A couple of questions...

Hello, first off I want to apologize for those newbie questions, but anyway I guess it's important stuff so here it goes :) 1. What's meant with "mud and tape", regarding drywall assembling? Also how am I supposed to install the foam backer rod in the perimeters? Is it a bad idea to just caulk under(if facing floor) every drywall sheet instead of using foam backer rods? 2. According to some guy's(Rod, doesn't have the book by the way) book, on page 62 he says: One point I want to be sure you get is that there is no advantage to using isolating clips or resilient channel with a true double wall assembly. Don’t waste your money by thinking that more is better in this case. I'm going to build a 2 leaf wall, one of them is already installed(brickwall) and the other one is going to be a framed drywall(2 or 3 layers) and i'm thinking of using sound clips, but according to the quote above i'm wondering if this is the kind of installation he's talking about? I can't see why it would be a bad idea to mechanically decouple the drywall from the frame, even if the brickwall(with a spring offcourse) is standing on the other side. 3. Regarding sound clips and furring channels, i've searched and wonder if there is some equivalent product or some manufacturer of RSIC-1 in Sweden, where I live. I also wonder where i'm supposed to find the furring channels(Hat track?) here in Sweden(Don't know the name of the product in swedish) 4. Regarding drywall mounting, is every layer of drywall supposed to be screwed to the frame(or furring channel)? example, if I have 3 layers of drywall, am I supposed to screw the first layer with 1/3 as many screws as supposed, adding up when adding layers. In that case I guess I will need 3 different lenghts of screws, for 3 layers of drywall. Thank you so much for the time!! It's really appreciated. Cheers Ossian

1. What's meant with "mud and tape", regarding drywall assembling? Also how am I supposed to install the foam backer rod in the perimeters? Is it a bad idea to just caulk under(if facing floor) every drywall sheet instead of using foam backer rods?

How do they finish drywall in Sweden? Here in the States we apply a layer of joint compound over the joints - we then bed a material (called tape) into the wet drywall........ this is sometimes paper - sometimes a fine mesh material...... Next we seat the material into the wet compound, smooting it out and removing any excess compound. We then apply more layers of coumpound over the application until we finally reach the level of finish we desire - some light sanding and we're ready for pain - wall paper - what ever finish you want to apply. Foam backer rods are easily installed - you can push them in place using your fingers - a pencil if the joint is to small for fingers. You want then setting about 1/4" back from the face of drywall before applying caulk. I explain in the book the importance of backer rod - it stops caulk failure caused by 3 point caulk applications...... so yes it is important to do.

2. According to some guy's(Rod, doesn't have the book by the way) book, on page 62 he says: One point I want to be sure you get is that there is no advantage to using isolating clips or resilient channel with a true double wall assembly. Don’t waste your money by thinking that more is better in this case. I'm going to build a 2 leaf wall, one of them is already installed(brickwall) and the other one is going to be a framed drywall(2 or 3 layers) and i'm thinking of using sound clips, but according to the quote above i'm wondering if this is the kind of installation he's talking about? I can't see why it would be a bad idea to mechanically decouple the drywall from the frame, even if the brickwall(with a spring offcourse) is standing on the other side.

You apparently are missing the point - I didn't say it was bad - I said it gained you no advantage - which means you are just throwing your money away....... That having been said - if you want to throw your money away - feel free - it is (after all) your money.........

3. Regarding sound clips and furring channels, i've searched and wonder if there is some equivalent product or some manufacturer of RSIC-1 in Sweden, where I live. I also wonder where i'm supposed to find the furring channels(Hat track?) here in Sweden(Don't know the name of the product in swedish)

4. Regarding drywall mounting, is every layer of drywall supposed to be screwed to the frame(or furring channel)? example, if I have 3 layers of drywall, am I supposed to screw the first layer with 1/3 as many screws as supposed, adding up when adding layers. In that case I guess I will need 3 different lenghts of screws, for 3 layers of drywall.

That's what is typically done - BUT - I reccomend that you read IR-761 - they established nailing patterns for drywall layers that should provide the best installation. Yup =- a different screw length for each layer........ easiest - least expensive way to go....... Rod

Thank you so much for the answer Rod! Is this wall design the kind of wall design you are refering to in your book, in that case, in my world it's going against the "rule"(?) of mechanical decoupling, could you please elaborate some more? I thought all kind of mechanical decoupling gave an advantage, but am I wrong here? I'm going to put up a 3 layer drywall with greenglue in between, will I not benifit from using RSIC-1 clips? I mean, the walls on the perimeter of the new drywall I will build is connected to the brick-wall facing the studio room(separating controlroom from studio room) which will conduct vibrations to the frame and then the drywall, am I missing something here? Once again, Thank you!

