Clera Windows + Doors Blog

Is Condensation on Windows Bad?

Condensation on windows can happen during any season of the year and is a common problem faced by homeowners. The burning question remains: Is condensation on windows bad? Well, this largely depends on where you find condensation on windows. 

Is it condensation on the inside of windows, outside the windows, or in between the glass itself? By first establishing where exactly the window condensation forms, you are one step closer to identifying what causes condensation on windows in your home. 

As a spoiler, the only kind of condensation that you shouldn’t be worrying about is when it happens on the outside of the window. Why is condensation on windows bad, otherwise? Read on to learn more! 

Condensation on windows happening on the outside

What Causes Condensation on Windows? 

In essence, condensation on windows occurs when the humidity in the air comes into contact with a cold surface. Now let’s talk about how condensation on windows takes place, depending on where it forms. 

1. Condensation on the Outside of Windows

So what causes condensation on windows when the moisture is on the external side? Simple. This happens when the air outside your home is humid and is warmer than your window glass. 

Therefore, exterior condensation on windows typically happens during the summer—a season wherein homeowners have their windows shut and their ACs on. But why is condensation on windows good news in this scenario? 

External condensation on windows means that your windows are doing a good job at sealing and insulating your home. Here’s why:

  • The exterior humidity stays outside, which is why the condensation is formed outside.
  • The glass is insulating very well since it is colder than the outside, meaning it is not transferring outside heat so easily.
  • All in all, your AC doesn’t have to work extra hard because of your window’s ability to seal the home.

But apart from the good news mentioned above, we understand that you still want to wipe away external condensation to see the view outside. Wiping or cleaning is one way to get rid of external condensation on windows. The other way is to wait for the sun to point at the foggy window, as this would clear up the condensation as well.  

2. Condensation on the Inside of Windows

Condensation on windows is only bad when it’s on the interior side of the window or in between panes. So now, let’s discuss the first type of “bad” condensation on windows. 

But before we proceed, take note that condensation on the inside of windows is generally not worrisome if it is tied to the following events:

  • Steam coming from the shower;
  • Excess steam coming from the kitchen with the ventilation hood turned off;
  • Extensive use of a steam iron within a confined space; and
  • Other similar events. 

In the above cases, condensation on the inside of windows is normal. 

However, if condensation on windows forms on the interior side without any direct cause, it could mean that your home’s humidity is too high. Therefore, the moment that the glass becomes colder than your home’s temperature (e.g. during nighttime or winter), the home’s humid air will then form condensation as it touches the interior side of the glass. 

In the above scenario, the good news is that your windows are keeping your home sealed because internal humidity cannot get out. The bad news is there could be a problem with your home’s ventilation system

a man measuring old windows that are lined with mould

High internal humidity doesn’t just cause annoying condensation on windows, it can also lead to the following: 

  • The formation or proliferation of mould or mildew;
  • Symptoms such as respiratory irritation, skin irritation, and the like brought about by the increased presence of mould or mildew;
  • Excess moisture in the home’s air that contributes to the deterioration/swelling/rotting of wooden components as well as the corrosion of metallic components.

For further details on how to address this type of harmful condensation on windows, go to this section

3. Window Condensation Between Glass Panes

Why is condensation on windows bad if it appears between the double/triple panes? It means your insulated glass unit is no longer sealed

To further explain why condensation appears within an insulated glass unit (IGU), which is typically double-glazed or triple-glazed, we need to talk about the parts of an IGU.

As an example, if you have an IGU that is double-glazed, then that means it has the following:

  • Two parallel panes of glass
  • A platform where the panes of glass are set on
  • Air, argon, or krypton (to add further insulation between the glass)
  • A seal around the glass

A well-sealed IGU is able to insulate your home and save extra energy; moreover, the interior side of the IGU does not come into contact with outside air, at all. However, an IGU wherein the seal is broken means four things: 

  • The glass unit can no longer provide the full range of benefits;
  • The window could be leaking through the faulty IGU;
  • The insulating air, argon, or krypton is already lost; and
  • The outside air is able to come in contact with the IGU’s interior, causing window condensation between panes. 

What should be done when faced with this type of condensation on windows? Read the next section to find out! 

condensation on windows between the window panes of a double-glazed window

How Do You Prevent Condensation on the Inside of Windows or Between Panes?

