Laminate vs. Float glass effectiveness?

[95svtcobta]

All,

I am in process of requesting quotes for the glass to do my studio window. Have read Rod's book, I understand the basics of matching the glass mass to the wall mass.

I'm running a double stud wall, with 2 layers of 5/8 drywall, which is pretty standard. Looking at the measurements and basic math, it would appear that a piece of 3/4" for one window and 1/4" for other would do the trick.

The window is approximately 48X40 +/- so I understand it won't be cheap, but I am curious as to where the trade off with Plate vs. Laminate is. My understanding is that Laminate Glass is more effective than Float/Single plane, but also more expensive.

In trying to do a cost benefit analysis, I'm at a loss as to the increased effectiveness of the laminate. Mass wise, I'll only pick up a negligible increase due to the PVB (or whatever is in the middle) with laminate. I understand the laminate is better at various frequencies, but at the end of the day I think the question is this:

Can I get thinner Glass if I use Laminated vs. Float. Is the 3/4" calculation based on math affected by the extra efficiency of Laminate? Can I save money and go with 5/8" for example? Can I use a sheet of plate for the smaller thickness window?

It's never as simple as it seems, I'm sure, but every couple hundred bucks helps....

Thanks for any information you can provide.

Jeff

[95svtcobta]

Sorry all,

I just ran a better search and it appears this has been answered a bunch of times...

Looks like 1/3 thickness of the drywall, and 1 size thinner for Laminate...

20/8 total drywall.... 20/24 ....I'd go 7/8th or 3/4 Laminate.

Hmm, unless the Float is WAAAY cheaper, it seems like I'm better off going with the laminate for much of the previously mentioned reasons....

Search is my friend, Search is my friend......

[Rod Gervais]

Originally Posted by 95svtcobta

Sorry all,

I just ran a better search and it appears this has been answered a bunch of times...

Looks like 1/3 thickness of the drywall, and 1 size thinner for Laminate...

20/8 total drywall.... 20/24 ....I'd go 7/8th or 3/4 Laminate.

Hmm, unless the Float is WAAAY cheaper, it seems like I'm better off going with the laminate for much of the previously mentioned reasons....

Search is my friend, Search is my friend......

Float is generally way cheaper than laminate.....

However - I am a bit confused about where your numbers are coming from - float glass weighs about 1.64 psf at 1/8" thick....... so 3/8" would be light in mass compared to the drywall on one side of your wall....... which weighs in around 5.25 psf........ so you need 1/2" to reach the mass level (it's slightly more mass however that's a benefit)

Now - there are things inside of your wall that don't exist in this window - insulation for example - which adds to the total isolation value of the wall.......

Also - once constructed your windows do not have as much air space as the wall assembly (unless you're using the window trims for stops as well)

And if the glass is splayed (like we generally see in a lot of control rooms) you'll have a much smaller air space.

For these reasons I recommend an additional 1/4" in glass thickness on one wall of the window opening (the fact that the coincidence is slightly different between the 2 pieces of glass doesn't hurt you either.)

So that would be one 1/2" pane and one 3/4" pane.

You can safely decrease that by 1/8" if you use laminated glass....... so 3/8" 5/8".

The calculations you came up with in your initial post were off a bit - the 1/4" would be pretty much useless.

Rod

[95svtcobta]

Rod,

Sorry perhaps my post wasn't as clear as I had hoped....

I had done the math prior for 2x5/8" drywall and got the 5.25 lbs/ft2 for each side or a total of approx 10.5 lbs/ft2 just for the drywall, not counting the benefit of the insulation, although as you mentioned, I forgot the 1-2" air gap in my calculations.

When I originally sized my glass I had planned on 3/4" laminate and 1/4 laminate for the second piece. I was thinking the total effect would be 9.84 lbs/ft2 + 3.28 lbs/ft2 for a total of approximately 13.04 lbs/ft2.

I was going to try not to splay the glass, or do it slightly to maximize the air gap.

My original question was how much better was the laminate glass with respect to cost differences based on thickness.

Basically if I had to go say twice as thick with float, the savings might not be that much, or if there was additional value to the laminate. Obviously if the laminate was 1/2 the weight, window assembly would be WAY easier.

I think the point that I missed overall, had to do with the thinness of my 2nd piece. I was thinking that if one piece was thick enough the other would just be "there". I see from your response that I should add another 1/8" to make up for some of the above issues.

