New studio/house build including John’s small studio design

Between each small section there will be a vertical join running from floor to ceiling

.... which will be caulked completely, and the studs bolted through to close the gap fully. You could then add a piece of drywall, MDF, plywood or whatever across the front of the studs, for an extra layer of security, if you really wanted to. And you could also leave a slight overlap with the sheathing on the end of each section, so that the next section can butt up against that, creating an even better seal...

Essentially the second frame you can now see is my attempt at trying to understand how a "conventional build" might look. Can I not add a second frame filled with mineral wool to act as acoustic treatment inside the final space?

You could, if you don't mind spending all that extra money, time and effort! And also provided that you want to start out with the room very dead, then add reflective/diffusive treatment on top of that to make it suitably live again.

In other words a second "faux" frame rather than loosing space through using acoustic treatment panels that may or may not be thicker than 70mm but probably cost a lot more than 70mm wood and mineral wool?

What happens if the treatment, which you WILL need to make the room live again, is thicker than 70mm?

I could change my initial 70mm frame to a 90mm frame

I would recommend that anyway, considering the large load those studs will be supporting for your inner-leaf ceiling.

To complete the build I fix a second "faux" frame to the inside of the room and load this frame with absorption treatment at a density that is based on how the frequencies are behaving at that point in the build.

As long as you have plenty of budget, and plenty of time, yes you could do that. I'm still not clear about why you would want to do it, but it is an option if you choose to go that way. But do be aware the you'll end up with a very dead, muddy, unpleasant room, which will then need treatment on top of it to return the needed life to the room. And you will have wasted the thickness of the second frame, all around the room, plus the thickness of whatever treatment is needed on top of it...

Assuming the above works then my thinking is that I lose no space inside the room,

I'm not following you: if you build your wall "inside out", then you end up with the situation you say you want, but without losing the depth of the extra frame all around the room. That's a lot of lost space. In both cases you'd need the final treatment added on top to restore the lost liveliness, and that would be about the same extra thickness in both cases, but with a normal inside-out wall you do not also lose the extra thickness of the additional "inner" frame, and you do not need to spend a large amount of money and time to build it.

Ok the rear wall will be filled with treatment only and covered with material to finish. I do a lot of web design work for a living outside of music and I could not resist seeing a different texture in the drawings so I re-used some elements from John's original file. I have read that slot resonators are tricky to tune well and I prefer simple over tricky so it is gone.

You could add some strategically placed slats in places over the corner superchunks, and also over the rear absorption, provided that you leave large enough gaps that they won't act as resonators, and that you also do not seal the cavity behind. You could place those at heights that are carefully calculated to restore some of the lost highs without causing unwanted reflections back to the mix position.

I have attached a pic below that hopefully clarifies the inner leaf layer

Remove that inner frame, do the walls "inside out" and you have the same situation acoustically, but the room is 90mm larger on all sides... - Stuart -

Hi Stuart, Thanks for getting back and I hope you are having a great end of year break (with any luck some holidays too!). I do hope I can get a final understanding of the best way to build this inner leaf as I should have my paint sealer for the inside of the outer leaf walls in the next week or so and then I hope to start framing up in January. With this in mind I have attached a picture below that I hope better explains visually what I am trying to understand so that I can lock down exactly how the inner leaf framing will be built and move on to creating a materials list. Below are two simple cross section images. This example ignores the ceiling, corners and windows and doors. But, the same framing approach will be used across the entire build for the walls and ceilings. I just need to know for sure if I go with A or B and why. If B makes more sense after reading below then I am not concerned about spending a bit more money on extra structural pine (that is really the only extra expense as far as I can see, i.e., all other materials are essentially the same and in the same quantity). Panel A is what I understand to be a standard inside out build: A = 100mm air gap (filled with mineral wool that does not bridge the inner and outer leafs) + 32mm of green glue separated Frychek (2 x 16mm sheets) + 90mm framing = 222mm thick Panel B is what I am trying to understand. I still do not understand why this approach is significantly different from an acoustic point of view when compared to Panel A. Yes there is extra cost for 70mm framing to build the "faux" frame that faces the inside of the inner leaf. More on that in a sec: B = 90mm framing (sitting in the 100mm air gap that is 10mm off the inside of the outer leaf; this framing gets filled with the same mineral wool as would be in Panel A's 100mm air gap, but here the mineral wool has some framing around it whereas in Panel A the mineral wool would occupy the entire air gap cavity ) + 32mm of green glue separated Frychek (2 x 16mm sheets) + 70mm framing = 202mm thick Now a bit more preamble and a few questions please :horse: Assuming I went with a Panel B approach, I would load the 70mm "faux" inner leaf framing with exactly the same treatment as I would for Panel A except it would be 70mm thick rather then 90mm. If the thickness of the treatment material is an issue then the "faux" frame would be made from 90mm structural pine instead of 70mm. So here is the first question: 1. Why would a Panel B approach result in a very dead, muddy, unpleasant room as compared to Panel A? In both the Panel A and Panel B approaches:

• The 32mm Frycheck is fixed to the 90mm framing (admittedly on opposite sides!)
• The inner leaf room treatment (i.e., mineral wool that sits in the inside out framing) would use the same material, admittedly the Panel B version in the pic shows a 70mm "faux" frame but as above this could be made 90mm and the inside final dimensions would be exactly the same and use exactly the same treatment material. If 70mm were possible there would be a small (2 x 20mm) 40mm gain in width.
• both have a 100mm space (cavity) between the inside of the outer leaf and the 32mm of Frychek that is filled with mineral wool.

The only real difference that I can see is:

• that the Panel B approach places the load bearing 90mm studs in the 100mm air gap so that the air gap is not 100% filled with mineral wool, rather it is approx 85-95% filled with mineral wool with the remainder being the framing.

I'm still not clear about why you would want to do it

So why would I do this assuming the extra expense in wood is ok and more importantly that there is no major acoustic performance and/or isolation issue?

• I can build the 90mm inner leaf framing first and load the inner leaf doors and window at the same time, caulk all of that, get the sparky in to run all the electrics, get the HVAC guys in to run all the venting and A/C, caulk and tidy up following these trades.
• I can then line the inner leaf with the two layers of green glue separated Frycheck and again caulk as I go without having to build and lift a series of heavy panels. In fact I am not even sure how I would fill the air gap with mineral wool easily and accurately if I were raising a series of panels, let alone managing the complexity of electrics, CAT6 and HVAC.
• The ceiling build seems to be easier and more manageable in my mind this way too.
• Then the final framing step would be to build this "faux" inner frame, soffits and superchunck bass traps.
• Toward the end I would install the floating floor, add material to cover the inner leaf treatment and any wood beading (or similar) where required for the final finish.

The downside is extra expense in wood but the definite upside that I see is a much easier path for the build. 2. MOST IMPORTANTLY is there any downside to the acoustic performance of the inside finished rooms that I do not understand or isolation performance issues? If so can you please set me straight and explain this in really laman terms, i.e, why is the Panel A approach better than the panel B approach from an isolation and also final acoustic performance inside the finished LR/CR? :D I want to get this right, but, at the same time I want to be able to build the space as physically easily as possible and also be able to co-ordinate the two trades that I can't do myself and know that their work is rock solid and functioning before I start sealing off such that it becomes hard to get back to fix things. For example, the Panel B approach would allow me to roughly test the air in/air out ventilation and silencer boxes before sealing off.

In both cases you'd need the final treatment added on top to restore the lost liveliness, and that would be about the same extra thickness in both cases, but with a normal inside-out wall you do not also lose the extra thickness of the additional "inner" frame, and you do not need to spend a large amount of money and time to build it.

I think your point about treatment above may be the bit that I am missing? 3. All along I have been assuming that the mineral wool that I use to fill the inside out studs for the Panel A approach or "faux" frame for the Panel B approach is the room treatment? If that is not the case then do you mean that the mineral wool that fills the studs facing the inside of the inner leaf is mainly for diffusion and absorption etc and that after this is covered with a finishing material (cloth etc) another series of panels need to be added to get the desired amount of liveliness back into the finished room? Again thank you so much for your time! I just can't put in words how helpful and knowledgable your input has been over what has now been many many months. I promise that the inner leaf build is very very close now :roll: Thanks, Ben

I just need to know for sure if I go with A or B and why.

