Which wall construction do you suggest

Before i proceed, i would like to know if any of these options is a big mistake. I have a double garage that I am splitting in half to build a studio. It has a roller door that runs along runners and curves and runs vertical to the ceiling. 1st issue is I need to build a new ceiling for half of my build to allow the roller door to open. The remaining half of the studio will have walls reaching the existing ceiling. So basically i will have a double brick back wall and side wall, and will build a side wall to split the garage down the centre, a front wall and a lower roof for roughly half of the build. I have attached a work in progress drawing (Structure) I'm still changing it, so don't pick it apart yet, this is just so you get the idea of the build. The idea is to build the inner shell, then the outer shell, having a double wall system. Whichever way i choose to do the wall structure will also be the structure for the new ceiling. I have drawn and know i can do all this without the inner structure being attached to the outer structure. Of the attached, which wall constructions that I have in mind best suits? We are close to a freeway which does provide some noise, but this is also about keeping sound in as most of my recording are direct. Obviously i would like to have the room as good as possible for vocals and mic'ing classical guitar when needed. 1.The inner and outer walls will be soundcheck plaster board. The drawings below are only showing timber studs and Bradford Rockwool bats constuction ideas. Is it worth adding timber sheets to the outside wall before applying plasterboard, or vise versa? 2.Where i have the staggered stud system in Diagram A.1 & A.2, the staggered studs are far enough apart that i could add a piece of timber board along the inside of the outer studs, also holding in the Rockwool bats. Worth doing for extra soundproofing? 3. Notice A.1 & A.2 have 10cm plate on floor and ceiling...effectively linking the inside and outside structures to the same plate. Diagram C.1 and C.2 show the same construction, however each inner and outer structure having their own plates on the floor and ceiling. is this much of an improvement in soundproofing than Diagrams A.1 & A.2? I look forward to any feedback, jokes and criticism. :lol: i will be starting in a couple of weeks as i am finishing the electrical requirements on the brick walls, in case we sell one day i don't want electricals in these walls that may have to come down! Pictures will follow!

C.2 is the best by far. A.1 and C.1 are for music purposes no better than a normal single stud wall. Andre

The idea is to build the inner shell, then the outer shell, having a double wall system.

That would be a three-leaf system! Bad idea. Or maybe even four leaf (see below). Even WORSE idea. You already HAVE your outer shell: it is the existing garage wall, which hopefully is only one leaf at present (maybe not: see below). You only need to build ONE additional "shell", which will be your inner leaf. No more, no less. You can only have two-leaves in your MSM system. Three or more tunes the resoannt frequency way to high, and reduces insulation at the bottom end. However, it's really hard to see how you are going to seal that roller-door airtight and still have it operable, if you want it to be your outer leaf. That is going to be your number one issue.

We are close to a freeway which does provide some noise, but this is also about keeping sound in as most of my recording are direct.

It's pretty much the same thing. If sound goes one way through a wall, it will go the other way through the wall in pretty much the same way. As far as I know, there's no such things as one-way isolation. So whatever you do needs to be done with the worst offender in mind. If the noise level outside from the freeway is higher (as heard inside the room) than is the noise level from your playing/mixing activities in the room (when heard outside), then that will be the level that defines the amount of isolation you need. You need to make real measurements with a sound level meter, both inside and out: You also need to define what acceptable levels will be, both inside and out. The largest difference defines teh isolation you need, and therefore your wall structure.

1.The inner and outer walls will be soundcheck plaster board.

Waste of money. Go for plain old drywall (gypsum board, sheetrock, plaster board, etc.): Mass is mass: the sounds waves don't care how much you paid for that mass, so go with the cheapest high-density mass you can get, which is plain old drywall in most places. In any event, the outer wall already exists, and probably isn't soundcheck. You said it is brick, and that's good: brick is a good isolator to start with. However, you did say it is "double brick back wall and side wall". Do you mean that it is a single-leaf brick wall that is built from two layers of brick, or do you mean that it is a cavity wall, built as two separate brick walls with a gap between? If so, you might already have a two-leaf wall. Unless the two sides of that wall are tied together mechanically, in which case you only have a single leaf. Do you have any way of checking that wall, to see exactly how it is built? Can you see "inside" it (assuming it is a cavity wall)?