Additionally, now that I see the approximate difference between the laminate and float I'm looking at is about 1/8" thickness, I'll be able to evaluate better the costs.

I have quotes for 3/4" Laminate and 1/4" Laminate.

I will get NEW quotes for 5/8" Laminate, 3/8" Laminate, 3/4" Float and 1/2" Float and make my decisions from there.

Thanks so much for your response, and I have enjoyed reading your book. Very valuable, and I have recommended it to several potential studio DIY folks.

Now if I can just finish my super door and HVAC system by May

PS: While it's not an issue with my window (only 48" x 38"), at what size does the thickness need to be drive by structural integrity, or do you do multiple windows at that point? Just curious and thanks again!

[Rod Gervais]

Originally Posted by 95svtcobta

I was going to try not to splay the glass, or do it slightly to maximize the air gap.

I've always leaned towards the splayed windows just because they look so darned cool.........

PS: While it's not an issue with my window (only 48" x 38"), at what size does the thickness need to be drive by structural integrity, or do you do multiple windows at that point? Just curious and thanks again!

I never EVER use more than 2 panes of glass...... the stiffness of thick panes of glass rigidly locked at the perimeter is pretty high - however when the glass gets real large I tend to oversize more for the purpose of stiffness during installation more the for the purpose of the window itself (up to a point anyway)

For example - at Power Station New England the glass is 3/4 and 1"..... the 1" being preferred over 1/2" with a window size of 4' tall by 16' wide.

When you deal with heights of 4' and less the width doesn't really influence the stiffness.

Wide, full height glass walls are a different picture however - there I would begin to look at thickness in relation to stiffness. Although I can tell you from experience that 1" thick annealed glass is pretty darn stiff........

Rod

[Demor]

Splaying is also usefull for getting rid of tripple or more reflections of light, has nothing to do with sound isolation but still... it can be very convenient to actually be able to look through the glass. It has to be more than a few degrees though otherwise it makes things worse....

[95svtcobta]

Demor,

Hmm, didn't really think about the fact that only a few degrees could cause potentially more problems...

Question, once you get past a few degrees, will the height difference between the two sheets be significant or does the neoprene(?) setting block have enough "margin" that it can compress on the vertical pane so they are OK. Or, I guess you could splay both pieces the the same.

Doe sit matter if the narrow width is on the top or the bottom? I would think for a window about 48" off the ground I would want the glass to angle downward for early reflections to be toward the floor, but if I position my cloud above properly, would there be value in the glass being angled up?

Thanks again!

[avare]

Originally Posted by 95svtcobta

Doe sit matter if the narrow width is on the top or the bottom? I would think for a window about 48" off the ground I would want the glass to angle downward for early reflections to be toward the floor, but if I position my cloud above properly, would there be value in the glass being angled up?

The reflections that are being refered to are of light, not sound.

Andre

[95svtcobta]

Originally Posted by avare

The reflections that are being refered to are of light, not sound.

Andre

Andre,

Roger that, I just figured if I was going to splay it for light reflection and glare, I might as well see if there was an acoustical relevance in the direction it was splayed (assuming the glare/light reflections don't care about the splay orientation).

[Rod Gervais]

That would depending on the lighting of course as far as the potential for glare - very difficult with conventional lighting sources to have lighting glare with a glazing installed as you normally see in a studio - which would be leaning in towards the room (so top heavy) unless you are pretty close to the glass.

On the other hand most lighting is installed above the line of the head - and given the right angle I can see a bottom heavy glass reflecting light back into one's face under a lot of lighting conditions.

However - my primary reason is not as much lighting as it is reflections in the glass itself - reflections meaning the mirroring effect that glass can have - with the potential for multiple images in the glazing given the right lighting conditions with parallel panes - that just drives me crazy.

Rod

[avare]

Originally Posted by 95svtcobta

Andre,

Roger that, I just figured if I was going to splay it for light reflection and glare, I might as well see if there was an acoustical relevance in the direction it was splayed (assuming the glare/light reflections don't care about the splay orientation).

There is no acoustical reason to splay glass.

Andre

[Demor]

I don't know exactly how much is needed to get rid of multiple reflections, all I know is our glass is about 15 degrees out of the vertical pane on either side. So that is 30 degrees measured from one window to the other. They are about 50 cm apart at the bottom splaying outwards to the top.

[Demor]

And yes there can be a accoustical reason, namely if it gets rid of a early reflection.

[95svtcobta]

Originally Posted by Demor

And yes there can be a accoustical reason, namely if it gets rid of a early reflection.

