Condensation Between Window Panes: Causes, Solutions, and Prevention

Insulated Glass Units (IGUs) are a cornerstone of modern window design, offering enhanced energy efficiency and durability compared to single-pane windows. However, even the most energy-efficient double-pane windows can develop issues over time, one of them being condensation between window panes.

If you have foggy windows and you can’t just wipe down the condensation, it’s likely that your windows’ insulating capabilities are slowly degrading. While condensation between panes seems like just an aesthetic nuisance initially, it needs to be addressed as soon as possible because it can cause damage to your windows and surrounding structures.

As such, if you want to learn more about the causes of condensation between panes and how to address this issue, keep reading! We’ll start by sharing some basic details about Insulated Glass Units, which are important for understanding condensation between window panes.

Key Takeaways

• Structure of IGUs: IGUs include multiple glass panes, spacers, desiccants, seals, and inert gas, working together to improve insulation and reduce energy loss.
• Causes of condensation between window panes: Seal failure, desiccant saturation, and thermal pumping can cause condensation between panes, compromising insulation and causing fogging.
• Solutions: Addressing condensation between panes often requires replacing the IGU or the window. Temporary fixes, like defogging services, can improve appearance but may not restore full functionality.
• Prevention: Investing in high-quality windows, proper installation, and regular maintenance can help prevent future condensation and improve your house’s energy efficiency.

What Is An Insulated Glass Unit?

Before discussing more about the causes of condensation between glass panes, let’s clarify what an Insulated Glass Unit is and what it consists of – these details will make things so much clearer when it comes to condensation.

A window has three main components – the frame, the sash, and the glass. In the past, windows had only one layer of glass. Although some homes still have single-pane windows, they are not energy-efficient, and many homeowners choose to upgrade to double-pane windows.

Therefore, when two or more layers of glass are incorporated into a window, they become an Insulated Glass Unit (IGU). An IGU does not consist only of glass panes. It also has:

• Warm-edge spacers, which keep the glass panes apart
• A desiccant, like silica pellets, that absorbs the moisture between the panes
• A seal that prevents moisture and air to seep into the IGU
• The space between the panes is usually filled with insulating inert gas or air.

All these components work together to transform the window into a strong barrier that separates the interior of your home from the harsh exterior weather, preventing too much heat loss and heat gain.

When condensation appears on the interior glass pane and you can wipe it down, it is linked to warm air indoors, as well as high indoor air humidity. Sometimes, condensation on the interior glass surface may indicate that the IGU does not insulate well. Conversely, exterior window condensation is associated with outdoor humidity levels and temperature differences between the air and the glass surface – this is not linked to poor IGU performance; if anything, exterior condensation indicates that the IGU is energy-efficient.

But what exactly goes wrong within an IGU when you notice condensation between the glass panes? Let’s find out!

What Causes Window Condensation Between Panes?

Condensation between two panes of glass usually appears when the seal fails. However, there are other factors that contribute to this. Let’s discuss each in detail.

Seals Are Not Completely Airtight

No matter how well a double-paned window is manufactured, seals have a finite level of impermeability. Over time, a small amount of moisture can seep into the space between the panes, which sometimes is an unavoidable physical phenomenon, even in well-constructed windows. This is why desiccants are added into IGUs – they absorb this minimal moisture, maintain a dry airspace, and prevent condensation.

Additionally, manufacturing imperfections or minor defects in the seal can allow tiny amounts of moisture to enter the window. While these imperfections may not cause immediate failure, desiccants yet again save the day, serving as a backup mechanism to address any moisture that does make its way into the airspace.

Desiccant Saturation

Desiccants like silica pellets are absorbent materials designed to maintain dryness within the airspace of double-pane windows by absorbing any moisture that enters that space. Without this silica desiccant, moisture could easily condense on the glass as temperatures drop below the dew point, leading to unsightly fogging or water droplets.

However, as the seal protecting this space degrades over time, the amount of moisture-laden air entering the window increases. Eventually, the silica becomes saturated, and the desiccant can no longer prevent window condensation, causing the window to appear foggy. At this point, the window is already considered to have failed and needs to be repaired or replaced.

Thermal Pumping

One of the reasons why window seals fail is linked to a process known as thermal pumping. Despite their seemingly stable appearance, your windows undergo a daily cycle of expansion and contraction due to temperature fluctuations. This repetitive motion from hot to cold creates continuous pressure fluctuations that stress the seal over time. Windows on the sunny side of the house experience these temperature fluctuations more often than shaded windows.

As the seal weakens, tiny fractures form. Gradually, they grow larger, allowing increasing amounts of air to seep through the cracks. In the case of windows that use argon gas for improved insulation, this process also results in the gradual loss of the gas, further reducing the window’s energy efficiency.

Window Frame Material

While the quality of the components added into an IGU and its manufacturing process are undoubtedly important, the frame material also plays a role in how quickly a window fails and condensation appears between glass panes.

For example, vinyl frames, while affordable and energy-efficient, have a higher coefficient of thermal expansion compared to materials like aluminum or wood. This causes greater long-term stress on the double-pane assembly, leading to a higher failure rate.

What Windows Are More Prone to Seal Failure?

In a nutshell, the windows mentioned below are more prone to seal failure and window condensation between panes:

• Windows that come with seals with minor imperfections.
• Windows that are on the sunny side of the house.
• Windows that are often exposed to high humidity both indoors (from cooking, showering, or drying clothes, for example) and outdoors.
• Windows made of vinyl frames.
• Windows made of poor quality insulating materials.
• Old windows.
• Windows in regions with extreme temperature fluctuations.

