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GBlist: More on IG seal failures...



I did some snooping and learned a bit about welded glass and IG seal failure
history.  I must say I don't feel much better about the IG seal failure risk
that seems to be out there among the hundreds of IG "fabricators".
 (Conversely, I am increasingly MORE confident about the checks and balances
the big guys have put into their IG unit production.... a confidence that
looks to be reflected in their IG warranties.)

Welded glass.  A Mechanical Solution.  A Mechanical Problem.  
Welded glass edges offered a reliable seal on:
1) small units
2) air spaces around .25 inches.

Then we wanted to improve energy efficiency.  Low-e coatings (metals) were
incompatible with the welding process.  Also, the process in its infancy was
limited to rectangles.  Also couldn't put gas fills in because of process
limitations.  (Yes, this is the short version.)

For small windows the seal lasted a long time.  Why? The FORCES were smaller
on the MECHANICAL connection.  Glass, as a mechanical connection, DOES NOT
like to move.  But for some reason, people wanted bigger windows..... guess
what happens?  Wind induced forces, movement of the outboard lite versus the
NON-movement of the inboard lite, barometric pressure, etc. all conspired to
break A LOT of welded glass.  The most telling example of this was the John
Hancock Tower in Boston.... raining glass shards.... (we'll talk about THIS
horror story in Denver)

What about using tempered glass?  Didn't work.  Couldn't weld it.

So, Can't make it big, can't make shapes, can't use low-e coatings, can't gas
fill it, can't ....  Well, you get the picture...  May it rest in peace....
or be the subject for some new innovation that cures all the previous
ills....

And about these air vented windows, WAIT before you jump into the pond....  
1)  Do I have to give up my low-e coatings?  But I LIKE those warmer surface
temperatures in the winter and the cooler surfaces in the summer.  I like the
energy savings in both summer and winter.  
2)  Do I have to give up gas filling?  More comfort and energy savings... 
3)  What do you mean that bugs and dirt get inside?   I like my view and the
ABSENCE of interior condensation.
4)  Are there really cost tradeoffs and savings?  Show me/us the data...

If these are the costs of going to air venting, I think I'll stick with the
organic seals offered by a reputable manufacturer and  replace them in 10, 20
or 30 years.... or whenever they fail.  I look at the warranty while I'm
sitting next to my warm low-e, gas filled, clear, no interior condensation
window in the winter.  Or maybe I'll read the warranty while sitting next to
my cooler, low-e, gas filled, clear window in the summer.....

Chris Mathis
MCSquared
"In God We Trust.  The rest bring data."


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