John Sayers' Recording Studio Design Forum Archive

Gregwor wrote:Any update on how you're going to deal with the vapour barrier and inside out wall construction?

Good question.
First of all: Just one vapor barrier. Not two. As Stuard said: We don't want to trap moisture inside our walls. And second, as Stuard already stated above as well:

Soundman2020 wrote:normal recommendation is that it should go on the surface that will be warmest in winter, and up against the sheathing with no air space

So I am going to install the vapor barrier in the inner leaf modules. Right up against the last layer, but behind the studs.
They will protrude to the edges and cover these as well. They will even protrude a little more than that (contrary to the picture) for sealing purposes later.
I thought about something like this (see picture). The vapor barrier is black.
It would be trapped between studs and last leaf-layer (OSB). After putting together and connecting all the modules the vapor barriers of those modules will touch at the edges and can be sealed there.
Same for the ceiling modules.

Version 2: You could also install it in a way it wraps everything (viewed from the inside). But I guess that's a bit tricky to do it right with all the studs and support bars. Imagine it as all the wood in the picture being completely covered.

After putting together and connecting all the modules the vapor barriers of those modules will touch at the edges and can be sealed there.
Same for the ceiling modules.

For the ceiling, you need your skeleton though. You can't just screw modules together like you do with the walls.

Greg

Gregwor wrote:For the ceiling, you need your skeleton though. You can't just screw modules together like you do with the walls.

Correct. For the sides modules are screwed together its just the same as with the walls.
For the other sides the modules are screwed to the skeleton's beams: There you can cover (wrap) the skeletons beams with the protruding vapor barrier from the edges of the ceiling modules. So two vapor barriers (either two ceiling modules in the middle of the ceiling or one ceiling and one wall module at the ceiling edges) will touch at all skeleton's beams. Overlap the two barriers and then you can seal them.

News: We finally have electricity!

For this we had to build our first wall section to mount the distribution box in order to actually take it into operation. We once planned to build this wall section (part of the outer leaf) later (after the acoustic rooms) to have more space to work in, but the authorities would not activate a distribution box that was mounted on a temporary stand or anything other than on a fixed wall. So we had to build this first. For this we also build some working tools, e.g. two large working desks to frame the wall modules on or a support table for the chopsaw.

Last week we have done the roof (outer leaf) insulation. Currently we are doing the wiring. The cables are mounted to the (outer leaf) wall and are going to be passed through the modules at the desired positions once they are build and installed in place. We also have a separate ground cable for star grounding. Besides the electric wiring we also decided to install a smart home system/KNX (https://en.wikipedia.org/wiki/KNX_(standard)), which is for building automation. In the beginning we just want to control the lighting in our building with that, but later we may expand it to AC control, door bell camera, etc. Also we want to use LEDs without exception and want to mount all the power supplies for the LEDs into the distribution box to outsource all possible electrical fields and audible noise source. Furthermore we have solar panels on the roof, which were installed last week and generate power for our building. KNX, LED and solar panels are the reasons for our distribution box being that large, if anybody may wonder.
All this planning and execution is done together with our electrician and an expert for KNX.

Here are some pictures of that happened recently:

Framing material (for the working desks and electrical distribution box wall section) delivered: Building the working desks Checking completeness and rough lengths Mounted the first module Never ending story: Digging for the water supply (by hand) Finally: Outdoor property electrical supply box (hole digged by hand) Framing on our finalized working desks (4,50m length, 1,40m width) Cutting vapor barrier Installing vapor barrier Installed OSB Installing drywall Installed electrical distribution box Finally found water supply and closed hole Solar panels on the roof installed

Support desk for the chopsaw allows setting up a length between 0 and 4m and to quickly cut multiple pieces of wood with the exact same length. (Don't worry, the wood in the last picture is just an example, not the working quality we build with ) Insulation delivery Insulating the outer leaf roof Cables and unroll device (very handy) Mounting cables to holders at the outer leaf wall Cable plan for the acoustic rooms. Includes 230V (black/grey), KNX (green), grounding (blue), AC (pink) and silencer box vents (orange). Sorry, but it's actually in German and visually hard to read due to the resolution picture restriction of this platform.

