny Kelly.

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