John Sayers' Recording Studio Design Forum Archive

Hi,
a couple of friends and I want to build a recording studio/rehearsal room. None of us have any experience in this area though, although I did read up un the material quite a bit. I made a very simple design and I'd like some advice/feedback.


The building will be constructed from scratch, so all options are open.
First, I created a square box, but I read that parallel walls are a bad idea. Is it OK just to adjust the live box? The roof construction might be difficult for as non-rectangular shape.

Secondly, my idea for the roof is a so called live roof, which means that there will be grass growing on top of the studio. This should keep it nice and cool (it is Brazil after all), look great and have a great sound isolation (20cm of earth). But the construction might be more difficult if the shape is not square.

Thirdly, what about the height? Is there a sort of optimal height as far a s acoustics are concerned.

Number four: (for now at least) what kind of material can I use between the walls (both of them will be brick, the outside ~15cm , the inside ~10 cm)to improve the sound isolation. Rockwool is very expensive here and all the nice alternatives are either expensive or hard to get. Just some suggestions: shredded paper, dried grass, old mattress foam (just the inside part), textile. Is any of that of any use?

Finally: any feedback on how to improve things is greatly apreciated.

Hi, and welcome.

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- Stuart -

oops, always read the manual eh? Please ignore the first post, here comes my second attempt:
I attached the design in better dimensions now The outside wall is brick, (laying down position), the inside wall can be brick too, if this is the best option, wood is only marginally cheaper, so brick might be the best option.

A repeat of my questions:
First, I created a square box, but I read that parallel walls are a bad idea. Is it OK just to adjust the inside box? The outside roof construction might be difficult for a non-rectangular shape. My idea for the roof is a so called live roof, which means that there will be a garden growing on top of the studio. This should keep it nice and cool (it is Brazil after all), look great and have a great sound isolation (20cm of earth). But the construction might be more difficult if the shape is not square. The inside box could have a flat roof, or sligtly inclined if parallel roof and floor are a problem (are they?), so to make only the inside non-square is a lot easier.

Secondly, what about the height? Is there a sort of optimal height as far a s acoustics are concerned.

Number three: what kind of material can I use between the walls (both of them will be brick, the outside ~15cm , the inside ~10 cm)to improve the sound isolation. Rockwool is very expensive here and all the nice alternatives are either expensive or hard to get. Just some suggestions: shredded paper, dried grass, old mattress foam (just the inside part), textile. Is any of that of any use?

Finally (for now at least): any general feedback on how to improve things is greatly apreciated (btw. I already ordered a couple of the much suggested books here).

other information: The construction at this size (height 2.60M) will cost about 16.000R$ (Brazilan currency = Reais. 16.000R$ is about $8.000, depending on the phase of the moon appearantly).
Building materials are cheap here, but the techy stuff like Greenglue is hard to come by. The total budget is 20.000R$
The studio equipment to start with I already have, minus a good PA, which I can get for about 1000R$, so that leaves about 3000R$ for acoustic treatment and isolation.

and btw, great forum! I was looking for something like this for a while.

That's better!

the inside wall can be brick too, if this is the best option,

Brick would be fine, BUT!!!!! You have to be very careful how you build the inner wall, making sure that NO mortar falls into the gap between the walls, and NOTHING AT ALL gets in there. There must be no connections at all between the walls. Builders who do not understand this will probably try to use metal ties to join the walls, or will work clumsily and let mortar fall back into the gap, where it can create a "bridge" between the walls. If you take great care to avoid this, then brick would be fine for your inner leaf, but if your builders cannot work carefully, then it would be better to go with normal wood framing and a couple of layers of drywall on top.

First, I created a square box, but I read that parallel walls are a bad idea. Is it OK just to adjust the inside box?

Yup. You can build your outside leaf as a rectangle with parallel walls, then adjust the angles of your inside leaf, as needed.

My idea for the roof is a so called live roof, which means that there will be a garden growing on top of the studio.

Sounds like a good idea, if you can keep it sealed, so that plant roots and water don't ever get through. And a 20 cm of dirt makes for good isolation, too!

... or sligtly inclined if parallel roof and floor are a problem (are they?),

Not a problem for the outside leaf. Build it whatever way is simpler. But build it massive!

