How to Unfog a Double-Pane Window: DIY vs. Professional Approach to Fix Foggy Windows

How to Unfog a Double-Pane Window: DIY vs. Professional Approach to Fix Foggy Windows

Updated: 08.01.2023

By Nina Tsoy

Insulated glass units (IGUs), commonly called thermal windows, are far more energy-efficient than single-pane glass windows. However, IGUs are prone to moisture accumulation, which results in windows fogging up in your house.

The million-dollar question posed to our team at Apex Window Werks: Can fogged windows be repaired? You’ll be happy to know the answer is yes!

This blog explains the reasons for misty windows and how to repair foggy windows to restore pristine views.

Why Double Pane Windows Fog Up

window fogging

What causes foggy windows in a house? Windows can become fogged for various reasons, but they all stem from the same phenomenon: water vapor in the air settling on a cold surface and forming tiny droplets.

These droplets scatter the light that passes through them, creating a cloudy appearance. Glass is usually one of the coldest surfaces in a home, so this is often the first place you’ll notice the fogging.

Common Reasons Behind Window Fogging

Condensation is when water vapor in the air turns into liquid water. This occurs when the temperature of an object, such as a window or refrigerator, drops below the dew point of the surrounding air.

These cool surfaces absorb moisture when exposed to warm, humid air, then release it when they cool down. It can be difficult to remove if the moisture becomes trapped between window panes, as the seals designed to keep window condensation out can also trap a lot of it in place.

Windows Fogging on the Inside

cleaning inside windows

Excessive humidity inside a home causes condensation on the interior of windows, especially during the winter when the difference in temperature between the interior and exterior of the property is most noticeable. This issue is particularly prevalent in kitchens and bathrooms, as these rooms generate more moisture due to cooking and showering.

Windows Fogging Between Panes

How double-pane windows work: Double-pane windows are made up of two panes of glass with a layer of argon gas sealed between them. The gas acts as an insulator, helping to keep the inside of the home warmer in the winter and cooler in the summer.

Unlike single-pane windows, if the air-tight window seals of double or triple-pane windows start to leak, the gas sandwiched between the two glass panes can escape. A sure sign is when condensed water droplets appear on the window’s interior.

Manufacturers typically include drying agents when they ship their double-glazed windows, but if there is a leak, these agents will not effectively remove any moisture.

How to Repair Foggy Windows

window fog

If your windows are foggy, there are several solutions to try. Replacing the IGU (insulated glazing unit) is an excellent option to avoid replacing the whole window. You could also use a defogging spray or shaving cream to reduce the fogging.

However, replacing your windows is the best way to fix the problem. If you need assistance, consult with your window manufacturer to find out if there is a lifetime warranty on seal failure. Doing so could save you money and protect your family from mold buildup. Old and worn-out windows can also drive up energy bills, so replacing them is the best long-term solution.
Note: After 15 or 20 years, IGU windows are expected to become less effective, and the seals will start to fail.

DIY Methods to Fix Foggy Windows

fogged windows

If you’re looking for a cost-efficient way to restore your windows to their clear and pristine condition, then DIY is possible, provided you’re confident in your repair abilities and have the time.
Here’s how to remove fog from your house windows:

Patch Broken Glass

A foggy window is sometimes caused by minuscule damage to your window’s glass, and you can offset this problem by repairing cracks; you can fix the gap by putting a piece of masking tape or clear packing tape on both sides of the window pane. Ensure the tape extends past the damage on all sides, and press it firmly against the glass.

Using this method, you may be able to keep the glass in one piece and stop condensation from entering the crack. However, it will not reduce the existing fog, and any bumps may cause the window to shatter, as cracks can weaken the window’s structural stability.

Warm the Windows

fix foggy windows

You can also get a heater with an adjustable stand to accommodate windows at different heights to help with defogging windows in your house. When you place the heater near a window, it quickly evaporates the window fog and adds warmth to the room, relieving some of the burden off your AC. Just like how defrosters work in cars, this blower eliminates pressure differentials and condensation.

Liquid anti-fog solutions are another option to prevent fog from forming again. These are usually used on bathroom mirrors and car windows and are easy to apply – rub the liquid onto the glass with a lint-free cloth until it disappears. Reapply it after a few days or when you see the fog again. Cleaning inside windows also helps to prevent water from sticking to the glass surface.