"A" makes more sense. Firstly, it it not coupled to the brick wall, like B is, secondly there's a bigger air gap (but you still do need to put insulation in there), and thirdly it uses much less in materials. You could, in fact, move that wall 10mm closer to the brick and still get the same amount of isolation. All of that is from the point of view of isolation. From the point of view of treatment, "A" also makes more sense: you have an extra 30% in the depth of the insulation.

Panel A is what I understand to be a standard inside out build:

Correct.

A = 100mm air gap (filled with mineral wool that does not bridge the inner and outer leafs) + 32mm of green glue separated Frychek (2 x 16mm sheets) + 90mm framing = 222mm thick

If you wanted to save a bit of space, you could reduce the air gap from 100mm to 90mm, to make it comparable to your "B" version, for a total thickness of 212mm, but it would be better to keep it at 100mm. Or if you need even better isolation down to even lower frequencies, then increase the gap even further, and/or add another layer of drywall.

Panel B is what I am trying to understand. I still do not understand why this approach is significantly different from an acoustic point of view when compared to Panel A.

Firstly, it is fully coupled to the brick wall! That's a major difference to start with. There is no separation at all; you show the frame directly touching the brick, so you do not have a fully-decoupled MSM isolation system to start with. It is coupled, there is major flanking going on, and there will be poor isolation. Next, your air gap is 10% smaller, thus driving up the MSM resonant frequency, and therefore reducing isolation. Third, your ceiling framing would have to rest on the outer 90mm framing, implying that the ceiling is also coupled to the both the inner-leaf and outer-leaf walls, once again reducing isolation. Fourth, you have thinner insulation on the room side of the wall, thus reducing damping at low frequencies. Fifth, you spend a lot more time, money, and effort to build a wall that provides much lower isolation than version "A".

Assuming I went with a Panel B approach, I would load the 70mm "faux" inner leaf framing with exactly the same treatment as I would for Panel A except it would be 70mm thick rather then 90mm

Which is a rather large difference! They would both be roughly the same, except that the thinner 70mm insulation in your "B" wall will not absorb down to such low frequencies as the 90mm in the "A" version, so you'd end up with a bit more "mud".

admittedly the Panel B version in the pic shows a 70mm "faux" frame but as above this could be made 90mm and the inside final dimensions would be exactly the same and use exactly the same treatment material.

In that case, the interior acoustics of both versions would be the same, except for the much higher materials and labor cost of the "B" wall for no discernible benefit.

I can build the 90mm inner leaf framing first and load the inner leaf doors and window at the same time, caulk all of that, get the sparky in to run all the electrics, get the HVAC guys in to run all the venting and A/C, caulk and tidy up following these trades.

Ummmm--- don't look now, but your electrical work goes INSIDE the room, not inside the walls. There is no difference for electrical. HVAC can also be done simply with inside-out walls: just hang the piping in place in the cavity until the wall is going up, poke it through the pre-drilled hole at a suitable time in the wall raising, then attach the evaporator unit at some future time, and charge the system as normal. There's no difference here either, or a very minor difference at best. Here's an example from an inside-out build that I'm supervising at present: There is the HVAC piping/electrical bundle, properly coiled in the wall cavity, awaiting installation of the evaporator unit in the future In this case you are seeing the view from the OUTSIDE of the building, as they have not yet put up the sheathing on the building exterior, so the wall you see beyond the bundle is the drywall facing of the inner-leaf inside-out wall. That bundle was hung in place BEFORE the wall went up, and threaded through it at the appropriate time, without accessing it from the outside. It's not hard to do.

I can then line the inner leaf with the two layers of green glue separated Frycheck and again caulk as I go without having to build and lift a series of heavy panels

From the same site: And all done by just two men... and a hand winch ("come-along"). Not hard. Heavy? You bet! Complicated to raise? Nope. Work smart, not hard! :) Each winch can pull 5000kg, and the safety straps can handle 20,000 kg. The wall weighs about 800 kg, IIRC. In this case, they had the advantage of being able to winch up from the outside in the middle of the wall, but you can easily use pulleys to winch from anywhere, or use a wall jack, or several other methods. Here's another one that I designed earlier this year and is currently under construction, much bigger, higher ceilings... and no access from outside: That was raised by one man, and three winches, and maneuvered into position, then lowered.

In fact I am not even sure how I would fill the air gap with mineral wool easily

Simple: Impaling clips! Attach them to the outer-leaf wall, then impale your insulation slabs on them. End of story.

let alone managing the complexity of electrics, CAT6 and HVAC.

Within the wall cavity, all of that runs in conduit either way, in all cases. The conduit goes in BEFORE the wall goes up, in all cases. No difference here either.

The ceiling build seems to be easier and more manageable in my mind this way too.

Why? I don't follow you. It has to span a greater distance, therefore the joists will be larger and more cumbersome to raise. How is that easier?

Then the final framing step would be to build this "faux" inner frame, soffits and superchunck bass traps

Soffits and bass traps will be needed in both cases, exactly the same. No difference here either.

Toward the end I would install the floating floor,

:shock: :ahh: :!: :roll: Huh? What floating floor??? Where did THAT come from? Why do you need to go to tall that huge expense and trouble, when you already have a perfectly good floor??? Is there something WRONG with your slab, that makes it unusable? Why do you want to lose so much extra headroom? That's a major expense, and major complication that I very much doubt that you need. Have you read this thread, to understand WHY you do not need a floating floor? viewtopic.php?f=2&t=8173

The downside is extra expense in wood but the definite upside that I see is a much easier path for the build.

I'm still not understanding you: How can it be easier to build two frames instead of just one? That doesn't even make any sense.

2. MOST IMPORTANTLY is there any downside to the acoustic performance of the inside finished rooms that I do not understand or isolation performance issues?

Let me turn that question around: Is there any up-side to going to all that extra trouble, time, money, expense, and effort, to gain no discernible acoustic benefit at all, either for isolation or for final internal acoustics? If there is no benefit (and there isn't!), they why bother doing it? Life is complicated enough already: why make it even more complicated, when you get no extra result at all?

If so can you please set me straight and explain this in really laman terms, i.e, why is the Panel A approach better than the panel B approach

Because it is easier, faster, cheaper, less complicated and equally effective! I can't explain it more simply than that....

I want to get this right, but, at the same time I want to be able to build the space as physically easily as possible

Can you swing a hammer reasonably accurately, without injuring anyone too badly? Can you operate a caulking gun? Can you operate a circular saw? Can you operate a hand winch? Can you operate a tape measure and pencil? Can you operate a staple gun? Can you operate a pair of scissors? That's as difficult as it gets. If you can handle those typical basic tools, then I don't see what the issue is.

For example, the Panel B approach would allow me to roughly test the air in/air out ventilation and silencer boxes before sealing off.

And why would that not be possible with the "A" approach? Here are the silencer boxes, installed, in the same studio build as above: The inside-out walls are already up at this point. I don't see any connection between why it would be easier to mount and test the silencers before or after the walls go up. Please explain why there would be a difference.

3. All along I have been assuming that the mineral wool that I use to fill the inside out studs for the Panel A approach or "faux" frame for the Panel B approach is the room treatment?

Nope! That's the BASIS of the treatment. There are two possible ways for tuning a room. You can either start with a very live, resonant, reverberant, reflective room, where all the walls are hard, solid, flat, reflective, and then add treatment over those to get the decay times DOWN to whatever is correct for each frequency band. Or you can start with a very dead, muffled, damped, absorptive room, and add treatment over that to get the decay times UP to whatever is correct for each frequency band. Both approaches work, but from opposite ends of the issue. With the first one, you start with hard surfaces and add absorption and/or diffusion tuned to different ranges until the room is under control. With the other, you start with absorption, then add reflection and/or diffusion tuned to different ranges until the room is under control. Personally, I prefer the second way: start out dead, then add life. Other studio designers prefer the opposite: start live and kill it. But both systems end up at the same final goal.

