Ceiling construction on double wall help please

[yofreshh]

Fellas,

As of this moment I'm building a new studio in my house in Amsterdam ( 4.8 x 3.6 x 2.2m ), I choose for the double wall construction. I'm building it in this order:

2layers drywall on the outside and 2 on the inside, 2.5cm air in between and off course a double 5x7cm wooden frame with the wright rockwool in between. Trying to get that STC rate of 60+

I understand all the constructions for the cornering, doors, windows, floors thanks to this great forum !!!
I only have one problem or question:

Since I have 2 walls, should I also make 2 ceilings? Since the walls may not, in any way, touch each other?? Can some one please make a drawing which illustrates my problemm I can not seem to find a solution on this forum ( I'm sure it's there..... but... )
Or does this work the same way as the floor, since the 2 walls are also on the same floor, can they also share the same ceiling?

many many thanks!!

-- Yofreshh

[Dan Fitzpatrick]

yes, you want a double ceiling as well.

the floor is more complicated, because it's impossible to have a double floor where the two sides (leaves) don't touch in some way ... you need to give more details about the existing construction where you are planning to build this.

[yofreshh]

Dan,

thanks for replying so fast, the situation I'm in is as follows:

The studio is going to be build on the ground floor, this is solid concrete, I have 2 neighboors on both sides ( real nice people..
Upstairs are my own bedrooms and I have nothing under me, so these are not the problem.
I want to make a floating floor on the concrete floor and build a double wall construction on that floor.
Nothing is touching any thing of the surrounding existing walls, so realy a room in a room. ( so with the double wall construction and ceiling this actually would be a room in a room in a room ??? )

So the double ceiling is really necessary, actually a ceiling on each wall? ( outside and inside )


thnx

[Dan Fitzpatrick]

no you wouldn't build the double wall on top of a floating floor. only a single wall (single leaf) and single ceilign (also single leaf). the existing walls and ceiling in the room would be modified to become your outer leaf.

i don't have too much time to explain it right now ... you should read up on the basics that are at the top of the construction page, that will help get you going.

[Dan Fitzpatrick]

also it's not a given that you want to float the floor. that is something to decide after careful study and weighing the pros and cons. you have a concrete floor to start with, which is already a pretty poor transmitter of low frequencies. you might focus your efforts on doing incredibly kick-ass walls and ceiling instead.

something to be aware of anyway

[yofreshh]

Dan,

I just build a floating floor in the room, now here's the thing. I have a big stereo in the kitchen which is next to the room I want to build my studio in. When I play loud in the kitchen, the bass is not felt on the concrete floor in the studio room, but when I step up the floating floor ( which is on rubbers , wood and mdf plates with isolation in between ) I feel the bass rumbling under my feet !!??
This is not a good thing wright, so it's better to build the walls direct on the concrete floor itself ?

-- thnx

[Dan Fitzpatrick]

the worry of something like this is what kept me from floating a floor. i chose instead to just use the concrete as my floor. concrete already isolates low frequencies fairly well.

it would be helpful to have some details on your floor.

how large is the airgap, how much insulation if any,

how thick and what materials is the top of the floor, etc.

what kind/ how thick is the "rubber" and how much is it compressing now that your floor is on.

a sketch would be good too.

however, without having any details i can tell you in general that two things that i may help with this probem (besides removing the floor). one, add more layers to the top of your floor. adding mass to the skin of the floor will lower the mass-air-mass frequency, if that is the cause of the resonance.

also, you want to add mass to the structure that is "floating" on the rubber. this can be in part from the extra layers of skin but also from the walls and ceiling that should be floated on the floor. however if you have not built your floor strong enough this may not be possible.

i hate to tell you, but it's possible that this may not be fixable ... you may have done this really wrong. it's hard to say without more details. you may just need to start over. i just gave you those tips above to give you some idea of what MIGHT help.

[len-morgan]

I just build a floating floor in the room, now here's the thing. I have a big stereo in the kitchen which is next to the room I want to build my studio in. When I play loud in the kitchen, the bass is not felt on the concrete floor in the studio room, but when I step up the floating floor ( which is on rubbers , wood and mdf plates with isolation in between ) I feel the bass rumbling under my feet !!??

I think what this means is that the calculations for the floating floor (or the variables you plugged into them) are wrong somewhere. You should know that you can't just laydown some kind of rubber/neoprene, lay a wooden frame on top of it, cover it with plywood and have a functional floating floor. The calculations are quite extensive and you need to account for the shape of the rubber, the weight that the floor will hold (and where will it be on the floor (i.e., if you build walls on the them, more of the weight is on the edges of the floor than in the middle so the distribution of rubber is different on the edges than you would need in the middle.

The second "problem" I see is that is sounds like you really ARE building a room-in-room-in-room (the outside room is the room the studio is being built in). If you build it this way, you are going to get LESS isolation than if you only built one new wall inside your house.