Is it worth adding timber sheets to the outside wall before applying plasterboard, or vise versa?

That all depends on what the existing outside wall is made of! And also what you plan to do inside the room / how loud it will be / how quite you need it to be outside the room / etc.

2.Where i have the staggered stud system in Diagram A.1 & A.2, the staggered studs are far enough apart that i could add a piece of timber board along the inside of the outer studs, also holding in the Rockwool bats. Worth doing for extra soundproofing?

That sounds like even MORE leaves, if I understand what you are saying! You can have two-leaves, and only two leaves in your wall. A one-leaf wall is limited by mass law, which means lousy isolation. A three leaf wall is limited by the low frequency response of the MSMSM system, which makes it a lousy isolator. You need two-leaf, and only two-leaf. So you don't need staggered studs, since the outer wall is already in place. You only need a single stud frame, with two or more layers of 16mm drywall on only ONE side of it, a 4" inch air gap (minimum) between the new leaf and the existing leaf, filled with rockwool (48 kg/m3 density). You can use wood panels instead of drywall if you really want to (OSB, MDF, plywood, etc), but they will have to be thicker to make up for the lost mass and lower density of the wood as compared to drywall, and they will most likely be more expensive. But basically, you'll need to provide a lot more of the details that are requested on the stickies at the top of this forum in order to get you more useful responses. Having said that, your single biggest issue is most likely going to be that garage door. If you have to keep it for aesthetics or for code, then I'd suggest that you split it in two vertically so that the other side can open while "your" side stays closed. You will have to seal your side in place permanently, make it airtight, and beef it up from the inside with mass, in order to use it as your outer leaf. If you don't do that, then you will never achieve decent isolation for your entire room.

i will be starting in a couple of weeks as i am finishing the electrical requirements on the brick walls, in case we sell one day i don't want electricals in these walls that may have to come down!

Your electrical system should NOT be on the outer leaf! It all needs to be totally and completely inside your INNER leaf (except, of course, for the one single point where you bring the main supply into your room). All internal electrical should be done with surface-mounted ducts and fixtures, in order to avoid making holes in your air.tight hermetically sealed inner-leaf. So any work you do on those existing brick walls is wasted. All you need on those is the one single line that will feed the entire room, which of course includes the earth conductor for your star-grounding system. One other thing you didn't mention is your HVAC system: What are your plans for that? - Stuart -

Stuart wrote:

That would be a three-leaf system! Bad idea. Or maybe even four leaf (see below). Even WORSE idea.

Thanks. I missed that completely. As you also wrote, a lot more (detailed) information is required. Andre

Thanks. I missed that completely.

No problem! It happens in the best of families! :) :lol: But I must admit it sure is unusual for ME to spot something that YOU missed, André! I better go buy a lottery ticket, while my luck holds out! Happy new year to you, by the way! Hope its a good one for you. - Stuart -

ok, I guess you have answered which structure to use, but i obviously did not explain my room and build well enough and feel compelled to explain your concerns. I have added 2 new documents. 1 is a google sketch document which gives you the idea of the garage and how my build will fit and how the floating ceiling will look. All sections in red is part of the build. The current structure of the garage to be left untouched is the grey coloured ceiling and brown walls (double brick to inside of house) The other is an excel doc with multiple spreadsheets showing garage plan, new studio structure plan, an attempt at 3-d to show you how the build fits in the garage with basic construction not to scale, and finally how i will be supporting the floating ceiling. I am working on the plans to scale in google sketch and excel as we speak. To clear some points up: WALLS - I am only building 2 new walls, and leaving the other 2 walls which are double brick walls which attach to the house as they are. I will butt a wall up against the short single brick wall ( 3rd wall I guess...as shown in excel doc), so i am not sure which structure to use for this bit, probably the single shell as you mentioned, as well as determining which wall construction to use for the walls i have to build from scratch which will probably be C2 (2 shells) The 2 shell structure will take a bit of work to do for the new ceiling part, but as i said, i am working on the plans in google sketch as we speak. DRYWALL - 1 layer inside on the inner shell , and timber boarding then drywall on the outer shell. is that pretty sweet? HVAC - no air conditioning or heating. Only vent currently planned is the door to the house. i was thinking of putting 2 small air vents in the wall? There is an open side-ways man hole which leads to the garage roof as you come down the internal stairs from the house . Not sure what to do with this other than put in a small door.

