New garden studio from the ground up in the UK

[stav]

Hi there.


First off, to mods, thanks for creating and maintaining an invaluable and fun space to hang out and exchange ideas with likely minded musos. Long time lurker, first time poster so please bear with me if I have got anything wrong with my first post. Happy to put things right if need be.


Background/brief:

I live in the UK and I would like your advice on a new one room studio I will be building from the ground up. I am currently in the planning and designing stages. Any advice or recommendations you might have would be most welcome at this early stage of the built.

Foot plan here
[img][IMG]http://i430.photobucket.com/albums/qq25/stavroskokkinos/Studio%20base%20plan_zpsiqf7rmqs.jpg[/img][/img]

Studio is going to be erected from the ground up in my back garden and will be a single room space+air lock lobby. I am also hoping to be able to use the air lock lobby as an extra recording space if need be (i.e. gtr amp iso or even vocal booth?). High TL figures are not a priority as I am not going to be recording loud bands or playing loud music. Studio will be used on a part time basis mainly (eves and w/ends) as a writing/mixing room and occasionally for solo/duet or overdub recording sessions. Due to the limited space available, I am building without planning permission and hence I am limited to an area below 30sq mtrs and max building height of 2.5mtrs. Budget avail around £20k.

Set up will be minimal based around an in the box quiet PC  system with Neuman KH1200 monitors. Studio will also house an upright piano.  Re studio dimensions, I have tried to stick to one of the recommended ratios I found in one of the studio design books (W3.43xL4.90xH2.62) that will give me roughly around 1570CF of volume and fits perfectly to the space I have available.  I am employing the services of a local studio building company to advice me on the interior acoustic shell and a local builder who will follow their advice (he has also read Rod's book back to back!). Studio will consist of a double leaf timber structure resting on a dwarf masonry wall that will be sunk along with the foundations 1mtr into the ground to ensure that internal roof H (2.62mtrs) is in keeping with UK build regs. Dwarf masonry wall will be tanked out and made water tight. A sump pump will also be fitted to provide extra insurance against flooding. Soil around here is sandy and free draining.


At this stage I need advice on what route to take with HVAC. Really torn which route to take with this as I have been considering the pros and cons of a fully ducted HVAC system VS a mini split one. There are many benefits that recommend a fully ducted system but at around £4.5K install cost, it is v.expensive and it set up will further reduce internal space by eating into my ceiling height. The mini split (+air vents fitted with silencers) alternative I have been recommended by my designer, comes in at a more realistic price (around £2.5K) but I have concerns re fresh air supply being freezing cold in the winter. I am aware of recommendations that combine a mini split+HRV unit but my studio designer claims that such system will end up costing around the same ball park figure as a fully ducted HVAC setup. Do you think there would be any merit in exploring the possibility of using the sound lock area as an exchange chamber to condition the air somehow or is this going to complicate matters even more for little benefit?
I would be interested to know what's the current way of thinking on these set ups around here.  Is there a particular set up you are currently using  that manages to supply fresh air and control humidity whilst keeping  noise levels to acceptable levels or low enough for recording? Are there any mini split AC models+HRV you would recommend? I have read about the all in one Daikin Sarara model which also manages to supply fresh air. Seems like the perfect solution but reading at the specs it seems very noisy (Sound power=55-57db – Sound pressure ranging from 23-39db). Has anyone got experience of this all in one unit in practice?

Wall design detail below. My designer has supplied partial drawings of the inner leaf only. Note the "inverted leaf" wall design using the stretched fabric over r/wool idea. Outer shell design is still to be decided on. Any advice/comments on how to construct outer timber shell would be most welcome.

[img][IMG]http://i430.photobucket.com/albums/qq25/stavroskokkinos/Wall%20and%20ceiling%20design%20detail_zps1dv20e28.jpg[/img][/img]

Side wall section detail here. Any comments or advice would be welcome.

[img][IMG]http://i430.photobucket.com/albums/qq25/stavroskokkinos/Side%20view%20detail_zpsxy39x3rn.jpg[/img][/img]

Thank you in advance for your time and valuable advice.


Stavros

[stav]

Anyone willing to comment on initial designs and questions re HVAC? Hope nothing wrong with my post!

Thanks in advance.

Stavros

[Soundman2020]

Hi there Stavros, and welcome!