Impact of Condensation Between Glass Panes

Window condensation that forms between the glass panes is basically water trapped within the IGU. If there’s enough condensation within that IGU, the water droplets may run down the inside of the glass and accumulate at the bottom of the IGU. These water droplets can also carve grooves into the glass surface – a process called riverbedding that permanently damages the glass surface. Water droplets can also cause corrosion to metal components.

Additionally, once the silica pellets become saturated, they get eroded by the air currents and accumulate on the glass surface, looking like tiny snowflakes.

Furthermore, the moisture that accumulates between the window panes may sometimes seep through the damaged areas, affecting the frame.

Last but not least, the more air enters the space between the glass panes, the more insulating gas escapes that space, which significantly reduces a window’s energy efficiency and insulating capabilities.

How to Remove Window Condensation Between Panes

When you notice condensation between panes, the best solution is to replace the IGU or the entire window. There are indeed some short-term solutions you can rely on, but they do not actually address the problem. To actually address this issue without replacing the window, you would have to replace the seal, which is extremely complicated and often as time-consuming and expensive as replacing the IGU.

Nonetheless, if replacing the IGU is not an option at the moment, you can definitely rely on some short-term solutions to prevent further damage to the window.

For example, if indoor humidity levels are high, you can use a dehumidifier. You can also use exhaust fans and open windows regularly to let the air circulate. If outdoor humidity levels are high, you can try reducing the vegetation around your double-pane windows, although this likely won’t help too much if the air in your region is generally humid.

Here are some other solutions to consider!

Check Your Window Warranty

Before addressing the issue yourself, check if your window is still under warranty. Magic double-pane windows, for example, have a 40-year warranty that covers the IGU. If the seal fails, Magic will cover all the costs for the defective parts and labour.

Defogging Professional Solutions

You may have stumbled upon professionals offering defogging solutions for condensation between panes. Basically, they drill a hole into the window from the outside, spray a cleaning solution into the air chamber and suck the trapped moisture out using a vacuum. Then, they insert a defogger device into the hole that releases the moisture that has accumulated during thermal pumping.

This does indeed sound like a good option, but not all window specialists approve of this solution because it does not repair the window. Instead, it simply removes the symptoms of a failed window. The failed seal is not repaired in this procedure, and the window’s insulation is still compromised.

Nonetheless, you can definitely try defogging your double-pane windows if you can’t replace the IGU at the moment. Plus, defogging also serves as a cosmetic improvement and can reduce the potential damage caused by moisture accumulation.

Replacing the IGU or the Entire Window

Replacing the IGU or the entire window is the most effective solution for severely compromised window seals. Replacing the IGU is undoubtedly more cost-effective than replacing the entire window unit. However, if the window is quite old or approaching the end of its lifespan, it’s worth considering investing in new window units.

Preventing Future Condensation Issues

Preventing future window condensation issues requires proactive measures and careful planning. Here are some tips in this regard:

• If you’re planning to replace your windows, choose high-quality ones. They are undoubtedly more expensive, but they will also last longer and successfully withstand temperature fluctuations without having their seals broken.
• If you live in a region like Ontario with harsh weather conditions, it’s best to go for ENERGY STAR-certified windows, which have passed rigorous tests to confirm their high-quality and insulating capabilities.
• Choose a reputable window company that provides professional installation services. Although the window quality is extremely important, installation is just as crucial. If the window is not installed and insulated properly, even the most energy-efficient unit will fail sooner rather than later.
• Check the window warranty for the seal. Magic windows, for example, come with a 40-year warranty that covers a broken window seal.
• Once you’ve installed your new windows, make sure to clean and inspect them regularly. Sometimes, there may be window condensation between panes, but it is only minimally visible, especially on windows always in the shade. If you inspect the windows thoroughly once in a while, you may catch problems early.

Looking for High-Quality Windows? Get Magic IGUs!

If you want to replace your windows with energy-efficient double-pane windows that won’t fail for 40 years or more, you should undoubtedly consider Magic units!

Magic windows and doors are manufactured precisely for homes in Ontario. They are designed to withstand extreme temperature fluctuations without experiencing broken seals, air drafts, water leaks, or any other issues.

We use the best-performing warm-edge spacers within our IGUs. Plus, the space filled with gas within our double-pane windows is larger than in other windows on the market, allowing us to add approximately 25% more inert gas. This translates into superior energy efficiency.

Additionally, our window frames – although having a vinyl wrapping – are manufactured with an aluminum-steel skeleton, which prevents the vinyl exterior from warping and cracking under extreme temperature fluctuations.

Curious to discover more revolutionary window features? Book a free consultation with us and see the Magic for yourself!

Frequently Asked Questions

Why are my windows fogging up between panes?

Condensation between panes is primarily caused by seal failure, which, in turn, can be caused by temperature fluctuations or manufacturing errors.

How do you get rid of condensation between window panes?

If you notice condensation between window panes, you can try reducing indoor humidity levels , address the issue with “defogging” professional services, or repair the broken seal. However, the best solution is to replace the glass panes or the entire window if it’s old.

Does condensation on windows mean poor insulation?

Interior window condensation is usually linked to moist, warm air landing on the colder glass surface, although it can sometimes indicate that the window doesn’t insulate well, and is more common with single-pane windows. Exterior window condensation indicates that the window is well-insulated. Conversely, condensation between panes indicates that the window seal is broken and its insulation capabilities are slowly degrading.

How can I tell if my window seals have failed?

You can determine if your window seals have failed by observing signs such as fogging between the panes, a milky appearance inside the window, and persistent condensation that doesn’t clear up with home remedies.

Is it better to handle condensation issues myself or call a professional?

For minor condensation issues on interior or exterior glass surfaces, DIY methods are often sufficient, but persistent or severe problems, especially between panes, should be handled by a professional to ensure effective long-term solutions.