Condensation on Windows – Causes & Solutions

Published April 19, 2022
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Window condensation is a common occurrence in many homes year-round. It is the natural process that occurs when warm air meets a cold surface such as window glass, and vice versa, releasing the moisture in the air as it is cooled to dew point temperature. While periodic condensation build-up isn’t harmful, frequent condensation can be an indication that your home’s humidity levels are too high or that a window seal has failed and requires replacement.

If left unattended, the excessive moisture produced by frequent window condensation can lead to rotting wood, mold, bacterial growth, insects such as termites, and higher energy costs. If you’ve noticed persistent window condensation in your home, call Lake Washington Windows and Doors to schedule a free in-home consultation. Our experts will be happy to advise you on the best way to keep your home safe and energy-efficient!

Is condensation on windows bad?

Condensation on windows can be both harmless and can cause problems. The answer to whether window condensation is causing any harm depends on the frequency and location where the condensation occurs. There are three parts of any window where condensation can accumulate including the outer window pane, inside pane, or between the two panes.

Exterior window condensation

Condensation that accumulates on the outside of your windows is not harmful and is actually a sign that your home is quite energy efficient.

Why am I getting condensation on the outside of my windows?

Exterior condensation occurs most frequently during summertime when outside temperatures are higher than the indoor air conditioning. As the warmer air outside touches the cold exterior surface temperature of the air-conditioned glass, the moisture in the air reaches its dew point, and condensation forms.

How can you prevent exterior window condensation?

If the condensation is outside the window, raising the temperature of your interior air conditioner will lower the temperature of the cold glass to match the outside temperature will make a huge difference. Another thing you can do is trim shrubbery away from house windows and doors. Plants produce a significant amount of condensation especially in the early morning and evening.

Interior window condensation

Condensation on the inside of your windows is also a sign of efficiency which commonly occurs during winter when outside temperatures are lower than the heated interior. However, frequent condensation can also indicate high humidity levels within your home that may need to be lowered. Moist air increases the likelihood of mold and the excess moisture caused by persistent condensation acts as still water where mold, bacteria, and pests can flourish. As that moisture builds, it can also cause the building materials of the window frame to rot.

Why am I getting condensation on the inside of my windows?

The natural reason for condensation forming on the innermost surface occurs as the interior temperature becomes higher than the outside temperature which is most common during winter. However, if interior condensation persists throughout the year, the likely cause is high humidity levels within the home due to poor ventilation.

How can you prevent condensation on interior windows?

If condensation accumulates on the interior panes, reducing your home’s humidity and increasing air circulation should solve the problem. You may consider installing a relative humidity meter which measures the relative humidity level in the air. Reducing excess humidity can be accomplished by installing portable or whole-home dehumidifiers and keeping your home heating system at a low constant temperature.

To increase air circulation, run kitchen and bathroom exhaust fans (especially at night), keep windows and interior doors open, and avoid draft-proofing kitchen and bathroom windows. Lagging cold pipes will also reduce surface condensation and improve a home’s insulation. Additionally, there are many other methods to reduce window condensation that can be implemented.

Condensation between window panes

Condensation between panes is usually a sign of a failed window seal that requires replacement. When a window seal fails, the insulating argon gas between the panes leaks out allowing moisture to enter. This reduces the efficiency of the window and the accumulation of moisture can lead to mold, bacteria, insects, and rot.

Why am I getting condensation between my window panes?

When the condensation accumulates between the panes, the primary cause is a failed window seal allowing moisture to seep through as the insulating argon gas leaks out, reducing the window’s efficiency.

How can you prevent condensation between window panes?

If the condensation forms between the inner and outer panes, the window will require professional attention. While there’s a possibility that the problem may be fixed without replacing the window, it’s most likely that replacement windows will be the most effective solution.

How do you stop condensation on windows overnight?

To prevent overnight condensation, there are some easy steps that can be taken.

  1. Opening windows at night will allow humid air to circulate while bringing cool fresh air inside.
  2. Keeping window curtains open will improve circulation and minimize condensation.
  3. If this is an issue due to outside lights, purchasing thinner curtains and keeping windows open will help.
  4. Leaving the bathroom fan, kitchen exhaust fan, and ceiling fans on overnight will help ensure your home is properly ventilated to reduce condensation build-up.
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Written by Lake Washington Windows

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