If that is not the case then do you mean that the mineral wool that fills the studs facing the inside of the inner leaf is mainly for diffusion and absorption etc and that after this is covered with a finishing material (cloth etc) another series of panels need to be added to get the desired amount of liveliness back into the finished room?

Correct. That's the most efficient way of doing it, in my experience, and waste the least amount of room space for the treatment. Adding life to a dead room can be done with relative thin treatment: Sucking the reverberance and resonance out of a very "live" room needs much thicker treatment, in the form of deep absorption, or deep tuned devices. I prefer to save space and go with the "thin" approach. I also think it looks better in the end.

I promise that the inner leaf build is very very close now

No problem! Take as long as you need to get the DESIGN perfect first, and the plan for actually building it. Only then should you pick up a hammer... Please, post your final design for the entire studio before you do any building!!!! Don't make the mistake of being one of those people who rush in where angels fear to tread... :) - Stuart -

Hi Stuart, Thanks again all I can say is your post is very informative and very appreciated! I understand now quite well, but, I am going to take a few days to re-read, absorb and then call up my earlier version of SketchUp based on the Panel A design and re-check all the dimensions very carefully, I am sure I can work with my helpers to construct some sort of fully system that will help us to stand up the walls; and I agree and understand that the HVAC and electrical can be pre-installed and loped hanging on the wall and then drawn through the inner leaf via the smallest possible pre-cut holes at the time that the walls are stood up. As for floated floor I think I used the wrong words, what I really meant was that I was going to place a click together style engineered board over the slab to finish the floor. Specifically I had hoped to use a bamboo board that I have left over from the upstairs build: http://www.quick-step.com.au/bamboo/arc ... ed-antique. By floated I meant this click together system rather than floorboard nailed or glued to batons. Are there any obvious issues with that? The impaling clips make 100% sense thank you! I'll reply in full over the next few days. Awesome :) Ben

As for floated floor I think I used the wrong words, what I really meant was that I was going to place a click together style engineered board over the slab to finish the floor. Specifically I had hoped to use a bamboo board that I have left over from the upstairs build: http://www.quick-step.com.au/bamboo/arc ... ed-antique. By floated I meant this click together system rather than floorboard nailed or glued to batons. Are there any obvious issues with that?

Ahhh! OK. That's normally referred to as "laminated flooring". I have heard that it is also called (incorrectly) "floating" flooring in some places, but it isn't really floating at all. Yes, that's fine. It's a good surface acoustically, and there are some really nice looking ones, aesthetically. You do have to have a fairly flat, level, even slab, with no bumps or depressions in it: Check the manufacturers specs to make sure your slab is flat enough. If not, you can level it with a thin layer self-leveling cement. Also use a good quality underlay. - Stuart -

Hi Stuart and everyone else who may be following my protracted plan/build,

Yes, that's fine. It's a good surface acoustically, and there are some really nice looking ones, aesthetically. You do have to have a fairly flat, level, even slab, with no bumps or depressions in it: Check the manufacturers specs to make sure your slab is flat enough. If not, you can level it with a thin layer self-leveling cement. Also use a good quality underlay.

Thanks yes the slab is brand new and flat and I will use a good quality underlay under the laminated flooring. I have attached my updated SketchUp file via an external link as the file is quite big (30MB). It can be downloaded from my dropbox account here: https://www.dropbox.com/s/swd2hkgua8d0d ... n.skp?dl=0 This updated file has a 100mm air gap between the outer and inner leaves. The inner leaf is a standard inside out design with 2 sheets of 16mm Fyrchek Gyprock facing the cavity and 90mm x 35mm H2 treated structural pine framing facing into the inner leaf rooms. I have added a series of scenes to the SketchUp file, from left to right these show the order that each inner leaf wall and ceiling panel will go up in. Although this wall build does not show it I plan to use fill the air gap with mineral wool prior to each panel going up (using impaling clips for the walls and just filling the ceiling gap). There are some scenes toward the end that show the mineral wool in the air gap. I also plan to coil all power and internet runs ready to come through the inner leaf and will also have the HVAC duct runs in place and ready to drop down through ceiling panels as required. Equally the AC copper piping will be in place ready to come through the inner leaf for both the LR and CR. I have been revising my materials list and have a few questions below. The thread mentioned below seems to confirm my research that Bradford SoundScreen is most likely the best readily available and cost effective Australian product for cavity/air gap insulation. It is described as mineral wool made from 65% recycled glass and has a density of 24kg/m3: htttp://www.johnlsayers.com/phpBB2/view ... ia#p136672 QUESTION 1: I have a 100mm wide cavity and was wondering if I can load that with SoundScreen R3.1 - 430mm x 1160mm - 110mm thick bats, i.e, will it be possible/ok for the 110mm thick batt to compress 10mm to give a final fitted thickness of 100mm without introducing any coupling/flanking between the inner and outer leaves? The only other alternative that I have been able to find is a Knauf Insulation batt that is described as glasswool, but, that is only 90mm thick with a density of 27kg/m3. It is 10m too thin to allow a single batt to fill the cavity and I am trying to avoid having to layer insulation in the 100mm cavity: http://www.knaufinsulation.com.au/en-au ... batts.aspx Further, my understanding is that cavity density should be approx 50kg/m3 for mineral wool and 30kg/m3 for fibreglass. Are the above products fibreglass or mineral wool? Both have glass in them, but, neither are described as fibreglass. Specifically, the Soundscreen that seems to be the product of choice here in Australia does say it is mineral wool, but, the 100mm thick version is only 24kg/m3 and that seems to be a long way from 50kg/m3. QUESTION 2: Stuart or anyone else out there on the forums, can you suggest a product in Australia that is either approx 50kg/m3 mineral wool or 30kg/m3 fibreglass? Anyone who has purchased recently and may have found the best cost effective solution that meets 50kg/m3 mineral wool or 30kg/m3 fibreglass specs I would love to hear from you. Thanks! I think I also have a little bit more planning work to lock in the silencer box placement. There is room outside the outer leaf to create a much larger silencer box that will have separate runs for air in and air out. But, there is only going to be approximately a 200mm x 400mm area where the ducting can enter/exit the outer leaf. That space will be carefully filled and sealed once the ducting has been run. QUESTION 3: As you can see in the design I was hoping to place them outside the outer leaf, but, I am wondering if that is likely to mean that noise will not be minimised at the vents inside the inner leaf, i.e., will sound build up after the silencer box in the actual duct? I do plan to ensure that the volume/surface area of the vents inside the inner leaf increase by 300% when compared to the 100mm duct, i.e., vents will be 300mm x 300mm. That’s about it for now. On the upside the paint to seal the inside of the outer leaf arrived today, so with any luck I can get those walls sealed inside a few weeks (time allowing). I decided to use Zinsser Watertite LX: http://www.rustoleum.com/product-catalo ... fing-paint This is certainly taking longer to get going than I had hoped due to day work, freelance work and landscaping the house which I’m happy to say is finished as of last weekend. Cheers, Ben

Hi Stuart, Sorry to ask again, but, I am talking to the only 2 suppliers for Green Glue here in Australia and also am trying to lock in insulation for the air gap cavity too. Fyrchek and wood are the least of my concerns at the moment as they are quite easy to source for a number of suppliers here. I will revisit insulation again once I get the inner leaf up, but, based on the information below there really does not seem to be much on offer here in Australia that meets the specs and suggestions I have read about on the forums. Can I please I get a best understanding of the following: QUESTION 1: Will I get any clear improvement in low frequency isolation if I were to use 3 tubes of Green Glue per 4' x 8' sheet (Best) as opposed to 2 tubes per 4' x 8' sheet (Optimal)? Best and Optional are based on Green Glue's suggested rates of coverage using their online quantity calculator. My calcs have a 4' x 8' sheet as being approximately 3m2. Given that I have 78m2 to cover then I make it that the 3 tube option would require approx 78 /3 x 3 = 78 tubes (Best) and the 2 tubes per sheet option would require 78 / 3 x 2 = 52 tubes (Optimal). If I understand correctly the Green Glue site data is based on the 2 tubes per sheet (Optimal) option. The quantities I can buy are the same as in the USA, as Green Glue is simply imported, so I can buy boxes of 12 tubes or a pail that is equivalent to 22 tubes. But the pails also require the purchase of a specialised syringe applicator. At this point I am thinking of buying the equivalent of 56 tubes:

1. 2 x 5 gallon pails (44 tube equivalent) + 1 x syringe + 1 x 12 tubes = 56 tubes, or
2. or 56 tubes (if that is more costs effective)

I will also be buying 1 x 12 box of the Green Glue noise proofing sealant. The above 56 tube option is about $820 cheaper than buying the equivalent of 78 tubes or the (Best) option. I could not see any information on the Green Glue website regarding 3 tubes per sheet despite their online quantity calculator suggesting 3 tubes per sheet as being better than 2 tubes per sheet. Next, choosing and locating insulation to fill the air gap here in Australia is starting to hurt my head a bit. As in my previous post above I can not find clear and obvious products or suppliers. There are a few issues:

• The suppliers do not clearly define if there product is of the mineral wool or fibreglass type. Some are described as mineral wool, some glass wool, some rock wool and then mineral wool ones are described as being made from glass. All up this is quite confusing. But, I am starting to think that there is no obvious fibreglass option, rather, mineral wool (called by a few names) seems to be the only option. There is polyester (Tontine Acoustisorb comes to mind) and some other materials, but, the forums seem to indicate that the data is just not available for these so I'm not looking at them
• Add to that the issue of density (kg/m3) and the fact that I'm hoping to find a 100mm thick 30 kg/m3 fibreglass batt or a 50 kg/m3 mineral wool batt and the number of options seem to be slim.

QUESTION 2: Stuart when you do get a chance could I please ask you to rank the following options for suitability? :oops:

1. Fletcher Insulation Pink Soundbreak http://www.insulation.com.au/products-1/pink-soundbreak (density 24-26kg/m3 and thickness 110mm): It's not clear if this is mineral wool or fibreglass, but, I'm guessing it is mineral wool the data sheet is here: http://www.insulation.com.au/LiteratureRetrieve.aspx?ID=202690
2. Bradford Soundscreen Acoustic Batts http://bradfordinsulation.com.au/home-insulation/walls/soundscreen (density 24kg/m3 and thickness 110mm): Is mineral wool and it's data sheet is here: http://bradfordinsulation.com.au/~/media/Files/Bradford/SoundScreen-Datasheet.ashx
3. Fletcher SonoBatt Premium http://www.ibatts.com.au/shop-online/residential-insulation/acoustic-insulation/glasswool-insulation/r30-100mm-sono-batts-580 (density 32kg/m3 and thickness 100mm): This is described as glasswool but I can't see it listed on the Fletcher Insulation site and some searches online seem to say it is discontinued. It would about $350-$400 more expensive than the first two options above assuming I can find it.

So that's it as far as I can see in Australia. I don't think any of the above are fibreglass, but, I could be wrong. If they are all mineral wool then none of them come close to the 50kg/m3 density that is recommended on the forums. QUESTION 3: Also when talking to one of the local Green Glue suppliers today it was mentioned that the 24kg/m3 and above insulation does not provide any real isolation benefit over lower 14kg/m3 options when cost is considered. Is that correct? Rather they said that the increased density really only assists to significantly improve the thermal insulation/performance. I think approximately a 1dB improvement in isolation was mentioned from memory by jumping from 14kg/m3 or so to 24-26kg/m3. But, this throws up more questions as I can't seem to find a lower density batt of any variety (fibreglass or mineral wool) that is 100mm thick so that leads me to think that I would need to double up these lower density batts to get a 100mm thickness and that would surely negate most if not all of any cost savings. So I'm hoping to lock in one of the above 3 insulation options unless there are other options that I can't find online? They are all essentially in the same cost range. Once again thanks in advance Stuart or anyone else who might be able to help with the above material ordering questions. Cheers, Ben

Howdy, I know I have a few decisions still to make, but, I was reasonably comfortable starting to seal the inside of the outer leaf over the last few days. As above I decided to use a latex style paint by Zinsser called Watertite LX (http://www.rustoleum.com/product-catalo ... fing-paint). In theory it has a 15 years guarantee for waterproofing and anti-mould. Given that two sides of the room are below ground I wanted to be sure that asy risk of water or mould issues over time were minimised. These walls with an exterior face that are below ground were designed and built with drainage and also sealed externally with a waterproof membrane at the time that they were built. But, to be further sure I decided to seal the inside again. The first coat was brushed in to make sure that there were no pin holes that were missed. The pics are after the first coast. On Tuesday I will roll a second coast with a big fluffy dollar designed for masonry painting. Tomorrow I am off to see a man about a dog ... :) ... actually I'm off with my building contractor to talk to http://www.gjames.com about silent acoustic laminated door and window glass, http://www.westaflex.com.au about HVAC fans and 100mm acoustic/thermal ducting and also http://www.extreme air.com.au about Daikin Ururu Sarara spilt systems. Here are some pics of the space with outer leaf sealing under way. I'll post some more pics after the second coat.

Hi again, I'm happy to say that the inside of the outer leaf is now sealed, the room cleaned and there are some pics of that at the end of this thread. I have also got quotes coming from G James glass for the inner leaf doors and window. They are quoting on 15-16mm laminated glass and also their silent glass which has a better acoustic performance due to a softer material between the sheets of glass that make up the laminate: http://gjames.com/glass/noise-control Next, a building materials supplier is coming next week to check my timber and Frychek materials list and to also confirm my span calculations given that two sheets of Frychek weigh approximately 25kg/m2. Also next Friday I have a meeting with with a HVAC supplier to talk about my room air exchange requirements (3 per hour), extractor fans, ducting and A/C. I hope that goes well. Their duct supplier provides 100mm diameter insulated ducting which I am planning to use for air in and air out. At this stage I'm still thinking that the A/C will be two splits. But, I am still trying to work out if I will but 2 x 2.5kW Daikin Ururu Sarara units or a different set of 2 x 2.5kW Daikin units. The bad bit about the Ururu Sarara units is that they are pricey and require two outdoor units which I'd prefer to avoid, i.e., they can not run off one outdoor unit, but, based on published specs their quietest operation is 19dB. Whereas something like the Daikin 2.5kW CTXG25PVMAW is more cost effective, but, on low it runs at 21dB, still that may be ok. It can always be turned off if it is getting in the way of a recording. On the upside these CTXG25PVMAW units can run off one outdoor unit and also have a dry mode to deal with humidity if required. My original best quote to get 2 x Daikin Ururu Sarara installed was circa $7K AUD. So I am reasonably sure I could save a few dollars by going with 2 x Daikin 2.5kW CTXG25PVMAW units and a Daikin 3MXS52LVMA 5.2kW outdoor unit. The cost saving on the units alone should hopefully pay for the air in/out ducting and fan. With any luck I will be able to get the whole HVAC system supplied and installed for less than the original $7K AUD quote. Finally, the preparations to lock in air gap insulation is still throwing up a few questions. The cheapest and also the most knowledgeable supplier that I have located here in Newcastle is the local http://www.insulfix.com.au warehouse. I talked to them the yesterday and as a result I do have a few questions. They supply the full Bradford range. The three products I looked at were Soundscreen 32kg/m3 glass wool, Ultratel 48kg/m3 glass wool and Fibretex 350 60kg/m3 rock wool. But as per usual I do have a few questions, Stuart (or anyone else who knows) if you do come across my last few posts and get some time to reply then it is answers to the following few questions that I would really like to know so I can lock in an order :) QUESTION 1: Is there any improved isolation performance from completely filling the air gap between and inner and outer leaf? i.e., if I were to place 100mm thick Fibretex 350 rock wool in the entire air gap would this isolate better than 50mm thick Fibretex 350 rock wool plus 50mm or clear air? I assume the answer is that completely filling the air gap will improve the isolation? Is that correct? QUESTION 2: The Fibretex 350 rock wool product at 60kg/m3 has the best NRC across the 3 products so I am thinking that is the way I will go. But, can I please double check again that a 60kg/m3 density completely filling the 100mm air gap WILL NOT result in a sound bridge between the inner and outer leafs such that the isolation is compromised, i.e., I only have 100mm air gap so the rock wool batt will be touching both the outside of the inner leaf and the inside of the outer leaf. Is there any risk here? Finally my Green Glue compound and sealant should be turning up today from http://www.ultrafonic.com.au :) Thanks again for the guidance! :)

I'm happy to say that the inside of the outer leaf is now sealed, the room cleaned and there are some pics of that at the end of this thread.

