Why is there condensation on the inside of your windows in the winter?

By Dan and Nick Cox:

Often during our Maryland winters, we get condensation on our windows.

Why? And is it a bad thing?

Well…the technical answer has to do with water vapor, the dewpoint, temperature, and humidity.

But the simple, non-technical reason that condensation often builds up on the interior of your windows is that as warm, humid air inside your home hits the colder surface of the windows, then turns into water droplets, otherwise known as condensation.

It’s the same idea as when the glass of your ice-cold drink drips all over the place on a hot, humid day.

Please keep in mind we’re only talking about condensation on the inside of the window. But it can also happen on the outside, and even between the panes of glass on double or triple pane windows, though usually for different reasons. 

So what are the biggest factors that cause interior window condensation?

Humidity of your indoor air.
There’s always some level of humidity in your home. Showers, bathrooms, and cooking,  heck, even breathing release moisture into the surrounding air. The more humidity plus cold outside temps equal more window condensation.

Lack of ventilation around the windows.
If there is reduced airflow directly in front of the window because something is blocking them such as drapes, blinds, plants, or furniture, then humidity will accumulate and possible increase condensation.

Is condensation a problem you should worry about?
Some condensation is actually pretty common, even on new windows. It doesn’t necessarily mean you need new replacement windows, but it also might. If yours are several years old, drafty, or rotted, then you might want to consider new windows.

The big problem occurs when you have excessive condensation over time because dangerous mold and mildew starts to build up, eventually rotting the wood, and even causing serious health concerns.

And it looks gross and very ugly.

So what can you do to reduce condensation on your windows?

• Use a dehumidifier in the winter to remove moisture in the air
• Direct moisture from your kitchen and bathroom to the outside by always using exhaust fans when cooking or showering
• Increase natural indoor airflow to the windows by raising blinds and shades, and moving furniture or plants that block the windows  
• Crack open a window for a little while
• Leave interior doors open as much as possible to circulate air

Do you have condensation, mold, or damaged window frames and think you need new windows?

Let us take a look, and we’ll give you an honest assessment about your existing window situation and your options.

The bottom line:

Reduce or remove moisture in the air, and circulate as much fresh air as possible.

It won’t necessarily prevent all condensation, but it’ll sure help reduce it.

If you have any questions, or want to schedule
your free, no-obligation window analysis,
call Dan or Nick at 301-368-3551!

On Top Home Improvements, Inc.
10818 Avonlea Ridge Place
Damascus, MD 20872
Tel: 301-368-3551
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