Rationel Blog

All you might ever need to know about Windows and Doors in Ireland.

How hard is it to break a double glazed window?

One of the most frequent problems with windows was their breakability. Glass broke so easily that replacing it was a glass-cutter’s most required service. Nowadays, windows companies are very rarely asked to replace broken glass because new windows are so hard to break.
Double glazed windows are so resistant that it would take real effort to be able to break them. First, there is the structure of the glass, that isn’t as simple as in the old days. Now, glass is treated and toughened so that it resists to shocks, footballs thrown by children, weather conditions and breaking and entering. It’s very difficult to break a double glazed window without making a noise.
All modern windows come with double glazing, which means that there are at least two obstacles to overcome in order to break the glass. First, there are the two panes of glass. If you throw something (a brick or a stone, for example) at a double glazed window, it’s very likely you break only the first pane and the second one remains intact. Second, the gas between the panes works as shock absorber. So hitting it in the middle won’t work.
However, there are situations when it’s imperative to break a double glazed window and you should know what to do and how to break it. Fires are the most likely situations where you might need to break through a window. So how do you break a window in this situation? You have three options:

  1. Hit the window in one of the lower corners with a heavy object (preferably a hammer). If you hit it in the middle, the object may bounce back.
  2. Use a breakoutglass unit. They are very efficient if used on one of the lower corners of the window.
  3.  If you break a hole in the first pane, then using the same object go through the hole you have made to break the second pane.
Window panes will shatter in tiny pieces, allowing you to escape.


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