Blown Windows: Cost to Repair or Replace Blown Windows

31 August 2021
Updated 4 January 2024

If you have blown out windows, it is important to know the cost of repairing or replacing them. The blown window phenomenon can happen because of a number of different reasons including strong winds and high-pressure storms. If your blown window has any cracks in the glass, then it will need to be replaced. In this blog post we’ll discuss how much blown windows cost to fix as well as what causes blown out windows in the first place.

What is a blown window

A blown window is a window that has been blown out or broken.

Blown windows occur when a gap between the glass panels opens up, allowing moisture to seep into the window unit. This gap can then subsequently lead to misting of the window, or what some term as “cloudy”. It’s often caused by damage to the window seals, deterioration, or damage to the window panes.

If you have a blown window, think about how much it will cost to fix it and what could cause a blown out window in the first place.

Causes of a blown window

A blown window can happen for many reasons, including strong winds and storms. Below are some examples of common causes of blown double glazing.

  • Ill-fitted windows
  • Damage or wear-and-tear of the window seals
  • Harsh chemicals used during cleaning, causing damage to the window
  • Windows that have aged and deteriorated

How to tell if my double glazed windows have blown?

The signs of a blown window can vary depending on what caused the blown out window.

The most apparent indication that your double glazing has blown is that between the glass panes, your windows become cloudy, foggy or hazy.

Early signs of blown double glazing may also be observed, such as water seeping through the window frame, which is yet another symptom that your double glazing is failing.

How to avoid a blown window

If you want to avoid blown windows, there are a number of things you can do. 

First, make sure your windows are sealed tightly by caulking around the edges and filling any cracks with silicone sealant. The idea is to fill any gaps and prevent moisture getting into the double glazed unit.

Second, try to keep your windows clean by washing them at least once every six months. Be sure to not use any harsh chemicals – as this can cause a blown window!

Third, if your local area is prone to strong winds, invest in storm shutters that will help protect your home from high-pressure storms. Metal window guards could also be added.

The most important thing is being proactive about blown out windows to try to prevent it from occurring, and thus saving you the cost of any repairs or replacement windows.

How to fix a blown window?

Usually, a blown window will result in replacement of the glazing unit (not necessarily the whole frame).

A blown window can sometimes be repaired, but it is not always an easy job and the problem will often reoccur. For example, there are kits available that allow you to drill through the window to release the moisture from the glass panes, fix the broken seal, place drying pellets inside, and then fill the hole in the window. But unless the seal is perfectly repaired, the misting is likely to occur again.

Cost to repair or replace a blown window

The price of replacing blown windows will differ depending on a variety of factors, including the number and size of the panes being replaced. The cost of replacing a single pane ranges from £50 to £150 per pane. It will be more costly to replace the whole window, if you’re looking to do so; costs for small windows range from £100, however, for larger windows, it could set you back by almost £900.

Single pane replacement cost

Window pane sizeAverage cost
200mm x 400mm£50
500mm x 700mm£70
800mm x 1000mm£120
900mm x 1200mm£150

Whole window replacement cost

Window sizeAverage cost

Keep in mind that these costs are estimates, and are likely to vary based on where you live, the type of window you have, the size of the window, and the fitting cost of the window installer that you choose.

How to repair a blown window

Due to the construction of double glazed windows, it’s actually more difficult to repair a blown window than it is to just replace it – and more cost-effective too!

Because the panes are hermetically sealed and filled with Argon gas, repair of a blown window is almost never carried out.

Our recommendation would be to find a local window installer and seek replacement. Our online tool can help you find a local window company who can help.