Let’s talk about the next steps for the problematic types of window condensation, particularly condensation on the inside of windows and condensation between glass panes. 

What To Do About Condensation on the Inside of Windows

1. Get Your HVAC System Checked

Modern HVACs have humidifiers and dehumidifiers to keep the home comfortable. When this is defective or poorly setup, the result could be high humidity. To put a stop to condensation on windows on the internal side of the glass, have your HVAC settings or functions checked by a professional. 

2. Set Up a Dehumidifier

As for areas not connected to your HVAC (i.e. the basement, the attic), you can purchase a standalone dehumidifier for that area instead. Dehumidifiers work by taking the moisture out of the air. They can both help to maintain humidity levels at a balanced range and reduce the moisture within the home, thereby protecting properties against issues such as mould and mildew.

3. Improve Ventilation for Heated Devices

Appliances like ovens, dryers, and radiators require a ventilation system to mitigate the amount of heat and moisture they push into the home. Installing a high-functioning ventilation system for these appliances will drive warm air out and limit moisture retention within the home. 

4. Don’t Worry About Your Windows—But Open Them Once in a While

Are you worried about the state of your windows? Don’t be. The good news in this scenario is that the windows are sealed well enough to keep humidity in. Once the humidity issue is resolved, you’ll have added comfort in your home once again—sans the inside condensation on windows! 

What you can do with your windows is to open them once in a while. This helps balance the humidity levels inside the home. However, it’s important to only open windows when the external temperature and internal temperature are similar—so as to minimize the loss of heated or cooled air.

B. What to Do About Condensation Between Glass Panes in Your Double/Triple Glazed Window

As we’ve discussed in the previous section on what causes condensation on windows,  condensation between the window’s glass happens because of a leaky insulated glass unit. Therefore, when this happens, you essentially have two options:

1. Get the Insulated Glass Unit Replaced

As long as you can find a manufacturer who can replace the insulated glass unit of your current window, this is the quickest and easiest option. Opt for low-E glass coating when getting a replacement, as low-E coated IGUs give more insulation and lower the chances of condensation and fogging. 

2. Get the Entire Window Replaced

This could be the better option if you are seeing a widespread failure of IGUs from the same substandard manufacturer. It could be time for a change

Similar to the tip we gave when looking for replacement IGUs, it is best to keep an eye out for low-E coated windows to get better insulation, reduce UV damage on your interiors, and also minimize the occurrence of condensation. 

There are essentially two types of low-E coating available in the market: 

  • Hard coat – this coating option is highly suitable for cold conditions such as those found in Canada, as it offers a high level of protection while allowing some of the sun’s rays to enter the home to aid with heating. 
  • Soft coat – this type assures a low level of solar emission within your living environment. However, they are usually used within warmer environments as a way to keep hot air outside the property rather than keeping it inside.

A low-E coated glass that is unlikely to get condensation on windows

Durable, Energy-Efficient, and Stylish Windows For Your Home

In this article, we answered a very popular question asked by homeowners: is condensation on windows bad? Ultimately, condensation on windows is a sign that the window is sealing the house really well. However, condensation between glass panes means it’s time for a window replacement. If you’re in this situation, we’ve got you covered!

Clera Windows + Doors is one of the most trusted manufacturers in the fenestration industry with an excellent track record spanning 40+ years. If you would like us to transform your home with durable windows that you can count on, contact us today or schedule a FREE consultation.  

Comments

3 Comments

  • Avatar for Jacob L. - Oakville Jacob L. - Oakville says:

    This is really helpful. I was not even aware of the rating system. This makes sense though. At least I know now to get a higher temperature window. My house is sealed up pretty well, and I could not figure out why there was so much condensation around the bases. I’ll probably be investing in a dehumidifier, and I may need to replace some windows in the near future.

  • Avatar for Michael Lan Michael Lan says:

    Great post. Yes, its definitely about turning on the heater and keeping that heat inside the house. My new replacement windows in my Toronto home has energy saving benefits, but it’s also made the house quiet too!

  • Avatar for Greg Greg says:

    Great stuff! I hadn’t stopped to think about it before, but just because my house is insulated well does not mean I am not going to have moisture buildup. I think the last tip is a great one. Opening up the doors and windows for a bit does wonders at keeping the air dry.

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