Dissimilar glass, does it matter which number comes first?

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Anlina
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Dissimilar glass, does it matter which number comes first?

#1 Post by Anlina »

I'm shopping for double pane windows with dissimilar glass thicknesses. I asked the dealer if
it makes any difference to ask for "1/4 over 7/32 laminated" versus "7/32 laminated over 1/4."
He says it's cheaper to get the outside glass thinner. Another salesman at the same store told me
it's better to have the thicker glass on the outside!

I'm getting windows specifically for outside noise reduction; will the order of the numbers affect that in any way?

Thank you!

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Windows on Washington
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Re: Dissimilar glass, does it matter which number comes first?

#2 Post by Windows on Washington »

Oberon would probably know. As a general rule, I like to run the thicker glass lite to the exterior if its noise you are worried about.

Anlina
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Re: Dissimilar glass, does it matter which number comes first?

#3 Post by Anlina »

Thank you, Windows on Washington! Does it make sense that doing it that way would be more expensive?

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HomeSealed
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Re: Dissimilar glass, does it matter which number comes first?

#4 Post by HomeSealed »

If the glass is identical from one package to the next with the inside pane simply swapped for the outside, no, it doesn't make sense to cost more IMO. Perhaps there is a detail missing here?

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Windows on Washington
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Re: Dissimilar glass, does it matter which number comes first?

#5 Post by Windows on Washington »

+1 to HomeSealed feedback.

No idea why it would be more if the IGU is the same. Heck...they get the IGUs put in backwards all the time and don't charge extra for it... :lol:

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Randy
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Re: Dissimilar glass, does it matter which number comes first?

#6 Post by Randy »

It can and often does cost more in my experience. A lot of manufacturers buy glass in bulk, and many of them rarely buy 3/16” or ¼” Low-E glass. It’s faster and easier to buy that glass clear, and use what they already have in stock for the Low-E side. Having to purchase a small amount of thicker Low-E glass can add to their cost and they pass that along.

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Windows on Washington
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Re: Dissimilar glass, does it matter which number comes first?

#7 Post by Windows on Washington »

Our climate is a bit more mixed than yours, we w can just flip the Low-e.

Anlina
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Re: Dissimilar glass, does it matter which number comes first?

#8 Post by Anlina »

Thanks, guys. :)
Windows on Washington...if the STC is the same no matter which order the numbers are, does thicker glass on the outside still help more with noise?

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Windows on Washington
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Re: Dissimilar glass, does it matter which number comes first?

#9 Post by Windows on Washington »

If they say its the same...its the same. No need in my book. Just made sense to me from a logic standpoint...but it wouldn't be the first time my logic was off.

Bobert
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Re: Dissimilar glass, does it matter which number comes first?

#10 Post by Bobert »

If you live in an area with hail or baseballs, I'd want the thicker glass on the outside as it will be stronger. Also, rain would likely be quieter when it hits the window. My consumers 2 cents for what it is worth.

masterext
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Re: Dissimilar glass, does it matter which number comes first?

#11 Post by masterext »

It does cost more. You are referring to noise reduction glass where they use 2 different glass thickness in a double pane IG. Example one pane is 3/16 and the other pane is 1/8. It reduces sound very well and is much less expensive than laminated glass.

Anlina
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Re: Dissimilar glass, does it matter which number comes first?

#12 Post by Anlina »

Thanks, Window on Washington!

Guy
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Re: Dissimilar glass, does it matter which number comes first?

#13 Post by Guy »

The glass choices can be very different. Here’s the choices I see most. The glass one and two can be flipped either way. I’d recommend the TWO on the exterior. These are for a single slider unit

1/8” one 3/16” two. STC 33 Casement 34
1/8” one 1/4” two. STC 33 Casement 35
1/8” one Laminate two STC 34 Casement 36

3/16” one 1/4” two. STC 32 Casement 33
3/16” one Laminate two STC 35 Casement 37

1/4” one Laminate two STC 35 Casement 38

You can see the Laminate glass carries the better rating. Our glass God Oberon would be my choice with WOW to answer anything glass. He has taught me more than I can remember. The standard IGU has 1/8” x 1/8” glass on each side. Each step up costs more money and adds weight to the window. Any choice with the Laminate glass would be the best. That little bit of bonding plastic that’s between the glass sheets gives you the best STC rating. It really deflects the sound wave verses any glass. Laminate outside with 1/4” inside will provide a superior rating. This will have a very heavy active sash. The thicker the glass the bigger the fee. The regular glass doesn’t really make the difference. The space between the two pieces does. An IGU with a half inch spacer isn’t as good as a three quarter inch spacer. The bigger the gap the better the STC rating. The theory is the sound wave will bend going between the glass pieces. It will bend more with the larger spacer. Now add the vinyl coating of laminate glass with that and your doing great. I’ll see if I have some saved explanation done by Oberon. He explains it much better than I do

Anlina
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Re: Dissimilar glass, does it matter which number comes first?

#14 Post by Anlina »

Thank you, Guy! I appreciate such an informative response.

I'm considering an STC of either 36 or 37, since the sound also comes in through other entries besides my
windows.

I just noticed that the STC for Milgard aluminum windows 7/32 laminate over 1/4 and 7/32 laminate
over 1/8 is the same (36)! How can that be? :)

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toddinmn
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Re: Dissimilar glass, does it matter which number comes first?

#15 Post by toddinmn »

My. Guess is that the laminate is doing most of the sound reduction or it is do to the smaller air space, just guessing.
It fours haze a slightly better OITC rating though.

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