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Why Are My House Windows Fogging Up on the Outside? Causes and Solutions

| August 10, 2024

We’ve all been there at least once – asking ourselves, “Why are my house windows fogging up on the outside?” This issue is actually more common than you think! And, most of the time, there’s nothing wrong with the windows – it’s typically due to the glass surface temperature being lower than the air temperature. As easy as that! However, this can also be a nuisance. That’s why we’ve prepared some solutions that can help you create a favorable environment around your house that prevents exterior condensation.

Furthermore, sometimes condensation seems to be on the outside but is, in fact, between glass panes. In this case, you may be dealing with a broken window seal. Either way, keep reading to discover everything you need to know about exterior window condensation!

Key Takeaways

  • Exterior window condensation occurs when the outside temperature is higher than the window surface temperature and the humidity levels are increased. It’s not a sign of poor window quality but rather effective heat transfer prevention by the windows.
  • Factors like regional climate, landscaping, and water features can increase outdoor humidity and contribute to exterior window condensation. Although you cannot control climate, you can slightly influence the humidity levels around your house by implementing various strategies, like adjusting the sprinkle activation schedule or arranging vegetation accordingly.
  • Sometimes it looks like condensation is on the exterior, but it’s actually between glass panes. In this case, you may be dealing with a broken window seal.

What Causes External Window Condensation?

First things first, let’s clarify what window condensation is. Condensation is the reverse of vaporization. While vaporization means that an element transitions from the liquid phase to the vapor phase, condensation occurs when a state of matter moves from the gas phase into the liquid phase. Obviously, condensation usually refers to the water cycle.

Then, we have to discuss the dew point because it plays a crucial role in the formation of exterior condensation. The dew point indicates the temperature a certain body of air is cooled at in order to be saturated with water vapor. When this body of air is cooled below the dew point, dew forms. In other words, when warm air comes into contact with a colder surface, dew forms on that particular surface.

Furthermore, the dew point is influenced by humidity levels. If the air is dry, condensation doesn’t form as easily because the surfaces must be much cooler than the air. On the other hand, when the air is humid, the dew point is higher, so condensation occurs more quickly. It’s enough for the surfaces to be just a few degrees cooler than the air.

This process is similar to what happens when you take a cold drink out of the fridge on a hot day. The cold surface of the drink attracts the warm, moist air around it, leading to condensation. The same phenomenon is responsible for the air droplets we can see on the grass on a spring or summer morning.

And here’s the good news – condensation on the exterior glass pane is actually a good thing! The cold glass and the condensation that appears on it are indicators that your windows are well-insulated and highly energy-efficient.

When You’re Most Likely to Notice Fog on Your Windows

If you’ve noticed that your windows seem to get foggy mostly in the morning, you’re not alone. Homeowners are more likely to observe exterior window condensation early in the morning, especially after clear, cool nights with no winds.

As such, here are the things that can affect how and when dew appears:

  • high humidity
  • the glass surface temperature is lower than the air temperature (which is common in the morning)
  • calm weather
  • energy-efficient windows
  • absence of clouds

This is why you often wake up to foggy windows, even if they were clear the night before.

So, is there a way to fix foggy windows? Let’s see.

How to Fix Window Fog on the Exterior?

If condensation forms on the exterior of your windows just once in a while, the best thing we can recommend is letting the sun do its job. It will dry the surface, and the condensation will quickly disappear. You can also wipe the window with a soft cloth to remove the dew.

However, if this is a regular occurrence, it may, in time, become a nuisance, especially if you can’t easily access the exterior window glass pane. So, is there something you can do? Influencing the condensation that forms on the outside of your windows can be quite difficult. After all, it would imply altering humidity levels and air temperature. While you definitely can’t change the weather, you can resort to some measures that may lower humidity levels around your house. Keep reading to learn more!

Factors Contributing to Outside Air Moisture

While the quality and temperature of your windows play a significant role in external condensation, they are not the only factors to consider. The moisture content in the outside air can also greatly contribute to window fogging. For example,irrigation practices in areas of intense use can modify the regional climate by increasing precipitation, evapotranspiration, and soil moisture, contributing to higher outdoor humidity levels. This means that if you live in a region with extensive farmland, you might be more prone to condensation.

In addition to regional factors, the immediate surroundings of your home can also impact the buildup of moist air around your windows. For instance, inadequate ventilation, often caused by surrounding structures limiting airflow, can exacerbate this issue. This is why homes in densely built areas might experience more window condensation than those in more open spaces, where warm air can circulate more freely.

Landscaping, Surrounding Airflow, and Irrigation

Believe it or not, the way you landscape your yard can affect window condensation levels. Dense vegetation around a home can elevate moisture and humidity levels as plants contribute to higher local air humidity. So, if you have a lush, plant-filled garden next to your house, it might influence window condensation.

That’s not to say that you need to get rid of all your plants, though. The strategic positioning of trees and shrubs can positively affect airflow around windows, potentially channeling winds to reduce the heat load on a home and lower humidity levels. It’s also recommended to avoid planting shrubs and small trees immediately adjacent to your house. It’s important to allow the sun and wind to reach your home to dry it up.

