does double glazing crack?

Happytosave

We just had double glazing installed. Whilst inserting a couple of panes, they cracked which the installers said was normal so they ordered new ones and replaced them. Is this normal? It didnt instill great confidence in me.
They also said that if the windows were hit by a cricket ball, they would also crack. I thought double glazing would be tough enough for these knocks?

macman

It's a double glazed unit (not a pane)-that doesn't make it any more resistant to hard impacts. For that you'd need toughened glass.
Not much glass would withstand a direct hit with a cricket ball!
It's easy enough to break a unit if you are careless or rushing the install, which is not unlikely. It's nothing to do with the strength of the unit itself.

pka_2

All glass will crack be it toughened, heat soaked or 'normal'. Double glazed just means that you get better thermal and acoustic properties than single glazed units. To be honest you are in a better off that they cracked during installation as quite often the installers can chip a corner of the unit during installation which can then crack several months later. It is then down to you to prove that the crack is due to a manufacturing/installation defect otherwise you would end up paying for the new glazed unit.
Even if you get toughened or safety glass, it is still likely to crack on impact from items such as cricket balls, the only difference being in the way that it will crack/shatter so as not to go in to shards which are more likely to cause injury.

scottishblondie

The only difference between single and double glazing is that double glazing is made up of 2 glass panes separated by a gap, which reduces noise/heat transmission etc. So as the others have said it will crack if mishandled and a good knock from a cricket ball will most likely break it.