John Sayers' Recording Studio Design Forum Archive

Thanks Stuart.

I must say I am still confused. I understand what you're saying about using insulation for sound dampening, but I still thought I was going to achieve an almost fully decoupled inner room.

My plan is to double board the existing roof and walls, and using insulation here was just an added element here. Then a totally separate inner frame which will not touch the beefed up garage walls and roof. (I know the main beams will go from inner to outer but that's something I'm going to have to risk. The inner wall will be framed round them and caulked where it meets. And I will see if I need to put sound board round them afterwards if needed. I know it's a long way from ideal, but I can't afford the work to take them down and put new higher ones in.)

So if I've added mass to my outer walls and roof (double layer board green glued together, insulation outside that).. THEN I have my air gap (2 inches minimum)... THEN I have my inner room made from double layer board green glued together, mounted using clips, with dampening insulation on the outside of that, which doesn't touch the outer apart from the beams.. am I not getting good enough?

I know "good enough" isn't ideal. Is your criticism of this whole plan based on the beams touching the outer structure?

Thanks again.

John

but I still thought I was going to achieve an almost fully decoupled inner room.

The only way you'll get "an almost fully decoupled inner room" is if your inner leaf is ONLY making contact through your concrete floor slab. If there is ANY elements of the outer leaf penetrating or even slightly touching the inner leaf, then it's game over. You might as well have not built your inner leaf. It's like playing the old board game called "Operation" where you try not to touch the guys body. But even a slight graze of your tool completes the circuit and the buzzer goes off.

My plan is to double board the existing roof and walls, and using insulation here was just an added element here.

If you do build a room in a room, you will need insulation between your inner and outer leaf. NO void space allowed!

Then a totally separate inner frame which will not touch the beefed up garage walls and roof.

Okay, with this design, it is "almost fully decoupled" and would yield the best results. However, the way your building is assembled, there are buttresses/gussets that stick out which would mean to avoid them, you'd have to build on the inner dimension of them which would make your room tiny. OR, see next point:

(I know the main beams will go from inner to outer but that's something I'm going to have to risk.

These buttresses/gussets will stick through your inner leaf and yield the entire room in a room concept useless. With some fancy planning, you might be able to design your inner leaf walls and ceiling such that you can avoid having these touch your inner leaf system and box around them to maintain your inner leaf mass and seal. There needs to be no risk involved. Either do a true MSM design, or don't.

The inner wall will be framed round them and caulked where it meets

Your entire outer leaf needs to be caulked. Then the inner leaf needs to be caulked. Two different "rooms", air tight. Neither of them should ever "meet" except at the concrete floor slab. Period.

And I will see if I need to put sound board round them afterwards if needed. I know it's a long way from ideal, but I can't afford the work to take them down and put new higher ones in.)

Don't build this on "I will see if I need" or "afterwards if needed". Build it with confidence. SketchUp a detailed plan and we will make sure your design will work before you lift up your hammer. Don't stress, we'll make sure you save money and have awesome results. I think you need to start 3D modelling this and see where problems will arise. From there, you will see where your plan will fail or succeed.

So if I've added mass to my outer walls and roof (double layer board green glued together, insulation outside that)..

Double layer board everything, yes.
"insulation outside that" -- you mean "inside" right? Yes, you need insulation for your exterior wall, for sure.

THEN I have my air gap (2 inches minimum)...

No void. The insulation should entirely fill your wall space. This is the "spring" part of the Mass Spring Mass equation.

THEN I have my inner room made from double layer board green glued together,

If you do a true MSM design, yes, you would make your inner "leaf" (we call it leaf here, not room per say) frame. Then yes, you would have two layers of drywall with GG between them. Note: GG is just the name of the brand. It doesn't actually glue the boards together. It does the opposite actually. It's just like a snot. You still need to screw the drywall to the framing members. That's the end of your build process. See notes for the next point:

mounted using clips,

The only time you use clips would be if you do NOT build a MSM system. What I mean is, if you didn't frame an inner leaf, you would put clips on your outer leaf studs and joists, then fix drywall to them.

with dampening insulation on the outside of that,

There's more to treating your room than putting insulation on your walls, but yes, if you want to start your treatment stage with a dead room, and then bring it back to life according to your measurements, sure. This is typically the case when rooms are built inside out. If they aren't built inside out, it often makes sense to add insulation as your measurements determine. In your build description above, you're implying that you will build your walls conventionally, not inside out.

which doesn't touch the outer apart from the beams.. am I not getting good enough?

Not sure what you mean by having your treatment insulation not touch "the outer apart from the beams".

I know "good enough" isn't ideal. Is your criticism of this whole plan based on the beams touching the outer structure?

Yes. To repeat what I said above, if you have any part of your outer leaf (in your case your "beams") touching or sticking through, exposed to your inner leaf, it literally voids the purpose of the inner leaf all together. If this is the case, you're better off using clips + hat on your existing framing. It won't offer the amazing isolation that a fully de-coupled inner leaf would (especially at the low frequencies), but it is still decent, especially at higher frequencies. The clips are pretty expensive, but this method would save you quite a bit of space as well.

To address a comment you made 2 posts back:

then use resilient bars to fix the double layer fire board over the top of this

Resilient bar is not the same as isolation clips + hat channel. Resilient bar makes a direct connection to the framing. Some is better than others, but with improved isolation comes the trade off of strength. The more holes in the bar, the more isolation it has. But, the more holes the bar has, the weaker it is. That's why isolation clips + hat channel is great. It is strong and the connection to the frame is through a rubber. There is also less chance of shorting out drywall screws to the framing when using clips and hat compared to resilient.

I hope we are getting you closer to a usable plan here!

Greg

1) Then a totally separate inner frame which will not touch the beefed up garage walls and roof.
2) ... the main beams will go from inner to outer ...

Those two statements are incompatible. It seems you are still not grasping the concept that a "leaf" is an entirely complete, "envelope" or "shell" that is absolute sealed air-tight, is not penetrated by anything, and has no mechanical connection at all with anything else: it stands alone, all by itself. There is no conceivable way that you can have a sealed shell with no connections to anything, and also have huge. massive beams penetrating through it.