Cool! Looks good. And I'm betting that you probably noticed a difference in the internal sound after having sealed the block surface...? Not a huge change, but noticeable.

They are quoting on 15-16mm laminated glass and also their silent glass which has a better acoustic performance due to a softer material between the sheets of glass that make up the laminate:

Right. It seems they use the thicker "acoustic PVB", which does indeed provide a slight improvement in isolation, as compared to the normal PVB interlayer.

Next, a building materials supplier is coming next week to check my timber and Frychek materials list and to also confirm my span calculations given that two sheets of Frychek weigh approximately 25kg/m2.

Don't forget to include the rest of the dead load: insulation, lights, electrical wiring, GG (if any), the weight of treatment that will be hung from your ceiling, the weight of the joists themselves, nails, screws, mud, tape, caulk, paint, etc. You need to consider all of that in your dead load. Local code might also require that you assume some live load, even though there isn't any obvious live load...

to talk about my room air exchange requirements (3 per hour),

Why so low? Most specs talk about at least 6 to 8.

Their duct supplier provides 100mm diameter insulated ducting which I am planning to use for air in and air out.

Flex duct? Be careful with that stuff: It needs to be installed properly in order to get the published static pressure drop. It must be stretched out to its full length, there must be no kinks or restrictions (eg. from draping it over joists or thin saddles), and any bends must be broad radius. Also, did you confirm that 100mm duct is big enough to carry your flow volume at the correct flow rate?

My original best quote to get 2 x Daikin Ururu Sarara installed was circa $7K AUD.

:shock: For that price, I would SERIOUSLY consider going with a single AHU that can handle both rooms, and a suitable ducted system. I suspect it would be considerably cheaper to do that. And a lot quieter, too!

With any luck I will be able to get the whole HVAC system supplied and installed for less than the original $7K AUD quote.

I did not see any mention of your silencer boxes in there... Did you consider the cost of building those? MDF and duct liner are not cheap....

The three products I looked at were Soundscreen 32kg/m3 glass wool, Ultratel 48kg/m3 glass wool and Fibretex 350 60kg/m3 rock wool.

I would go with either the 32 kg/m3 fiberglass, or the 60 kg/m3 mineral wool. Those are both in the ballpark of where you need to be.

QUESTION 1: Is there any improved isolation performance from completely filling the air gap between and inner and outer leaf?

Absolutely! The difference between "no fill at all" and "completely filled" can be as much as 16 dB! In your case, partial fill might get you 5 or 6 dB, and complete fill might be 9 or 10 dB.

if I were to place 100mm thick Fibretex 350 rock wool in the entire air gap would this isolate better than 50mm thick Fibretex 350 rock wool plus 50mm or clear air? I assume the answer is that completely filling the air gap will improve the isolation? Is that correct?

Yes. complete filling is the best, assuming that your local fire code permits that. (It probably does, but check with your inspector).

But, can I please double check again that a 60kg/m3 density completely filling the 100mm air gap WILL NOT result in a sound bridge between the inner and outer leafs such that the isolation is compromised, i.e., I only have 100mm air gap so the rock wool batt will be touching both the outside of the inner leaf and the inside of the outer leaf. Is there any risk here?

As long as it is only "touching" on both sides, that is fine. Problems only occur if it is significantly compressed. In other words, if you have to force it into place to make it fit, then that's not good, but if it just fits in smoothly, that's great. 100mm batts in a 100mm space is fine. 100mm batts in a 50mm gap is not. - Stuart -

Hi Stuart, Thanks again for getting back.

And I'm betting that you probably noticed a difference in the internal sound after having sealed the block surface...? Not a huge change, but noticeable.

Yes there was an ambient change I feel it is more reflective now than it was prior to sealing.

Don't forget to include the rest of the dead load: insulation, lights, electrical wiring, GG (if any), the weight of treatment that will be hung from your ceiling, the weight of the joists themselves, nails, screws, mud, tape, caulk, paint, etc. You need to consider all of that in your dead load. Local code might also require that you assume some live load, even though there isn't any obvious live load...

Will do!

Why so low? Most specs talk about at least 6 to 8.

Ok I had thought the minimum would be ok but no point in getting this wrong! Below are my calculations that I'll talk to the HVAC folk about so that the correct system can be set up: LR area: 5.4 m² volume: 15 m³ refresh rate/h = 8 LR volume of air flow per minute = refresh rate * volume / 60 LR volume of air flow per minute = 8 * 15 / 60 = 2m3/m or per second 0.3333m3/s CR area: 12.6 m² volume: 36 m³ refresh rate/h = 8 CR volume of air flow per minute = refresh rate * volume / 60 CR volume of air flow per minute = 8 * 36 / 60 = 4.8m3/m or per second 0.08m3/s

Flex duct? Be careful with that stuff: It needs to be installed properly in order to get the published static pressure drop. It must be stretched out to its full length, there must be no kinks or restrictions (eg. from draping it over joists or thin saddles), and any bends must be broad radius.

The duct I had been looking at (in an uniformed way) and talking to the supplier about are: http://westaflex.com.au/ducting/unilok-fr1.html http://westaflex.com.au/ducting/v-flex.html

Also, did you confirm that 100mm duct is big enough to carry your flow volume at the correct flow rate?

No not yet, if worse comes to worse then I will just have to lower the ceiling to accommodate larger diameter ducting I guess, i.e., if this has to happen then I hope to be able to use no greater diameter than 125mm-150mm. Do you think I'm likely to require more diameter than that? I'll report back after I talk to the HVAC folk later next week.

For that price, I would SERIOUSLY consider going with a single AHU that can handle both rooms, and a suitable ducted system. I suspect it would be considerably cheaper to do that. And a lot quieter, too!

Yep the cost of the Ururu Sarara's was bugging me. Thanks for mentioning an air handling unit as I had not thought of that and as a result will call http://www.pacifichvac.com who are also near me to get some advice. They do say they work on small projects, but, if my job is too small then hopefully they can recommend someone to help if I don't get the answers I am hoping to get when I see a local HVAC supplier later this week, i.e., if they don't really do the V part of HVAC. There really are few options here in Newcastle. Can anybody help with any more information about smaller scale AHU units in Australia? Everything I can see at the moment seems to be more like the sort of equipment that you would find in a very large building.

I did not see any mention of your silencer boxes in there... Did you consider the cost of building those? MDF and duct liner are not cheap....

