How to Fix Condensation in Double Pane Windows

window with condensation
  • 3-10 hours
  • Intermediate
  • 250-2,000

Your home’s windows are a major contributing factor to temperature control. So when things aren’t quite right with a window, it’s a concern worth addressing. Condensation between window panes is a pain, and it can be tricky to resolve. Check out our rundown for a few ideas to try.

What Is a Double Pane Window?

There are myriad different types of windows. One way they are distinguished from each other is by the number of glass sheets. A single pane window has a single sheet of glass.

They are highly inefficient when it comes to energy savings because cold air seeps right through in the winter and air you’ve paid to warm seeps out. A single pane window offers no insulation.

A double pane window has two sheets of glass with a space between them. This space contains gas, such as argon or krypton, which creates a buffer, adds strength to the window, and improves soundproofing.

There are also triple pane windows, which feature, you guessed it, three panes of glass. This style of window, therefore, has two layers of gas, one between each set of glass sheets. A triple pane window is the gold star in energy efficiency.

Each additional layer of protection brings insulation that creates a more comfortable environment inside the house and reduces costs for both heating and cooling the home.

Can You Remove Condensation Between Double Pane Windows?

The answer to this question is yes, with stipulations. First, you need to understand how the system works and what’s causing the condensation to develop in the first place.

Why Windows Collect Condensation

window with condensation

As mentioned, the space between the glass sheets is filled with gas. It also often contains a desiccant that eliminates moisture. The system relies on an airtight seal around the window.

If there's even a slight break anywhere in the seal, fresh air will invade the space, driving the gasses and desiccants out. Since fresh air contains moisture, this leaves nothing to combat the collection of condensation between the window panes.

What Does Condensation in a Double Pane Window Look Like?

You may see it as a minor fogging in a corner of the window or across the face of the glass. More likely you will see actual water collection, with beads forming and running down the glass.

Over time, this will lead to mold inside the windows. Windows that are collecting condensation are inefficient, costing you money through energy loss. Plus, the compromised windows will restrict your view.

Can Fogged-up Double Pane Windows Be Repaired?

Kind of. The condensation can be removed and the windows can be resealed. However, this is really a temporary fix. You’ll probably never get back the full integrity of the original window, but in the short term, you can improve your view and keep the mold at bay by driving out the moisture.

Many window professionals don’t offer this service because they recognize it isn’t a long-term solution. Some do perform this type of window restoration though.

Some Types of Windows Cannot Be Restored to Fix Condensation

The process for removing condensation from double pane windows is described below. However, not all windows are good candidates for the procedure. Specifically, tempered glass is extremely difficult to drill or cut.

It is not recommended to attempt any type of moisture repair on tempered glass windows. Sliding doors may also be made from tempered glass. Large windows with expansive glass may be tempered too.

For windows and doors with tempered glass, one of the two types of replacement described below are your only option.

Restoring a window with condensation may be a job for the professionals, but we’ll outline the steps here for a comprehensive understanding of your options.

Fixing Window Condensation

Step 1 - Drill Holes

drill cutting hole in glass

To release the moisture trapped between the glass panes, window repair professionals drill small holes in the outside window pane.

Step 2 - Release Air

A device is then used to suck the air and moisture out from between the sheets of glass. Chemicals are pushed into one hole and released out the other, leaving the inside glass surfaces clean and condensation free.

Step 3 - Mitigate Future Moisture Collection

At this point, the window can be left as is, in which case moisture will likely collect again at some point in the future.

The hole can also be sealed in an attempt to keep moist air from reentering the space.

Another option is to use one-way air vents that release moist air to keep condensation from forming while keeping new air from entering the space.

However, none of these solutions are long-term. In addition, none will make up for the energy loss as a result of the lost gas buffer.

Long-term Solutions for Condensation in Double Pane Windows

There are a few ways to attack the issue of foggy windows that are longer lasting than the Band-aid solution of drilling the window.

Replace Glass Panes

For a lasting solution to the problem of window condensation, replace the window panes where the seal is broken. For a window with a solid frame, replacing the panes is a less expensive and time consuming solution than replacing the entire window.

Step 1 - Figure Out Size and Type of Window

Before you remove any wall material, calculate the size of your window and get the replacement on hand.

A double pane window replacement without a frame comes as a unit that includes the two glass panes with the argon gas sealed between them. You don't want to replace only one pane of glass—replace the unit even if you’re not replacing the frame.

Standard sized windows will be easier to find and quicker to get to the job site. If you decide to install a non-standard size window, allow plenty of time for the custom build.