Think it through, and you'll see that there no way you can do that. EITHER you have a decoupled two-leaf system, OR you have beams from the outer-leaf that penetrate into the inner leaf. You can't have both.

but that's something I'm going to have to risk.

It won't be a risk at all! The result is absolutely predictable, and well-understood: If you have any solid mechanical connection at all between your inner-leaf and outer-leaf, even a single nail, then you have no isolation. If you don't believe me, then borrow an old-fashioned tuning fork from an old-fashioned musician, and do the following test: tap it on something solid, and hold it out in front of you at arms length: Can you hear it? Nope. At best, a very, very soft, distant, muted tone. Now tap it again, and put the base of the shaft down on the top of the desk or table in front of you, at arms length. Can you hear it now? You bet! Loud and clear. That tiny area at the bottom end of the shaft, is way more than plenty to create a very excellent acoustic connection. So imagine what half a dozen massive beams would do...

The inner wall will be framed round them and caulked where it meets.

And what will be the durometer rating of the caulk that you use? On which shore scale? How will you ensure that there is enough deflection in the caulk to cause it to isolate? What frequency will you tune it to? How will you ensure that it decouples? Caulk is meant for sealing, not for decoupling. Getting two objects to decouple is nowhere near as simple as just making a gap and filling it with caulk.... More likely than not, the caulk will couple them, not isolate them. The only time it would isolate is if you manage to get the durometer of the caulk just right, and force it into the gap just right, so that it has a static deflection of around 20% when it has cured.... I have no idea how you would even go about trying to accomplish that...

And I will see if I need to put sound board round them afterwards if needed.

HOw would you manage to do that, if your room is already built? You would need to cut large holes in your drywall so you can add the framing that you would need around the beams to support the "soundboard", and without any of that touching the beams, then somehow seal it all up again, air-tight, with the correct insulation in the air gap...

Here's an equation that you should be using by now:
If you don't recognize that, or don't know how to use it, then there's a big problem here.

There's a simplified version, which assumes constant air paramaters:

Fc=c[(m1+m2)/(m1m2d)]^.5

Where:
c=constant (60 for empty cavity, 43 for cavity filled with insulation)
m1=mass (surface density) of first leaf (kg/m^2)
m2 mass (surface density) of second leaf (kg/m^2)
d=depth of cavity (m)

That's a lot simpler to understand.

Once again, if you don't know what that equation does, then there's a problem.

So if I've added mass to my outer walls and roof (double layer board green glued together, insulation outside that).. THEN I have my air gap (2 inches minimum)... THEN I have my inner room made from double layer board green glued together, mounted using clips, with dampening insulation on the outside of that, which doesn't touch the outer apart from the beams.. am I not getting good enough?

Firstly, Green Glue is not adhesive, and you cannot use ot to "glue boards together". That's not what the product does, and attempting to use it as glue would be disastrous. Better go take a look at their website, to find out what the product is, what it does, and how to use it.

But that's beside the point for your plan.

Next, a 2" air gap is way too small: you need at least a 4" air gap, but your rafters appear to be 2x10s, at least, so I don't see how you could get just a 2" air gap in any case....

But that's also beside the point for your plan. The real problem with your plan, is this:

which doesn't touch the outer apart from the beams..

"apart from the beams". If even the tip of a tuning fork is enough to totally and completely couple the leaves, then how well do you think a 4x10 beam will do the job?

Is your criticism of this whole plan based on the beams touching the outer structure?

The beams don't just happen to "touch" the outer structure: they ARE the outer structure! Everything visible in your photos at present IS the outer leaf. All of the parts are in physical contact with each other, very firmly attached mechanically, and creating a wonderfully solid acoustically homogeneous single unit.

Here's a test you can do: Go place your ear up against one of those vertical posts, and get someone else to tap on other vertical post with a small hammer, on the opposite side of the room: Do you hear the sound in the post? Yup, you sure do! Now look at the surface area of one of those posts. Let's say, for argument's sake, that those are 4" faces, 6 feet high. So there's a surface area of about 288 square inches on the face of each post. The surface area of a typical 8" speaker cone is about 50 square inches. So each of your posts has a surface area about 6 times larger than that of a speaker cone.... I think you are starting to appreciate the problem! Instead of looking at the posts, look at those beams spanning across your room: How much surface area do you think is in each beam, considering all four faces? For argument's sake, let's call it 2,000 square inches, to make the math easy. That's about the same as 40 speaker cones... OK, so a wood beam is nowhere near as efficient as a speaker cone, but I'd hazard a guess and say that it's a lot more than 1/40th efficient!

So now so you see the dilemma? It does not matter how well you manage to seal and decouple those beams where they pass through the inner-leaf: simply because the ARE the outer leaf, you now have the outer-leaf INSIDE THE ROOM! And with a massive huge surface area, it will be able to both transmit all outside sounds into the room, as well as pick up all inside sounds and transmit them to the outside world...

The problem is that your phrase ""apart from the beams" = "Zero isolation".

As Greg pointed out: if any part of your outer leaf penetrates into your inner room, or even touches the inner leaf, then you don't have isolation, and you wasted a lot of money, time, and effort on building it.

and using insulation here was just an added element here.

You seem to have missed the point here too! Using insulation is not an "added element"! It is a basic, fundamental part of the isolation system! As I mentioned, insulation accomplishes many important tasks at once, including acoustic damping of resonances, changing the way air deals with heat, lowering the speed of sound, and others. If you do NOT put insulation in your wall, then you trash your isolation. The interior or your wall becomes an undamped resonant cavity...

Insulation is not an optional add-on: it is an integral part of the MSM system. Take a look at the equation above, and you'll notice that the constant jumps from 43 to 60 if you don't put insulation in your wall. That's a HUGE jump! nearly 40% That's how much your f0 jumps up the scale, if you leave it out....

It seems that you are assuming a lot of things that are not correct, and no taking into account the things that you need to take into account.

Any studio build starts (or should start!) with one very basic, simple number: "how much isolation you need", in decibels. If you don't know that, then everything you plan on doing is just wild speculation, and pure guesswork. Right now, neither we nor you have any idea how much isolation you need. All we know is that you need more than you are getting right now, but we don't even know how much that is!

