Broken glass mystery

[BeatTheSeasons]

I recently dismantled, moved and then re-erected an old 12' x 8' greenhouse in my back garden.

I managed to break 10 panes in the process - some were dropped, some were cracked when my dog jumped on a pile of glass on the ground, and still more broke in the cold snap as they were stacked up and water got between them and froze.

I have now put about half the panes into the frame and you would think they would finally be safe once in place, but no.....

I have just been outside and found a whole side section of 3 panes has smashed at some point in the last 24 hours.

And I only just came back from the glazers with 10 replacement panes!!!

It's the second time this has happened - a few days ago it was just one pane from a side section that mysteriously broke.

This time it looks like there was an impact from inside, as nearly all the glass is laying OUTSIDE the frame.

What could be causing this????!!!!

- Could it be be birds flying in the open front or back and then trying to fly out the sides? The panes are pretty clean, but not invisible.

- Could it be another kind of animal? I am in an urban area so the choices are fairly limited.

- Could it be due to stresses on the frame? Or something to do with the effect of the wind on a frame which is only partly glazed?

Any suggestions would be gratefully received as I am finding this very frustrating, as you can imagine.

[Capsid]

Maybe it is that the greenhouse is not quite square and there are stress points on the panes especially during cold nights when the metal frame will contract and expand.

[BeatTheSeasons]

That seems plausible, although it still surprises me that 3 panes all broke at the same time.

The other thing that might be stressing the glass is that I have used some modern clips, which are larger or "deeper" than the old ones, and so this puts more pressure on the glass. I might try and find some old style clips to reduce this effect.

[Snadger]

Maybe it is that the greenhouse is not quite square and there are stress points on the panes especially during cold nights when the metal frame will contract and expand.

I would agree.

Also, until all the panes of glass are in the greenhouse there will be movement and possibly a wind tunnel effect.
I personally would not add any more glass panes until you have enough for the full greenhouse.

[Aberdeenplotter]

Glazing clips hold the glass against the frame from the ouside and pressure from inside is normally minimal but if there are missing panes and there is any wind at all, it is easy to understand how glass can be blown outwards.

I agree with Snadge, do not add any glass until you can cover the whole structure.