7 Stop Ice Build Up on Windows

It is cold. So cold in fact that I am sitting on the couch, with a blanket on my legs and a scarf around my neck. It is so cold that there is ice forming on the inside of all our windows and doors. Yes, on the INSIDE. If anyone wants to know where all the glaciers have gone they are on the bottom of my windows.

When we first discovered this last week we thought all of our windows and doors would need replacing. Surely ice on in the inside must be a sign of leaks and crap windows right?  Turns out it is actually the opposite of what we thought. Ice and water build up inside your windows and glass doors typically occurs in houses that are air tight. The house does not vent on its own causing condensation to build up on the windows. It has gotten so bad for us that days have gone by where we were not able to see out a single window unless we wiped it first.

Got more ice on your windows than you do in your drink?  Follow these tips to correct the problem, prevent recurrence and ensure you do not develop mold.

Check your humidity settings
You need to adjust it with each season to ensure your house is at the proper humidity for the temperature outside.  Here is a good rule of thumb (in F) based on engineering studies and an average house temperature of 70F/21C:

Ours was still set for summer temperatures so I lowered it from 40% to 25%. This by far has had the largest impact on the reduction of condensate and ice build up. After a few days of making the adjustment I can open the windows in the morning and see outside rather than just seeing foggy windows.

Open your window treatments  
Yes this goes against everything we know about energy efficiency. We have been told to keep our curtains and blinds closed to keep the heat (or cold) in. The problem is that by keeping them closed when the outside temperatures dip to the point that you have polar bears camping out on your lawn, you are blocking airflow around your windows. When the airflow is blocked you are going to get buildup of condensation on the windows which will freeze to form ice.

I opened all of our window treatments as soon as I got up and within a few hours all the windows were completely clear of ice and fog. I closed them again when the sun went down to keep some of that heat inside at night.

Ice build up on window when I first got up in the morning.

Just a few hours later after opening the window treatments

Soak up the condensate
If the condensate that builds up while you have the window treatments closed gets soaked up by a towel then it will never have the chance to turn into ice. Now that doesn't mean that the towel won't freeze, it just means it will be easier to remove than having the entire window covered in ice. Place rolled up towels on the window sill but not touching the window glass. This will allow for proper air flow while also absorbing any water that may collect at the bottom of the window. When you open the window treatments in the morning use the towel to wipe up and excess water and then hang it to dry. 

Now if you are like me and you opened your curtains one day to let some additional light in and found not just ice and water but mold and mildew then you need to ensure you remove it safely with natural products

Have you ever had ice build up on your windows? What did you do to correct it?

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Humidity chart via Kohles and Bach


  1. This is awesome! How did I never know this before. Thank you! With this crazy cold weather, we have been having quite a bit of ice build up.

  2. Great to know about opening window treatments! Much prefer being able to see outdoors especially in the winter! Cheers!

  3. I never heard of this phenomena! But, air tight homes are not good...I grew up in an area where radon was an issue so we were always told to keep a window open a crack. Thanks for sharing!

  4. Thank goodness it hasn't been very cold here but I'll keep this all in mind for when (and if) the temperatures drop - thanks!

  5. My windowd only get condensation where sashes lock and somedtimes on the bottom but not on every window in the house.

  6. Thank you for this info! We have been having this problem for weeks now! We have a central humidifier, I checked it and it was still set on the 40s, so I set it lesser than 20(?)! Our current Outdoor temperature is -35C and there's ice build up on ALL our windows!!! I opened All our blinds and turned on our ventilation!!! Hoping to see results!!! *crossing my fingers*

  7. Jen and Joey -- it looks like you have the same windows we do. Does the manufacturer's name begin with a "P". We do not have window treatments and we have a whole house ventilation unit that operates throughout the winter and does not go below 25%. Condensation is always present as well as ice and mold grows on the sashes. I think it is absurd to mop up all the condensation every day. Water puddles heavily on the inside sill and it would take at least an hour and several towels as we have over 30 windows, some twenty feet high. Any other suggestions?