Your very first course of action, before you carry on with any of your plans, is simply to define how much isolation you need, in decibels. Get yourself a decent hand-held sound level meter, set it to "C" weighting and "Slow" response, and do a series of measurements to determine how much isolation you need, and set that number as the most basic parameter for your design. If you don't know that, then you don't know anything! There's nothing at all to go on.

So do that first: get the meter, do the tests, and let us know your conclusion.


- Stuart -

Thanks again Stuart and Greg

Your advice has been very welcome indeed.

How can I say this - but I've had a major rethink on the eve of the job starting. We have a large garden and I have decided to abandon the garage conversion idea and instead ask my builder (who I know is good and who I trust based on his previous work for us) to build a new structure from scratch.

He's being incredibly accommodating and flexible considering he was due to start today, and is running with the change.

So, we're looking at building a concrete base and then making something new.

The available area is 6m x 4m. Again not huge but more than I would have had in the garage.

I know that a brick built structure would be preferable, but it sounds that budget-wise, timber is more affordable for me. The last studio my band recorded in was a timber building, so I know it's doable.

This will have block and brick up to damp level on top of a concrete base. Then timber.

I fully appreciate I need to do a lot more reading and research, but my questions right now are:

With those dimensions, would you recommend just a single room still? There would be enough space for a control room and a small recording room I believe.

What would be the concept if timber is used for the bulk of the build?

What should the roof/ceiling be made of? As it'll be a timber build, that will make concrete not an option.

I've already done the research re planning permission and it will not be needed. I'm advised by my builder that building regs will (i.e. inspection).

I live in a quiet lane, with no through traffic. Outside noise is minimal. The new location in my garden is away from other driveways even so there will be no car noise at all. I will as suggested get a meter and look into how much noise reduction I need to aim for.

But for now, even your initial thoughts would be appreciated.

And thank you again for the time you've spent on my garage idea.

John

We have a large garden and I have decided to abandon the garage conversion idea and instead ask my builder (who I know is good and who I trust based on his previous work for us) to build a new structure from scratch.

That's probably a very smart move!

considering he was due to start today,

Ummmm... This is probably not a good time for you to find out, but just DESIGNING a stud fully usually takes a couple of months, and that's assuming that you already have a good working knowledge of both acoustics and also building design. I would really, really, really suggest that you put the entire build on hold for six months, until you can get it properly designed in full detail. If necessary, maybe pay your contractor something for his trouble so far, and let him know that he'll be re-hired once the new plans are finalized.

So, we're looking at building a concrete base and then making something new.

Your best bet is a monolithic slab on grade. Relatively fast and easy to pour, and an excellent base for a studio.

The available area is 6m x 4m. Again not huge but more than I would have had in the garage.

So 24m2 for the footprint of the slab? That's decent. Allowing about 30cm all around for the walls, that leaves you with an interior area of about 5.4 x 3.4, which is roughly 18m2. That's fine for a control room. With careful selection of materials and good design, there could be a bit more space than that, especially if it turns out that you don't need huge amounts of isolation.

I know that a brick built structure would be preferable, but it sounds that budget-wise, timber is more affordable for me. The last studio my band recorded in was a timber building, so I know it's doable.

That's fine. You can get excellent isolation and excellent acoustics with wood-framed construction on a monolithic slab. Here's an example: http://www.johnlsayers.com/phpBB2/viewt ... =2&t=21368

This will have block and brick up to damp level on top of a concrete base.

That's an unnecessarily slow and expensive way of building a foundation. Unless the land slopes very steeply, the fastest, best, simplest, least expensive, least complicated foundation is a monolithic concrete slab-on-grade. It combines the footers and slab into a single pour, which can be done in a day. Of course, it takes time BEFORE that to dig the trenches and place the form work, but that's the same time you would have needed to dig the trenches for your proposed brick foundation.

I fully appreciate I need to do a lot more reading and research,

Yup! Realistically, that time will be about six months before you are ready to pick up a shove and move the first load of dirt to start the foundations...

With those dimensions, would you recommend just a single room still? There would be enough space for a control room and a small recording room I believe.

While it might be POSSIBLE to physically fit in a control room and a vocal booth, I wouldn't recommend it with only 18m2 to play with. The minimum recommended size for a control room is 20m2, according to specs such as ITU BS.1116-3, and EBU Tech-3276, among others. That's about as small as you can go and still get good acoustic response with simple treatment. It is possible to go to a smaller size, yes, but the smaller it is, the more complicated it gets to treat it and still get decent acoustics. And the smaller it is, the worse it will be from the point of view of overall frequency response, time-domain response, and specifically modal response.

I'mnot sure if you have seen Martin's thread, but if not take a quick look: http://www.johnlsayers.com/phpBB2/viewt ... 10&t=21539 That room is about 14m2, and it is giving us significant problem in getting the treatment right. Your room will be just a bit bigger than that, assuming you do not try to split it. If you DO try to split it in two, then it will be much smaller, and much more complicated.

If you could go up to maybe 7m c 5m footprint, then yes, it would be possible to fit in both a control room and also a small vocal booth. That's the case with Kirk's studio, currently under construction: http://www.johnlsayers.com/phpBB2/viewt ... 0&start=15

What would be the concept if timber is used for the bulk of the build?

Still the same concept: fully decoupled 2-leaf MSM construction. In other words, you build one stud frame on the edge of the foundation slab, and put weather-proof sheathing on the outside of that frame (no sheathing on the inner face of the framing!), then you build a second stud frame about an inch away from that, and put sheathing on just ONE side of that framing as well. Fill the entire cavity with suitable insulation.

What should the roof/ceiling be made of? As it'll be a timber build, that will make concrete not an option.

Actually, you COULD do a concrete roof a timber framed walls if you really wanted to, but it would be complex and takes up too much space for the larger-sized framing. It's better to go with wood framing all around.