Hey

I am currently planning the HVAC system in more detail and want to decide on products. I want to use a ductless multi-split AC (one indoor wall-mounted unit in every room) and an duct-mounted air handler with heat recovery for fresh air supply and stale air exhaust. The latter is used just for the live and control room. AC units must be installed in all rooms, because we will not have any other heating (frost protection).

Here is the main layout. Note that all the air handling (everything that's not AC-related) is done at the ceiling above the rooms. Everything that is depicted above HAR/WC/Lobby will not penetrate the normal room's wall, because it's actually above the HAR/WC's ceiling. The only wall penetrations happen where the silencers are placed and at the intake and exhaust of the air handler to the outside.
Live Room
ca. 100qm³ air volume

flow rate: 5-10 air changes per hour. Choosing 5.
5x100m³ = 500 m³/h (= 8,33 m³/min)

maximum air speed/velocity: 300 ft/min. Choosing 150 ft/min.
150 ft/min = 2743,2 m/h (= max 45,72 m/min = max 0,762 m/s)

duct cross sectional area (flow/velocity):
A = 0,182196 m² (= 182,196 cm²)

circle (A = pi * r²)
r = 7,6 cm -> d = 15,2 cm
-> next best round duct size would be 18 cm

square (A = h * h)
h = 13,5 cm


Control Room
ca. 60m³ air volume

flow rate: 5-10 air changes per hour. Choosing 5.
5x60m³ = 300 m³/h (= 5 m³/min)

maximum air speed/velocity: same as live room, see above

duct cross sectional area (flow/velocity):
A = 0,109361 m² = 109,361 cm²

circle area (A = pi * r²)
r = 5,9 cm -> d = 11,8 cm
-> next best round duct size would be 15cm

square area (A = h * h)
h = 10,46 cm

Rule: Cross sectional area must change suddenly by a factor of two (impedance magic).
Rule: At least 2 baffles. Choosing 3.
Duct Liner: 25mm to each side.

3D models and exact dimensions of silencers will follow soon.


AC and HVAC products
Currently I am looking at these units in particular:

Air handler: Mitsubishi Electric LGH-80RVX-E (up to 800m³/h at 34,5dB, 250mm duct connectors)

AC: Panasonic Etherea R32 Multi-Split Series
Outdoor unit: CU-5Z90TBE (for 5 indoor units, 11,5 kW)
Indoor units (WC, HAR, Lobby): CS-MZ16TKE (1,6 kW)
Indoor unit (control room, live room): CS-Z25UD3EAW (2,0 kW)
Indoor units seem to be quiet regarding their data sheets (19/24/37 dB at low/middle/high)


Issues
I am currenctly facing some issues for which I cannot find any help (yes, I used the search function ):

1) Condensate pipe
Is there a special way how to treat those? I've read that it's suggested to lay it in curves to increase sound energy loss inside, but of course always downwards. But may it be even good/necessary to build something like a mini-silencer, through which the pipe goes or is there any other trick?

2) Duded indoor units
Wall-mounted AC indoor units for multi-split systems are way cheaper (just here in Germany?) than ducted indoor units (1/4 the price). Generally is there a big disadvantage to not use a ducted indoor unit? It's nice to integrate it into the ceiling or combine it with wooden acoustic elements and to not see a wall unit at the wall, but are there any technical problems having the AC not directly combined at the fresh air intake? I've read that the air handler and AC have to precisely adjusted to each other.

3) Splitting/merging air streams
I want to use one air handler for both sound rooms together. But how do I adequately split the duct to exactly split the air stream in the wished air streams? In this case a 950 m³/h air handler unit's output into 600 m³/h (to live room) and 350 m³/h (to control room)? Just using an Y-piece and adjusting the duct sizes will not be enough, I guess, due to different duct lengths, until the air streams reach the rooms. Is there a formula or calculator for doing this? Same goes for merging two air stream back to one into the air handler.


