John Sayers' Recording Studio Design Forum Archive

I am ready to put in new windows for the control room, and vocal booth.
I have already made my window sills ready to install 2 pieces of laminated glass for each window, 1 sheet 3/8", the other 1/2".

Here is my question, and where it gets interesting...

I called my local glass man, and he called his supplier to get my 4 pieces of glass. His supplier is north of my studio, in the city of Seattle. This supplier told him that he has done many pro studio window installs, and that my design is "OLD SCHOOL", and that he recommends a new system comprissing of a single massive pane of tempered laminated glass that is multiple layers fused together, and a small air pocket in the middle, totaling a thickness of 1 3/8" thick. He says it yields better stc results than the typical 2 angled pane system.

Has anyone heard of this before? recommendations? give it a try?
I have alot of bookings stacking up, so I need to get rolling.

Thanks for your replies,
The Generator

There is nothing magical about window design. There are two main factors involved: mass and space. The more of each, the better the isolation.

It boils down to a question of

1) how much isolation is required to match the wall isolation;

2) how much space is available for the space between leaves;

3) what is needed in the walls to support the glass; and

4) cost.

On a space (thickness) basis, the guy is right. On a reality basis, no.

Transparently;
Andre

Thank for the reply. I can afford the glass. The issue for me is, is this idea of a SINGLE, 1 3/8"window comprised of the laminated layers & air pocket, as described better than going with the traditional 2 pane windowsystem comprised of 3/8" pane and 1/2" pane?

If not, then I will go the traditional 2 pane way. I do alot of drum tracking and the wall is a 12" thick,3 layers- 2 5/8" drywall with sound stop between, double leafed wall, floating.

Considering my wall construction, what would be the draw back besides basic cost?

Thanks,
The Generator

Tremendous overkill.

Glass is approximately 3 times as dense as gypsum wall, so you for a match you want 1/3 the thickness of gypsum in each leaf.

do alot of drum tracking and the wall is a 12" thick,3 layers- 2 5/8" drywall with sound stop between, double leafed wall

If I am reading your post correctly, which is hard, your wall construction going from room to another is something like

5/8 gypsum
sound stop (whatever that is)
5/8 gypsum
stud
stud
5/8 gypsum
sound stop (whatever that is)
5/8 gypsum
5/8 gypsum

So, the 3/8 pane in the first leaf and the 1/2 in the second will match very well.

Go beyond that and you will be getting the sound through the walls.

BTW a 1 3/8" window will have worse isolation than the spaced system described above.

Clearly;
Andre

Gen, the thing to remember here is that STC is ALSO "old school" as far as REAL isolation goes - it's based on speech isolation, NOT music, and as such is biased to a center frequency of 500 hZ - for drum isolation, what you need mainly is low frequency isolation. The physics of sound isolation haven't changed "schools", what works is mass and distance - so if you put your glass in as Andre reccommends, you'll have a LOT better LF isolation than any 1-piece "Thermo-pane on steroids" system that only has a total thickness of 1-3/4" -

About the best STC you'd get with a total thickness of 2 panes plus air gap that = 1-3/4", would be STC 38 figuring standard plate glass; laminated would up that by maybe 3-4 dB, I don't have a way to calculate that - at 50 hZ, your TL would be about 30 dB, with a worst case dip to 28 dB @ around 80 hZ - not too impressive for drum iso...

Now, if you take those two pieces of 3/8 and 1/2" glass, and put them 10 inches apart (don't tilt either one unless you have to for glare purposes, or perhaps for sound REFLECTION control within one of the rooms) you'd end up with STC 49, with a low of 38 dB @ 63 hZ -

Now, factor those #'s up a few dB for using laminated instead of plate glass, and you've got a decent amount of iso for drums - and believe me, you'll notice the difference of 10 dB or more. Just remember that the SMALLEST air gap in a splayed glass window is what determines the TL at low frequencies, along with the mass of each pane - so if you tilt one or both glasses, you will reduce this iso noticeably.

Be sure to vent the middle of your windows using rockwool or rigid fiberglass around the gap between frames; this helps kill some flutter between panes and generally helps TL of the wall/window system... Steve