John Sayers' Recording Studio Design Forum Archive

Hi

I've looked through this forum and find all the comment really useful, although equally scary!

I'm a lifelong musician looking to turn most of my garage into a relatively soundproofed room where I can record vocals, guitars, maybe even drums, and also mix.
Through reading and asking questions, I feel I have enough knowledge to have a go (with a builder I'm using), but I wanted to clarify one thing.

My garage is timber walled on three sides and breeze block on the other. The floor is concrete (to which we're adding more concrete to level it) and my nearest neighbour is 15' away.
As per the attached (rough, apologies) diagram, I'm intending to use around 3/4 of my garage space for my studio. I'm planning to build a room with in room using a timber frame, insulating with rock wool, having an air gap, and fixing drywall.
My builder is first planning to insulate and drywall the existing garage outer walls and roof (a pavilion style that goes about 12 foot from the ground - see photo). Then make the inner room.

Should the inner room consist of a double framed wall - i.e. two separate frames each containing insulation, with a gap between, with two layers of drywall joined with green glue on each outer wall?

Or should the inner room have a single frame only, with the two layers of drywall on the inside of this? And fix the double layer of drywall, insulation to the existing garage walls?

Hope this make sense.

Also - my builder has says he intends to use "Sound Board 'A'" by which I presume he means specialist acoustic board. If I'm having a two-leaf wall system, with two layers of board on inner and outer wall, is it sufficient to use normal drywall rather than acoustic board - as it's a lot cheaper?

Appreciate your feedback.

Hi. Please read the forum rules for posting (click here). You seem to be missing a couple of things!

The floor is concrete (to which we're adding more concrete to level it)

Instead of concrete, I'd suggest adding self-leveling cement. It's a lot easier to get a flat, level, smooth surface using a product that is specifically designed to do exactly that.

I'm planning to build a room with in room using a timber frame, insulating with rock wool, having an air gap, and fixing drywall.
My builder is first planning to insulate and drywall the existing garage outer walls and roof (a pavilion style that goes about 12 foot from the ground - see photo). Then make the inner room.

You seem to be misunderstanding the concept of "room in a room". More accurately, what you need to do is to create a fully decoupled 2-leaf MSM system. The two leaves are: 1) The "outer leaf", which is your existing garage structure, and 2) The actual "inner leaf", which is a simple wood frame with drywall on ONE side only. That's it. There are no more rooms, walls, frames or anything else involved. Since you plan to use only part of your garage (not the entire thing), then you'll have to build a partition across the garage to section off the part you won't be using, thus completing the "outer-leaf" around the part you will be using.

If you add drywall to the existing garage framing and then build your studio, you will have created the dreaded "three-leaf system", which will ALWAYS give you WORSE isolation for the low frequencies than the equivalent 2 leaf would have, all other factors being equal. Never build a 3-leaf wall if you can possibly avoid it, nor a 4-leaf, 5-leaf or any other number of leaves. Only ever build 2-leaf, unless there's some really valid overriding reason to not do that.

Should the inner room consist of a double framed wall - i.e. two separate frames each containing insulation, with a gap between, with two layers of drywall joined with green glue on each outer wall?

No. The inner-leaf is a single stud frame with sheathing on just ONE side of that framing. The sheathing might consist of several layers, if you need high isolation, but they all go on top of each other, on the same single side of the frame.

Or should the inner room have a single frame only, with the two layers of drywall on the inside of this? And fix the double layer of drywall, insulation to the existing garage walls?

Yes to the forst part of that question, no to the second part. The existing stud frame should stay exactly as it is: if you put drywall on those studs, then you will create a 3-leaf system. If you do not have enough mass in your existing outer-leaf, then you might need to "beef it up" by adding drywall up tightly against it, in between the studs, but not ON the studs. When you do the math to figure out the isolation of your wall, then you can decide if you need to do that or not. But if you do need more mass there, then it all has to be in one "bunch", all together, pressed up against the existing sheathing, as one single leaf with no air gaps in between.

Also - my builder has says he intends to use "Sound Board 'A'" by which I presume he means specialist acoustic board. If I'm having a two-leaf wall system, with two layers of board on inner and outer wall, is it sufficient to use normal drywall rather than acoustic board - as it's a lot cheaper?

Think of it this way: sound waves are not snobbish, and can't read price tags anyway, so they really don't care how much you pay for each kilogram of your mass: All they care about, is the mass itself. Price is meaningless to them. The equations for calculating your isolation also have no place to insert the price... All the equations use is "mass". Period. End of story. So get the lowest cost mass that will do the job. It's that simple.