ok...just an update so if anyone can see any issues, hopefully they are kind enough to let me know. For a quick overview, this is for a double garage that i will be converting half of it as my own little studio. I have attached the plans to scale, and included another with gyprock (sorry about the coloured plaster!), and the last pic includes the stairs leading into the room from the laundry and the overall look. I have got Bradford 2.0 Soundscreen rockwool and will be using 2 x 10mm gyprock on the outer and 1x 10mm on the inner....another layer of something may be added to the inside, depending... i may have to look to strengthen the dropped ceiling to support the weight The room isn't a perfect rectangle, which may assist with the bouncing of sound, however trial and error of placing absorbers and diffusers and where to place my desk will obviously be required. The lower roof is required to allow the garage door to roll along it's runners...this brings the height level down unfortunately, but will also give options when mic'ing the acoustic to see which area sounds better. Otherwise mostly i direct input anyway. The main priority is to limit sound from coming in... and out, so i can turn it up a bit the best i can with what I have. The floor is currently concrete, and i will be laying floor boards, maybe on a layer of carpet underlay to limit and cracking sounds when walking on it, and the floor does drop 70mm from back to front of garage. i will be posting pics for fun as we start building in 2 weeks. So any feedback before then is not expected, but appreciated. Note: a light and fan have been installed, and the garage lights moved across to the other side where we park. All Power is on the brick walls that you see in Overall pic.

will be using 2 x 10mm gyprock on the outer and 1x 10mm on the inner....another layer of something may be added to the inside, depending...

That isn't thick enough. 10mm drywall has a higher resonant frequency and much less mass than 16mm, which is what you need (or 15mm if you can't get 16).

The room isn't a perfect rectangle, which may assist with the bouncing of sound, however trial and error of placing absorbers and diffusers and where to place my desk will obviously be required.

What did you say you want to use the room for? Control room or live room? If it is for a control room, you absolutely do want to get it symmetrical, at least for the front half: Also, "trial and error" is not a good way to find the position for your desk and treatment! That will take a very long time, and most likely will not get you to the optimum solution. Is there any reason why do not want to go with the normal "standard" layout and treatment?

The lower roof is required to allow the garage door to roll along it's runners... The main priority is to limit sound from coming in... and out, so i can turn it up a bit the best i can with what I have.

sorry, but those two are incompatible. You cannot retain an operating garage door and also expect to get good isolation. And certainly not by using 10mm drywall! No way. Sorry, but that just ain't gonna fly!

the floor does drop 70mm from back to front of garage.

Simple solution: Self-leveling cement.

and i will be laying floor boards, maybe on a layer of carpet underlay to limit and cracking sounds when walking on it,

Why not go for proper laminate floor, on proper underlay?

a light and fan have been installed,

But what about HVAC? A simple fan is not going to cut it! - Stuart -

Firstly, the garage door operates on the outside of the build. That is why I have lowered half the ceiling, so the garage door will run along it's tracks and then over the section where i have lowered the ceiling. In no way will the garage door be seen from inside the build. The room is more for me playing guitars, bass, electric drums and keys for fun and recording, which will for the most part be recorded directly with no mic'ing. But yes, i do then do some mixing and "attempt" at mastering on Boss BR1600 and Korg D3200. I do get friends who come around also to play, so the main requirement is limiting sound from travelling to the next door neighbour some 20m away and from a main road some 100m away. I am not going for absolute perfection, but am trying to limit sound leakage in and out as much as possible. I found this morning, i can get a choice of Particle Board 16mm or 18mm, very cheap from a friend. i am thinking of layering this on the outside wall, covered with 13mm plaster, and same on the inside. Glad I've ordered nothing yet except for Bradford Soundscreen!

Firstly, the garage door operates on the outside of the build. That is why I have lowered half the ceiling, so the garage door will run along it's tracks and then over the section where i have lowered the ceiling. In no way will the garage door be seen from inside the build.

