Question on Glass thickness to match brick waall density

Hey guys just had a quick question relating to the thickness of glass that i would require for my control room window. From what i gather the thickness of at least one layer of glass should match the density of the wall construction. Please correct me wherever i am wrong. So a single leaf of my studio wall should have roughly a density of 2000kg/m3 as it is a 3" thick Brick wall with one side plaster and cement putty. what would be the thickness of glass required for my controll room window. Obvioulsy its a double leaf wall with the same dimension as above for both the walls so id greatly appreciate some advice on the thickness and kind of glass required to build my studio window. Here is a link of the glass that i might be sourcing for the windows. http://www.aisglass.com/ais_acousticglas.asp Do let me know wht u think ?

Easy, glass has a density about the same as brick has. That means, your class thickness should be equal to your brick thickness. WOOOOT?! yup, that's a whopping 3" laminated glass piece there! (a laminated pane can me multiple pieces of glass seperated with foil, ask your dealer). It's gonna be expensive. :( The link to your dealer to be seems fine :)

umm yea i think it is gonna be extemely expensive :shock: :( . I mean u reckon i need 3" thick glass. Cause i dont think ive really seen any studios with glass that thick for their controll room windows. (Or maybe i havent seen too many studios) any suggestions on wht is the least amount of thickness off glass i could use. Id obviously be using the usual method of two panes with variable thicknesses at a slight angle but really ????? do i need to get 3" thick laminated glass ?? Thanks for the help guys ?

Id obviously be using the usual method of two panes with variable thicknesses at a slight angle

You don't need the "slight angle" for acoustic purposes. Acoustic myth. It wont help. Angling might help for visual purposes (reducing reflection of room lights, equipment and people in the glass), but it does nothing for isolation of acoustics, and in fact will REDUCE your isolation. Not sure about thickness, but 3" sure does sound like a lot! What are your overall target numbers for isolation? That will help dictate the thickness that you actually need. It makes no sense to have a fantastic STC-60 window if you have an STC-30 door, wall or ceiling somewhere as your weak link. That would just be a waste of money. Most people here go for thinner glass. Search the forum for keywords like "window" and "laminate glass". You should find many threads showing what others have done, and how successful they were. Do you have Rod's book? Check the chapter on windows. 3/8 and 1/2 are two numbers that come to mind. - Stuart -

If your wall is brick, and you wanna have a window in it. Yes, it needs to be 3". Else it'll be your weakspot. Seriously, you have a brickwall between CR and LR ? Acoustically it would have a little advantage concerning reflections... but not worth mentioning.

If your wall is brick, and you wanna have a window in it. Yes, it needs to be 3". Else it'll be your weakspot. Seriously, you have a brickwall between CR and LR ?

Not when he has a single leaf wall. In the case of a single leaf brickwall he can also go with 2 pieces of glas with an airgap between, same like a drywall 2 leaf system, to gain his TL. When he has a 2 leaf wall with both sides of these thick brick, than he has to ask himself if he realy need this amount of isolation......^^ PS: normal floatglas has a destiny of 2500kg/m³ which is 500kg/m³ more than his brick. cheers Mika

Allright guys thanks for all the info. Am doing my bit of reading up. Just to give a more visual idea of wht im talking about. Here is an earlier pic of the wall while it was being built. Pay no attention to the thicker left side as those are the pillars to support the door frame. therefore thicker than the rest of the wall. The right side is where the thickness is visible for both the walls (about3") and that is the spot for the window. The rooms are now built and the window frames have been installed (Seperate frames for each wall). Ro - to answer you question, and also Mika's, yes all the walls in the studio are double leaf 3" thick on each leaf brick and mortar with a facing of plaster and now waiting for a coat of white cement Putty. The 2 rooms (Control Room and Booth) are identical in dimension and are built on seperate isolated concrete floors. So i think i might have made things clearer now and hopefully not more confusing. Hopefully the pic will help. Now let me know ppl if i can use two layers of thinner glass in each frame also wht thickness would be ideal. Ill try and get pic of the walls with the frames in it. Cheers

After we know your wall design, i have to agree with Ro. You need one piece of glass per leaf which matches the same mass like the leaf itself, to get the same amount of isolation. After we know that your brick has a mass of 2000kg/m³ and floatglas has 2500kg/m³ you will end up with a glassthickes about 80% of the brick thickness. You have 2 leafs, so you need 2 pieces of this thick glass :wink: Do you realy need this amount of isolation? cheers Mika

yes all the walls in the studio are double leaf 3" thick on each leaf brick and mortar with a facing of plaster and now waiting for a coat of white cement Putty.

