ᐅ Window cracked – stress fracture or external impact?

Hi everyone!

One of our windows has a vertical crack! At first, our site manager said it was a stress crack. The window also no longer opened or closed properly.

A few days later, he backtracked and said it must have been caused by the exterior plaster or that children had thrown stones. So now he wants to shift the responsibility.

Unfortunately, it’s difficult to take clear pictures...
The crack runs straight down vertically, and there is a small chip in the middle as well.

Thanks a lot for your help

As a layperson, I would wonder what kind of object could cause such damage. A stone, trowel, or whatever would always apply a point load—wouldn't it then tend to chip or crack in a star-shaped pattern?

If there is no sign of any mechanical impact anywhere on the crack, it is most likely a stress crack. The glass can be examined for such signs instead of just making claims.

I completely agree. If a stone hits it, you’ll see an impact mark and it will crack all around it...

I have never seen a crack like this when a pane breaks due to a ball, stone, or something similar. What does the exterior plaster have to do with it? Aren’t those his workers? He is supposed to hand over a defect-free house to you. In the end, it shouldn’t really matter who is to blame.

I would say that this is definitely a stress crack. We had the same issue; it looked almost identical but was replaced without any problems...