HOW it operates is not the issue! The problem is THAT it operates. Since it MOVES therefore it cannot be SEALED. It also has next to no useful mass. Therefore it is useless as your outer leaf. Therefore you have no isolation. Even worse, even though it is useless as your outer leaf, it IS still a leaf, so you cannot even put another leaf behind it, since that would give you a three leaf wall! In other words, there simply is no way around your dilemma. Either you have to give up operability of the garage door in order to seal it and add mass to it somehow. Or you have to give up the idea of getting the kind of isolation you want. You can't have both. And you most certainly cannot have them with such low mass leaves. I did warn you about this in my response to your first post, but you seem to have missed that entirely, because you never did mention what you were going to do about all of the rather large and glaring points that I brought up, and now you are back again, repeating more or less the same thing you said the first time. Which will not work the way you think are hoping it will.

I am not going for absolute perfection, but am trying to limit sound leakage in and out as much as possible.

Fine, but you still have not defined NUMBERS. You absolutely do need to do that. You can't just guess about how loud you think you might be: you need to measure it, with a sound level meter, while your buddies are doing their best to make the biggest possible noise that they normally make, inside your garage. You can't just guess how quiet you need to be, either: you need to measure that too, at your neighbor's place. Play loud full-spectrum music inside your garage at 4 o'clock in the morning, and keep on turning it down and down until it is no longer audible at your neighbors place, and measure that level. The difference between the two is how much isolation you need. That will dictate the kind of construction you need. This isn't a guessing game: it is science. If it turns out that you need 45 dB of isolation, that requires one kind of construction. If it turns out that you need 75 dB, that requires another kind. You cannot know which kind you will need until you measure the real numbers with a real meter. Only THEN can you start deciding what ind of structure and mass you will need, and what kind of insulation, etc.

i can get a choice of Particle Board 16mm or 18mm, very cheap from a friend. i am thinking of layering this on the outside wall, covered with 13mm plaster,

Why would you want to do that? That makes no sense. You already have a lot of mass in your outside walls, since you say they are brick. Brick is many times more dense than wood. You'd need MANY layers of particle board just to double the mass of those bricks, and all that would buy you is 6dB of additional isolation. Not worth the effort. Most likely what you will need is a two leaf MSM system, all around, with plenty of mass on each leaf, and fully sealed, airtight. That wood makes no sense at all up against your existing brick walls, but would make a lot more sense as part of your inner leaf. - Stuart -

Stuart, I'll put my hand up and say I haven't been clear, because from my explanations and pic, you are not understanding what i am doing. Despite that, you have given me a few things i obviously need to think about. I'd just like to clear up some points. The garage door is not a leaf. It is not attached to the build . From the back of the garage i am building a partition wall down the centre of the 2 car garage. 1 part to park the car, the other to use for the studio. As the new partition wall reaches the front of the garage (where the roller door is) I am stopping just short of the garage door and having a second partition wall parallel with the garage door, but not linked to it in any way. This pic i have added a translucent garage door and you can see how i am not building the wall right up to it. And this shows how the garage door moves without disturbing what i am building. So the only place i need to add Particle board and gyprock is on the 2 new partition walls. To support the lowered roof ( to allow the garage door to function ) which will also be particle and gyprock, I have planned to add a stud wall for just a short space along the brickwork. This also works because that part is only single brick. All the remaining brickwork for the 2 walls does not need to be touched because it is double brick as it is attached to the house. Hope this helps. My friend who is a builder understands it. A lot of your points i swept aside because i could see you did not understand what i was building. My apologies for not being clear. But as i said, you have brought up other good points which can relate to this build and I'm taking these on board.

The garage door is not a leaf. It is not attached to the build .

Irrelevant. It is still a leaf. Being attached or not attached to the rest of the building has no effect, acoustically, on weather or not it is a leaf. What matters is that it is a large flat surface with appreciable mass, separated by an air gap from another large flat surface with appreciable mass. Period. So the only way that your door could NOT be a leaf is if you can figure out a way to make it mass-less, or figure out a way to eliminate the air gap between it and the partition. Like it or not, that door IS your outer leaf.

I am stopping just short of the garage door and having a second partition wall parallel with the garage door, but not linked to it in any way.

