How To Clean Double Pane Windows

Picture this; it’s a bright, sunny day, making it a perfect opportunity to throw open your curtains and let some natural light into your home. As you do, you’re not greeted by the beautiful outdoors. Instead, all you see is fog created by trapped condensation. Immediately, how to clean double pane windows is the only thing on your mind.

Cleaning the exterior of a double pane window is straightforward, often requiring no more than vinegar mixture and a cloth. Cleaning inside double pane windows is trickier. Drilling into the glass might be necessary, though dehumidifiers nearby or desiccant along leaks in the seal may do the trick.

Otherwise, you may have to take more drastic measures, like replacing the panes. If you want to try and avoid that, here’s what you need to know about how to clean double pane windows.

How To Clean Double Pane Windows

What Is a Double Pane Window?

Before digging into how to clean double pane windows, it’s crucial to understand why it’s challenging. Also known as dual pane windows, double pane windows feature two sheets of glass within the frame.

There’s a small gap between the two panes filled with air or argon gas, depending on the type of window. The reason the gap is present is it provides a stronger temperature barrier. That way, heat during the summer and cold in the winter don’t easily alter the temperature inside your house.

Both of the window panes sit in a frame together. Along the exterior edges, a seal maintains the integrity of the air gap between the panes. Additionally, it helps prevent condensation from developing between the sheets of glass and prevents dirt, pollen, small insects, and more from getting into that space.

How Double Pane Windows Work

How Double Pane Windows Work

As the name suggests, double pane windows have two sheets of glass. Both pieces of glass are held in one frame together. Along the outside edges, there’s a sealant, preventing any air transfer between the panes while keeping undesirable materials out of the interior of the window.

Double pane windows work by creating a better barrier between your home and outside elements. The layer of air or gas between the two panes makes it harder for heat or cold to transfer between your house and the outside. Plus, there’s an extra layer of actual glass, making the barrier even thicker.

Why Double Pane Windows Get Foggy

Why Double Pane Windows Get Foggy

Double pane windows get foggy when condensation builds up in the air gap between the two sheets of glass. Usually, this occurs when one of the seals around the glass panes is damaged, falls off, or is removed. When that happens, moisture can get inside the panes, making them appear foggy.

In some cases, other materials may also get between the panes once the seal is damaged. Pollen and dirt may travel in with the moisture. If it gets on the panes, it may lead to smudging and streaking inside the window.

At times, even small bugs may work their way between the panes. If this happens, they may create smears on the glass, too, causing them to look a bit hazy.

What Causes Window Seals to Break?

Window seals can break for several reasons. Over time, changing temperatures outside can potentially compromise the seals. When sunlight hits the exterior pane or temperatures rise enough, the glass expands. When that happens, pressure is put on the seal. Then, when the temperature falls at night, the glass contracts, shifting the seal again.

As time passes, that expanding and contracting can essentially loosen the seal. In some cases, the seal won’t remain bonded to the glass, leading to a failure. Once that happens, moisture, dirt, and more can end up between the panes.

In some cases, improper cleaning may damage a seal. Aggressive cleanser or strong pressure – either manually or from a spray washer – may lift the edges of the seal. If the edges go up far enough, a seal failure occurs.

Seals also simply wear out with time. If the material dries out, it’s less flexible. As a result, they may crack instead of flex in response to temperature changes or other shifts in conditions, even if they aren’t dramatic.

Mold and moss may harm seals, too. Along with trapping moisture against the seal, they may physically push up or under the material, compromising the integrity of the seal.

How to Clean Double Pane Windows

When you need to clean double pane windows, using the proper approach is essential. When you’re dealing with the exterior, you usually want a streak-free finish, but you also need to ensure you don’t damage any seals along the way.

If you’re trying to clean the inside of double pane windows, it’s a far harder and riskier task. However, that doesn’t mean it can’t be done.

Cleaning the Outside of Double Pane Windows

Cleaning Windows Outside

1. Create a Vinegar Cleaning Mixture

While traditional glass cleaners might seem like a good idea, they may contain ammonia or alcohol. Along with potentially leaving streaks, some chemicals may dry out the seals, causing them to fail sooner.

