Sound treating a large concrete shed, with small roof cavity

[Vonkrumm]

Hi Guys,
I have a shed that we are restoring (8m x 6m), which I hope to convert to a studio.
We are about to replace some of the iron on the roof, so I wanted to ask a couple questions before we do.
Sound treating is the main issue, but it would be nice to have it somewhat sound proof.
This will be for recording demos, and a place where my brother and I can learn mixing/mastering.
We will record some instruments but no drums or anything too loud.

Currently I have:
Walls - Single concrete blocks, approx 150mm
Floor - Concrete Slab, over 300mm
Internal stud walls - None (for now)

Planned:
Windows and Doors - New thick 10mm pane glass
Roof - New Colourbond iron, Rockwool R4 195mm thick (roof cavity only 200mm), and keeping the old plasterboard (checker type).
Roof is pitched about 3.33deg
(Side Wall Heights are 2.4m and 2.75m)

My questions are basically:
1) Would the above work for a first recording space?

The shed is old with lots of gaps in the corners of the roof (between the colourbond and the cement walls mainly), and there are gaps around the windows, doors ect.
I plan to seal everything up with acoustic sealant, put in some new rock-wool insulation for the ceiling (even the RW3 type).
If I do this, I am hoping this would be ok….
If more sound proofing is needed I can look at internal stud walls, more gyprock on the ceiling, a room within a room ect.

2) If there are any sound guys that are in the Adelaide area, I may need to hire someone for a second opinion

Budget: $3000 (not including shed renovations)

[Soundman2020]

Hi there "Vonkrumm", and Welcome!

I have a shed that we are restoring (8m x 6m), which I hope to convert to a studio.

That's a very nice floor area for a studio. There's a document called ITU BS.1116-3 that lays out the specifications that a room needs in order to be usable as a "critical listening room", and one of those specs is a minimum of 20m2 floor area, maximum 60 m2, so your place is well within that, and heading for the high side. That's great, as small rooms need a lot more acoustic treatment than large rooms to make them sound good. In fact, if you wanted to, you could probably have a nice sized control room and a small isolation booth inside that area.

However, there's one key dimension you didn't mention: Height! Sound is 3D, so you do need to consider all three dimensions in everything you do.

Sound treating is the main issue, but it would be nice to have it somewhat sound proof.

Don't short-change yourself by downplaying your need for isolation! That's a mistake that many first-time studio builders often make. They figure that there are no neighbors close by, so they don't need to isolate, but that is totally ignoring the OTHER direction: incoming sound. So there is nothing in Adelaide 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 your nearby house either, such as water running in pipes, fans, pumps and other motors, doors closing, people talking, vacuum cleaners, washing machine, radio, TV, .... There's hundreds of possible sounds that could destroy a good recording, if they get into the mics in your studio, while you are tracking. Are you CERTAIN that your room will not get any of that? It's not just while tracking either: you will quickly learn that while mixing and even more so while mastering, you need a very quiet environment, so that you can clearly hear all the subtle things in the mix that can make it or break it. If you can't hear them, then you can't mix them or fix them!

You should probably think through your isolation requirements again. Rain on a tin roof is LOUD. Hail on a tin roof is DEAFENING. So every time it rains on your studio, or a thunderstorm comes through, you'd have to cancel your recording/mixing/master session.

This will be for recording demos, and a place where my brother and I can learn mixing/mastering.
We will record some instruments but no drums or anything too loud

Great! So you do need pretty good isolation! If you are recording QUIET instruments, then your mics will be picking up a higher-than-normal noise level, precisely because the music is quite. So there will be MORE of the outside ambient noise getting into your recordings... Especially if you are using condenser mics for tracking (as you should be, in many cases!), since those are notoriously sensitive to picking up distant, quiet sounds along with the louder close sound that you actually wanted...

Currently I have:
Walls - Single concrete blocks, approx 150mm
Floor - Concrete Slab, over 300mm

Great! That's a pretty good start for getting decent isolation. And a 30cm thick slab is EXCELLENT! Very unusual to have it that thick. Was this some type of industrial shed previously? Maybe with heavy equipment parked on it? There's not too many other reasons to have such a massive slab, but it is good news for you!

Windows and Doors - New thick 10mm pane glass

Not very much, so that will need upgrading for your isolation. And that's just the windows: what about the doors?

