Questions regarding a wall

Hello peps, I've just written contract on a 100 square meter place allready divided in 26 resp 73 square meters with a 16 cm thick brick wall. I'm planning on having control room in the 26 sqmeter room, and there is a door between the two rooms in the brick wall, i'm also going to put a window between the rooms. Now I wonder, is it necessary to increase the wall or is a massive brick wall of 16 cm(about 6 inches) thick enought to isolate the rooms from each other? Will I be able to install 2 layer window without increasing the depth with satisfying results? Can I achieve enought satisfying results with just one door, as(I guess) the wall is too thin to install 2 doors? Otherwise i'm planning on installing another gypsum wall with an airgap between it and the brick wall, making it at least 30 cm thick, but this will be rather complicated due to the conditions in the room. What do you guys think, will I need the more space and isolation of another wall with 2 doors and bigger air gap for window, or will it be enought with just the concrete one? Thanks a lot! Ossian

I dont think it will be enough, since rooms are coupled. You need to go for Mass-Air-Mass, in al 6 (or 5) sides

If you still decouple 1 out of the 2 rooms, that might be enough. Can you do any testing now? Take a snare and kick drum into the room?

lilith_envy wrote:

If you still decouple 1 out of the 2 rooms, that might be enough. Can you do any testing now? Take a snare and kick drum into the room?

Not preserved: Thick walls.jpg

Can't really do any testing, as there already is a thinn door(which I should replace) and a whole for the window. Is the attached picture so called decopuling? why will I benifit from this compared to just build a wall on the side towards the studio room? Thanks

You need all walls to be decoupled,not just the wall towards the other room

Is the attached picture so called decopuling? why will I benifit from this compared to just build a wall on the side towards the studio room?

If you just build a single wall between the rooms, it would have to be directly attached to the existing walls and ceiling, so therefore sound will flank around it. It will not isolate. In order to isolate, you have to decouple completely, which implies building a "room within a room", as in Lilith's model. Like Javier said: No mechanical contact at all between the inner "leaf" of the wall, and the outer leaf. The same applies to the ceiling. The inner ceiling rests only on the outer walls. No contact at all with the outer "leaf". Anything less wont work. - Stuart -

So to my understanding, the coupling in the intersections between the planned new wall and the already build brick walls will make the wall useless? is the resonance going to be that big, making the new wall useless? I've illustrated the place in a pic included. http://img13.imageshack.us/img13/497/studion.th.jpg The small area will be control room, the large studio room. All the thick lines is 5 inch thick brick wall. The "dotted" line is where i was planning to put another wall up, will this not work for isolation between the two rooms? Will the 5 inch brick wall not isolate enought for the isolation to be accepted with another 3 layer single leaf drywall? I'm planning to use two doors and a dual window design between the rooms. Thanks a lot for the help Ossian

is the resonance going to be that big, making the new wall useless?

It's not the resonance that causes the problem: It's the coupling. The side wall and ceiling are in common to booth rooms, so there will be direct transmission of sound through the structure of the building itself, which will "flank" around your dividing wall. Put your ear up against that existing wall, close to one end of it, and get somebody to tap on it sharply with a hammer, close to the other. You will hear the tapping coming through the wall itself, not through the air. The vibration is conducted along the structural members of the wall. If you build a 2-leaf divider wall between the rooms, then the leaves will be directly coupled to each other bu the existing side walls, and the floor, and the ceiling. Sound waves will make one wall vibrate, that vibration will be directly transmitted through the structure to the other wall, which will vibrate too, thus transmitting the sound into the room. In order to prevent that from happening, you have to "de-couple" the walls completely, such that there is nothing in common between them. No mechanical links at all. In order to do that you need to build a "room within a room" for at least one side. Resonance won't even come into the equation until you decouple, since it will be insignificant compared to the flanking. And if you build your walls correctly, the resonant frequency will be so low that it won't matter, and it will be damped so well as to not be a problem anyway. Provided that you decouple everything, of course. - Stuart -

Listen up - the easiest way to picture what they mean by the coupling problem is this...... stand in a room - one foot from a wall and put your ear up to a glass - what do you hear through the glass? Squat - nadda - nothing....... Now - take that same glass - and hold it up to your ear - place it then up against a wall where you can barely hear 2 people talking on the other side - what do you hear? - Clean and clear voices that you can understand........ Don't touch the wall = uncloupled = no transmission - Touch the wall = coupled = everything passes through........ Easy enough to understand....... Rod

rod gervais wrote:

Listen up - the easiest way to picture what they mean by the coupling problem is this...... stand in a room - one foot from a wall and put your ear up to a glass - what do you hear through the glass? Squat - nadda - nothing....... Now - take that same glass - and hold it up to your ear - place it then up against a wall where you can barely hear 2 people talking on the other side - what do you hear? - Clean and clear voices that you can understand........ Don't touch the wall = uncloupled = no transmission - Touch the wall = coupled = everything passes through........ Easy enough to understand....... Rod

Thanks Stuart and Rod for the illustration, I just tried this in the rooms on the walls, and the intersecting walls did not pass anything that was created in the wall with the window and door. So I guess as long as the wall doesn't touch the paralell wall, it will be fine? Thanks

At Trafalgar studios we were next to a classic terrace house - I asked the owner one day if they heard the sounds we were making and she said- only if I put a glass to the wall and listen through there. I had 24 piece bands playin on the other side of that wall and thunderous guitar amps roaring at 3am.

John Sayers wrote:

At Trafalgar studios we were next to a classic terrace house - I asked the owner one day if they heard the sounds we were making and she said- only if I put a glass to the wall and listen through there. I had 24 piece bands playin on the other side of that wall and thunderous guitar amps roaring at 3am.

Now thats a rather sturdy wall :) I've made some more research, and to me it seems just one of the wall sides(of various reasons) is conducting the sound inducted in the wall on the live room side, which makes it 1/4 of the frame will conduct sound to the new wall, will this make the wall useless? Is there any effective way to reduce these vibrations to the frame/wall? Fiberglass? Rubber? Caulk?