John Sayers' Recording Studio Design Forum Archive

Does the control room glass need to be laminated or can i get tempered? I know it needs to be 5/16ths and the other 3/8ths minimum .

And does the glass have to be angled? Im getting conflicting answers in the searches I've done.


Thank You.

Anyone ?

Laminated is better, but more expensive. Tempered is fine if you want to save some money.

I know it needs to be 5/16ths and the other 3/8ths

How did you determine that? 5/16ths would be right for a leaf with one and a half layers of 5/8" drywall, assuming it is laminated glass. How thick is your drywall on that leaf?

- Stuart -

Im going off the recording manual

WINDOWS AND DOORS
Windows and doors require special construction because no matter how much you seal your walls if the windows and doors aren't built correctly your isolation will be ruined. The main thing with windows is that they must have the following features:

Different Glass Thickness. It is essential that the two sheets of glass be different in thickness. I recommend that you put the thicker of the two panes on the control room side. The thicker the glass obviously the better the sound isolation plus the thicker glass has a lower resonate frequency. Unfortunately thick glass is expensive. I would suggest you try 8mm and 10mm glass. (5/16", 3/8"). Any thinner and you are going to start getting resonate frequencies from the glass and inadequate sound isolation.
Angles. The two sheets of glass must be at an angle to each other else the two sheets will interact in a resonate sympathy and the sound reduction properties will be reduced. You can angle the glass as in the following drawing but don't forget that the glass can also be angled in the horizontal plane as well as the vertical plane.

My walls are 5/8ths plus rockwool Staggered Studs, 5 1/2 inch air between the drywall. The window air gap im also trying to determine.

Thank You

Exactly. Like John says there, that's the minimum thicknesses that you would want, and thicker is better. The way to determine how much you actually need, is to make sure that the surface density of your glass is the same as the surface density of the rest of the wall. So if you have more layers of drywall, then you need thicker glass to maintain the same surface density across the entire wall. In your case, if you are using only one single layer of 5/8" drywall on each leaf, then then those numbers are fine. If you use more than one layer, you'd need thicker glass. Rule of thumb: Glass is about three to four times the density of drywall (very rough), so you need glass that is about one third the thickness of your wall, or thicker.

Also, John no longer recommends angling glass for acoustic reasons: "... The two sheets of glass must be at an angle to each other". More recent research has shown that it is counter-productive for isolation, since the side where the glass panes are closer together will have lower isolation and higher MSM resonance, due to the reduced air gap.

John wrote that manual a long time ago, and it has not been updated.

Here's a post from a couple of years back where John mentions this:

http://www.johnlsayers.com/phpBB2/viewt ... it=#p99679

You might still need to angle glass a bit to avoid light glare, but it's better to plan your lighting carefully so that no glare is possible. If you do angle it, then you should increase the air gap and thickness of the glass to compensate for the lost isolation.

The window air gap im also trying to determine.

It should be at least as deep as the gap between the drywall leaves, and more if you can. Windows are a weak spot, so it pays to "hedge your bets" a bit, and increase the air gap and/or glass mass (thickness), if you can.


- Stuart -

Thank you so much for clearing that up. I did search and didnt see this level of clarity. Thank You

that is good to know!

I use the recording manual on here as a reference constantly, is there anything else that we should be aware of? Anything where further research has shown otherwise?

I use the recording manual on here as a reference constantly, is there anything else that we should be aware of? Anything where further research has shown otherwise?

Probably lots of things by now! That's why it is important to stay up to date on advances in acoustics: It is a relative new science, and progress is being made all the time.

One other thing that might have changed is the recommendation for floating floors. This is how it stands today:

http://www.johnlsayers.com/phpBB2/viewt ... f=2&t=8173
http://www.nrc-cnrc.gc.ca/obj/irc/doc/p ... /ir802.pdf
http://www.johnlsayers.com/phpBB2/viewt ... f=2&t=8134
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=8135)

That's the other "biggie" that comes to mind, but there might be more.


- Stuart -

Mr. Stuart Soundman2020

You are quite awesome as well as a very patient person. Not only has this forum been a boon for me, but your wisdom and help has shown me the light on several things. Sorry to hijack this thread, but again THANK YOU SOUNDMAN2020!

You're embarrassing me!

- Stuart -

I think my biggest problem right now is flanking on the ceiling... I have a large gable roof above the ceiling and it is insulated with standard tempature insulation. But I dont want to do much ceiling work so Im going to try it out first.

I would think that if you needed it later on, a layer of 5/8" drywall and some greenglue would definitely help out on the ceiling. Looks to be a great little space!

I wouldn't be sure that the extra ceiling drywall would overcome the flanking connection that you have with the new wall framing attached directly to that ceiling.

But I dont want to do much ceiling work so Im going to try it out first.

So what's teh plan if it doesn't work? As RJ said, adding mass to that ceiling is not going to help with the flanking.

It seems to me that you only option if it doesn't work out, is to tear down the walls again so you can decouple them properly from the ceiling, then take out the ceiling and decouple that too, then put it all back together again. Seems like a lot of extra work. Wouldn't it be better to fix that now, before you get too far?

- Stuart -

Perhaps a layer of insulation, neoprene or foam strip sandwiched between the top of the wall and ceiling (well caulked afterwards) may give enough decoupling - similar to decoupling a wall from the floor.

I don't see how that would help, either for the floor or for the ceiling. You still need to nail, screw or bolt through the neoprene in order to provide the necessary structural integrity, and the nails, bolts or screws once again create direct flanking paths. That is only useful if you also use properly isolated and decoupled bolts, but in order to do that you'd need access to the other side of the ceiling anyway.

The other possibility is to use proper isolated sway braces on the tops of the walls, but here to you'd need access to the other side of the ceiling, in order to attach them.

- Stuart -