Roof is pitched about 3.33deg

So basically it is flat? 3 degree pitch is pretty much nothing at all: barely enough to get some water run-off. And for a metal roof, that is surprising! I would suspect that there would be leaks where the metal sheets overlap, with such a flat angle. Assuming that the roof slopes across your shed, over that 6m span, a slope of 3.3° means that it is only 30 cm higher on the high end than it is on the low end. That's not really enough to handle good water run-off with tin roofing. If you are going to replace that roofing, I'd suggest that you consider replacing the trusses too, and get a more decent angle on that. You need at least an 20° slope to get good run-off.

1) Would the above work for a first recording space?

Yes, definitely! There's enough space to get good isolation, a good size control room, and a small isolation booth.

The shed is old with lots of gaps in the corners of the roof (between the colourbond and the cement walls mainly),

Air-tight seals on everything is critical to getting decent isolation. Even a tiny gap or crack can have serious effects on your isolation. Your walls are cement block, so they will also need sealing: use any decent quality masonry sealant for that, or even ordinary paint. Cement is porous, so it MUST be sealed.

I plan to seal everything up with acoustic sealant,

put in some new rock-wool insulation for the ceiling (even the RW3 type).

For acoustics, the RW rating is irrelevant. What you need to look at is the density and the type of insulation. For mineral wool, you would need something with a density of around 50 kg/m3. If you use fiberglass insulation instead, then it would need to be around 30 kg/m3. Other types would be different again.

If more sound proofing is needed I can look at internal stud walls, more gyprock on the ceiling, a room within a room ect.

That should be your first priority! First, before you do anything, define how much isolation you actually need, in decibels. That's the key starting point for any studio build. If you build the place then find you need more isolation, the only solution is to rip it all down and start again... So it is very, very important to get that part right from the start. Pretty much any other issue can be fixed without too much trouble, but insufficient isolation is a deal breaker, and it means going back to square one. There's nothing you can do to a finished studio to fix inadequate isolation, without doins major surgery on it...

2) If there are any sound guys that are in the Adelaide area, I may need to hire someone for a second opinion

These days, you don't need a local guy to design your studio for you. Modern technology makes it a breeze to design, build, treat, and tune a studio remotely. With pretty much all of he studios I design for my customers, it is very, very rare that I actually visit the site. I have designed places all around the world without every going to the actual location. It's the same with John Sayers: the majority of his studios have been designed and built by "remotes control".

For example, here's a studio that is nearing completion right now, so you can see how the process goes: the corner control room thread That is almost done: he's just building the desk right now, then we'll do the final tweaking, and he can make music! Here's another on currently under construction, also getting close to completion: thread about Steve's high-end control room in New Orleans And here's one that was completed a while back, so you can see the final outcome: thread about Studio Three Productions' studio All of those were done 100% remotely. I have never been to any of those places, never met any of the owners in person, and actually never even spoken to them on the phone! It's all e-mail, these days.

In other words, you don't need to find a local guy: there are many capable studio designers around who could design your place remotely.

It would be good if you could post some photos of the shed as it is now, along with a diagram showing the dimensions and the locations of doors, windows, support columns, etc. That would help is get a better idea of what you are dealing with.

- Stuart -

[Vonkrumm]

Hi there "Vonkrumm", and Welcome!

Thank you sound man! I didn't expect such a reply I am truly grateful
My Side Wall Heights are 2.4m and 2.75m, so that's were the 3deg slope is from.

Don't short-change yourself by downplaying your need for isolation! That's a mistake that many first-time studio builders often make.

We do have lots of noises, like dogs... even though it is a quite part of town. I will have to buy a sound meter and find out how much isolation I need, like you said.

And that's just the windows: what about the doors?

My only door does have a sheet of glass in it. A poor choice I now understand.

Air-tight seals on everything is critical to getting decent isolation.

So I can use something like a foam gap filler? I know high density is preferred, but if there are lots of large gaps, then how do you sound proof these (without spending a fortune on acoustic sealant)?

For mineral wool, you would need something with a density of around 50 kg/m3. If you use fiberglass insulation instead, then it would need to be around 30 kg/m3

I believe RW3 and RW45 are UK ratings for similar density insulation to what you mentioned (30 kg/m3).
I must be on the right track
(But shit that stuff is expensive... )

there are many capable studio designers around who could design your place remotely.