So, you would build some type of roof that rests on the outer-leaf walls, and you would have two options in how to do that: 1) Build it as a sealed roof that needs no ventilation under the deck, and thus allows you to put the mass directly on the roof. Or 2) Build it as a typical ventilated roof, where air flows under the roof deck to keep it cool in summer and prevent condensation in winter, which implies that the roof cannot be the outer-leaf of your MSM system, so you will need to have a "middle leaf" ceiling of some type, below the roof, to complete the sealed envelope of the outer-leaf. If you take a close look at the corner control room threas, you'll see that's exactly how we did it for his studio. There's a typical vented roof up there, then a vaulted "middle-leaf" ceiling under that, which creates the top of the actual outer-leaf shell. That's the reason for the raised-tie roof trusses: to gain extra height under the exterior roof, for the "middle-leaf" ceiling, so that the final inner-leaf ceiling can still be nice and high. One option for using your garage would have been to modify your existing roof trusses to make them into raised-tie or collar-tie, but that's not so easy to do for your shape of roof. Possible, but not simple.

So in both of these cases, once you have completed the outer-leaf shell of the building, fully sealed, air-tight, and with consistent mass (surface density) all around, then you can build your inner-leaf ceiling below that. The inner-leaf ceiling sits on top of the inner-leaf walls, and the most efficient design is the "inside-out" method, where you build a sturdy "backbone" frame work, then raise several "modules" in between the members of the frame. Once again, the corner control room studio is a good example of that: you can see how it was built from the photos on his thread.

I've already done the research re planning permission and it will not be needed. I'm advised by my builder that building regs will (i.e. inspection).

So you are going to do this under "permitted development" rules? IF so, be careful with that! There are restrictions on the maximum height you can have for the roof. That's what Kirk ran into: Even though he went with a flat "bloc-and-beam" roof, there still would not have been enough height to fit in the HVAC system and also still get good acoustic height for his studio. Which is why we decided to dig down a bit laying the foundation below ground level, with some steps down. That allows him to have plenty of room height (which is critical for good acoustics), and still not exceed the "permitted development" regulations. I'd suggest that you consider doing this in your case too! That does mean that you can't have timber-framed walls below ground level, though. You could do yours the same as Kirk did up to ground level, then timber framing above that, or you could just do the whole thing the way he did.

I live in a quiet lane, with no through traffic. Outside noise is minimal. The new location in my garden is away from other driveways even so there will be no car noise at all.

So there is nothing in Cheshire that could trash your recording sessions? No thunder, rain, hail, or wind? No aircraft or helicopters flying over? No sirens from ambulances / police / fire engines? No trains? No cars arriving / leaving / driving past? No dogs barking outside? And nothing in the nearby houses either, such as water running in pipes, fans, pumps and other motors, people walking on floors, doors closing, people talking, vacuum cleaners, washing machine, radio, TV, furnace.... There's hundreds of possible sounds that could destroy a good recording, if they get into the mics in your control room. Are you CERTAIN that your room will not get any of that?

I will as suggested get a meter and look into how much noise reduction I need to aim for.

A while back I wrote a post about how to test a room acoustically, to decide on treatment, and you need a sound level meter to do that. So part of that thread describes what to look for when buying a sound level meter: http://www.johnlsayers.com/phpBB2/viewt ... =3&t=21122 . You can ignore the rest for now (you'll need it a year from now, when your room is completely built, and you are about to start treating it...), but do take a close look at the part about meters.

But for now, even your initial thoughts would be appreciated.

The best advise I can give you at this point is: slow down! Put the construction on hold for at least six months, perhaps as much as a year, and take the time to firstly learn all the basics of acoustics, then to learn all the basics of construction and construction design, then to learn how to use SketchUp, then to actually design your place, in complete detail. Once the design is finished, in all aspects and complete detail, only then can you start thinking about calling your contractor again, and ordering materials and tools.

So please just use this same thread to document your design process as you work through it, and then your actual build.

- Stuart -

Thanks Stuart.

I appreciate your latest advice. And yes ideally I would wait and do more preparation, but for various compelling reasons which I won't go into here, that's not an option. Work starts tomorrow and I hope I've picked up enough from your (and Greg's) input to make a good job of it.

I do hope you won't abandon me, and help me as best you can in these circumstances!

That's an unnecessarily slow and expensive way of building a foundation. Unless the land slopes very steeply, the fastest, best, simplest, least expensive, least complicated foundation is a monolithic concrete slab-on-grade. It combines the footers and slab into a single pour, which can be done in a day. Of course, it takes time BEFORE that to dig the trenches and place the form work, but that's the same time you would have needed to dig the trenches for your proposed brick foundation.

There is a slope close (but not too close) to the build. And my builder already knows the ground as he excavated it to build a patio and a deck. So a monolithic slab is not an option he tells me.

Still the same concept: fully decoupled 2-leaf MSM construction. In other words, you build one stud frame on the edge of the foundation slab, and put weather-proof sheathing on the outside of that frame (no sheathing on the inner face of the framing!), then you build a second stud frame about an inch away from that, and put sheathing on just ONE side of that framing as well. Fill the entire cavity with suitable insulation.

Thanks for this summary. From this I read that we're overdoing it. From the outside of the building, the current plan is :
Pine cladding fixed directly onto
OSB board fixed to
Timber framing
Between the batons: Rockwool RW3 100mm insulation (density 60 kg/m3)
Small air gap
Rockwool RW3 100mm insulation
Timber frame
Double thickness fire board (with green glue between) fixed directly to frame

Do I need all of this? The OSB board for instance? If this is still not giving me MSM with full decoupling, I must be infuriating you. Please count to ten.. again.. and tell me in the same format as above what I should do?

Actually, you COULD do a concrete roof a timber framed walls if you really wanted to, but it would be complex and takes up too much space for the larger-sized framing. It's better to go with wood framing all around.

So, you would build some type of roof that rests on the outer-leaf walls, and you would have two options in how to do that: 1) Build it as a sealed roof that needs no ventilation under the deck, and thus allows you to put the mass directly on the roof. Or 2) Build it as a typical ventilated roof, where air flows under the roof deck to keep it cool in summer and prevent condensation in winter, which implies that the roof cannot be the outer-leaf of your MSM system, so you will need to have a "middle leaf" ceiling of some type, below the roof, to complete the sealed envelope of the outer-leaf. If you take a close look at the corner control room thread, you'll see that's exactly how we did it for his studio. There's a typical vented roof up there, then a vaulted "middle-leaf" ceiling under that, which creates the top of the actual outer-leaf shell. That's the reason for the raised-tie roof trusses: to gain extra height under the exterior roof, for the "middle-leaf" ceiling, so that the final inner-leaf ceiling can still be nice and high. One option for using your garage would have been to modify your existing roof trusses to make them into raised-tie or collar-tie, but that's not so easy to do for your shape of roof. Possible, but not simple.