You need to STOP RIGHT NOW and do some research (this site and others) on "triple leaf walls" and read some of the contruction "diaries" here before you do any more work. It sounds to me like if you continue on the road you're on, you're going to spend a lot of money, loose a lot of floor space, and not get anything close to the results you need and want.

len

[yofreshh]

Len

wow, that's new to me, are you saying that my existing house walls ( which are all solid concrete around the room ) allready function as a soundproof part? Is this enough allready?
I really want to build a studio in which I can work late ( ok, who doesn't ), without disturbing the neighbours. I have a small studio upstairs right now which is allright but too small and too noisy after ten p.m.

So what are you saying is the best in my situation, a single stud tripple leaf wall, inside my room? I'll post the situation.

The original ceiling is concrete and the floor also, so are the two walls to the neighbours.

The top drawing is the intension I have with the room , since i have to keep the access to the garden. The Control room itself measures 3.6m x 4.8m.
The ceiling of the room is 2.45meters

cheers,

[len-morgan]

wow, that's new to me, are you saying that my existing house walls ( which are all solid concrete around the room ) allready function as a soundproof part? Is this enough allready?

That's not quite what I'm saying. It is obviously NOT soundproof enough. Please read the very first thread in this category and READ ALL the references there so that you can learn a little more about the science of accoustics.

So what are you saying is the best in my situation, a single stud tripple leaf wall, inside my room?

NO NO NO. You NEVER want to build a triple leaf wall system. If you do, you might as well knock down the cement walls you have! You haven't really provided us with enough information to help you beyond the basics. If you read the first thread as I suggested ("Don't even think about posting...") you will see there are several questions that we (or anybody else) needs answers to in order to help you better.

As real quick guidance, you want your cement wall to be on leaf and then you will build a new wall inside of that, that is "open" in the back and has at least 2 layers of dry wall on the INSIDE of this wall only. Nothing on the back. You want as large a gap as you can afford (measured from the cement wall to the back of the first layer of dry wall) but anything more than 12" or so won't buy you much. You need to put insulation between the studs of this wall before the drywall goes up and use wire or string or something to hold it up (or just friction if it's wide enough). You'll put ceiling joists on this new wall so that none of your new wall/ceiling system touches the structure ANYWHERE with the possible exception of attachment to the floor.

Now, go read the material I've referenced and you may even be able to answer a lot of your own questions. If you can't, we'll still be here.

len

[yofreshh]

Len,

I'm a dutch guy so excuse me for my English , but what do you mean by " you want your cement wall to be on leaf " ?
As you can see by the drawing of the room, there's is a large open space on the left side of the room, this is partially an open hallway to the kitchen and partially open stairs to the first floor. ( see new drawing ) I've been reading this forum for almost six weeks now and there is an enormous amount of very good info stuck in my head now. But what I need is someone who tells me in a simple way ( maybe with a simple drawing ) what to build for the best result.

Say I build the control room with the wall thats open on one side ( as you recommend ) then what happens to the left wall, should there not be another wall again with the double gypsum on the outside?

cheers, Y

And which walls should be on leaf, the entire back and front walls ( to the neighbours )?

[len-morgan]

'm a dutch guy so excuse me for my English , but what do you mean by " you want your cement wall to be on leaf " ?

Your English is forgiven - In this case it was a typo on my part. It should be "one" not "on."

len

[yofreshh]

Len

something like this? The pink wall is a leaf against the concrete walls and the pink wall crossing the room is a wall with the leaf on the outside of the frame ( open back ), insulation in between.

The orange wall is the inner control room wall, with the leaf on the inside ( open back ) on wich I lay the ceiling, correct?

About 3 inch of air between the walls.

[knightfly]

http://www.johnlsayers.com/phpBB2/download.php?id=5061

Between you and the world (people you don't want to hear you) you need mass, air(or insulation) and mass. No more, and no less. When you add another air gap of any kind (insulation, the proper kind, is considered "air") you will WORSEN the isolation of sound.

So if you already have concrete walls, THOSE are your first "mass" - all you want in addition to that is a SECOND mass, with air/insulation BETWEEN the two masses.

If you're building a floated room, the floor should have enough insulation between inner and outer mass that the insulation gets slightly crushed - otherwise, the inner floor is NOT DAMPED and will ring at it's resonant frequency (and harmonics) -

Here's an example of multiple practice rooms, but same method -

http://www.johnlsayers.com/phpBB2/download.php?id=4141

HTH... Steve

[len-morgan]

yofreshh,

The only part of the pink wall you might want to keep is the vertical part. As Steve said, the cement wall just as it is will be your outer leaf. Don't do anything else to it or isolation will suffer.

You could move your left side vertical orange wall out to where the vertical pink wall is now. This will give you more floor space. The only thing you will give up is the double door leading out to the rest of the apartment. If you make this an RGD ("Really Good Door"), you should be ok.

len