Osse, the whole intent of building seperate walls inside the building are to decouple them from the exiting frame. The are many different isolation clips you can use to make your walls rigid (utilizing the existing frame) without creating flanking paths between the old and the new. And these clips will cost you much less than RSIC clips and hat channel once all is said and done. If you do this right - the inner wall is already decoupled - how can you then gain from decoupling yourself from the already decoupled wall? This is like working for the "Department of Redundancy Department". In fact - if you frame with 2x6 @ 2' centers - you will actually have a slight advantage with low frequency without the RSIC clips. But - in the end - you will never gain by trying to isolate yourself from an already isolated member.... isolated is isolated...... Rod

So what you mean is simply decouple the frame from the perimeter walls? What kind of clips is used for this? I've thought about the idea, but never seen any products doing it.

Osse, Just forget the clips and build a wall decoupled (not touching anything but the floor) from your existing brick wall

How am I supposed to do that, as I guess I have to fix the frame to something, otherwise the wall will be loose and with air gaps around... Or am i missing something?

:shock: Well. you are supposed to build 5 walls inside your current room (4 walls plus a ceiling). They will support each other very well if built properly

I'm going to build a 2 leaf wall, one of them is already installed(brickwall) and the other one is going to be a framed drywall(2 or 3 layers) and i'm thinking of using sound clips, but according to the quote above i'm wondering if this is the kind of installation he's talking about? I can't see why it would be a bad idea to mechanically decouple the drywall from the frame, even if the brickwall(with a spring offcourse) is standing on the other side

Just adding to what the others said: The reason why you wont gain anything is because, if you build a proper 2-leaf room, then the second leaf is already decoupled from the first leaf. It makes no sense to decouple it again. In other words, you have to build the frame for your second leaf a couple of inches away form the brick wall, such that it does NOT touch the brick wall, nor the other walls, nor the ceiling. It only touches the floor. So it is decoupled. Adding RC or clips will not gain you anything additional, since what they do is to decouple, but your wall is already decoupled, so they don't do anything. Of course, if you were planning to build your second leaf by attaching it to the brick wall, or to the other walls, or the ceiling, then that isn't a proper 2-leaf wall anyway, so that would be a different situation. Like Javier said: if you don't build all fives sides of the room fully decoupled, then you didn't build a 2-leaf system, so you'll have coupling and flanking going on, and you won't be well isolated. - Stuart -

I get it. But of some reasons I can't build the wall around the whole room, and for isolation purpouse(other than decoupling the wall facing the studio room), I don't need it, so I'm thinking if there is any way of building a 3 layer gypsum board wall with frames coupled to the other walls, then install RSIC-1 clips and decouple the gypsum boards from the frame. Would be much easier solution for me, and as the brick wall allready has some good attenuation abilities I won't need a like 70STC wall. What do you guys think? Will this work? As I said, I don't need total isolation between the two rooms, and the brickwall allready reduces noise rather good.

Hi Ossian.

I'm thinking if there is any way of building a 3 layer gypsum board wall with frames coupled to the other walls, then install RSIC-1 clips and decouple the gypsum boards from the frame.

Yes. No. Maybe. That's about as good an answer as you can expect, since there isn't enough information to give you a better answer. Without seeing a detailed SketchUp model of what you are planning to do, its hard to say if the plan you describe will do anything useful to achieve your goal, but the simple answer is: Most likely not. Sound will simply flank around the wall, through the side walls and the ceiling. A wall like that very probably won't isolate well, regardless of whether or not you put RC or RSIC clips, or ten layers of gypsum board on it. It wont work because sound will probably go around it, not through it. One again, you'd be wasting your money.

I don't need total isolation between the two rooms, and the brickwall allready reduces noise rather good.

So then why are you even thinking about RSIC clips and decoupling? You say you don't need much isolation and that you already have it! Sorry, but your posts aren't making much sense. You say that isolation isn't important, but then you say that you want isolation, and then you say that you already have isolation anyway!!! ???

I won't need a like 70STC wall.