No no mention of silencer boxes, but, I have factored their cost into my budget. I will most likely be building them myself using duct liner and specs from posts on the forums that you have compiled. Probably a design very close to this: viewtopic.php?f=2&t=11508&start=165 Stuart, thanks for clearing up the air gap insulation questions! I will go with the Fibretex Rockwool 350 as it is a bit more dense, but, more importantly it is available in 100mm thickness so it will sit nicely in the gap without requiring cutting or multiple layers etc. That's about all for now. I'll post again after I have talked to as many HVAC people in my area as I need to to find someone who I can trust to do what I need and install the most cost effective solution. The aim is definitely now to see if I can install a ducted system with one air input and one air output for each room that incorporates an AHU to look after the air exchange as opposed to 2 multi splits and a separate ventilation system. Thanks, Ben

Hi folks, This one will be quick. I have finally found a HVAC designer in Newcastle who really seems to know his stuff and whose company only designs HVAC systems. So I am taking a deep breath and am about to jump in and get a custom design sorted out. The designer has built recording studio HVAC before, worked with studio designers and acoustic experts. He has assured me that it is definitely possible to ensure that all sound is attenuated (silenced) prior to the room inputs and outputs, air is slowed and the inputs and outputs are carefully designed to allow air to slowly fall quietly into the room. Air exchange will be built into the system to achieve the required 8 changes per hour. Once I have a design, which will be created around Daikin products, I can then tender that out to installers that work with Daikin. There are quite a few installers who do this and 3 have already been recommended and have worked with the designer before. The HVAC design is a cost that I had not allowed for to date, but, I strongly feel that it is absolutely essential to get this right so I am willing to take the jump and accept the cost. This will delay the start of the build by a few weeks, but, again I think it will be worth it. The cost for the install may be a bit more than the initial budget too, but, the designer has assured me that I will not need to create silencer boxes as all noise will be stopped and air will be slowed prior to the entry and exit points. Assuming this is correct then there will be a saving from not having to create silencer boxes that will go some way to offsetting any increased cost incurred by paying for a custom design and a small increase in equipment and installations costs. The designers site is here for reference: http://www.evconsulting.com.au That's all for now.

the designer has assured me that I will not need to create silencer boxes as all noise will be stopped and air will be slowed prior to the entry and exit points.

I would be REALLY interested in how he plans to silence an HVAC duct without a silencer! That would be a neat trick... :) Perhaps he calls it by a different name, but unless he's using "eye of newt and tongue of bat" technology, there is no other way to silence an HVAC duct, except by silencing it! At some point, there must be several 90° changes in direction, sudden changes in cross section, some form of baffle, and acoustic absorption. I'm not aware of any other method for changing the speed of air flow except by having a change in cross section, nor any other method for allowing air to move while blocking sound, except by forced changes in direction. Combine that with absorption, and you have a silencer box. Maybe you can ask him to show you some examples of how he "slows down the air and blocks loud sound" without silencer boxes. Photos...

Air exchange will be built into the system to achieve the required 8 changes per hour.

Some form or HRV? Is that the plan?

which will be created around Daikin products,

I'm just curious: Why are you locked in to Daikin? They are expensive, and they are not the only show in town. Is someone offering you a major discount on Daikin that you can't get on any other brand? But anyway, I'm most intrigued about the silencer that this guy designs that isn't a silencer... I'd love to see more info on that... - Stuart -

Hi Stuart, I'll definitely post as much information as I can and pictures too. The plan is that the designer will come out on site first so we can have a more detailed discussion prior to any design and drawings. As discussed on the thread I had hoped to keep the ceiling air gap to 100mm to get a finished height of approx 2800mm, but, I know already that the minimum ceiling air gap is most likely going to be 150mm and even that may increase. I really am aiming to not go more than 200mm so that I can keep a height of around 2700mm in the finished rooms. I have rechecked finished dimensions using Bob Golds modes calculator and a finished height between 2650mm-2800mm does not seem to change the overall result. QUESTION: I do not plan to increase the wall air gap to match whatever the ceiling air gap ends up being as I just do not want to lose width or length in the finished rooms. Is that ok?

Perhaps he calls it by a different name ... At some point, there must be several 90° changes in direction, sudden changes in cross section, some form of baffle, and acoustic absorption.

We have definitely talked about multiple 90° turns, insulation in the duct and cross sectional change. So yes it is likely that a different name is being used for the silencing process. Specifically, the word attenuation was used. By no silencer box, that was just really me trying to say that I hopefully won't need to build silencer boxes that are inside the inner leaf as that work will be done in the ceiling air gap prior to entry/exit inside the room. If I am right then the silencer box budget will go into the cost of the HVAC design and install and I am hoping to keep the HVAC expense as cost effective as I possibly can. I will post more after I have had a face to face discussion, but, it is my laymen understanding that all silencing will be done outside the room and the air delivery and expulsion inside the rooms will be via what was called a "scoop" rather than a vent given that the air has already been mixed, cooled, slowed and silenced by that point. I think "scoop" is a cool name (pun intended :yahoo: ) for a delivery and return point mechanism that incorporates insulated, cross sectional change relative to the duct diameter. But, once I know more I'll certainly post the information. I must say that EV Consulting are the first people who I have talked to that immediately knew what I was talking about and had designed for recording studios before.

Some form or HRV? Is that the plan?

Heat recovery was discussed, but, so was size of equipment relative to the size of my project along with a range of initial possibilities to keep the final solution as compact as possible and also as cost effective as possible while still keeping the solution quiet and hitting the required number of air exchanges.

I'm just curious: Why are you locked in to Daikin? They are expensive, and they are not the only show in town. Is someone offering you a major discount on Daikin that you can't get on any other brand?

Yes, I understand that Daikin is a more expensive option. I think that brand was mentioned as the design company work with that line a lot. But, my understanding is that the design will not be tied to just Daikin. Mitsubishi and Temperzone (Hitachi?) were also mentioned. I don't want to go with a brand that is known to have reliability issues and equally I do not intend to go for the dearest brand just for the sake of it. Hopefully, there will be middle ground on brand as that will come down to discussions with installers once I have a design to shop around. Below is a snippet from the initial email response from the designer after I had outlined the job requirements including room sizes, exchange rates and noise levels etc.

A few points jump out at me.
 
1. For a professional studio, your equipment is going to constantly pick up the background noise the split systems create.  When you turn them off, its going to get uncomfortable in the space pretty quickly.
2. The capacity offered (capacity was a reference to a 2.5kW Daikin Ururu Sarara in each room) would be excess for what you require.  Being such a well insulated room which is not exposed to direct sunlight, the only heat in the space is going to be generated by your electrical equipment, lights and the heat that people in the space give off.
3. The air exchanges you talk about is really about providing “fresh air” for occupants of the room.  Ordinarily with reasonable filtration this is set at 7.5l/s/person.
4. To do the job properly, a ducted system with an acoustically suitable air distribution system would be recommended.  The problem you then face is any ducted system is going to be oversized, i.e be of greater capacity than what you require and will be more expensive.
5. Aside from the equipment capacity, the Issues that need to be addressed are :
    ·   Attenuating equipment noise, start with low noise equipment, keep it out of the space, internally insulate the duct and provide min 2 off 90 degree bends in any duct before it enters the room.
    ·   Keep Air Velocities low.  After the equipment, the next main culprit for noise generation is air travelling through ducts or out of grilles.  You need to keep the speed of the air slow to minimise         this noise.  I would suggest that your 100mm space may make it challenge to keep air velocities down.
    ·   Vibration.  In larger studios we have worked with, we have not installed grilles but used insulated air “scoops” to supply and exhaust air out of the space.
    ·   Penetration sealing. Penetrations through your room fabric need to be effectively sealed.
 
You mention an air exchange unit which I gather would be an air to air heat exchanger.  These are good where you require large amounts of fresh air into a conditioned space.  This is not really the case for your space as the air being exhausted may well be hotter than what is being supplied in.