I am happy to look into this remotely.
I know this is a small budget, but I want to do it right.

If you build the place then find you need more isolation, the only solution is to rip it all down and start again...

Included are some pictures of the shed.
The large opening will probably have a new stud wall up half way, then window.
This is a large space and ideally I was going to have some of it as general office / workspace.

My thinking was, soundproof the ceiling - seal the gaps - then it should be fairly good isolation, right? (i.e. ground and walls are cement).

Then if I need more insulation, I can build a room within a room later on, if needed.
(i.e. add stud walls, and double layer gypsum later)

This way, I may also get away with only doing the back corner (8x4m in total).
(the partition wall would be in line with the cross beam and poles, shown in the pictures).

[Vonkrumm]

Also, a quick question:

Would 27kg/m3 Earthwool be suitable for the ceiling?

I can see a lot of people making their own traps from high density batts.

Not so much lining the whole ceiling....

[Soundman2020]

Would 27kg/m3 Earthwool be suitable for the ceiling?

Do you have a link to that product? I assume that "Earthwool" is actually mineral wool, 20 27 kg/m3 is a bit on the low side probably, but it would still work.

Not so much lining the whole ceiling....

In many places, people often use rolls of "pink fluffy" fiberglass for roof insulation, but that's usually just for thermal purposes. However, it is still pretty good for acoustic purposes too.

I will have to buy a sound meter and find out how much isolation I need, like you said.

Exactly! That should be the very first thing you do, before you build anything. First determine how much isolation you NEED, then build accordingly.

My only door does have a sheet of glass in it. A poor choice I now understand.

Not necessarily! How thick is the glass, and how is the door made? It is is a solid wood door (not hollow-core), and the glass is fairly thick, then you should be fine.

So I can use something like a foam gap filler?

To seal the gaps and make it air-tight, yes, but expanding foam has practically no mass, so it won't do anything to get the surface density of your outer leaf consistent all around, plus it is "closed cell" at the microscopic level, so it has no useful acoustic damping properties.

then how do you sound proof these (without spending a fortune on acoustic sealant)?

I think if you compare the cost of a bunch of "foam in a can" and see how far each can goes, against the cost of typical flexible non-hardening bathroom caulk, you'll find that the foam isn't very economical...

I believe RW3 and RW45 are UK ratings for similar density insulation to what you mentioned (30 kg/m3).

Those are thermal ratings, not acoustic ratings. The thermal rating of insulation tells you nothing useful about the acoustic properties. For example, Styrofoam polystyrene panels have pretty good thermal ratings but zero acoustic uses.

I am happy to look into this remotely.
I know this is a small budget, but I want to do it right.

I saw your PM, and I did reply.

Included are some pictures of the shed.

Actual real pictures of the physical shed in the real world would be more helpful: Those SketchUp images do help yes, but the real shed itself would be better.

One thing I did notice in the model, is that you have internal support posts holding up the roof... Ooops! That's a big problem! You'll need to figure out what to do about those...

And that also tells me that your roof trusses or framing, is not very beefy: you won't be able to add much mass to that. You'll need a structural engineer to take a look at the existing roof structure and tell you how much extra load you can safely put on that. You don't want your roof collapsing on your head!

My thinking was, soundproof the ceiling - seal the gaps - then it should be fairly good isolation, right? (i.e. ground and walls are cement).

Assuming that you can get hte same surface density (mass per unit area) on the roof as you have on the walls, then yes! But metal sheeting has far, far lower surface density than concrete block... Just a small fraction...

Isolation for a building is only as good as the weakest part. If you have great walls but a terrible window, then the window wins. If you have great walls but a terrible roof, then the roof wins. Whatever part of your building has the LOWEST isolation, is what your TOTAL isolation will be similar to. In other words, if your walls give you 45 dB of isolation, the windows 35, and the roof only 25, then your total isolation will be close to 25. It will NOT be 45....

Then if I need more insulation, I can build a room within a room later on, if needed.
(i.e. add stud walls, and double layer gypsum later)

Right! Assuming that the outer leaf is already good...

This way, I may also get away with only doing the back corner (8x4m in total).
(the partition wall would be in line with the cross beam and poles, shown in the pictures).

Having the support posts inside your isolation wall is a really good move. I often do that. As long as it leaves you enough space for the actual studio room, that's fine.


- Stuart -