So what DO you need then? Without numbers, nobody can even guess at the construction that you'll need to get to that number. Especially when you say that you don't need it anyway, and that you also already have it! :) The isolation in your room will only ever be as good as the isolation through your weakest link. If your "weak link" happens to be the ceiling, or the floor, or one of the side walls, or through the windows, or the doors, then that is as good as it can possibly be, no matter how well you build your dividing wall. Sound does not travel in straight lines, so a single wall cannot stop it, no matter how thick that wall is. Sound travels as waves, and waves simply wrap around walls, especially at low frequencies. To stop waves getting in, or out, you MUST build a sealed box. There is no other way. If the box isn't sealed, sound WILL get in, or out. Simple basic physics. Think of it like an aquarium: To build a good aquarium that holds water, you need five pieces of glass: One for the floor, and four more for the walls. If you take out any one of those, then it's useless: it will not hold water at all. If you replace four pieces of glass with cloth, cardboard, newspaper and a sponge, then it won't work either: The water will still leak out. In order to work as an aquarium, it must have water tight walls on all five sides. But what you are saying you want to do with your room, basically, is that you want to build an aquarium that has only one really good thick glass wall, and with the others made from sponge, cloth, etc. The simple answer is: that won't work! If water leaks out through ANY of the walls, then it is a useless aquarium. If sound can get in or out through ANY of the six sides of your room, then it is useless. The same for your room: The isolation will only be as good as the worst wall, whichever that one happens to be. And since you haven't told us anything at all about the other walls and the ceiling and the floor, we can't even tell you how bad the isolation on those will be. I'd suggest that your best course of action is to download the "SketchUp" program from Google (it is free), and use it to make an accurate model of the space that you have, the post it here for us to look at. Then also give us a detailed description of the building, and what you want to do What are ALL of the walls, and the floor, and the ceiling made of? How thick is each one? What is on the other side? What is the purpose of the room? Record a symphony orchestra? Or record a single flute? Or a rock band? Or is it just for you to practice? How loud will it be inside? How quite does it have to be outside? How loud are things around you? Consider things like your neighbors, roads nearby, airplanes flying over, trains, mechanical noise in the building, wind, rain, etc. Also consider your municipal bylaws, and the legal limits they impose on sound levels. Etc. Nobody here can help you with good advice if you don't provide this type of information. Basically, right now its like you are saying "I have a piece of rope here. Do you guys think it is long enough?" The only possible answer is "Long enough for WHAT? And how long is it anyway?" Sorry if I'm sounding harsh, but all of this is already laid out in the post at the beginning of the forum that says something like "Don't post here until you have read and complied with all of this". Please go back and read that post again, then provide all of the details requested, so that we can help you. We really would like to help you, but we cannot do that unless you give us enough information to make it possible! - Stuart -

Hello Soundman, and thank you for your detailed response. I guess I'm too short of info to really give you a pic of the situation, I'm going to try making it detailed. Here is an attached picture of how the room looks like: The lines drawn around is the brickwall, approx 6 inches thick, the dotted line is where i'm supposed to build the drywall, the thicker part is approx 3-4 times as thick as the regular brickwall parts. I have tapped on the wall facing the studio room, and felt if there were any energy conducted to the perimeter walls in the control room, on the thicker part, I felt nothing, on the ceiling, just a little, on the floor, just a little, on the wall facing outside, just a little. Which gives me the conclusion of that if I can resist those vibrations going into the drywall, It might isolate better than just making them all coupled to the frame which is coupled to the perimeter walls, is this conclusion true to reality? I guess the perimeter walls will conduct some of the sound from the live room to the control room, but most of the sound will be conducted throught the wall between the rooms, and with a decoupled drywall between I guess this will attenuate even more of the direct sound from the wall. What I meant was that as the brickwall right now is isolating rather good, but I wish to get a little better isolation, the drywall won't need to have extremly good STC value, and another point for the wall is to be able to install double glass window and two doors with a spring between. Once again, I really appreciate your help Soundman, I hope I made myself clear enought this time for you to be able to understand the situation!

Why cant you build all walls decoupled? Space? Your solution doesnt make any sense at all. Its like saying "I want to paint my walls white, but I cant, so I will just paint them black first and then apply a white layer when the black one isnt even dryied out" You have the option to build decoupled walls from the start, and you are going for building coupled walls and just puting RC clips to improve that. To me thats a waste of money and it wont perform well

I guess the perimeter walls will conduct some of the sound from the live room to the control room

Exactly. That is called "flanking". Sound will get around your divider wall, by flanking through the side walls and ceiling, and floor. If the floor is a concrete slab poured directly on the ground, then that won't be too much of a problem, but the walls and ceiling will be: No matter how good you make your divider wall, sound will ALWAYS flank around it. Unless you build a room-within-a-room, then you will not have good isolation. You cannot make the laws of physics go away just by wishing and hoping that they won't apply to your room. They will apply to your room in the exact same way that they apply to every other location in the universe. And there is another major issue here: My guess is that the space above the ceiling is shared by both rooms. If so, then your weak point is right there: sound will flank very well around your wall through that air space. And once again, you still have not given us any numbers or information about those rooms, such as how loud you will be in there, how quite it must be outside, what type of music you record, what instruments, etc, etc, etc. All of the stuff that is asked for in the most important post on this forum. Once again, without knowing that, there really isn't much anyone can do to give you advice. If you only ever plan to record a single harmonica in there, then you already have everything you need. But if you plan to record things like drums and bass guitars, and you have neighbors close by, then you have a problem that cannot be fixed in the manner you are proposing. It can only be fixed by building a proper "room-within-a-room", exactly like Rod's book explains, and exactly as you'll find all over this forum. - Stuart -