Secondly, what about the height? Is there a sort of optimal height as far a s acoustics are concerned.

As much as possible! More space is always better. For your control room (CR) 3 or 3.5 meters is good. For a live room, even more than that, if you can.

Number three: what kind of material can I use between the walls ... shredded paper, dried grass, old mattress foam (just the inside part), textile. Is any of that of any use?

Not really. None of that is much good as an acoustic absorber. You need something open cell, fiberous, etc. It needs to have roughly the right density, and roughly the right gas flow resistance characteristics. Apart from mineral wool and fiberglass insulation, I've also heard of cotton batts and even sheep's wool being used, but I guess they need to be treated in some way for protection against fire, fungus, rotting, etc. But forget about mattress foam (it is closed cell usually) and the other stuff.

Porto Alegre, ehhh? I haven't been there yet. I was in Sao Paolo a couple of weeks ago, and I've been to Rio several times, but not to Porto Alegre. Maybe one day!


- Stuart -

Thanks for the reply Stuart,

that makes things a lot clearer.
I am left with three questions though:

1) The walls will be connected at the base obviously. Even if I use different stones for the foundation, they will be connected someway. Won't this connection transmit the sound anyway from the inner to the outer leaf? How can I make sure this will not hinder the sound isolation?

2) About the material in the 'spring' (between the walls):
If I leave it open (just air) will the sound transmit a lot easier than using e.g. rockwool? The loudest noises I am concernd about are on the one hand occasionally passing cars at about 400m distance, a lawnmower (you spell it like this?) at about 200m and a sort of disco at 200m, that only plays loud music occasionally. Is it worth it to invest into rockwool or something similar or will the double brick wall suffice you think?

3) I modified the design of the inside box to something like this: (Now I realise the lower part does not need to be angled. )
I am wondering about the angles, is a five degrees angle enough to imrpove the sound reflection issues?

Porto Alegre is in the south of Brazil (capital Rio Grande do Sul). Unfortunately the equipment and materials for studio construction are a bit harder to come by here then for example São Paulo. The studio will be on a ranch nearby (30 Km) off Porto Alegre.

thanks again!

Nadish

The walls will be connected at the base obviously. Even if I use different stones for the foundation, they will be connected someway. Won't this connection transmit the sound anyway from the inner to the outer leaf? How can I make sure this will not hinder the sound isolation?

Well, yes, there will be some flanking, but it should not be an issue, since you will be building on a concrete slab that is sitting directly on the ground, right? That's about as good as you can get from simple construction, and it does not sound like you need anything more complex, as those noise sources you mentioned seem to be far away.

But, if you really do want total isolation, then the way to do it is to build the outer wall on its own separate foundation, then leave a small gap (a few mm), then pour another foundation and the slab all together as one piece, and build the inner wall on that. It's a bit more expensive, but if you really do need it, then that's the way to do it. If the slab is already poured, then you have two options: Build another foundation around the outside of that, for the outer leaf, or cut the slab around the perimeter, just inside the original foundations that were part of the original slab, and pour new "inner" foundations under the edge of the reaming slab. It's the same principle: eliminate the connection between the two foundations. However, that does not seem to be necessary in your case.

About the material in the 'spring' (between the walls):
If I leave it open (just air) will the sound transmit a lot easier than using e.g. rockwool?

I'm not sure about for brick walls, but for normal double-stud drywall construction, putting insulation inside makes a difference of about 10 dB. In other words, it reduce the perceived sound level to half of what it would be without the insulation. So yes, it does make a big difference. Once again, in your case that may or may not be an issue. If you don't need maximum possible isolation, then you can probably skip the insulation, as long as you are aware that you will have reduced isolation.

One question regarding your layout: What is the purpose of that room? Is it a control room, where you will be recording, mixing, and doing critical listening? Or is it just a practice space?


- Stuart -

Nadish,

What is the ground like in your area. Is it hard rock, sand, dirt or some combination?

xSpace wrote:...Is it hard rock..

funny

...Is it hard rock..

If you are grounded on hard rock, then do you need heavy metal in the walls???