AC installation
I've exported some 3D images of our framing for our meeting with our AC-guy to showcase our project and to roughly explain the room-in-room concept and why it's important to remember that it's no ordinary build. I will attach them for you getting an impression on the rooms. The AC-guy and his team will build the AC in 2 stages: First they will install the outdoor unit, all the chopper pipes and electrical cables and check for pipe tightness. After that we will seal the outer leaf penetration made to the connect the outdoor unit, probably DIY-build the draining pipe (see issue no. 1 above) and build up the inner leaf walls and ceiling joists. After that (just before installing the ceiling modules) they will continue with the AC with stage 2: installing the indoor units to the prepared pipes and cables and activation and testing of the whole system.
Until next time,
Phil

Okay, and I guess I have some more questions.

To hide and manage all audio cables and especially to run them invisibly to the control room desk I would love to put those in a floor channel. I know a concrete slab is a good studio floor, but I guess our floor have to differ from that. For using floor channels we need to raise the floor a bit with cement screed to integrate those floor channels. The channels can run flush to the upper surface of the floor and will be just covered with the floor finished material as removable cover (see pictures). The cement screed can be installed without any insulation in between (bonded/composite screed) and is structurally very similiar to the concrete slab. So I'd assume that the good acoustic properties of the concrete slab can be extended to our new raised floor due to them acting as one unit. In fact we just reinforce the slab. That cannot be that bad, can it?!
But now I am thinking about how to treat the door openings. Assuming having a 14cm floor construction (concrete screed and a wooden or laminate finish), should:

a) the floor also be build "underneath" the doors or
b) should we leave the bottom layers of wood (sole plate) of the wall construction in place to makeup for the missing height?
The standard method would be A, I guess. But the advantage I see in B are that we can pour the cement screed just inside the room itself - it would be limited by the sole plates around it, also at the doors. Also we have wood underneath the door openings, which may be a better material to later build the door frames on?

Another reason for the cement screen would be that our front door of the building is already installed onto the sole plate and is therefore raised up to 14cm above concrete slab level. I thought of compensating that door level with the screed in all rooms to have even floor heights. Or would it be better to just have a step downstairs after entering the building and leave out screed at all? But what about the floor-wiring with channels than? Alternatives? How do other people connect their control room desk without cables lying on the floor?

As you might see, I am confused. I will keep researching the forum and net for answers. But maybe somebody can also comment on this.

Aaand another quick idea/question regarding the framing: I once decided to use 16x6 framing lumber. Would it be equivalent to use 12x8 instead of 16x6 lumber? The cross section remains the same, but we could save 4cm space at each wall.

Obviously the insulation depth decreases as well, but I guess we will have a good amount of insulation in the rooms later on, anyway. Any other downsides to this idea?

Aaand another quick idea/question regarding the framing: I once decided to use 16x6 framing lumber. Would it be equivalent to use 12x8 instead of 16x6 lumber?

That's HUGE framing! Are you talking imperial, or metric? Imperial framing of nominal 16" x 6" is enormous! As is 12" x 8". But if you are talking about metric, I'm not sure what you mean: 16cm x 6cm is an unusual size that I haven't heard of where I live.

Also, are you talking studs or joists? If you are talking about joists, then it's not just the cross sectional area that matters: it's the actual dimensions. You can understand this if you imagine a hypothetical 25cm x 10cm joist, which has a cross sectional area of 250cm2. A joist that measures by 1cm high by 250cm wide has the exact same cross sectional area, but a joist only 1cm thick is not going to hold up anything, no matter how wide it is!

If you don't know what size joists to use, the do NOT guess! Call a structural engineer to come take a look, and give you his professional opinion, in writing.

- Stuart -

Soundman2020 wrote:Are you talking imperial, or metric?

