Condensation in Your Home? Don’t Blame Windows

Written by Roone Unger of EXOVATIONS
Updated October 13, 2015
Windows sit with blinds partially open inside.
Windows are the place where moisture is most visible, not a condensation source.
Photo courtesy of Bill Myrick

When you see condensation on the glass, it’s natural to blame the windows in your home. But it's not that simple. A pro explains how to discover the real cause.

“Why are my new replacement windows getting condensation on the inside of the glass?”

This is a common question from homeowners in general. Sometimes homeowners may consider replacing their windows in an effort to cure this problem.

To tackle this question, it helps to determine what causes window condensation.

A matter of extremes

Condensation is visible evidence of moisture in the air. It may appear as water, frost or ice on the surface of windows and doors. This occurs more frequently during the winter months because of the extreme differences between inside and outside air temperatures.

The warmer the air, the more water it can hold. This means the air in the center of a room will hold more water than air in cooler areas of your house, near the doors and windows.

When the warm, moisture-laden air moves toward a cooler window or door wall, it cools down and it can no longer hold the moisture it held when it was warmer. This moisture appears as water on the glass and frames of windows and doors.

The causes

Windows do not cause condensation; they just happen to be the place where moisture is most visible. Condensation is a sign of excess moisture in the home. This can be caused by temporary factors or more long-term conditions.

Temporary

New construction or remodeling: Building materials contain lots of moisture. As soon as the heat is turned on, this moisture will enter the air and settle on door and window glass. This usually will disappear following the first heating season.

Humid summers: During humid summers, houses absorb moisture. This will be apparent during the first few weeks of heating and then should dry out.

Temperature change: Sharp, quick and sudden drops in temperature, especially during the heating season, will create temporary condensation problems.

More permanent conditions

Poor ventilation: Insufficient attic or soffit ventilation can trap moisture in the home. Having sufficient ventilation will allow moisture and humidity to escape.

Excessive humidity: This can be caused by poor ventilation, but also can be a result of an unbalanced heating and air system or a need to add additional ventilation, such as bathroom or kitchen exhaust vents.

Related: Is poor attic ventilation damaging your roof?

Tips to reduce indoor moisture

Controlled ventilation and elimination of excessive indoor moisture can keep humidity within bounds. Here are some suggestions to help reduce indoor moisture:

•  Turn off or set back furnace humidifiers until sweating (condensation) stops. Remove pots of water on radiators or kerosene heaters.

•  Use exhaust fans or open windows slightly in the kitchen, bathroom and laundry room during periods of high moisture production, such as when cooking, taking showers or washing and drying clothes. Clothes driers must be vented outside. Do not hang clothes to dry indoors.

•  Keep the basement as dry as possible by waterproofing floors and walls.

•  Make sure attic vents are unobstructed.

•  Place all houseplants in one sunny room where the door can be kept shut. Avoid overwatering.

•  Opening windows slightly for a brief period of time will allow humid air to escape and drier air to enter.

•  Use a dehumidifier, properly sized, to reduce the humidity in the house.

Related: Improper attic ventilation can mean higher energy bills.

Taking control of the problem

Excessive indoor humidity and moisture are not the result of your new windows. You should consider the amount and severity of window condensation as a sign that moisture damage may be taking place inside the walls or ceiling cavities of your home. This can lead to rotting wood, deteriorating insulation and blistering exterior paint.

A version of this article previously appeared on BuildDirect.com.

About this Experts Contributor: Roone Unger is the founder and CEO of EXOVATIONS and Total Exterior Franchise Systems, providing home exterior remodeling services in Cumming and Atlanta, Georgia.  Follow this contributor on Twitter and Google+.

As of January 9, 2015, this service provider was highly rated on Angie's List. Ratings are subject to change based on consumer feedback, so check Angie's List for the most up-to-date reviews. The views expressed by this author do not necessarily reflect those of Angie's List.