My builder tells me he's planning a 'warm roof' which I assume is the same as a sealed roof. Like the walls, from the outside he's planning weather resistant covering, membrane, OSB board, the Rockwool RW3 insulation, timber frame.. air gap, Rockwool RW3 100mm insulation, timber frame, double thickness fire board (with green glue between) fixed directly to frame (not using resilient clips as I believe it's decoupled inner room).

Above the inner leaf will be acoustic venting ducts that lead down to vents in the inner ceiling for air in and out (if need be with silencer boxes mounted under the inner ceiling).

So it's the same question as per my walls above. But also, will a sealed roof like this be OK? Or do I need to do the middle leaf to address a possible condensation issue?

So you are going to do this under "permitted development" rules? IF so, be careful with that! There are restrictions on the maximum height you can have for the roof.

I believe I have checked all the regulations. Because the building will not be within 2m of the boundary, I can go up to 3m - see attached snip from the local government website.

So there is nothing in Cheshire that could trash your recording sessions? No thunder, rain, hail, or wind? No aircraft or helicopters flying over? No sirens from ambulances / police / fire engines? No trains? No cars arriving / leaving / driving past? No dogs barking outside? And nothing in the nearby houses either, such as water running in pipes, fans, pumps and other motors, people walking on floors, doors closing, people talking, vacuum cleaners, washing machine, radio, TV, furnace.... There's hundreds of possible sounds that could destroy a good recording, if they get into the mics in your control room. Are you CERTAIN that your room will not get any of that?

I fully appreciate what you are saying but it is indeed a very quiet environment. But I believe what I am doing will give me the isolation I need.


Finally, I did look at the threads you suggested. Some very impressive work indeed.

I am honestly not aspiring to that level at this point in my life. Maybe I will one day. I will have to do my learning in the place I'm having built.

Stuart, I know it's not what you like hearing, and I totally realise you have my best interests firmly in mind, but this is happening and I'd rather put out to sea in this craft with you as a virtual mate.

Thank you again.

John

I'm strapped for time, but I will say this (if you're starting tomorrow):

DIG DOWN BELOW GRADE!!!!

Your silencer boxes and HVAC take up a TON of room. Your ceiling height will be very very short if you don't go down some. Try to gain even a few feet. The more, the better though. Seriously, trust me on this one. You NEED the height!

Also, I understand there is some "compelling reasons" you have to start the build now. I won't say that's fine, but okay, you must start. I get it. Stop as soon as you're allowed to stop though. If that means getting the shell up and then you can break, do it. You literally cannot build something this complex without a 3D plan and a bunch of calculations. We care, we don't want you to fail. Also, if you can stretch those dimensions at all, even a quarter of a meter, do it.

I look forward to your progress pics tomorrow night from the build start tomorrow morning! I hope *fingers crossed* that I see a deep hole being dug. . .

Greg

And yes ideally I would wait and do more preparation, but for various compelling reasons which I won't go into here, that's not an option

I really hate to be harsh, but sometimes a rude "wake-up call" is what you need, so here it is:

If it is not an option to stop building now, then it is not an option for you to have a successful studio. Period. Stop. End of story. It really is that simple. You CANNOT successfully build a studio without proper planning. It WILL NOT WORK. That's about as categorical and in-your-face as I can make it.


So the choice is yours: Start building tomorrow and fail. Or be sensible, stop building, plan properly, and succeed.

We have seen this happen time and time again on the forum: People absolutely convinced that they MUST build RIGHT NOW, and that their extreme urgency will somehow invalidate the laws of physics, allowing them to bypass the fixed rules of nature that everyone else must live by. Because it is life-or-death for them, the Universe realizes this, and will allow sound to NOT follow the normal rules, but only for their specific situation, just because they are in a hurry.... Sound will bow down to them, because their situation is so important....

Not gonna happen!

Sound waves will behave exactly as they always do, for your studio, just like everyone else's.


In every single case where we have seen this on the forum, not one has succeeded. None. Zero. Zilch. I very much doubt your case will be the first...

In every single case where this route has been followed, where we have warned people to stop, wait, design, then carry on, and they have ignored our advice, believing that they know better, and their situation is "different", not one has ever produced a successful studio. In fact, not one has even produces a studio at all!

Let that sink in for a minute. Why would your case be any different?

The ONLY times that there has been success, is when people have heeded our advice, stopped, planned properly, and built it right. In some cases, they even had to tear down stuff they had built wrongly already, then start again. Such as this one: http://www.johnlsayers.com/phpBB2/viewt ... =2&t=17363 (read the first few posts, carefully....)

I do hope you won't abandon me, and help me as best you can in these circumstances!

I'll try, but I really don't hold out much hope of being able to help someone who has made a conscious decision to fail.

And my builder already knows the ground as he excavated it to build a patio and a deck. So a monolithic slab is not an option he tells me.

Really? That sounds very strange! The experts normally recommend monolithic slabs precisely FOR difficult ground... I'm wondering if your builder maybe has a vested interest in going with the long, slow, expensive process, that will put a LOT of extra cash in his pocket (a couple of thousand pounds extra, at least, probably...) rather than the fast, efficient, low cost process? I wonder .... Hmmmm..... It makes you think, doesn't it?

Fact: Your builder is NOT qualified to make this decision. A soils engineer or structural engineer is the ONLY guy who can tell you the right way to do this. Period. Do NOT make the mistake of trusting the guy who stands to make a stack of money, when making major, key decisions like this! Trust the qualified, certified export engineer, who has no vested interest at all, and actually does know what he is doing.

Before you do anything, hire one, tomorrow morning. Get him in, and get his report. Tell him you'd like a monolithic slab, and ask if there is any good reason why that would not be good for your situation. Ask him to explain, clearly, what the pros and cons are of the various types of foundation.