That's about all for now. Hopefully more soon. Thanks, Ben

Hi Stuart and fellow forum posters, I thought I should post to say that I'm still here and some progress has been made. 1. I have sourced my Rockwool and am ready to order 2. I have also sourced my frame, beam and Frychek supplier and again am ready to order 3. I have sourced the sliding doors and window and am ready to order I am now just waiting on the HVAC design. Once I have that I can shop it across a few local installers and then I should be able to get going. At this point I am planning to get the parts of the HVAC that can be installed outside of the outer leaf done first including any concrete cutting/re-re-sealing to get the ducting through. Once I know that is under way I will order the wood, drywall and rock wool and also grab all the fasteners and bits and pieces we need from the local hardware shop. The glass has a 5 week lead time so I will most likely order that fairly earlier on with the aim of it arriving when we are ready. Given that the glass is heavy the supplier will install it. We will get the frames ahead of time so that they are in place and ready for the supplier to fit the glass into. That's all for now. Thanks, Ben

Hi again, Today I ordered my Rockwool (100m 60kg/m3 Fibretex 350 made by Bradford here in Australia) for the air gap cavity and also Ultratel glasswool with an Ultraphon lining (25mm 48kg/m3) to line my silencer boxes. http://bradfordinsulation.com.au/commer ... bertex-350 http://bradfordinsulation.com.au/commer ... t/ultratel The supplier is www.insulfix.com.au (Cardiff branch) and they have been very helpful and had the best price could find on the east coast of Australia. I have also placed a deposit on the inner leaf sliding doors with G James who were recommended by John. The inner leaf control room door is 2400mmm x 2100mm with 17.5mm laminated glass and an acoustic inter-layer. The pair of slider between the CR and LR are 2000mmm x 2100mm and are the same except one is 13.5mm laminated. The inner leaf LR window is 16.38mm laminated glass again with an acoustic inter-layer. I am waiting on HVAC quotes and will be ordering my LVL beams, frame and Fyrcheck next week. So, hopefully this thing may actually get started soon! Cheers, Ben

I love updates! I'm still following along on your thread, Ben, and dying to see photos once you have those things in! - Stuart -

Hi Stuart, Thanks! Your assistance and advice has been absolutely invaluable and I am also equally dying to get going over the next few weeks. I have now also ordered my 150mm beams and 90mm framing timber. Both are T2 termite treated just in case. The same supplier is also providing all the 16mm Frycheck. So all the main materials are now ordered. My friend, who is main the builder, and I will head to Bunnings over the nest week or so to grab fixings, impaling clips and other bits and pieces like adhesive to stick the Ultratel to the inside of the baffle/silencer boxes. I have my first HVAC quote in and though expensive I was reasonable happy to find that the price for a 5.5 kW Daikin ducted system with air handling unit and all insulated ducting, fans and bits and pieces totally installed was only 20% more than installing 2 x 2.5kW Ururu Sarara units. I will have to pay for concrete cutting on top of that though. So hopefully that will not be crazy expensive. I'll chat to the HVAC people after ANZAC day to see if they recommend a contractor for that. I also realise that I have not posted anything about the HVAC so I thought I would show the design and also a few updated SketchUp files and as per usual a few questions :roll: With any luck I am not doing anything crazy! The HVAC design delivers 100l/s to the smaller live room and the remaining 220l/s capacity of the system is split 50/50 along two runs into the larger control room. So the control room has two separate 110l/s runs. If I understand correctly this means that the velocity in the two control room ducts is close to the 100l/s velocity going into the live room as opposed to a single run with 220l/s within the same diameter resulting in higher velocities. The ducting is 200mm Westaflex Quadroflex oval equivalent insulated (25mm) ducting with an open cross sectional area of approximately 0.03141m2. The velocity of this 100l/s in the 200mm ducting is 3.1831m/s or a whopping 626.59fpm that is obviously too fast. (http://westaflex.com.au/ducting/quadroflex.html) So, the plan is to transition from the 200mm duct into a 25mm Ultratel lined box (300mm x 300mm) that has a consistent cross sectional area of .09m2 this equates roughly to a duct diameter of 338mm and my understanding is that this should reduce the speed from 3.1831m/s (626.59fpm) to a more acceptable 1.1145m/s or 219.39fpm. These boxes have roughly 3 times the cross sectional area of the 200mm duct rather than 2 times that I have read across the forum. I hope this is not an issue as the physical size of the duct, my available air space in the roof between the inner leaf and outer leaf, the required flow rate to achieve the required air exchange and the finished height (to get the room modes right) all see to be pointing toward a 300mm x 300mm baffle box. I know that sounds big, but, I need to slow the air. I am planning on using the depth of the inner leaf beams to get a bit more height in the boxes without loosing extra finished height. QUESTION 1: I am hoping that I will still get some acoustic impedance benefit even though the cross sectional area moves to 3 times rather then 2 times the duct diameter? Is that a reasonable assumption, I did try to google but could not find anything definitive? Also please note that I am hoping not to box the Quadroflex duct in, but, the entire area above the inner leaf will be filled with 60kg/m3 rock wool. There will be at least 100mm above all ducting and boxes. And the entire system outside of the outer leaf is also insulated with 25mm duct liner. In the lower areas of the ceiling air gap the rock wool will be thicker again. The baffle boxes are quite long at around 3 metres and I am hoping they turn enough to stabilise the air prior to the registers. The HVAC designer has recommended a series of slots (rather than a grill) that increase the delivery surface area again by roughly a factor of two beyond the cross sectional area of the boxes. In addition I am planning on uniformly increasing the the cross sectional area of the baffle box as the registers approach. So I am hoping that the final air speed will drop again. By how much though I must admit I am unsure. Still my thinking is that the cumulative area of the 4 slots in the live room is .16m2 and and .2m2 in the control room. .16m2 is roughly 1.8 greater than 0.09m2 and .2m2 is roughly 2.2 times greater. If these were duct sizes then a cross sectional area of .16m2 would roughly equate to 450mm duct and .2m2 to 500mm duct. The velocity of 100l/s in those two diameters would be .62876m2 (123.77fpm) and .5093m2 (100.26fpm). QUESTION 2: I don't expect to get those last two feet per minute velocities. But, is it reasonable for me to assume that the air velocity will stay well under 300fpm given that I am increasing cross sectional area from 200mm (.03141m2) oval equivalent duct > consistent 300mm (.09m2) baffle box > register ? You will also notice that I have changed the baffle setup inside all of the baffle boxes after talking to the HVAC designer about wanting to uniformly increase the box volume as the registers approached. I also split the air in box into two separate compartments in the control room to avoid the two air flows crashing into each other just prior to the register. So instead of one register there are now two symmetrical ones in the control room as in the SketchUp image. I was less concerned about the air out in the control room. Provided it stays quite I am happy to leave that to split of it's own accord and find its way out the two exits points. My builder and I will be looking after all the inner leaf HVAC install. The contractor will do all the work outside of the outer leaf as depicted.

With any luck I am not doing anything crazy!

Well, think about that: You are building your own recording studio! so yeah, I'd say you certainly are doing something crazy! If not, you wouldn't be here on the forum... insanity is sort of a prerequisite... :)

These boxes have roughly 3 times the cross sectional area of the 200mm duct rather than 2 times that I have read across the forum. I hope this is not an issue

That's fine. What's important is a sudden transition from one cross section to another that is at least twice the size. That sudden transition creates an impedance mismatch for sound waves trying to move through, which provides considerable attenuation. Imagine using a tweeter without a waveguide... same principle.

I know that sounds big, but, I need to slow the air.

:thu: yup!

I am hoping that I will still get some acoustic impedance benefit even though the cross sectional area moves to 3 times rather then 2 times the duct diameter? Is that a reasonable assumption,

Yep! In fact, the greater than change, the better the mismatch. Ideal is to have a small tube opening out into infinite air, suddenly...

The HVAC designer has recommended a series of slots (rather than a grill) that increase the delivery surface area again by roughly a factor of two beyond the cross sectional area of the boxes.

Careful with that... slots with large "webs" between them create turbulence in the air flow. Turbulence = noise. That would be fine for a typical home, office, shop or school installation, where you want the HVAC system to create some low air noise, but not for a studio where you want it silent. The air should make no noise at all. It would be better to look for special low noise registers, that have a large ratio of open area to vane area, and guide the airflow smoothly, without creating turbulence. Not the typical register that you find in Home depot (or Bunnings!).

So I am hoping that the final air speed will drop again. By how much though I must admit I am unsure.