Foot plan here ... [link to photobucket]

Please follow the forum rules and post all your images directly on the forum. We have so many old threads on the forum, where people linked to off-site image hosts that later died or changed, that it's just a wast of time and energy to deal with those threads. Without the images, the threads are basically useless, since much of the discussion is about the images...

I am also hoping to be able to use the air lock lobby as an extra recording space if need be

Unfortunately, you can't do that. Sorry. It wont work. Anything inside your MSM cavity is not isolated from either side! It's not isolated through the outer leaf, and neither is it isolated through the inner leaf. All you have on each side is a single leaf governed by Mass Law...

If you want to have an extra recording space, such as an iso booth, then it has to be built as such. You could achieve that by building a complete inner-leaf within your sound lock space. That would work.

with Neuman KH1200 monitors

I'm not familiar with that model. Is it something new? Or did you mean the KH-120A?

Studio will also house an upright piano.

If that is inside the CR, it's going to need some careful design. That's a very large piece of furniture, and having it placed asymmetrically could mess up your room acoustics. It can be done, but you'll need to be careful.

I have tried to stick to one of the recommended ratios I found in one of the studio design books W3.43xL4.90xH2.62)

That's pretty close to Louden's 2nd ratio, so you should be fine with that. However, you have splayed walls (the side walls are angled outwards at the rear of the room), so therefore simple room ratios are not applicable, and simple room mode calculators won't give accurate predictions. Those only apply to rectangular rooms. If you want accurate predictions, your designer will have do some finite element modelling, and finite element analysis (FEM/FEA), and hopefully he's an expert at setting up boundary conditions correctly in the software, and is also an expert at interpreting the results. That's pretty heavy math going on there...

Rectangular rooms are much, much easier.

I am employing the services of a local studio building company to advice me on the interior acoustic shell

Did they tell you it was OK to use your MSM cavity as a recording space? Did they do the layout shown in your diagram? Did they design that acoustic treatment? Did they do the speaker geometry? If so, then you really, really, REALLY should look for another place! There's so much wrong with that, that it needs a complete reset. To start with, there's almost no rear-wall bass trapping at all, and no place to put it, despite that being a very small room and needing a huge amount of bass trapping. The only bass trapping in there is in the front vertical corners, where it won't have much effect, is wildly insufficient, and is occupying the space that would be much more useful as speaker soffits. There's space where it could go, in the rear upper horizontal corner, but for some unknown reason that possibility has been destroyed by the badly done shaping of the rear inner-leaf: instead of following the outer-leaf there, there's a strange and hard-to-build angled section that drops down a whopping 30 cm! Which creates a compression ceiling in the totally wrong location, when nobody even uses compression ceilings even in the CORRECT location these days (Tom Hidley himself stopped using them many years ago, and he's the guy who invented them!). That is just purely wasted space, totally unnecessary, and in a prime location for a major and very useful bass trap.

I can't understand why a studio designer would do that: it makes no sense.

Other problematic issues: the speakers are on the desk, incorrectly located, incorrectly oriented. The front window seems to have only one single pane of glass in it, so you do not even have an isolation system (in which case you are wasting a huge amount of money on building an inner-leaf when you don't need one). Even if there are two panes in there, that inner-leaf pane is absurdly angled UPWARDS, where it will create reflections that get to the mix position. There is no acoustic need to angle glass in a studio in any event: that's a myth. Beginners error. There might be an aesthetic reason to do so, to avoid glare from lighting, but in that case the glass should be angled DOWN, not up. The way it is now, you are guaranteed to have glare from your lighting getting to your eyes, AND ALSO acoustic reflections getting to your ears.

More: The front section of the ceiling, directly over the speakers, is parallel to the floor, while the next section is steeply angled but starting way too far back to be useful: there will be major reflections from that flat section, and there is no place to put a cloud there to deal with them. The side walls are splayed, but the angle is not great enough to create a RFZ. There is no first reflection point treatment. The window sills are above eye level. The rear wall is a 3-leaf system, and therefore has poor isolation in low frequencies, as well as being a resonant cavity in itself. It is also totally reflective, which is the exact opposite of what it should be: (for true RFZ design, the rear wall must be extremely absorptive in low frequencies, and diffusive in high frequencies, but that wall is the exact opposite. That's a huge problem). There is a fresh air inlet but no stale air exhaust. The silencer box is grossly under-designed, in comparison to the inner-leaf. You say you don't need much isolation, yet an attempt has been made to give you a huge amount of isolation. Except that it won't work anyway, because of the window and door issues, and the HVAC issue, and the incorrectly done inside-out issue. So you'd be spending a huge amount of money on materials and methods that you do not need, while NOT spending on the things that you DO need. There is carpet on the rear floor, when carpet is almost never used on control room floors, since it distorts the acoustic response of the room, and messes up the psycho-acoustic effects too. The drawings for the walls and ceiling show materials that you do not need, arranged in a sandwich that is counter productive. There are no vertical studs shown at all in any of your walls, so it's difficult to see how they could even stand up (they are mentioned in one of the drawings, but not shown in any of them). There are horizontal members in strange places. There is some type of "acoustic foam" specified to go under the walls when it is NOT needed and does nothing for you anyway (extra unnecessary cost). The floor also specifies unnecessary elements...