There's only one problem here: he'll want to know what total load you are going to put on your foundations, but you don't have a clue about that, because you have not planned a single thing about it! You have no idea at all what your dead load and live load will be: So how in hell can your "builder" tell you what dimensions, materials, and techniques you will need for doing the foundation? How can he even give you a cost estimate, when nobody yet knows how much weight the foundations have to support?

This makes no sense at all....

Does your builder even know how to do a monolithic slab? What specific structural reason does he give you for his suggestion? Not just "Well, gee, umm... I think... errr... I don't like doing it that way", but an actual, structurally valid reason.

Thanks for this summary. From this I read that we're overdoing it.

Why do you think that is overdoing it? Isn't that exactly what I said in my post?

Pine cladding fixed directly onto
OSB board fixed to
Timber framing
Between the batons: Rockwool RW3 100mm insulation (density 60 kg/m3)
Small air gap
Rockwool RW3 100mm insulation
Timber frame
Double thickness fire board (with green glue between) fixed directly to frame

In what way is that different from what I said?

Also, did you use this equation yet? " Fc=c[(m1+m2)/(m1m2d)]^.5 " I gave it to you yesterday, and mentioned that if you do not understand it, or do not know what it means, or have not yet used it, then there is a SERIOUS problem here! It is one of the most basic, simple, KEY equations that you MUST use on your walls, if you hope to avoid failure. "Failure" can take two forms here: 1) you finish the place and the isolation is so lousy that it is not usable as a studio. 2) You finish the place and have much more isolation than you need, which is nice, but it also cost you much more than you should have paid, so the only guy who wins is the builder.... again....

Learn what that equation means. USE IT! Then base your build on the results you get. If not, then there's no point me trying to help you any further.

My builder tells me he's planning a 'warm roof' which I assume is the same as a sealed roof.

"Assuming" is a very, very bad way to design a studio. Starting a build without even having the complete plans in hand, either electronic or on paper, is a plain stupid way of building a studio!

Do you have the complete plans in hand?

Sorry to be so harsh again, but if there's one thing that I'm known for on the forum, is calling it like I see it. No beating about the bush. No pulling punches. No PC crap. Just laying it out in front of you, in all it's ugly glory. IF you start building a studio, and you do not have the plans in place, that's stupid. I have no other way of describing it.

Show me the detailed plans for your "warm roof", exactly as it will be built in your specific case, with all the dimensions, and then I can tell you if it is what you need, or not.

My builder tells me he's planning a 'warm roof' which I assume is the same as a sealed roof. Like the walls, from the outside he's planning weather resistant covering, membrane, OSB board, the Rockwool RW3 insulation, timber frame.. air gap, Rockwool RW3 100mm insulation, timber frame, double thickness fire board (with green glue between) fixed directly to frame

What the dimensions for the lumber? What span? What is the truss design? What live load and dead load did you use for the loading calculations? What deflection are you considering for the joists? What decking will be used? What is the slope of the roof? What is the nailing schedule? What is the membrane? What is the final finish surface of the roof? How much will it weigh? What is the surface density? What is the MSM f0 frequency in combination with the inner-leaf ceiling?

If you cannot answer those questions directly from the plans you have in your hand right now, then it would be foolhardy for you to proceed. Not knowing all of that is sure sign that there is no planning going on here, and that's a certain indicator of failure. Guaranteed.

Let's take this piece by piece:

"weather resistant covering" - What type? How thick? What mass? What surface density? How is it attached?
"membrane" - What type? How thick? What mass? What surface density?
"OSB board" - How thick? What surface density? How is it attached? How are the joints between boards sealed?
"Rockwool RW3 insulation" - How thick? Why? Why not semi-rigid fiberglass? Or fluffy fiberglass? Or cellulose? Or something else? How will it be held in place?
"timber frame" - What dimensions? What span? What load is on that (live and dead)? Wheat deflection?
"air gap" - How big? Why do you want empty air in your cavity, when I already spent a lto of time explaining that your cavity should be completely filled for maximum isolation? Did you not understand the difference between the constant being 43 or 60 in the equation?
"Rockwool RW3 100mm insulation" - Why?
"timber frame" - Dimensions? Span? Load? Deflection?
"double thickness fire board" - What thickness "fire board"? What is "fire board"? Surface density? Attachment? Seals?
"with green glue between"- Why? What coverage pattern?

Etc.

So many questions... and I'm betting there are very few answers...

(not using resilient clips as I believe it's decoupled inner room)

You just "believe" that it is decoupled? You don't KNOW this for a fact? Yet you plan to start building tomorrow?

Above the inner leaf will be acoustic venting ducts that lead down to vents in the inner ceiling for air in and out (if need be with silencer boxes mounted under the inner ceiling).

Where is the AHU? What is the heating/cooling/dehumidifying capacity of that unit? What sensible heat load did you consider in your calculations when you decided on that unit? What latent heat load? What occupancy? What flow rate did you calculate you need for your room? What will the flow velocity be at the registers? How much make-up air will you be adding? How much stale air will you be dumping? What size duct work is the correct size for this situation? Will that be rigid or flexible? Lined or not lined? What will the static pressure drop of your system be? Can the AHU handle that static pressure load? How will you prevent the pipe bundle from flanking between leaves? Where will the heat pump go? Where will the condensate drain go?

If you did not understand all of those questions immediately, without googling them, and if you don't have all the answers in your plans already, then you have no business building this place yet: it will fail, since it will not be ventilated correctly.

The simple, and rather silly, explanation that your builder gave you of " venting ducts that lead down to vents in the inner ceiling for air in and out" shows that he does not actually have a clue about studio HVAC. What on earth is an "acoustic venting duct"? I've never heard of one of those! I've been designing HVAC systems for studios for many, nany years, and I have never come across that term ever before. Because it's somthing your builder invented himself, on the spur of the moment, since he doesn't actually have a clue.

(if need be with silencer boxes mounted under the inner ceiling)

You are kidding, right? Do you have ANY idea how BIG such boxes are? Clearly not. I certainly would not want one of those hanging from the ceiling in my studio!

