brick wall options...which one?

jtvrdy · Post by **jtvrdy** » Thu Sep 11, 2003 8:43 am

Hi,I'm planning to build a studio, on the outside the max permision is 45dBA so I need a very good isolation.
which one of these wall options is better for isolate ? or other idea ?

http://www.mamaproducciones.com/vaporst ... ages/A.jpg
http://www.mamaproducciones.com/vaporst ... ages/B.jpg
http://www.mamaproducciones.com/vaporst ... ages/C.jpg

thanks,

knightfly · Post by **knightfly** » Sat Sep 13, 2003 1:12 am

Josep, I would go with the second drawing - for most efficient use of materials in wall/ceiling construction, you want ALL the mass to be in only TWO leaves, with as much air space as you can spare between the two. A leaf is defined as a center of mass, made up of any number of layers, as long as there's no air space it is still ONE leaf.

I would also put as much insulation (spun fiberglas) as you can afford or fit between the two brick leaves; it will help sound proofing by about 12 dB over just plain air.

If possible, you should also "render" both sides of the outer wall before building the inner one - Then render the inside of the inner wall as well. Rendering means plastering over the bricks with about 12-13mm layer of plaster/mortar. Bricks tend to be kind of porous, so the rendering will improve sound isolation by several dB. Between the insulation and rendering, you should gain at least 20 dB over plain, un-rendered brick walls with no insulation.

With the mass of those brick walls, low frequency isolation should be several dB better than with just multi-layer drywall... Steve

jtvrdy · Post by **jtvrdy** » Sat Sep 13, 2003 9:33 pm

sorry I forgot in the drawing...the outer wall is already rended on both sides and yes the inner wall will be redered inside also.
with this second option and without insulation how many dB of reduccion I will have ?
and with 80mm of fiberglas on the outer wall inside the air space?

thanks,

knightfly · Post by **knightfly** » Sun Sep 14, 2003 2:01 am

Josep, I don't have exact figures available on double brick walls that have been laboratory tested - the only thing I can go on is this -

http://www.saecollege.de/reference_mate ... 0Chart.htm

A single, rendered brick wall tested at STC 45, and your brick are slightly thicker - I estimate maybe STC 48 for one wall, + 6 dB for doubling the mass, + about 8-9 dB for the air space and the same for insulation - I'd guess you're looking at about 68-70 dB if you use great care in building, getting everything hermetically sealed.

Please keep in mind, though, that there are a LOT of variables here - any ONE of them chosen WRONG, and it screws up the whole thing... Steve

jtvrdy · Post by **jtvrdy** » Sun Sep 14, 2003 10:48 am

ok

if I need to put a window on this wall ,with 10 and 8mm glass I will respect the 68-70dB reduction ?

and for the floor,instead of using fibergals as a insulation can I use fine sand that have density and don't transmit vibrations?

knightfly · Post by **knightfly** » Mon Sep 15, 2003 12:38 am

"with 10 and 8mm glass I will respect the 68-70dB reduction ?" -

Sorry, no way will you be able to get that high isolation when glass is involved - check out this professional studio design/construction site's page on glass and you'll see what I mean -

http://www.wsdg.com/resources/resour.php?SL=te&BL=2

-they're specing 1" laminated single glass (25mm!) at not quite 40 dB, so two spaced panes might reach 56-58 dB, and would cost about $1500 to $2000 for a 1 meter by 2 meter double glass studio window, just for the glass with no frame... Steve

jtvrdy · Post by **jtvrdy** » Mon Sep 15, 2003 4:18 am

thanks for the link very interesting

so I need to increase the separation between the two glases...

do you know the formula to calculate the necesary separation between two leaves with a known STC to obtain one desired total STC ?

knightfly · Post by **knightfly** » Mon Sep 15, 2003 2:31 pm

Josep, first of all I'm not sure from your questions, but I really HOPE that you're not trying to get the isolation from your neighbors AND still have an outer wall with a WINDOW in it? You do realize that STC takes NOTHING into account below 125 hZ, and that going by STC ratings you would probably need about STC 90 or 100 in order to keep noise below 45 outside when playing drums inside?

That said, here's a helpful calculator (download it, then double-click the .exe file to run) - the demo is free, not sure what the real thing costs.

http://www.insul.co.nz/download.html

I just found this and havent had time to play with it yet, so you're on your own with it... Steve

jtvrdy · Post by **jtvrdy** » Tue Sep 16, 2003 8:01 am

thanks for the calculator I'm playing with it....really good

I will try to draw what I'm thinking

jtvrdy · Post by **jtvrdy** » Wed Sep 17, 2003 4:41 am

the cost of the calculator is 1000€+VAT

well ,if we only take a single brick wall with window like this:

the red represent a single 140mm brick wall (STC54)and in green the double glass with 10+6 separated 240mm(STC50),we have a "similar" reduction also at low frequences!

so if I double this wall at 250-300mm I will obtain a good total reduction.

knightfly · Post by **knightfly** » Wed Sep 17, 2003 1:44 pm

Josep, is that going to be the wall between control room and tracking room? Should work pretty good.

I figured that the full version of that calculator would be expensive - otherwise, there would have been a price and a "buy it" button on the site... Steve

jtvrdy · Post by **jtvrdy** » Thu Sep 18, 2003 6:55 am

between control room and tracking room I will have TWO of them separated 300mm,you could see it on this drawing it is only a initial sketch...

knightfly · Post by **knightfly** » Sun Sep 21, 2003 11:58 am

"between control room and tracking room I will have TWO of them separated 300mm" -

Josep, is this what you mean? If so, don't start construction yet, please... Steve

jtvrdy · Post by **jtvrdy** » Mon Sep 22, 2003 5:12 pm

yes this is,
remember that the two panes on the wall are tuned to similar reduction as the brick wall(above graph)in order to have a more homogeneous reduction as the wall,then I now could consider wall+air+wall (medium mass+air +medium mass) because I can't separate the air for the brick and the glass.
I 'm not sure if this is correct.....??

knightfly · Post by **knightfly** » Mon Sep 22, 2003 7:55 pm

Josep, this is more what you'd want to do here - run the 600mm dimension through the Insul calculator with 6mm and 10mm glass; any time you use more than two leaves, even glass, in a wall, you LOSE... Steve