Demor, Yeah that's what I was getting at...the direction of the reflection is different depending on if the glass is angled up or down. I expect I might have a cloud over the general area above the window, and I have (will have) hardwood floor in the mix room. I don't think a thin rung will do too much, so I was considering the advantage of the reflection going into the cloud (at least from some angles).

The point about the glare shooting back up is a consideration though....

We're still trying to decide between pendant style lighting handing or various levels of floor and table lighting. I would think that would impact the visual glare/reflections also...

Looks like I need to map out some lighting lines now...

Thanks again guys!

[Rod Gervais]

Originally Posted by Demor

And yes there can be a accoustical reason, namely if it gets rid of a early reflection.

Nope - sorry - but angling the glass to make it top/bottom heavy or installing it parallel with the face of wall is not going help with that....... not unless this is a very VERY tiny window.

Let's assume for a moment that there was a location on a large window that would reflect back to the desk........ changing the angle of the glass (in the vertical plane) would change the location (on the glass) of the reflection point - but there would still be a reflection..... just picture it in your mind's eye - let's say that with a vertical plane of glass (at eye level) you could see the speaker in a mirror - this would mean an early reflection form that point to the listener - if you angle the top of the glass out the mirror point simply rises - angle out the bottom and it drops - but the mirror point remains.....

Quite simply put, this is not the reason we install angled glass.........

Rod

[Rod Gervais]

Originally Posted by 95svtcobta

We're still trying to decide between pendant style lighting handing or various levels of floor and table lighting. I would think that would impact the visual glare/reflections also...

Personally I would avoid pendant style lighting.

I never use that in any of my designs.

I just had some removed from a studio I was recently hired to look at (as a consultant) in order to determine how to fix some problems they were having.

You're installing a light fixture hanging on a guitar string (for want of a better analogy).

Picture fixtures that buzz when a note is played...... that's one of the problems they had in their studio........ Their problem was with E - not any other note - just an E ( any E below middle C)

Perhaps your particular fixtures wouldn't have a problem like that - but that is not a chance I would ever take with one of my designs.........

Rod

[Demor]

Originally Posted by Rod Gervais

Nope - sorry - but angling the glass to make it top/bottom heavy or installing it parallel with the face of wall is not going help with that....... not unless this is a very VERY tiny window.

Let's assume for a moment that there was a location on a large window that would reflect back to the desk........ changing the angle of the glass (in the vertical plane) would change the location (on the glass) of the reflection point - but there would still be a reflection.....

If you are far enough away from the glass like me you don't see the speakers anymore. And its not tiny its about 110 cm x 550 cm. so........

But I see your point, it will only work if you don't see any reflection of you speaker.

[Rod Gervais]

Originally Posted by Demor

If you are far enough away from the glass like me you don't see the speakers anymore. And its not tiny its about 110 cm x 550 cm. so........

But I see your point, it will only work if you don't see any reflection of you speaker.

My point is that if the speaker is set so that it mirrors with the glass perpendicular to the floor of the room - you will still see it if you angle the glass - the reflection point will simply be moved up or down depending on the angle of the glass.

If you are far enough away from the glass and positioned so there is no reflection point - then the angle of the glass is meaningless in that regard.

I have never angled glass in order to deal with acoustic reflections - and I have designed more than a few of studios.

Rod

[Demor]

Originally Posted by Rod Gervais

.....
If you are far enough away from the glass and positioned so there is no reflection point - then the angle of the glass is meaningless in that regard.
.....

I don't think you got what I said... I don't have a reflection in the glass BECAUSE it is tilted. If you are more than 2,5 meters away from the glass you don't have to tilt it alot to stop seeing the reflection of the speaker.

[avare]

Why do people think that glass will reflect sound and drywall will not?

Andre

[Demor]

Of course drywall will reflect , but not in my face, because above and below the glass is not a first reflection point.

[Rod Gervais]

Originally Posted by Demor

I don't think you got what I said... I don't have a reflection in the glass BECAUSE it is tilted. If you are more than 2,5 meters away from the glass you don't have to tilt it alot to stop seeing the reflection of the speaker.

Please define "a lot"............ a picture of what you're talking about would be even better...........

[Demor]

Sure, I'll post a picture if you want one, but I don't see the point. I know you understand the displacement of a reflection 2,5 meters away at 15 degrees. English isn't my first language so I hope you get what I'm getting at.

[Rod Gervais]

I'd love to see the pic - thanks