I could go on and on, but I'm hoping you get the picture. The entire thing is an acoustic nightmare, not to mention the complexity of building such a strange shaped building with an even more strangely shaped inner-leaf. I very much doubt that you'd be able to pull that off for £20k. You probably could build a pretty good studio that size for around 20k, but not using that complicated and very much unnecessary design. Just go with a plain rectangular outer shell, and a plain rectangular inner-leaf as well. Build the room as a conventional RFZ design, with the usual treatment. Nothing complicated is needed, since your needs are not complicated. You say you don't need extreme isolation, and since your outer leaf is shown as being thick concrete, you only need a single layer of 16mm plasterboard for your inner-leaf (provided that you leave a decent air gap and put enough insulation in it). The design can be simplified considerably, saving you a lot of money, and also greatly improving the acoustics.

Studio will consist of a double leaf timber structure resting on a dwarf masonry wall that will be sunk along with the foundations

Huh? Then why do the drawings not show that? It's VERY confusing when your text describes one thing but the architectural drawings show something entirely different!

Also, is it even legal to use a dwarf wall as the basis for supporting such a heavy structure? Why not just to a conventional foundation wall on top of a monolithic slab?

Really torn which route to take with this as I have been considering the pros and cons of a fully ducted HVAC system VS a mini split one.

For a single room building like that, there is no point at all to having a ducted system. That only makes sense in a multi-room facility. The AHU is going to cost a fortune, there's no place you can put it that makes sense, and you don't even need it: a simple mini-split system will do exactly the same job. Just look for a system that has a very quite evaporator unit, or if you can't find one like that, then consider boxing it in with a silencer system to keep it quiet.

There are many benefits that recommend a fully ducted system

Who is "recommending" it? Let me guess: the guy who wants to sell it to you, or the guy who wants to charge you a fortune for installing it? 'Nuff said...

a fully ducted system ... set up will further reduce internal space by eating into my ceiling height.

Hang on a sec: you seem to be a bit confused: regardless of what type of air conditioning system you install, you will ALWAYS still need ducting, silencer boxes, and a fan. Whether you use an AHU in your ducts, or just a split system on the wall, you absolutely do still need ducts! If not, how would you get fresh air into the room? And how would you get stale air out of it? The studio will be completely sealed, absolutely air-tight, twice over, so if you plan to breathe in there and stay alive, then you do need to bring fresh air in, and therefore you also do need to take the stale air out. There are legal requirements for that, for all habitable spaces (yes, yours is a habitable space), and even if there were no legal requirements, there are common-sense requirements.

So to re-cap: you need ducting, silencer boxes, and a fan to move air through your room, regardless of the type of A/C system you choose. If you choose a ducted type (AHU), then that complicates the ducting further, since it must be specifically designed to handle that. On the other hand, if you go with a mini-split system, then your ducting can be simpler.

but I have concerns re fresh air supply being freezing cold in the winter

Then put a heat exchanger in! Or design the duct system, so that it is not a problem!

I am aware of recommendations that combine a mini split+HRV unit but my studio designer claims that such system will end up costing around the same ball park figure as a fully ducted HVAC setup.

Sounds about right, but if you design the ducting properly, you probably wouldn't need a heat exchanger.

Do you think there would be any merit in exploring the possibility of using the sound lock area as an exchange chamber to condition the air somehow or is this going to complicate matters even more for little benefit?

Once again, you cannot do that because your sound-lock is show as being part of the MSM cavity! It would be a really bad idea to duct outside air into your MSM cavity, for oh-so-many reasons....

I would be interested to know what's the current way of thinking on these set ups around here. Is there a particular set up you are currently using that manages to supply fresh air and control humidity whilst keeping noise levels to acceptable levels or low enough for recording?

