When I go to the local Caribbean Supplier they recommend the "middle of the road" 7/16 Sentinel for windows and 9/16 for sliding doors. From what I have read on the forums the 7/16 seems to be 3/16 glass 0.090 PVB 3/16 glass. The China quote is 11.52mm glass plus 12mm pvb plus 6mm glass. Ignoring the whole window system for a moment, is the glass/pvb/glass offered by the Chinese company not thicker and therefore better? The brand of hardware the Chinese manufacturer uses is Australian Doric and the glass is tempered. Sorry if I am misunderstanding!

No worries Anne, your post title was asking about interpretation of terms, and that's what we are after. I apologize because my initial response was way too cryptic and didn't really give you the information that you needed to help make a decision. And I am going to get technical and long-winded...sorry for that, but I think it's important here to do so....so here goes

The China quote is 11.52mm glass plus 12mm pvb plus 6mm glass. This isn't really possible (I will try to explain why as this gets longer), but - 7/16 seems to be 3/16 glass 0.090 PVB 3/16 - is correct and makes perfect sense. However I am going to suggest that the 7/16" laminated glass as you wrote it isn't what you were actually quoted.

Also not sure if you have a preference for using metric or english since T&C uses both, but I will be using both somewhat interchangeably because that's how it's done in glass/window industry (weird I know!). But I believe that it will help to clear up some confusion (hopefully), or maybe make it worse (I hope not!).

First quote: 11.52mm Clear + 12A + 6mm Clear Laminated

This looks like a quote for an IG unit, not like a quote for a single monolithic laminated lite. First, no one makes 11.52 glass thickness or 12mm pvb and while on first glance as written, it does appear that the 6mm is laminated and 11.52 is clear glass, that makes no sense (see previous comment), so I am assuming the 11.52 as laminated and 6mm as monolithic float.

As I mentioned earlier, your statement that 7/16 seems to be 3/16 glass 0.090 PVB 3/16, is correct and in fact that is an excellent make-up for an impact lite. Since 7/16" converts to 11.11mm, which is thinner than the 11.52mm from the quote, why doesn't 3/16 glass 0.090 PVB 3/16 equal 11.52?

In North America glass is floated (manufactured) using metric for glass thickness. The metric thicknesses are commonly replaced by their english equivalents in general usage, often by the window companies who use the glass, 3mm as 1/8", 4mm as 5/32", 5mm as 3/16", 6mm as 1/4"...so on.

And while 3/16" is commonly referred to as fractional equivalent of 5mm, 3/16" is actually 4.76mm and not 5mm. Typical glass thicknesses used in residential applications in North America include 2.3mm, 3.0mm, 3.9mm, 4.7mm 5.7mm, and window companies (and glass folks) in North America often do refer to 3/16' and 4.7 as 5mm in general usage, while in other parts of the world, including China, glass is manufactured as 3mm, 4mm, 5mm, and 6mm.

Since 4.7mm doesn't actually measure 5mm it's not allowed to be exported to either Europe or China as 5mm. So should "7/16 seems to be 3/16 glass 0.090 PVB 3/16" be calculated as 5mm / .090pvb / 5mm or as 4.7mm / .090 pvb / 4.7mm? That will depend on where the glass came from and what was originally specified.

Metric equivalent of .090" pvb is 2.28mm, no variation, so using all metric means 5.0 + 2.28 + 5.0mm = 12.28mm while 4.7 + 2.28 + 4.7 = 11.68mm, both are close but slightly thicker than 11.52mm, so which one is this the actual make-up?

Here's the rub, in China 5mm is 5mm (actual 5mm is also made in USA and that glass can be exported as 5mm), not 4.7, so if glass is 5mm + 5mm total, then 11.52 allows for only 1.52mm interlayer thickness not 2.28mm (.090) and it happens that 1.52mm is equivalent to .060". (See quote 2).

I am suggesting that the first quote was actually for 5mm / .060" pvb / 5mm not .090 pvb. This make-up is not suitable for your application. It will not pass impact cycle requirements of either MDCA (large missile) or ASTM 1996 (missile level C, D or E).

Second quote: 5mm Low E +1.52pvb+5mm+1.52pvb+5mm half tempered glass, clear

This make-up is not standard and honestly doesn't make a lot of sense.

There is no reason that i can think of for the middle lite in the laminated package, i fact they probably would have been much better off simply bonding the two .060" interlayers together as a single sheet of .120" and going with that.

Unless for some reason they wanted to make the overall unit 5mm thicker by adding a third sheet of glass in the middle of their laminated sandwich, I would consider that the middle lite isn't necessary or particularly desirable for any reason i can think of.

Also and my personal opinion is that a 5mm / .120" pvb / 5mm would be stronger than the make-up in the quote (and .090" pvb is usually (not always) adequate), so I can only assume that they are guessing at what should work...and the first quote would not.

Also and please remember (and i can't over emphasize this enough)...the glass is only part of the equation. Keeping the glass secure in the hole in your wall is vital and you need to be dealing with someone who actually knows how to make this work.

And all this is why I said that I wouldn't use either quote.

I hope it's helpful.

Thank you I really appreciate you spending your time on this. That finally makes it all very clear. I spent a lot of time searching for answers online and the only other helpful ones were ones you had posted years ago! I will be sure to pass on some free accounting advice to the next person that needs it, in your honour.

You're welcome, and I am glad that I was able to help. If you have further questions going forward, please don't hesitate to ask.

I will be sure to pass on some free accounting advice to the next person that needs it, in your honour.

That's really great, Thank you in return!

Ann, can we get an update? Did you get the windows and doors from China?