As a result, you may want to go with a vinegar window cleaning solution. Put ½ cup of white vinegar in a standard, clean spray bottle. Next, add ½ teaspoon of liquid ammonia-free dish soap. Then, add two cups of distilled water. Put the lid on and shake to combine.

2. Wipe Window with a Clean Microfiber Cloth

Before spraying any cleaner on the window, wipe it down with a clean microfiber cloth. That way, you remove any loose dust before you get started. Plus, it’ll help you see where any stuck-on grime is positioned, allowing you to focus your efforts there if necessary.

3. Spray the Window with Cleaner

Carefully spray the window with cleaner. You want to create a light mist across the surface, not cause drips that run down to the seal, so use a soft touch.

If the window is larger and particularly dirty, you may want to work in sections. That way, you can prevent trips along the way and make the most of the cleaner before it starts to dry out, something that can happen quickly, particularly in drier climates.

4. Clean the Window with a Clean Microfiber Cloth

After spraying the window, use another clean microfiber cloth to wipe it down. Apply steady, gentle pressure. While residential window glass is reasonably tough, pushing too hard could lead to flexing, potentially causing it to crack or shatter.

You’ll want to wipe with a bit of speed, too. If you move fairly quickly, you shouldn’t see any streaks along the way. However, if you do, you may be able to wipe them away with a dry section of the microfiber cloth.

If you end up with a stubborn spot, respray that area and wipe it again. Usually, you can repeat this as often as necessary until any marks on the outside of the glass are gone.

If you’re dealing with a large window, you can use a vehicle sponge or squeegee to do the cleaning. Just make sure they’re lightly damp before you begin to limit drips and streaking.

Cleaning the Inside of Double Pane Windows

Cleaning Double Pane Windows Inside

In most cases, trying to clean the inside of double pane windows isn’t a wise idea. If there is moisture, fogging, or streaking on the interior, there’s a seal failure. Since the integrity of the window is compromised, it’s best to work with a window repair or replacement professional. That way, the underlying issue is addressed quickly and safely.

However, if you want to try and handle the problem, you have options. Each comes with its own risks. Additionally, one creates small glass shards that can be harmful and may cause the window to break completely, making it particularly dangerous.

Using a Dehumidifier and Desiccant to Remove Moisture

If the only issue you’re seeing is condensation inside the window, reducing the humidity in the area near the window may handle the problem, at least temporarily. You can place a dehumidifier near the window, allowing it to remove moisture from the air. In time, this will dry out the condensation, clearing any fogginess.

Trying Desiccant to Remove Moisture

In some cases, desiccants will also work. For that, you may need to place it near a broken seal. If you’re unsure where the seal is damaged or isn’t broken in a spot where you can place desiccant, this approach may not work.

There are desiccant containers designed to remove moisture from larger areas, like closets. However, even smaller packets – like what you find when purchasing shoes – may help. Just be aware that desiccant is incredibly harmful if swallowed. Don’t leave it lying around if there’s a chance it’ll be consumed by anyone, including small children, pets, and more.

Drilling Holes to Promote Airflow

As a last resort, you could potentially drill holes in the glass. With this, you’re promoting better airflow, reducing the odds that moisture will build up on the panes.

It’s important to note that not all glass is drillable. Tempered glass is one example of a material that shouldn’t be drilled. Even if you take your time and use the tools designed for the glass, it typically shatters.

At a minimum, laminated glass is challenging to drill. In some cases, it isn’t possible if you’re using standard home improvement tools, particularly if you want to avoid damaging the window.

If your windows are potentially drillable, a typical drill bit isn’t going to do the trick in many cases. Instead, you need a drill bit designed specifically for window glass. Working slowly is also a necessity.

However, it’s a dangerous solution to use regardless of the kind of glass and tools involved. Along with creating tiny glass shards, any window you drill might shatter.