Yes, there's a lot of companies out there that make wonderful claims about how well their products isolate sound (or even worse, how well they "soundproof"... as if that was even a technical word that acousticians use...), but in reality, there is no product that can beat the laws of physics. There's no magical ingredient that a drywall manufacturer can add to the mix to make his kilograms more effective than anyone else's kilograms: Pixie dust doesn't work, and unicorns seem to be in short supply... so all that we have is mass. be vary wary of claims about products that fly in the face of science. The way walls isolate is well understood, the calculations are simple, and there's only room for three parameters in those equations: how much mass you have in the wall, how deep the air gap is in the wall, and how much "damping" (insulation) you have in the air gap. That's it. It's a simple Mass-Spring-Mass system, where the drywall on each side of the air gap is the two "masses", and the air in between is the "spring", which is damped by the insulation. A very well understood system.

In other words, compare the surface density (kilograms per square meter) of the various building products that are available in your area, such as ordinary drywall, fire-rated drywall, MDF, OSB, plywood, fiber-cement board, etc., and see which one has the lowest cost per kg. That's the one you want.

- Stuart -




- Stuart -

Thanks Stuart. I appreciate your response. (By the way I've updated my profile also )

I have amended the diagram (again apologies for its' rough and ready-ness) and would ask the following please.

Two of the exterior garage walls are made of featherboard timber (quite thin) on studs. The front is two sets of timber double doors with thicker wooden posts to their sides and centre. I have attempted to show this more accurately, attached.

If, as you helpfully suggest, I partition the area of the garage I wish to use for my studio, I imagine I will have to partition in front of one and a half sets of the front double doors as shown also. Would it not be best then to instead extend this partition to make the outer leaf (shown in blue) - i.e. a frame with two layers of drywall on the outside of this with rockwool underneath, then the air gap; followed by the inner leaf (in red) with the same make up but with the drywall on the inner side? (All both walls and ceiling). And leave the current garage exterior walls and doors untouched?

I'm not sure I'm following what you suggested... If I just add insulation only flat against the inside of the existing garage walls with no drywall there (the double doors would be an issue as I was aiming to have one of these - shown - as opening) .. and then build a single frame for the inner room with drywall on the inside only, am I NOT then getting the two leafs of drywall & insulation as shown in Rod Gervais's STC 63 diagram?

Would it work if I did what I suggested above (aiming for the STC 63 set up with a frame within a frame - my blue and red boxes on my diagram) and left the existing garage structure alone completely?

Sorry (again) if I'm unclear or ignorant (or both). I very much appreciate your advice.

Thanks
John

I'm not sure if those were windows or doors in your drawing for your room in a room, but here's how I would do it. Sorry if I messed anything up. I drew this up as quickly as possible. The pink is insulation.
The stuff that looks like OSB is OSB.
The white is drywall.
The wood looking stuff is wood. And the concrete is concrete.
I used a tan color to represent your existing doors.
And I didn't draw any sheathing, but this should give you the general idea.

Basically, seal off your doors using a ton of mass. Between every layer of material, use Green Glue compound. Seal everything with sealant.

The inner leaf is all inside-out except the concrete wall (the one on the bottom of my picture) as I figure it's probably best to leave a gap there for the MSM equation to work as well as to provide space between the outer wall and your vapour barrier.

For scale reference, the inner walls are 2x4's. The outer is 2x6 and the wall sealing up/beefing up the garage door is 2x6.

I left you dimensions (rough, based off of your initial diagram) to show roughly how big of space you'll have. Not how thin your room is (not even 6 1/2 feet wide!) You really should consider using the entire space as I'm not sure what good 4' of hallway is going to do you. However, acoustically speaking, that 4' will make or break your room!

Greg

By the way I've updated my profile also

Start from the right hand side of your diagram, outside the walls, and move your way inwards, counting the leaves as you go: Breezeblock = leaf #1, blue line " leaf #2, red line = leaf #3. The same is true for the doors at the top (which do count as a leaf) and also the wall at the bottom. They are all 3-leaf walls.

This is the concept you need to emulate:
The outer wall around everything in that image, is equivalent to your garage wall, and is the outer leaf (yours is a bit different, since one side is breeze block and he other three are just siding on studs, but the same idea applies). But since you are only going to use a part of that space, not all of it, you need to partition off that area. You can see the L-shaped isolation wall that was added here to do that, across the far corner, completing the other two sides of the "outer leaf" around that isolated area. Then the single "inner-leaf" was built inside it. This is just to illustrate the concept, of course: you'd need to adapt it to fit your scenario, but the concept is there. In your case, you will need to build the isolation wall sufficiently far away from the double doors that they aren't an issue. In other words, far enough away that the resonant frequency is way below the bottom of the audible spectrum. (Isolation walls are resonant systems, and need to be tuned. The equations for tuning them are very simple). Assume that your doors would be in the bottom right wall of this image, and you'll get the right perspective.

