Failed Windows - 4 Reasons why your clean windows STILL look hazy!

Failed Windows? Uggh!!! If you live in a coastal community like our lovely beaches along the Central Coast of California, you may have noticed a common issue with your dual-paned windows – a hazy or foggy appearance, which indicates that there is moisture or condensation between the panes. Sometimes the windows may even  look streaky or tarnished after they have been properly cleaned.

Failed windows can be a frustrating and unsightly problem, especially when you want to enjoy the beautiful views of the ocean or the hills surrounding your home in a town like Cayucos or Avila Beach. This problem is not unique to our area and affects homeowners across the country. We will examine the causes of dual-paned windows failing in this blog post, as well as possible solutions.

Failed windows in Morro Bay, CA. On The Spot Window Cleaning
Purplish haze from tarnished Low-E coating
Low-e window failing in Morro Bay, CA. On The Spot Window Cleaning
Up close look at a hazy window

What Are Dual-Paned Windows?

The most typical kinds of windows for newer homes are dual-paned windows, commonly referred to as double-paned or double-glazed windows. They consist of two panes of glass separated by a space filled with air or a gas like argon. Insulation is provided by the area between the panes, which keeps your house cool in the summer and warm in the winter. Dual-paned windows also provide additional benefits such as reducing outside noise, improving energy efficiency, and blocking UV rays.

Why Do Dual-Paned Windows Fail?

There are several reasons why the seal can fail:

  1. Age: Dual-paned windows have a lifespan of around 15-20 years. As they age, the seal between the panes can become brittle and crack, allowing air and moisture to enter.
  2. Poor installation: If the windows were not installed correctly, the seal may not have been properly applied, leading to premature failure.
  3. Extreme weather: The seal may expand and shrink as a result of exposure to high temperatures, such as scorching summers or freezing winters, which can result in failures and cracks.
  4. Physical damage: If the window is hit or impacted in some way, the seal can be damaged, allowing air and moisture to enter. Some chemicals may cause damage to seals as well.

Although dual-paned windows are intended to survive for many years, they occasionally experience problems. The most common reason for dual-paned windows to fail is due to seal failure. The seals around the edges of the window can weaken and break down. Often the first sign of failure is a purplish distortion that sometimes has machine marking or even handprint formations - indicating corrosion of the low-e coating on the internal surfaces of the window.

It may be that the added element of the salt air in our beach towns like Pismo Beach, CA, can quicken the decay of the window seals.

What Causes Haze or Moisture Between the Panes?

When dual-paned windows fail, moisture can seep into the space between the panes. The way the moisture appears can vary throughout the day depending on how warm the window gets. 

At other times, oxygen is introduced into the window through a failed seal causing some corrosion and a tarnished look of the low-e coating.

In addition to the aesthetic issues, moisture between the panes can also cause other problems including a reduction in insulative properties.

Moisture between panes of a dual-paned failed window. On The Spot Window Cleaning in Grover Beach, CA.
Severe Moisture BETWEEN the Dual Panes. Picture taken before service.

Why Does Moisture Appear After the Windows Are Cleaned?

Like a cold drink developing moisture on the outside of an otherwise dry glass, the difference in temperature between a cleaning solution and the internal surface of the glass can cause the moisture that is already between the panes of the window to condense into more visible droplets. Windows can even develop moisture patterns in the same pattern as the movements of the scrubber during the cleaning process. This is not moisture being pushed through the glass during the cleaning process, but is the condensation process as described above.

What Can Be Done to Address the Issue?

Oftentimes glass companies request the windows be professionally cleaned to be sure a hazy looking window isn’t due to a buildup of dirt and grime. A great course of action is to call reputable window cleaners like On The Spot Window Cleaning out of Grover Beach, CA. A good window cleaning company can often assess the extent of the damage and recommend the appropriate course of action.

Some companies offer a method of drilling into the windows to install vents and try to remove the moisture without replacing the windows. This type of service has varying success and can often complicate future cleanings of the windows. 

A good glass installer should be able to assist with the best solution to replacing a failed dual-paned window. Many times just the glass can be replaced without replacing the entire window. Be sure to check with the manufacturer to see if your windows are under warranty.

How Can You Prevent Dual-Paned Windows from Failing?

While dual-paned windows can fail for a variety of reasons, there are steps you can take to help prevent seal failure and other issues. Your windows must be regularly maintained if you want to keep them in good shape. Here are some pointers to keep your windows in good condition:

  1. Check the condition of the seals surrounding your windows on a regular basis.
  2. Keep your windows clean, both inside and out, to prevent dirt and salt from accumulating on the seals and possibly causing damage.
  3. Be very cautious about placing items or films on the glass that can cause the window to heat up even more than what should be expected for your climate.
  4. Keep the moving parts of your window in good working order to prevent overstressing the window during opening or closing.


Dual-paned windows are an excellent investment for homeowners in our wonderful community. If you're experiencing issues with your dual-paned windows, don't hesitate to contact us at On The Spot Window Cleaning. We'll be happy to assess your windows and recommend the best course of action to restore them to their former glory. With our help, you can enjoy the beautiful views of San Luis Obispo County with regular window cleaning and recommendations for when it’s time to replace a failed window.

Here is a great video from a window installer explaining window failure: What is a Window Seal Failure & What to Watch For

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