Oops! Of course I mean metric (12 cm x 8 cm instead of 16 cm x 6 cm). And of course I mean studs (Joists are 22 cm x 6 cm). And you're right, Stuard: I know it is an unusual size. But it's available at our lumber dealer as well as other dimensions with no extra costs.

And in case of the joists you are also very right, it matters a lot. But studs? Due to the vertical force the cross section size should matter most. Of course the extreme example of 1x250 is not working here, too, yes.

The 16x6 variant once was okay for our structural engineer (I wasn't aware of it being an unusual size back then and he also didn't tell me). Although it was just an oral evaluation, nothing in writing unfortunately... (he just calculated the whole outer leaf, which was then build by a company)

For studs, then either is probably fine. There's not much difference there. However, the thinner your wall air gap is, the lower the isolation will be, so don't go too thin! The normal recommendation is to never go less than about 10cm for the gap between the inner leaf and the outer leaf (which you will have in any case it seems, with either of the options you mentioned), but a larger gap is better. Do the math to make sure you will have the correct isolation at the correct frequency range.


- Stuart -

Alright, thank you very much Stuard!

Any thoughts on my AC issues in the post before?

Hey,

News time! The first part of the AC installation is done now (outdoor unit, cables and most of the copper pipes). Ventilation follows next. And we are currently also building a wall to delimit the garden section from the street.
Meanwhile I also found answers for most of my questions from the posts before.

SchwertPhil wrote: 1) Condensate pipe
Is there a special way how to treat those? I've read that it's suggested to lay it in curves to increase sound energy loss inside, but of course always downwards. But may it be even good/necessary to build something like a mini-silencer, through which the pipe goes or is there any other trick?

Source for laying in curves: http://www.johnlsayers.com/phpBB2/viewt ... pe#p141192
A traditional silencer box will not work for this, but the curve-laying is kind of similar to that. I will try to decouple the condensate pipe by laying it in curves and also will end it inside a drainage hole of the concrete slab to avoid a outer wall penetration. The drainage hole is inside the kitchen area of the lobby.

SchwertPhil wrote: 2) Duded indoor units
Wall-mounted AC indoor units for multi-split systems are way cheaper (just here in Germany?) than ducted indoor units (1/4 the price). Generally is there a big disadvantage to not use a ducted indoor unit? It's nice to integrate it into the ceiling or combine it with wooden acoustic elements and to not see a wall unit at the wall, but are there any technical problems having the AC not directly combined at the fresh air intake? I've read that the air handler and AC have to precisely adjusted to each other.

We chose the concealed duct indoor units. They are not as cheap as the wall units, but I like its advantages regarding ceiling and ventilation integration. Whether we integrate the device inlet with the room-outlet of the ventilation system (combined system) or not (separate systems), I will decide later. Maybe we even build a mechanism to switch between both.

SchwertPhil wrote: 3) Splitting/merging air streams
I want to use one air handler for both sound rooms together. But how do I adequately split the duct to exactly split the air stream in the wished air streams? In this case a 800 m³/h air handler unit's output into 500 m³/h (to live room) and 300 m³/h (to control room)? Just using an Y-piece and adjusting the duct sizes will not be enough, I guess, due to different duct lengths, until the air streams reach the rooms. Is there a formula or calculator for doing this? Same goes for merging two air stream back to one into the air handler.

Basically air seems to act similar to water in this context. I will use a Y-piece in combination with a size reduction (on one side) and a throttle pieces.

SchwertPhil wrote: Assuming having a 14cm floor construction (concrete screed and a wooden or laminate finish), should:
a) the floor also be build "underneath" the doors or
b) should we leave the bottom layers of wood (sole plate) of the wall construction in place to makeup for the missing height?

Will go for b).

And here are some visual updates. Note that the garden wall is just the unfinished core wall. It is getting a natural stone wall look afterwards. Also note, that the wall penetrations of the AC pipes are not sealed, yet.

Some updates from the jobsite in form of pictures. Please note the picture comments.

Jan 2019 Mar 2019 Apr 2019 May 2019 Jun 2019

Jul 2019