- Stuart -

thanks for the usefull + funny comments

One question regarding your layout: What is the purpose of that room? Is it a control room, where you will be recording, mixing, and doing critical listening? Or is it just a practice space?

It will be used for practicing and recording. The listening room is currently designed as a room with just a single wall. In the first design picture it is the room at the right, with the gray square depicting the mixing table. It might be a good idea to 'double-wall' this room as well?

The ground is very hard. The top layer (60cm) is sand and stones, under there hard rock. The construction guy tells me I just need a groove at the location of the walls and put a layer of (fairly big) stones in there to make the foundation. The concrete floor will be supported only by these stones and will be free from the ground.
As I see it now we won't go for a 'disconnected' foundation. I will check out the pricing of the isolation material and decide if we have the money to use it. It's a shame it is not something I can insert after the stuff has been built....

Nadish

It will be used for practicing and recording. The listening room is currently designed as a room with just a single wall. In the first design picture it is the room at the right, with the gray square depicting the mixing table. It might be a good idea to 'double-wall' this room as well?

OK, then I guess there is an issue with terminology here! What you are drawing as the large rectangle is normally called the "live room" or "tracking room" here. The other, smaller room on the right (where you have your console) is your "control room". And you have the control room layout turned sideways! You should have your speakers firing down the LONGEST axis of the control room (CR), not across the room, as you show. So the console should be rotated 90 degrees, and facing the wall where the dimension that reads "230" is. The door into the control room from outside should be in the middle of the back wall, so that you have space for bass trapping in the rear corners. It looks like it is more or less in the right place.

Yes, you will also need an "inner leaf" around the control room. Which means that 230 cm is not going to be enough. You'll need around 15 to 20 cm for the leaves on each side, so that would make the interior dimension of your CR less than 2 m. You could do that, but it would make it very narrow I'd suggest that either you move the dividing wall to the live room (LR), or that you make the slab bigger: You probably want about 3 m for building your control room. And if you have the space and the budget, then go for even more.

I'd also suggest that you download SketchUp from Google, and use that to design your room in 3D: It takes a while to learn SketchUp, but it is an excellent tool for designing room. We all use it here. And best of all, it is FREE!

Model the rough outline of your rooms in that (accurately) and post it here. Then folks here on the forum will be able to download it and try to give you ideas of how to lay out your rooms effectively.

The construction guy tells me I just need a groove at the location of the walls and put a layer of (fairly big) stones in there to make the foundation. The concrete floor will be supported only by these stones and will be free from the ground.

Are you sure he understands how much MASS you are going to be putting on that slab? Two sets of brick walls plus the double leaf roof/ceiling, is a lot of mass. Is that a good enough foundation to support it all? We are talking about many tons of mass here.

The concrete floor will be supported only by these stones and will be free from the ground.

Do you mean that the entire slab will not be touching the ground? That would be BAD! You DO want the entire slab sitting directly on undisturbed original ground (not on backfill), since the ground "damps" the slab acoustically. You do NOT want to leave a gap under your slab. So basically you need to dig a ditch around the edge, where the walls will go, and the size of the ditch needs to be dimensioned according to the load. You might also need another ditch in the middle, underneath the place where the wall between the CR and LR will go. Then you need to level the area of ground in between the ditches, so that it is reasonably flat all over, with no big dips or valleys. Then you build a wooden framework around the edge of everything to hold the concrete while it sets, probably line the whole area with plastic, put in your metal work, rebar, grids, or whatever you have in Brazil for that for reinforcing concrete, then pour the concrete.

I'm sure Brien can explain to you other things you need to do there, as he is into construction professionally, and I'm just repeating what I've learned.

But the point is that your slab should be "on grade", meaning that it sits directly on the ground, and it needs a tough foundation to support the load without cracking or sinking.

How thick are you planning to make the slab? It needs to be thick.

You might want to consider laying conduit inside the concrete, for the cables that connect the LR to the CR, and for power, phone, internet, etc.



- Stuart -

Nadish wrote: The ground is very hard. The top layer (60cm) is sand and stones, under there hard rock.

Nadish

Hardrock it is!!!