That's what I understood from your original post. It was not hard to follow. you made it clear the first time. That "second partition wall parallel with the garage door" will be your inner leaf. The garage door itself is the outer leaf. There just isn't any question about it. Even if you could figure a way to make the garage door hover in mid-air a few inches away from the partition, it would STILL be a leaf. It has a large surface with mass, and it is separated from another large surface with mass, therefore it is a leaf. it is part of an MSM system. Therefore it will resonate a a certain frequency, governed by the laws of physics, and it will amplify sound at that specific frequency, and it will not start to isolate sound until 1.4 times that frequency, and it will only start to isolate well at roughly twice that frequency. In other words, it will behave as any other MSM system in the known universe. The laws of physics will apply to it in the exact same manner as they apply to all other MSM systems

And this shows how the garage door moves without disturbing what i am building.

Once again, the manner in which it moves is irrelevant: What matter is simply that it does move. If it moves, then sealing it correctly to work as it should, (since it undeniably IS in fact your outer leaf), will be really, really hard. How does your builder plan to seal it hermetically? What products does he plan to use to seal the door itself, how does he plan to seal it to the runners? How does he plan to seal the door to the threshold? How does he plan to seal the roll to the frame above?

So the only place i need to add Particle board and gyprock is on the 2 new partition walls.

No, you need to add it on your ENTIRE inner leaf, AS WELL as the two new sides of your outer leaf. If you want to isolate well, then you CANNOT do it with a single-leaf fully-coupled wall, which is what you are planning at present (at least, you cannot do it without adding an unreasonable amount of mass). Your best and cheapest option is to do it with a fully decoupled complete MSM structure, which implies two full leaves all the way around, on all four walls and the ceiling. Your existing "double-brick" walls are most likely acting as single leaf anyway, since I doubt they were built correctly as MSM walls. So, once again, if you want acoustic isolation (and it seems that you do, or you would not be going to all this trouble) then you have no choice but to build a proper 2-leaf decoupled MSM system all the way around, for the exact same reason that if you want to build a fish tank, you have to put glass on all the sides and the bottom. A fish tank that has glass on only two sides and half the bottom will not hold water. A fish tank that has one wall made of two layers of cardboard and another wall made of sponge, will not hold water. A studio made the way you are planning to make it, is equivalent to a fish tank made like that, and it will not hold sound in exactly the same manner as the fish tank will not hold water.

I have planned to add a stud wall for just a short space along the brickwork. This also works because that part is only single brick.

In other words, you plan to make one wall of your fish tank out of sponge...

My friend who is a builder understands it.

Has he also studied acoustics? Test him: ask him to calculate the resonant frequency of the MSM system that WILL be formed by your garage door and the new inner leaf that you propose. If he does in fact "understand it", as you claim he does, then it should be a piece of cake for him to do that. Based on that, he can also predict what your STC rating will be (roughly). However, the fact that he didn't already do so, and already warn you about the problem you are about to create by doing it your way, tends to make me believe that he actually does NOT understand. He might well be a great builder, but unless he has studied acoustics, what he knows about building is not very useful when it comes to building a studio... Building a studio is absolutely nothing at all like building a house.

A lot of your points i swept aside because i could see you did not understand what i was building.

Well, I hate to say this, but the reason I even posted them was because I DID understand what you are trying to do, and I could see that YOU did not understand what you are trying to do. Yes, I'm sure you understand what you want to accomplish in terms of how to build it, how big it will be, and what you want to do inside it, but clearly you don't understand the acoustical issues of what you are getting yourself into. You might want to think twice about "sweeping aside" the points that people here bring up about your build. After all, I imagine that you did come to this forum in the first place because you wanted solid acoustical advice about how to build your room correctly, right? So then why would you "sweep aside" the solid acoustical advise that people are giving you? That would be kind of like going to the doctor and telling him that your cough wont go away, but then when he prescribes medicine for you to swallow, you "sweep aside" his advice because he clearly doesn't understand that the cough is in your lungs, not in your stomach... - Stuart -

:D fair enough, then the garage door will be a predicament. i have to do the best i can with that issue. I guess i need to, for example, build a 1m square box in a garage and soundproof it the best one can. It can't, and doesn't need to be perfect fyi..i was more saying that my friend understands the build, which i incorrectly thought you had not grasped. He would not be knowledgeable on acoustics. Thanks for your advice mate.