Your garage doors, of course, will have to be bolted in place and sealed up. They won't be usable any more.

Posting photos of the actual garage, several views, from the inside and the outside, would help us to understand things better.

- Stuart -

Thanks Gregwor and Stuart. Much appreciated.

Stuart, as requested, I've attached several photos.

I lay awake last night thinking about all this. Not sure it helped!

In your diagram, am I not getting three layers with the current garage exterior wall, the partition, then the inner room layer?

It would really help me if you could describe exactly how each layer should be constructed.

As for the ceiling height, because the main horizontal support beams are only 6' from the floor, I intend to build my inner room frame higher than these, with a new flat ceiling say 8' from the floor mounted on the new frame, so that they will be within the inner room. I appreciate this is less than ideal as they will touch the outer layer, but I don't have the budget to do anything else. And my plan is to insulate them and caulk round where they meet the new walls.

Thank you so much.

John

In your diagram, am I not getting three layers with the current garage exterior wall, the partition, then the inner room layer?

The only spot it would be a three leaf design would be with the existing garage doors. Since you have actual wooden doors, it's possible for you to beef them up, make them rigid and seal the heck out of them. Most other people have think crappy metal garage doors and the way I drew it for you would be how you deal with those.

As for the ceiling height, because the main horizontal support beams are only 6' from the floor, I intend to build my inner room frame higher than these, with a new flat ceiling say 8' from the floor mounted on the new frame, so that they will be within the inner room. I appreciate this is less than ideal as they will touch the outer layer, but I don't have the budget to do anything else. And my plan is to insulate them and caulk round where they meet the new walls.

This is a beautiful building! Sadly, without a major overhaul, I can't see how you're going to make it work as a true room in a room. Maybe Stuart can point you in a better direction, but clips and hat might be your only option :-S

Greg

Thanks Gregwor. It is indeed a beautiful building and we're lucky to have it (moved here five months ago).

Re the ceiling, I totally appreciate I'm going to end up with a somewhat flawed studio space. But I'm currently trying to make music in a small untreated attic up a ladder! I know this won't be perfect but I do hope it will get me another step along and be a big improvement. (Lord, I hope so given the money we're about to spend on it !)

I understand what you're saying about the garage doors. I didn't want to seal them up just in case it's a problem when we come to sell (not for a while given how stressful buying and selling houses is in the UK!).

I appreciate your input very much indeed.

John

Re the ceiling, I totally appreciate I'm going to end up with a somewhat flawed studio space. But I'm currently trying to make music in a small untreated attic up a ladder! I know this won't be perfect but I do hope it will get me another step along and be a big improvement.

I wouldn't say it's going to be flawed. You're smart enough to have come on the forum before building. If you had built without checking here first, THEN it would have been flawed.

Having any space is better than no space. I'd love to see some pictures of the attic space just for fun!

The garage will be a huge improvement from your attic space, I'm sure!

(Lord, I hope so given the money we're about to spend on it !)

With some studying and 3D modelling, you'll know exactly how your room will perform BEFORE you start building it. You won't have to hope it works.

I understand what you're saying about the garage doors. I didn't want to seal them up just in case it's a problem when we come to sell (not for a while given how stressful buying and selling houses is in the UK!).

I've been in the middle of a move for a year and a half, so I feel your pain! Having said that, you will have to do some extensive building in your garage, so inevitably it will be a hassle when you sell.

Greg

Thanks again Gregwor. I feel your pain re moving !

I've attached a photo of my attic as you were interested

Also I have a question regarding the ceiling of my new inner room. Because it's a pavilion roof, and I'm using only part of the garage, when you look longwise down the new room towards my proposed mixing position, the ceiling on the right side will slope to follow the slope of the outer roof. On the left hand side, the builder's plan was to make it 90 degrees. The room will be used for both mixing and recording (not ideal I totally appreciate). But from a mixing perspective I understand that symmetry is good. So I feel I should tell him to slope the ceiling on the right side in the same way as the left.

In my very impressive diagram, Option 1 shows the builder's current plan. Option 2 shows what I think will be better.

The black lines are the current garage outer boundaries. Blue is a proposed new internal partition wall. Red shows my inner room. The black line that's highlighted yellow will have increased mass so it will be my second (outer) leaf. The partition wall (blue) will be the outer leaf on that side.

The ceiling across the width of the new room will be sloped at both ends, following the existing roof slope.

I think I'll post this question as a new post as well, but I'd be interested to know what you think.

Thanks

John

I've attached a photo of my attic as you were interested

That space looks cozy! Just needs some treatment and for you to rip out the rug!!

But from a mixing perspective I understand that symmetry is good. So I feel I should tell him to slope the ceiling on the right side in the same way as the left.