Take a close look at this image: it shows the dimensions for the HVAC duct system for a small control room that I designed for a customer a few years back. The room is very similar in size to your room, so you WILL need something like this: That is a "bird's eye view" from above the control room ceiling, looking down onto the inner-leaf ceiling, with the outer-leaf removed: all of that HVAC system goes in the space between the inner-leaf ceiling and the roof (or middle-leaf ceiling, as the case may be). Do you REALLY want all of that hanging from your ceiling, inside the room?

(This is probably the point where you and your builder will come up with a whole slew of reasons why you think you don't need an HVAC system for your room, but I can tell you in advance, before you even mention them, that I've heard them all before, and not one of them is valid: you DO need an HVAC system for your studio, if you plan on staying alive and healthy in there. There is no argument here. HVAC is not a luxury for a studio: it is a basic requirement. It is every bit as necessary as having a roof on top and walls around you. So please don't even wast your time trying to tell me why YOUR case is different, and the universe will also suspend the biological laws that govern your metabolism and how your respiratory tract works, just because you are in a hurry.... )

But also, will a sealed roof like this be OK?

I have no idea, until you show me the detailed plans. I have no idea what your builder means be "sealed roof" or "warm roof". Different meanings to different people in different building codes... A quick check on Google found this "definition": "A warm roof construction has many benefits over a traditional ‘cold roof’, essentially it is a ‘breathable roof construction’, which allows moisture to escape which in turn prevents damp and any associated decay problems. " If it is breathable, and allows moisture to escape, then it is NOT sealed, so it is NO use for your situation, unless you also add in a middle-leaf.

Or do I need to do the middle leaf to address a possible condensation issue?

Based on the above definition, it certainly seems that way! On the other hand, since your builder doesn't seem to know what he's talking about with foundations or HVAC, it is enturely possible that he's misusing the term "warm roof" as well, and to him it means something totally different. I can't tell what he has in mind until you show me the actual final plans for your specific "warm roof". Show me those, and I might be able to say. But I'm not talking about generic plans for other warm roofs: I'm talking about the specific, actual, real plans for your specific studio, drawn in complete detail, and approved by your local authorities. Show me those plans, and I can tell you if that will work, or not, acoustically.

I believe I have checked all the regulations.

Are you certain? The most recent version I have is 978-1-4098-5046-5, dated April last year. IS that what you have? That's what I used the last time I designed a studio for a customer in the UK. I'm assuming you are presenting this as a Class E situation?

You say the ground slopes slightly? Did you notice what point you have to measure your 2.5m, 3m, or 4m height from? Did you notice that, regardless of the height of the roof peak, your eaves cannot be higher than 2.5m? No, I didn't think you noticed that. Did you realize the implications of this limitation? No, I figured you didn't realize that either: it places a limit of 2.5 m on your outer-leaf wall height (since that is where you MUST measure your eave height), which implies an even lower height for your final inner leaf ceiling. Depending on span and construction, and allowing 40cm for the silencers, your final inner-leaf ceiling will be around 2m, maybe lower. Explain to me how you hope to get usable control-room acoustics for a ceiling that low... That's a little under 6'6".... (I hope you are not too tall, and don't get claustrophobic...)

You mean you did not know this already? That your assumptions and lack of understanding would lead to a room with an unworkable low ceiling height? You would have soon figured that out, if you would have planned properly.

Here it is, in black and white. Page 44: So no matter how high your roof can go, your walls CANNOT exceed 2.5m at the eaves. And that places a severely low limit in the inner-leaf ceiling.

I can go up to 3m

... assuming you do a shed roof, that's possible, yes. And for a gable roof, it could be 4m! But as paragraph (f) clearly states, your walls can be no higher than 2.5m at the eaves. THAT is the problem, not what you ASSUMED was the problem.

see attached snip from the local government website.

I'm well aware of what permitted development regulations for the UK state: I have designed several studios for customers, under these. One of them is Kirby's place, that I linked you too. And the above is the exact reason he decided to bight the bullet, and dig deep. His "eave height" is exactly 2.5m, but the internal outer-leaf shell height is 3.5m (11'5", roughly), and the inner-leaf ceiling height of his control room and iso booth, (with complete HVAC above) is 2.8 m (about 9'2"). Very decent, and very usable, acoustically. The final visual ceiling height in the control room, with all acoustic treatment in place, is 2.66m (not counting the cloud, of course). That's about 8'6" in imperial.. Higher even than the standard UK ceiling height, of 2.4m...

But I believe what I am doing will give me the isolation I need.

And fifteen years ago my kids believed in Santa Clause... but then they grew up, learned about reality, and now they no longer believe in that.... In other words, what you BELIEVE and what is REAL can be two very different things. The only way to tell if you will have the isolation you need, is to do the math. Just believing it to be enough will not make it so, any more than a small child believing in Santa actually makes him exist.

Believing and hoping and assuming, and guessing are really, really terrible ways to design a studio...

Finally, I did look at the threads you suggested. Some very impressive work indeed.

Take a close look at Kirk's thread: That is exactly what you need, and was built under Permitted Development, Class E. It's not far-fetched, "out there", or unreasonable: it is realistic. His will have a bathroom, kitchenette, isolation booth, control room, and entrance lobby. All within a 33.5m2 footprint. You could do the same. Or you could go smaller, and skip the extra rooms, leaving just the control room. Which is nearly 15m2 floor area, in Kirk's case, and could be about the same in your case.

I am honestly not aspiring to that level at this point in my life.

Then I don't understand what you are aspiring for! If you are NOT looking for a workable, usable, realistic control room on a 25m2 footprint with good isolation and good acoustics, built under Class E permitted development rules, then I must have entirely misunderstood your thread! That's what Kirk's thread is about.

Stuart, I know it's not what you like hearing, and I totally realise you have my best interests firmly in mind, but this is happening and I'd rather put out to sea in this craft with you as a virtual mate.

I'm not going out to sea on a boat that I suspect will sink! I'll happily watch from shore, and shout encouragement every now and then, if you want, but I do hope you know how to swim, because your boat ain't gonna float...


- Stuart -


PS:

DIG DOWN BELOW GRADE!!!!

YES!