If you have a sprinkler system or water features in your yard, they might be influencing the humidity levels around your home. You can try adjusting, let’s say, the sprinkler schedule to avoid high humidity levels in the morning. Similarly, if there are any bodies of water (lakes, rivers) located close to your house, they can be the cause of high local humidity levels.

Exterior Condensation: Is It on the Outside or Between Window Panes?

Let’s shift our focus to another common phenomenon – fogging between window panes. If you’ve ever noticed a hazy appearance on your windows that doesn’t seem to go away no matter how much you clean, it’s likely that your window is fogging between the panes. At first thought, you’d say that the condensation is on the outside glass surface. But if you run a finger on the inside and outside surfaces and it leaves no trace, the condensation is definitely between the glass panes.

To understand what causes condensation between panes, we must clarify how insulated glass units (IGUs) work.

When two glass panes are used for a window unit, they form an insulated glass unit. As such, double-paned windows are IGUs. These panes are, in turn, separated by spacers made from malleable materials that allow them to contract and expand with movement within the glass unit. Then, the space between the glass panes is filled with gas, usually argon or krypton gas, which insulates the environment.

Then, we have the seals, which basically seal the two glass panes together. Over time, these seals fail. If the window has two seals, the second one may hold for a while if the first breaks – but not indefinitely. This leads to moisture buildup between panes.

In this case, moisture can enter the space between the panes from both the inside and the outside.

What Can You Do?

Naturally, cleaning the condensation that forms between glass panes is impossible. Leaving it there is also not a solution. Condensation between glass panes is an indicator that your windows aren’t performing at their best, and their condition will only worsen over time.

So, what can you do if you’re dealing with condensation between window panes? It’s generally recommended to seek professional advice. An expert will assess your window’s condition and inform you if it’s possible to replace the seal or if you need window replacement.

Windows Fogging on the Inside

We’ve covered a lot about exterior window condensation and fogging between panes – the former indicates your windows are performing at their best, while the latter is probably a sign that the seal is broken. But what about the condensation that appears on the inside glass surface? Does it have anything to do with exterior glass condensation? Not really. In this case, the cause is interior air humidity.

Humid indoor air can be caused by general climate conditions. For example, while Ontario winters are rather dry, the summers are quite humid, so naturally indoor humidity levels will be higher during the summer. Furthermore, indoor humidity levels are affected by:

  • poor ventilation, which can cause problems when you shower or cook, for example
  • a lot of indoor plants
  • poorly insulated windows and doors
  • leaks

While condensation that forms on the interior glass surface isn’t a problem, moisture can eventually damage your property and affect your health. Therefore, it’s recommended to reduce indoor humidity by using dehumidifiers and proper air conditioning systems, as well as checking for leaks. You can also use kitchen and bathroom exhaust fans to remove excess moisture.

Get the Best Replacement Windows in Ontario with Magic!

If your windows have exceeded their lifespan and show signs of wear and tear, it might be time to replace them. Luckily, Magic’s got the best replacement windows in Ontario that will last more than 40 years!

Our windows feature the most technologically advanced systems:

  • the patented Parallex Hardware that makes our windows and patio doors completely maintenance-free because they lack cranks and hinges.
  • the advanced Hybrid Fusion Frame technology, which is a combination of vinyl, aluminum, and steel that makes the frame highly durable and energy-efficient.
  • the unique retractable screens, shades, and blinds that improve our units’ energy efficiency and guarantee convenience and privacy.

We also provide expert installation services that ensure perfect insulation and ease of operation.

In addition, if exterior condensation forms regularly in your area, you’ll definitely be happy to have Magic windows! Why so? Because their exterior glass panes are much easier to clean compared to other products on the market! Our revolutionary opening mechanisms guarantee access to both glass panes from the inside. So, even if exterior condensation forms, you can easily wipe it out from the inside!

Summary

Windows usually fog up on the outside due to high outdoor humidity levels. Well-insulated windows are more prone to exterior condensation, which is a sign they’re doing their job! Sometimes, you may think you have exterior condensation, but it’s actually between glass panes. In this case, you may be dealing with a broken window seal. If the condensation is on the interior glass surface, you have to address indoor humidity levels. You can use dehumidifiers to reduce window condensation.

In addition, if your windows are quite old, they may play a role in the amount of condensation that forms. If you are looking for an expert to assess their condition and advise you whether it’s time to replace them, contact Magic for a free, in-home consultation!

Frequently Asked Questions

Why do my windows fog up on the outside?

Your windows fog up on the outside because the glass is cooler than the moist air outside.

What causes condensation between window panes?

Condensation between window panes is typically caused by a failed window seal. This allows moisture to enter the space between the glass layers.

How can I reduce condensation on the inside of my windows?

To reduce condensation on the inside of your windows, make sure to maintain proper ventilation, control indoor humidity levels, and ensure your windows are of good quality and properly sealed.

Do energy-efficient windows help reduce condensation?

Energy-efficient windows can help reduce window condensation because they keep the interior glass surface at an adequate temperature. However, highly energy-efficient windows are more prone to exterior condensation, which is a sign that they are properly insulated.

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