Yes. The way I normally do it is to go through the complete design process for the room, doing all the air flow volume / rate / velocity calculations, because you will still need the exact same amount of fresh air coming in / stale air going out, regardless of what type of air conditioner unit you choose. All of that depends on one single factor alone: the total internal air volume of the room. Once you know that, then based on the required number of room-changes-per-hour, it is a simple matter to figure out the air flow volume that you will need. Once you know that, based on your chosen NC curve (or NR curve), it's a simple matter to figure out the maximum permissible air flow velocity. When you know the air flow volume and air flow velocity, it is a simple matter to figure out the internal duct cross section that you will need to do that. Then you allow for the thickness of the duct liner, and that gives you the size of the actual duct itself. Based on that you can calculate the size of the silencer boxes (using a factor of at least 2 to get a decent impedance mismatch at each end), and that will give you the internal cross section of the silencer boxes. With that in hand, once again allow for the thickness of the duct liner inside the silencer box, plus the thickness of the plywood used to make the boxes, and you get the outside dimension of the silencers. Once you know that, you can design the MSM gap size at the relevant locations in the room to allow for the silencer boxes, or if it that would take up too much space, then put the silencer boxes outside the building and/or inside the room, instead of in the cavity. (The thickness of the plywood used to make the poxes is dictated by the surface density of the leaf that the box is in, or by the maximum required isolation, whichever is smaller). In turn, the leaf thickness and MSM cavity depth are determined from the amount of isolation you need in decibels for your studio, and the frequency spectrum that needs isolating.

That's the process I normally follow. The equations are not that complicated, and going through the whole process is the only intelligent method for designing the room. It might take a couple of days to work through all of that, and you might need to do it several times as you tweak here and there, but if you don't do it, then you are just guessing, and that's a really, really bad idea for studio design. There's only a very small range of possible correct answers, and there's an infinite range of wrong answers. You can imagine what your chances are of guessing one of the correct ones out of an infinite range, purely by chance... (Hint: your chances of doing that are infinitely close to zero....)

But once again, this entire process is the same regardless of the type of air conditioner. What changes if you go with an AHU is that you need to loop the exhaust duct back as a return to the inlet of the AHU, and duct the AHU outlet back into the supply trunk, and you might also need a bypass system, adjustable damper valves, and a system controller with temperature, humidity and CO2 sensors... whereas with a mini-split, you only need one simple fresh air duct system, one simple stale air duct system, and a fan at some point to move the air.

Are there any mini split AC models+HRV you would recommend?

Look for the quietest one you can find. The compressor unit (heat pump, or "outside unit") doesn't need to be that quite, unless it might annoy the neighbors or people in your house, but the evaporator unit or "indoor unit" needs to be as silent as possible. Here too you need to do the full set of calculations on sensible heat load, latent heat load, based on occupancy, gear, lighting, climate, etc., to figure out the correct capacity HVAC system for your studio. If you get one that is over-sized, it will only run in short bursts at minimum power and you'll have wild swings in your temperature and humidity. If you get one that is undersized, it will run at full power for very long periods, making a lot of noise, using a lot of power, overloading itself, and burning out after a very short life span. You need to get the right unit for the job, after doing all the math.

I have read about the all in one Daikin Sarara model which also manages to supply fresh air.

Well, yeah, but it's only a trickle of fresh air, there's no silencer on that supply line, and you still need to have an exhaust duct to get the stale air out.

Your studio is a hermetically sealed box. You can only blow a small amount of air into it before the pressure rises to the limit of what the fan can handle. Think of it this way: if you blow into an empty coke bottle, you can only force in a very small amount of air, no matter how hard you try. If you want to blow more air into the bottle, you have to cut a hole at the other end to let some out: that's your exhaust duct. If you don't have that, then no matter how good your Daikin Sarara is, it just won't move any air.

but reading at the specs it seems very noisy (Sound power=55-57db – Sound pressure ranging from 23-39db).

Yep. 23 dB is not loud at all, but 39 dB is. That's nearly four times louder! A very large range.

Wall design detail below. My designer has supplied partial drawings of the inner leaf only.

Way too "partial", and way over designed for what you need. You said "High TL figures are not a priority as I am not going to be recording loud bands or playing loud music. ". Fair enough... so then why does your design show show the basics for an extremely high TL? If you don't need it, why is it designed like that? Also, it would help to know exactly what the design criteria is here: how much isolation (TL) do you really need, in decibels? What level is that wall designed for? In other words, what TL goal did you give your designer? Or stated another way: How many decibels of isolation did you tell him you want?

