[Shop-talk] Exploding storm door

[David C.]

The upper half of my storm door has exploded...twice.

It's a conventional storm door, upper and lower window.  The upper is 
fixed, the lower can raise or lower for ventilation (screen behind it.) 
Twice now the upper pane has just exploded.  It's tempered glass so it 
makes a million little pieces that I have to vacuum up out of the cracks 
between the deck boards.  The first time it (apparently) happened when 
we weren't around because my wife just noticed the door broken.  Today 
when she opened the main door it exploded inward, apparently from the 
suction of opening the main door.  All I can think of is thermal cycling 
is weakening the door or it's expanding into the frame which may be 
keeping it from expanding freely or something.  (The door faces due east 
and the front door behind it is white.)  Oddly enough it was pretty 
cool, in the low 70s and cloudy all morning.

It seems like if this was a common problem I would have heard of it 
before.  I'm thinking of replacing it with polycarbonate this time.

Any ideas?
Thanks
Dave