Wow! OK, so it seems like you really do need two panes of 3" thick glass, if you want to retain the same level of isolation that the wall is giving you. That is not going to be cheap, but it sure will give you great isolation! However, I do see a door in the same wall as the window... The door and window connect the same two rooms, right? So that door is going to be your weak point. What are your plans for that door, and what level of isolation is your target there? Once again, if the door will only give you STC-40 (for example) then there isn't much point in going for STC-70 windows (I have no idea if two panes of 3" laminate glass will get you STC-70: just guessing wildly). - Stuart -

wow. now thats smething i hadnt planned on befre getting into this. The reason for the Brick walls was not for extremely high levels of isolation but because here in India Brick and masonry walls are the preffered method of building and the workers here are more accustomed to this method. So i chose this over Gypsum and woodframing. (though that is wht i will have for my ceiling). Again i am not looking for massive levels of isolation but i am looking for good enough isolation so as to achieve clean recordings without any leakage between the rooms. There will be the occasional Drums that i will record there with various other Indian classical instruments and other ethnic percussions etc as i work a lot on fusion. Some horns and Sax. So i need to be able to retain those sounds within the rooms. I really didnt think id need to go with such thick glass and am not sure tht i would be able to fit it into my budget. :( As for the doors i plan on making solid core wood doors about 2 inches of ply wood is wht id be using there. Double doors with a gap of about 1 and a hlf feet between them. might use 2 layers of plywood with a thin layer of celoflex inbetween (to dampen any vibration tht might be caused) between for the door construction. Here is a link again to the kind of glass i wanted to buy for the windows http://www.aisglass.com/ais_acousticglas.asp But if i really have to go with much thicker glass id probably not go with this particular variety as it seems roughly 8 - 10 times the price of normal float glass for the same thickness. Thanks for trying to help me with all this guys . Hope someone can help me come u with a solution for thewnidows. Cheeers guys

Hey Ankit, OK, so if all you want is to get good isolation, and you don't need the same level as your wall, then I reckon you could go with the design that Rod discusses in his book: Two panes of glass, separated by several inches, one pane is 3/4" laminate and the other is 1/2" laminate. Build it like Rod's book outlines, and it will work fine. - Stuart -

3" is a lot, indeed. But to match your wall (which was your question) you need it about that thick. By seperating the glass into 2 pieces with air in-between you still need to match the density of brickwall. I know it's expensive... but it WILL give you descent isolation :)

thanks a lot stu and ro for being so helpful. I guess im gonna take a lil of everyones advice, follow rod's book for the design and try and buy the thickest laminates glass i can afford at the time and move on from there. You guys have been great as always. Hres a link to my build thread if anyone is curious and ill be updating it soon with pics (as soon as i like how things are looking :P) and more questions. cheeers brothers :)

No worries :) ps. the link's miss'n

sorry . That was quite stupid. heres the link. viewtopic.php?f=2&t=11498 ALso while im back here. I found out wen id gone to inquire about the glass that there was a procedure that was usd here according to the glass dealers, for acoustical purposes, where they used two sheets of 6mm glass or more which is sealed leaving a small gap in between which is basically vaccum and using this method they say they can give me whtever thickness panes i want. So basically it would be something like one pane = two sheets of 6mm or 12mm glass with say another 12mm of vacuum in between this would effectively give me one leaf of my window. so if i used this method and ive tod hahad both my leaves made out of this sort of a pane would it be a good or bad idea according to you guys. Is this a practised method of making windows which is known of and called something or was the guy basically bullshitting me?? Also my other option would be, if i needed glass tht was atleast 1" thick then id have to go for normal non laminated glass as the shops here apparently say tht they dont recieve or keep laminate glass in that thickness. Any posssibilties here ? Thanks

ganeshaa wrote:

ALso while im back here. I found out wen id gone to inquire about the glass that there was a procedure that was usd here according to the glass dealers, for acoustical purposes, where they used two sheets of 6mm glass or more which is sealed leaving a small gap in between which is basically vaccum and using this method they say they can give me whtever thickness panes i want.

according to the galss dealer.. does he have any knowledge on acoustics? Mostly the argument is "it works". Hmm, yeah. well. How do you know? And is it the best solution? etc.

So basically it would be something like one pane = two sheets of 6mm or 12mm glass with say another 12mm of vacuum in between this would effectively give me one leaf of my window. so if i used this method and ive tod hahad both my leaves made out of this sort of a pane would it be a good or bad idea according to you guys. Is this a practised method of making windows which is known of and called something or was the guy basically bullshitting me??

Depends, if you have a one leave wall then yes, this might work. If you have two walls (leafs) you need 2 glass leafs as well. Then this is not a good idea.

Also my other option would be, if i needed glass tht was atleast 1" thick then id have to go for normal non laminated glass as the shops here apparently say tht they dont recieve or keep laminate glass in that thickness.

The fun thing is that laminated glass are just multiple sheets of floatglass put together with foil in between. It can be, theoretically, as thick as you want. Find a good glass dealer who can deliver what you ask.