Your silencer boxes and HVAC take up a TON of room.

YES!

Your ceiling height will be very very short if you don't go down some.

YES!

You NEED the height!

YES!

Also, I understand there is some "compelling reasons" you have to start the build now. I won't say that's fine

Neither will I! In fact, I'd say that unless the "compelling reasons" is a guy standing next to you with a gun against your head, telling you he will pull the trigger unless you start tomorrow... then there's no reason at all to actually start tomorrow. It's foolish.

This is like he said he wants to go on vacation, and is leaving tomorrow: You ask here he is going, and he says "No idea". How are you getting there? "No idea". Plane? Train? Car? Bus? Bicycle? Roller-skates? "No idea". How long will it take? "No idea". What clothes did you pack? "No idea". How much will it cost? "No idea." What will you eat? "No idea". Do you have any idea at all where you are going? "On vacation! And I really REALLY have to leave tomorrow... even though I don't have a clue about where I'm going or what I'm doing"....

That's what I'm reading above.

You literally cannot build something this complex without a 3D plan and a bunch of calculations.

YES! Very, very true.

I hope *fingers crossed* that I see a deep hole being dug. . .

I'd differ slightly here: I would MUCH rather see nothing at all happen tomorrow, except that the entire thing gets put on hold, and common sense takes over....

But I'm not expecting to see that either....

Well, three days later, and no response, so I guess that's yet another "I know better than you guys, and I'll do it my way and it will be fantastic!" response.

Please do keep updating the thread with photos of the build, so we can see how you do it, and how it works out for you, even if you don't want our advice any more.

- Stuart -

OK I'm back. Ready for some more haranguing yes, but I know I'm getting good advice as well, so here goes..

I haven't stopped the job. BUT I have done a lot of thinking and talking with my builder and the plan has changed.

I'm going to have concrete block exterior walls now instead of a timber outer.
The interior decoupled room within a room will be a timber frame with double layer acoustic board as before (walls and ceiling).
I've asked him to dig down as suggested here to give me more interior height.
I've properly looked at the planning and building regs as advised here and now understand what I can do.

I'd appreciate help on the the exterior roof. My budget definitely won't stretch to a concrete roof.
Should I tile it and have acoustic board above the rafters (or will OSB suffice). Then there'll be my gap - within insulation - before the inner ceiling of double acoustic board as above. Will this be sufficient mass? How can I beef it up if needed?

Also, on the exterior block walls, my builder is talking about putting batons on the outside of the block, and putting timber cladding on them. Will the gap between the block and the cladding matter? Should I insulate that?

OK. I've donned a second thicker skin and am holding my breath.

John

I'm going to have concrete block exterior walls now instead of a timber outer.

Smart move! That, right there, gains you significant isolation. Just remember to seal the inner surface of the blocks before putting up your inner leaf. Concrete, brick, and most masonry surfaces in general are porous, which means that air can move through them. If air can get through, so can sound. So seal the surface with a good masonry sealant.

I've asked him to dig down as suggested here to give me more interior height.

Another smart move! You won't be sorry. Yes, it is additional expense, but your resulting studio will be much better for it.

The interior decoupled room within a room will be a timber frame with double layer acoustic board as before (walls and ceiling).

Forget using specialized and expensive products that you don't need, like "acoustic board". Just use ordinary drywall. Sound waves cannot read the price tags on your mass-building materials, so they won't be impressed if you bought really expensive mass. They just react to the mass, pure and simple, so get the least expensive mass that will do the job. I normal go with one layer of OSB directly on the stud faces, then one or more layers of fire-rated drywall over that. OSB is similar in density to drywall (a little lower, but not much), and having that as your base layer means that you not only get good mass, but also a nailing surface around the entire room! So you don't have to hunt for studs when you need to nail or screw some piece of treatment in a certain place. Make the OSB thick, and you can hang whatever you want on it. It is also structurally much stronger than drywall, so you get excellent sheer strength in your walls. Etc.

I'd appreciate help on the the exterior roof. My budget definitely won't stretch to a concrete roof.

I would recommend beam and block. It's cheaper and simpler than trying to pour a concrete roof, and keeps the mass of the walls, so you get a consistent high mass, high surface density shell around you. Great isolation.

Should I tile it and have acoustic board above the rafters (or will OSB suffice). Then there'll be my gap - within insulation - before the inner ceiling of double acoustic board as above. Will this be sufficient mass? How can I beef it up if needed?

Do the math! You have the equations.... Work through it, to make sure that the mass and the air gap are correct for the MSM resonant frequency that you need, and the isolation that you need. And remember that the TOTAOL isolation of your studio is only as good as the weakest part. So if you have great walls, fantastic doors, wonderful windows, top-notch silencer boxes, but a lousy roof, then your overall isolation is lousy... and you wasted a hell of a lot of time, money, and effort in all the other things....

Also, on the exterior block walls, my builder is talking about putting batons on the outside of the block, and putting timber cladding on them.

You could do that, yes, but do the math here too: you'd be creating a 3-leaf system, so there is a potential (low probability if you have concrete block walls, but still not zero probability!) that there will be an unwanted resonance issue that trashes your isolation at certain frequencies. So do the math for three-leaf systems, to check for that.

Also, you live in the UK: I would not put up a timber exterior on the building. Timber and weather do not go together well. Consider using vinyl siding, or even better, fiber-cement siding. There some really nice looking fiber cement planks that imitates wood planks, and you can seal it and stain it to get a very convincing effect. And the fiber-cement won't rot. I did my shed in the back yard like that, decades ago, and the fiber-cement still looks decent. But I used timer trim on the edges of the roof, and that needs constant attention: re-varnishing every few years... not nice.

Another option for your building exterior is plain old stucco, or exterior grade plaster. Good stuff.



- Stuart -

Should I tile it and have acoustic board above the rafters (or will OSB suffice). Then there'll be my gap - within insulation - before the inner ceiling of double acoustic board as above. Will this be sufficient mass? How can I beef it up if needed?

Here's a link to my calculator that you can easily change materials on to see how they will perform. It should be easy for you to compare your ceiling and your walls!

Gregwor & audiomutt’s MSM Transmission Loss Calculator Version 2

Greg