Step 2 - Remove Old Windows

There are many types of windows and removal can take many forms. Take a look at your system to figure out the best way to dismantle it. Score paint with a sharp razor if needed in order to access screws. Look for screws along the frame. Remove the screws to remove the panes.

Another approach, depending on the design of your window, is to score the putty on the inside of the window between the glass and the frame. Then go to the outside of the window and remove any vinyl strips around the glass. Use a small prying device to get behind the strips.

Try to avoid damaging them so you can put them back into place after installing the new double pane window. If they look brittle, however, get new pieces when you purchase your window. Both the putty and the strips help hold the glass in place so with them gone you can remove the glass pane.

Use a glass suction tool made for windows. This is a suction cup with a handle that sticks to the glass. Once the tape and holding strips are removed, the suction tool has a handle and can manage the weight of the glass for easy removal.

Step 3 - Clean up the Frame

If your project does not include new framing, clean up the window opening by scraping away old sealant.

Step 4 - Apply New Sealant

Use a roll of double-sided cushioned tape around the frame where the replacement double pane window will go. Press it firmly in place, starting in one corner and working around the frame. Then peel away the protective coating on the outside of the tape.

Spray the outside of the exposed tape with a layer of glass cleaner immediately before installing the window. This will keep the window from sticking too firmly while you make adjustments.

Step 5 - Install the New Double Pane Window

gloved hands installing window

Use the glass suction tool to place the new window into the opening. Reinstall the trim pieces back into place around the outside of the window.

Complete Double Pane Window Replacement

For a home with older, inefficient windows, you’ll be doing a complete replacement, including the frame. It’s a bit more work than the pane replacement described above, but is still achievable within the DIY realm.

Step 1 - Measure and Order

Measure your existing window and buy a new one. Make sure you have the window in your possession before moving to window removal.

Caution—If your windows are older than 1978, they may have lead-based paint and should be removed by a professional equipped to deal with the toxins.

Step 2 - Remove Old Window and Frame

Cut around the entire window opening with a circular, or similar, saw. Stay close to the edge of the window, but you can allow a bit of room to work. The gap will be covered up later in the process, so cutting a few inches away from the window edge is fine.

Use hand and manual saws, depending on your particular situation, until the surrounding material has been removed.

Once you’ve removed the surrounding materials, the window and frame can be removed. You may need to use a chisel or saw to cut through some of the framing holding the sashes or window frame in place.

Cut out around the frame to a width that equals the trim you plan to use around the window. This is typically around four inches, but have your trim available so you can be precise. Use a straightedge to create a line for the cut. Be as precise as possible, but know you will be filling the surrounding gap with sealant at a later step.

Step 3 - Install Flashing

Leaks are the most common issue with new window installations. Therefore, it’s critical you seal every possible entry point for water. Think of it as putting a rain jacket around your window.

Every layer should overlap from top to bottom so any water that runs down the house runs over the top of the layers, rather than having an opportunity to seep underneath.

The first layer of protection is called flashing. There are many forms of flashing, from preformed corner protectors to rolls of cut-to-size self-stick flashing tape.

Apply the flashing tape along the bottom of the window frame from corner to corner, making sure it covers the entire area. Press the flashing tape into corners and edges for a solid seal. Only apply the flashing tape or corner protectors on the bottom of the window at this time.

Step 4 - Place Shims

Ensure your window will set level inside the window frame. Use shims to lift one or both sides to make it level. Use flashing tape to hold the shims in place.

Then dry fit the window, making sure it sits level. If it doesn’t, install more shims until it sits correctly. Remove the window and set it aside.

Step 5 - Apply Sealant

hands with caulking gun sealing window

You’re ready to install your window! Start by using a tube of sealant, applied with a caulk gun. Run a thick bead of sealant all the way around the frame, where the window will press into the window stops. These are the ledges on the inside of the window frame.

So Should I Restore or Replace My Double Pane Window?

Consider the factors as they pertain to your situation. If you’re looking for a short-term fix or don’t have the funds to replace a portion or the entirety of a window, a restoration will buy you time. It’s hard to say how much time, but it is an option.

Remember that a restoration won’t replace the gas inside the panes, which will substantially impact the insulative qualities of the window. So while you’ll save money on the process, you’ll lose money through energy consumption costs.

If you have the means, a window replacement is the best solution to fix condensation in double pane windows. Learn more about Laminated vs Tempered Glass Windows so you know what you’re dealing with. If your foggy glass is in a door, find more information in Door Window Installation Explained.