Replace the Window Sash

If you need to replace the frame holding the glass in place, known as a window sash, you might be able to save money by purchasing a new one from a local home center. This is only possible if the existing window is an exact match with the new-construction window. Unfortunately, replacement sash kits are often tied to specific brands and must be special-ordered by the manufacturer.

Use a Dehumidifier

Using a dehumidifier effectively reduces humidity levels in your home and makes it healthier and more comfortable. While dehumidifiers generally consume low amounts of energy, you can also opt for rechargeable types that don’t need to be plugged in. To avoid unnecessary moisture buildup, you should keep the air moving by slightly opening doors and windows. This will allow dry air from outside to come in, preventing foggy windows.

Replace the IGU

If your window frame is in good condition, replacing the insulated glass unit (IGU) is the best option for a single defective window. However, replacing glass panels is an intricate process, so be sure to read up on how to perform the process properly! The replacement cost will depend on your window’s size, shape, and customization.

Defog and Reseal the Window

windows fogging up in house

Drill two small holes near the bottom of the pane, and then use a cleaning solution or a dehumidifier to remove the moisture. After the window fog has been eliminated, spray an anti-fog solution inside the glass and add small vents before sealing it with clear silicone caulk. While this is a less expensive way to fix the cosmetic issue, the window will be less energy efficient.

Replace the Entire Window

If your glass is foggy and your window is not operating correctly, such as not closing completely, it is time for a fogged window replacement. If only one window is affected, contact the manufacturer to see if it is still under warranty (if purchased within the last 10-15 years).

The cost of replacing a window depends on its size, style, and customization. For example, the average price for a standard double-hung window is $600. If you have a double-hung, single-hung, or sliding window, you can replace the broken sash rather than the entire unit.

How to Prevent Your Home Windows from Fogging Up?

repair foggy windows

To ensure your windows last for decades and remain fog-free, install them correctly and have proper ventilation throughout your home.

Here are a few extra tips to maximize the longevity of your energy-efficient Glass, whether they have vinyl, aluminum, or wooden window frames:

  • Invest in high-quality windows: If you want to reduce your home’s energy use, it’s worth checking with your window manufacturer to see if they offer a lifetime guarantee on their products. Up to 25 to 30% of your home’s energy is lost or gained through windows; having the best quality windows can make a big difference;
  • Install windows correctly: Have confidence in the contractor installing your windows. Research their background and inquire about their expertise with windows to ensure they are qualified. Improper installation can lead to issues with window glass and seals;
  • Perform Routine Maintenance: Examine your windows regularly every couple of months. Look for signs of deterioration, such as damage to the sash or a broken window seal. This way, you can spot any issues before you need to replace your windows, and if you are not in an emergency, you’ll get the best price when you need to buy new windows. Also, learn how to clean the inside of windows properly to reduce condensation buildup;
  • Ventilate Your Home: Kit out your house to encourage good air circulation.

Even during the winter, keep fans running to prevent warm air from accumulating near your windows:

  • Use a dehumidifier to remove moisture from the air that could get between window panes;
  • Buy a window film kit to protect your windows and regulate temperatures;
  • Open the windows and doors in the rooms you use often;
  • Weatherstrip your walls;
  • Keep outdoor gutters clean;
  • Allow proper fireplace ventilation;
  • Keep air vents open.

Should I Hire Professional Window Glaziers?

Yes! If anything goes wrong with your DIY foggy window repair, your warranty on the windows will no longer be valid. Resealing a foggy window unit or replacing the gaskets with a window frame does not come with a warranty; however, a professional glazing company will provide a guarantee when replacing a broken glass unit.

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Conclusion: Call Expert Defoggers

The fog that forms between window panes is trapped moisture. Depending on the material of the frame, this condensation can cause mold, mildew, rot, and decay. Furthermore, it reduces the energy efficiency of the windows – all of which you want to avoid.

Are your windows foggy and ineffective against DIY window repair methods? Let Apex Window Werks help! Our foggy window repair company works with windows of all sizes and shapes at a reasonable price. Contact us today for a free cost estimation and to immediately schedule the service.

Nina Tsoy

Nina Tsoy

With over 15 years of experience in the window repair, replacement, and manufacturing business, Nina is in charge for strategic solutions and exceptional operational performance at Apex Window Werks. This allows her to offer innovative techniques and solutions to address any window-related problem, all while adhering to industry standards and best practices.

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