Before you drill, you can put painter’s tape onto the glass. In some cases, that’ll help prevent tiny shards from spraying out, though it isn’t foolproof. Beyond that, you’ll want to keep the holes as small as possible, positioning them along the seal about 2 inches from the corner.

Work slowly, applying gentle, even pressure. Remember, the drill will move forward quickly when you get through the pane, so don’t be too forceful, or you may strike the second pane, damaging it.

In most cases, one or two holes is enough. Once they’re in place, you can position desiccant near or through the holes. Positioning a fan to flow air through the holes may help, too, as well as setting a dehumidifier nearby.

How to Identify a Broken Seal on a Window

In some cases, foggy double pane windows are the first sign people notice when a seal fails. However, it’s possible to catch potential issues earlier.

At times, simply inspecting the seals can make signs of wear and tear or damage incredibly clear. Unevenness, ragged edges or thinning spots may indicate a seal has failed or may do so soon.

In some cases, distorted glass is a sign that a seal failed. If the air leaks out, it may cause the panes to collapse slightly into the air gap area. Since that creates a gentle curve, anything viewed through the window may look distorted.

Will Condensation Between Window Panes Go Away on Its Own?

Condensation between your window panes can go away on its own. Changes in the weather or the conditions inside your house could cause the water to evaporate, removing any fogginess from the panes.

However, when conditions are shift again, the condensation can return. Essentially, you can enter into a repeating cycle, where the moisture condenses and evaporates over and over again until the source of the problem is appropriately addressed.

Are Cloudy Windows Bad?

Generally speaking, cloudy windows are an issue if fogginess exists between the two panes of glass. In that case, the seal failed, so the integrity of the window isn’t what it was previously.

Once moisture is present, it creates an environment that may promote mold and mildew growth. If water begins to build up in the space, it can damage the window frame and surrounding structure, potentially requiring a significant repair to fix.

Additionally, when the air leaves the gap, the glass may collapse into that space. When that occurs, the glass might crack or break, creating a safety issue. Plus, it’s potentially exposing the interior of the frame or your home to the elements and reducing the effectiveness of the barrier between internal and external temperatures.

How to Prevent Condensation in Double Pane Windows

If you want to prevent condensation in double pane windows, ensuring the seal remains in good shape is the most important step you can take. Avoid using harsh cleansers on the seal. Additionally, don’t apply too much pressure when cleaning.

Reducing the humidity level near the window can lessen the odds of condensation, too. Either a dehumidifier or desiccant can remove excess moisture, potentially preventing condensation from building up.

Otherwise, fixing the broken seal is your best bet. You’ll either need to replace the damaged seal, the window panes, or the entire window, depending on the source of the issue.

Can Double Pane Windows Be Resealed?

In some cases, you can reseal double pane windows. However, this is usually a job for professionals. Otherwise, even a small misstep can lead to new issues faster than you’d expect.

Additionally, whether you can reseal the window may depend on the seal that’s failed. Exterior seals may be addressable, while some on the interior of the window may be difficult to replace, even by a professional.

With this option, ensuring that all of the moisture is removed is essential. Often, that’s far harder to do than one would expect, particularly if you live in a humid area. But if the moisture isn’t addressed, it can end up trapped between the panes. Then, if the resealing job is solid, getting it out again may be incredibly difficult.

Since resealing double pane windows is difficult, replacing the windows may be better. This is particularly true if trapped moisture causes any damage, as resealing won’t address issues with the frame or surrounding structure if they arise.


At this point, if you were wondering how to clean double pane windows, you should have a solid idea of what to do. In most cases, handling the exterior of the windows is simple. However, condensation between the panes is far harder to address, potentially making drastic measures like drilling or window repairs or replacements necessary.

Did you find out all you wanted to know about how to clean double pane windows? If so, let us know in the comments. Also, if you have a family member, friend, or colleague who would benefit from this information, please share the article.

Written By: Yevgen

YevgenI'm a DIY nut, and the founder and chief editor here at Weekend Builds.
This site is a result of my DIY passion, and to share the joys I have experienced fixing, building, and creating things over the years.

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