Correct.

Blue is a proposed new internal partition wall.

Other than hanging some shovels or whatever on the hallway that will be left in your garage, what is the purpose of the hallway? I feel like it's such a small space, it's silly to go through the hassle of leaving the hallway. You could have a way better recording space (that is symmetrical) if you use the entire garage for your studio.

Red shows my inner room.

I know it may just be terminology here, but I thought we decided it is basically impossible to effectively build a fully decoupled inner leaf MSM room. Or are you still going to try and design it so it works? Again, I thought you were just going to use clips and hat instead?

The black line that's highlighted yellow will have increased mass so it will be my second (outer) leaf. The partition wall (blue) will be the outer leaf on that side.

If you desperately need that hallway, then yes, this is cool! Again, I'd use the whole space and find a wall somewhere else to hang my gardening tools or pedal bike.

I think I'll post this question as a new post as well, but I'd be interested to know what you think.

Try to keep all posts related to your build on this thread. It is impossible for members (including myself who is actively following your build) to jump around thread to thread trying to follow questions and answers pertaining to your design. It is okay to make a new thread if it is a generic question that hasn't been answered before. The cool thing about the search feature is that if anyone typed "pavilion roof", it would show this thread. Then, they could read about your entire design and hopefully learn something!

Greg

Hi Gregwor

Glad you like my attic - if not my rug !

Sadly, after talking it through with my wife, it is what it is, so I will have to make do with the partitioned space in the garage.

Gregwor wrote:I know it may just be terminology here, but I thought we decided it is basically impossible to effectively build a fully decoupled inner leaf MSM room. Or are you still going to try and design it so it works? Again, I thought you were just going to use clips and hat instead?

Not sure what you mean by clips and hat. Can you elaborate?

I've attached what looks to be the final plan, metaphorical warts and all. Once again, your views are appreciated. If I could do any part of this better within the parameters I've got?

And yes, I take your point about keeping all the elements in one thread. Makes sense.

Thanks

John

Not sure what you mean by clips and hat. Can you elaborate?

I've attached what looks to be the final plan, metaphorical warts and all. Once again, your views are appreciated. If I could do any part of this better within the parameters I've got?

Your air gap and MSM looking diagram implies that you've figured out a way to do a true room in a room? I personally can't wrap my head around how you'll pull it off with the buttresses and angled roof.

Also, your diagram states "compacted insulation". Insulation should never be compressed.

The only way I can make sense of how you may pull this off is using the RSIC clips and hat like I posted above.

Greg

Cheers Greg

I have instructed my builder to use resilient bars - I've read this is a similar option to the clips?

Regarding the compacted insulation - I did think that, as you wrote, insulation shouldn't be compacted as that will negate its dampening role.

My builder suggested it to add mass to the existing exterior garage walls and roof - fix heavy duty insulation slabs pressed into damp proof membrane on the walls (or the felt on the roof) then use resilient bars to fix the double layer fire board over the top of this. While aiming to minimise any gaps. And then fix rockwool insulation with pins to this board on the inside, which would be the start of the air gap between my outer leaf and inner room wall.

Would it be better to add mass to the outer boundaries with, say, plywood and fit the fire board to that, rather than trying to achieve more mass with insulation slabs?

I appreciate your time and patience with me on this.

John

Insulation is not mass. The density of insulation is about one twentieth that of drywall, so you would need to have it TWENTY TIMES thicker, just to get the SAME mass.

In addition, the purpose of insulation is not even to add mass to the wall! The purpose of insulation is to damp the acoustic resonances going on inside the wall, as well as to change the way air deals with heat from adiabatic to isothermal, and in addition to slow down the speed of sound, and increase the acoustic depth of the gap. THOSE are the reasons why you put insulation in the wall, not to add mass.

The insulation MUST be teh correct density for the task, in order to accomplish the above. If it is too dense, it will have very poor low-frequency damping characteristics, and if it is not dense enough then it won't have enough Gas Flow Resistivity to do the job.

Use ONLY the correct TYPE of insulation, and the correct DENSITY. Do not, ever, compress it, as that destroys the very properties you bought it for!

You really should read the book "Master Handbook of Acoustics" by F. Alton Everest (that's sort of the Bible for acoustics). You do need to understand WHAT you are doing and WHY you are doing it, or you will make mistakes along the way. This book will help you understand.

Resilient channel is not as good as the combination of isolation clips + hat channel, and neither of those is as good as a fully-decoupled inner leaf. But as Greg said, if you want to keep your framing the way it is, then you don't have many options. It's going to be a royal pain to get the drywall on the various angles of the ceiling and walls to line up and seal: you will have to work very, very VERY carefully to make that happen.


- Stuart -