Note the "inverted leaf" wall design using the stretched fabric over r/wool idea.

Actually, the correct name for that type of isolation system is "inside-out" construction. It is not called "inverted leaf". The reason we know that here on the John L. Sayers forum, is because John L. Sayers invented it! And since he invented it, he gets to call it whatever he wants. The name he chose is "inside-out isolation construction", which makes a lot more sense than "inverted leaf"!

Whoever told you that is is called "inverted leaf" has a problem: Google "what is inside-out isolation construction" and also "what is inverted leaf isolation construction", and see what you find in both cases...

Someone is pulling your leg if they are promoting John's invention under another name. This forum is the home of inside-out isolation.

Which is why I can tell you unequivocally, that not only is your designer using the wrong name for it, but he's also completely misunderstood how it is supposed to be done, and made a total mess of it!

Outer shell design is still to be decided on.

Huh????? Then how come it is ALREADY SHOWN on your drawings???? You mean you made us read all the way through your entire post, showing us a complete set of full annotated architectural drawings, only to tell us right at the end that the drawings are actually completely WRONG, and that in reality you haven't yet decided how to build it at all?

Any advice/comments on how to construct outer timber shell would be most welcome.

I would have thought that if you are using a competent "local studio building company to advice me", then they would know how to approach that issue!

This just doesn't make much sense. When designing a studio, the very first, most basic parameter is the amount of isolation that will be needed, in decibels. In other words, you start out with the question "How many dB of TL do you need?". Based on that answer, you design the isolation system. It can be either conventional construction or inside-out construction: that matters not at all for the isolation calculations. The important issue here is to choose the construction materials and the construction method that will produce the required amount of isolation.

That is the starting point with studio design.

Once you have that decision made, and since your slab has to be limited to a certain size to meet regulations and also fit on the available piece of land, and also fit your budget, you now automatically know the largest possible dimensions of the interior surface of the inner-leaf. Now you can look for the closest room ratio that will give good modal response, and you can make any "tweaks" to the slab size that might be suggested by that ratio. With those decisions now "written in stone", the acoustical layout and geometry of the room can be decided on, based on the specific speakers that you will be using in there, and the major furniture and equipment that you need to put in. And that, in turn, will lead to the initial placement of the basic acoustic treatment for the room, which also depends on whether or not your walls and ceiling are inside-out or conventional, among other factors.

There's a procedure that should be followed for designing a studio if you want to end up with a usable room. But it seems the exact opposite has happened here! Instead of starting with the fixed parameters, then adjusting the variable ones accordingly, it seems like your designer has decided what the variable ones should be in advance, set those in stone, and now wants to adjust the fixed ones!

There's only one comment I can add to that: it wont work. That approach is doomed to failure.

That's like designing a car based on what steering wheel and dome light you want inside, and what type of carpet you like, then working backwards from there to define the engine size, wheelbase, and transmission!

Now that I think I understand the design philosophy that seems to have been used here, I can also understand why the design is so full of errors... The entire process has been done backwards, starting with the finished product, then trying to come up with a way to get there from an unknown initial state!

I would really, really suggest that you should completely scrap what you have, and start all over again using the conventional method for designing a studio. Start by defining what you want and need, then work forward intelligently through the logical sequence of steps that a real studio designer uses.

Any comments or advice would be welcome.

I probably already said more than was necessary, and I'm sorry if it came over as being too harsh or too blunt, but I'm sort of known around here for "telling it like it is", not pulling any punches. "Brutally honest" is a term that probably fits well... But there's just so much wrong with that design that maybe this "shock treatment" is what you need to hear to get your attention, so you realize just how bad it is.

My suggestion would be the same as I already mentioned above: Throw the entire design so far in the trash, start again with a clean slate (and a different designer!), and do it right this time, moving forwards from the starting line with your eyes open, instead of running backwards from where you think the finish line might be, in darkness, with your eyes closed...




- Stuart -

[stav]

Thank you Stuart for taking the time and for your helpful comments. If you don't mind me I am intending to follow up your recommendations with a pm.

Kind regards

Stavros

[Soundman2020]

If you don't mind me I am intending to follow up your recommendations with a pm.

Sure! No problem.

- Stuart -