I only ask because you could be having a situation with traffic, mowers, etc. that are behaving on the ground like it were Newtons cradle. The airborne sound may not be as big an issue as the actual flanking in the ground through the rocks. Which was leading me to think that cutting your slab may not have worked as you would have hoped for.

Wow, lots of input here, great! It´s a good thing we didn´t start anything yet...

What you are drawing as the large rectangle is normally called the "live room" or "tracking room" here. The other, smaller room on the right (where you have your console) is your "control room".

thanks for the update on studio talk

Yes, you will also need an "inner leaf" around the control room. Which means that 230 cm is not going to be enough. You'll need around 15 to 20 cm for the leaves on each side, so that would make the interior dimension of your CR less than 2 m. You could do that, but it would make it very narrow I'd suggest that either you move the dividing wall to the live room (LR), or that you make the slab bigger: You probably want about 3 m for building your control room. And if you have the space and the budget, then go for even more.

I'd also suggest that you download SketchUp from Google, and use that to design your room in 3D: It takes a while to learn SketchUp, but it is an excellent tool for designing room. We all use it here. And best of all, it is FREE!

Great tip this sketchup. Unfortunately I have only asccess to internet these days through an internet cafe. I managed to install the program though, but until next week I won´t have access to all the 3D model goodies that exist already. Nevertheless I created a basic sketch of the studio. With an inner leaf for the listening room as well: (I added the source file as well, to enable anyone to snoop around in more detail)
The roof of the live room is designed flat, but maybe a slight inclination would be better, to avoind parallel floor and ceiling?

And you have the control room layout turned sideways! You should have your speakers firing down the LONGEST axis of the control room (CR),

the brown box is the new position of the mixing table. The room will not be completely symmetrical though, due to the window and door to the live room. I put a window directly in fron of the mixing table, but actually I think a window on the long side of the wall makes more sense, I guess Acaustically it does not make a lot of difference because of the existing asymmetry?

Are you sure he understands how much MASS you are going to be putting on that slab? Two sets of brick walls plus the double leaf roof/ceiling, is a lot of mass. Is that a good enough foundation to support it all? We are talking about many tons of mass here.

This guy created na lot of buildings on the ranch, including a lot bigger and more complex. Alle of these are still standing upright, so I guess he knows what he is doing. I will however suggest to him to put the concrete touching the floor. Another suggestion would be a wooden floor. I read somewhere on the board that a wooden floor with a concrete roof gives good results acoustically. What do you think?

Just to be clear: nothing has been built yet, so now is the time to change things if needed. However. Next monday the architect will drop by to get the design sketch and he will create the actual design document for the constructors to work with. But I guess we´re almost there with the layout of the rooms...

thanks again guys

Hey Nadish,

Maybe something like this might work:

Thanks for the suggestion stuart,

It leaves me with a couple of questions though:

1) The extra walls for the CR you created are meant to replace the existing ones?

2) The shape you created for the CR leaves various spaces. Aren´t they going to create an exztra resonanse or something like that? If not, I like the idea and I could use the two spaces at the top to place the computer and any other noisy things.

3) Why did you replace the LR angled walls? It seems I loose more space with your solution. My architect tells me the foundation will be more complicated if I don´t leave an even space between the walls, so I will leave the LR rectangular and solve the reverberation problem by acoustic treatment.

4) I plan to simplify the design of the roof by placing the live roof directly on top of both the inner and outer leaf. I know, this will compromise the sound isolation a bit, but I think due to the weight of the roof (concrete + 20cm earth) and the relative quietness of the environment it won´t be a big problem. I have to cut some corners to stay in the budget of R$20K.
a quick cost calculation leaves me with:
foundation: 2K
walls 5K
work 6K
electricity 1K
doors/windows/ventilation etc. 1K
Flooring 1K
So to have a space of 2K for the acoustic treatment I´ll have to leave the roof within 2K


By the way, I misunderstood the construction story these guys were telling me (my portuguese is still not that good). He meant to tell me the walls will be supported by the stones and there will be an inner slab of concrete directly on the ground, inside the stones but not supported by the stones. The stones are needed to isolate the concrete from the moisture that will be coming downhill when it rains. The roof will have an inclination of about 20%, but this depends on the demands of the live roof.