Easy to calculate: It's the air flow rate, divide by the open area of the register. For example: if you have a rate of 100 L/S, which is the same as 0.1 m3/S or 100,000 cm3 per second, and an open area of 500 cm2, then the flow speed will be 100,000 (cm3/s) / 500 (cm2) = 200 cm/s. Which is about 390 fps or 2 m/s. Look at the units of each and you'll see how that works: You have "cubic centimeters per second" divided by "square centimeters" so what you are left over with is "centimeters per second". Of course, that assumes no friction losses, no turbulence, constant pressure, constant temperature, etc. so it isn't 100% accurate down to the n'th degree, but it's a very good back-of-the-envelope approximation. The key to understanding that is to not look at the air flow in "liters per second" but rather "cubic centimeters per second".

QUESTION 2: I don't expect to get those last two feet per minute velocities. But, is it reasonable for me to assume that the air velocity will stay well under 300fpm given that I am increasing cross sectional area from 200mm (.03141m2) oval equivalent duct > consistent 300mm (.09m2) baffle box > register ?

I didn't do the above math on your actual numbers, but if you do it, you'll be able to answer your own question! :)

You will also notice that I have changed the baffle setup inside all of the baffle boxes after talking to the HVAC designer about wanting to uniformly increase the box volume as the registers approached.

I'm not so sure that's a good idea: part of the key to the way silencer boxes work is to have sudden large changes in cross sectional area, which causes the sudden impedance mismatch at the transition, for sound waves. Yes, it also causes turbulence in the air flow, which should be avoided, but there's a rule of thumb in HVAC that says if you have a long straight run after a sudden change in direction, then the airflow will return to smooth flow after a distance of about 5 times the effective diameter of the duct. So having a long straight path after the last baffle will do the same as having a gradual increase in cross section, but with the added acoustic benefit of the impedance mismatch.

I also split the air in box into two separate compartments ... So instead of one register there are now two symmetrical ones.

I often do that in my studio designs, but I go the other way: I bring in both ducts right next to each other in the center of the box, and have the air moving outwards from there. That has the added advantage of each duct being able to transition into a much larger cross sectional area, and having all the turbulent mixing going on right away, far from the registers. PM me, and I'll show you how I did it in a studio that was just completed not too far from you, up near the Queensland border... Your overall design looks good, but there's room for improvement in the details... - Stuart -

Well, think about that: You are building your own recording studio! so yeah, I'd say you certainly are doing something crazy! If not, you wouldn't be here on the forum... insanity is sort of a prerequisite... :)

:yahoo:

Careful with that... slots with large "webs" between them create turbulence in the air flow. Turbulence = noise. That would be fine for a typical home, office, shop or school installation, where you want the HVAC system to create some low air noise, but not for a studio where you want it silent. The air should make no noise at all. It would be better to look for special low noise registers, that have a large ratio of open area to vane area, and guide the airflow smoothly, without creating turbulence. Not the typical register that you find in Home depot (or Bunnings!).

Thanks! We are building everything inside the concrete so I will start hunting down low noise registers with a high ratio of open air to vane.

Easy to calculate: It's the air flow rate, divide by the open area of the register. For example: if you have a rate of 100 L/S, which is the same as 0.1 m3/S or 100,000 cm3 per second, and an open area of 500 cm2, then the flow speed will be 100,000 (cm3/s) / 500 (cm2) = 200 cm/s. Which is about 390 fps or 2 m/s. Look at the units of each and you'll see how that works: You have "cubic centimeters per second" divided by "square centimeters" so what you are left over with is "centimeters per second". Of course, that assumes no friction losses, no turbulence, constant pressure, constant temperature, etc. so it isn't 100% accurate down to the n'th degree, but it's a very good back-of-the-envelope approximation. The key to understanding that is to not look at the air flow in "liters per second" but rather "cubic centimeters per second".

Cheers I'll crunch the numbers after I have located suitable low noise registers and will repost what I hope to achieve by way of air speed at the registers.

I'm not so sure that's a good idea: part of the key to the way silencer boxes work is to have sudden large changes in cross sectional area, which causes the sudden impedance mismatch at the transition, for sound waves. Yes, it also causes turbulence in the air flow, which should be avoided, but there's a rule of thumb in HVAC that says if you have a long straight run after a sudden change in direction, then the airflow will return to smooth flow after a distance of about 5 times the effective diameter of the duct. So having a long straight path after the last baffle will do the same as having a gradual increase in cross section, but with the added acoustic benefit of the impedance mismatch.

I think I must have misunderstood some of the posts I have been reading! Straight is definitely easier to make and I think I should be able to get a straight run that is 5 times the effective diameter before the registers.

I often do that in my studio designs, but I go the other way: I bring in both ducts right next to each other in the center of the box, and have the air moving outwards from there. That has the added advantage of each duct being able to transition into a much larger cross sectional area, and having all the turbulent mixing going on right away, far from the registers. PM me, and I'll show you how I did it in a studio that was just completed not too far from you, up near the Queensland border...

That makes a lot of sense! I'll have a play with repositioning the two control room air in feeds and I will PM too :idea:

Your overall design looks good, but there's room for improvement in the details...

Again thanks so much for passing an eye over things it is very much appreciated, Ben

Hi forum folks, I thought I'd post a few pics as most the materials for the inner leaf build have now arrived and are stored away. Framing and placing rock wool in the air gap as we go should be starting within a week or so. The HVAC installation is scheduled for 4 weeks from this weekend. Core drilling through the outer leaf in 1-2 weeks time. I'll post more pictures as we progress. In the meantime as soon as the electrician has checked out power, light and cat6 runs and the cables are looped in position we will start framing up at the far end where we will not impact the HVAC install. The main materials for this initial framing phase are:

• 46 packs of Bradford Fibretex 350 100mm Rockwool stored under the house with each pack covering 2.2m2
  Not preserved: IMG_1670.jpeg
• 2 packs of 25mm Bradford Ultratel glasswool with a black Ultraphon coating with each pack covering 17.2m2 to line the baffle/silencer/plenum HVAC boxes
  Not preserved: IMG_1669.jpeg
• more linear metres of H2 treated 90mm x 42mm LVL smart frame in 5.4m lengths than I care to count given that it all has to be cut and joined
• 21 H2 treated 150mm x 42mm LVL beams in 3.6m lengths
  Not preserved: IMG_1672.jpeg
• Again more Fyrchek and 50mm drywall screws than I care to consider and yep 3000mm and 3600mm sheets of 16mm Fyrchek are definitely heavy
  Not preserved: IMG_1671.jpeg
• 5 boxes of Green Glue and 2 boxes of Green Glue Noiseproofing sealant
  Not preserved: IMG_1680.jpeg

Hi, My builder/industrial designer friend and I have started framing up over the last three days. We are moving slowly and taking our time. After we build a frame section, we are screwing the first layer of 16mm fyrchek to the frame, then applying green glue, fixing the second sheet of 16mm fyrchek, standing the section up into place, checking it is straight/inline etc and then fixing it to the concrete slab with Ramset Ankascrews. We will have a few wall panels where we are not be able to stagger the drywall joins. We will seal with green glue company acoustic caulk to compensate for this and I hope this issue will not result in a large loss of isolation. Stuart, can I ask your opinion on whether I should be worried about a seam that is not staggered? I am also yet to seal the inside wood/drywall seams with acoustic caulk so no caulk can be seen in the attached pic. We have been slipping the rock wool into the air gap cavity as we go. My electrician is due next week to run conduit and cable for the the power, light and cat 6 runs ready for as to draw through the framing. We have until june 20 before the hvac installers will be on site and our aim is to have the first baffle box/ceiling panel up before then so that the vac installers can run duct and their spigot into the side and we can see how that is done. At this point we are aiming to fit the remaining duct into the remaining baffle boxes. The hvac installers will have already run the other ducting, we will just be attaching and sealing the duct into the baffle boxes (assuming we can other wise I'll ask the hvac guys to come back and do each one as it is ready). If I ever do this again I will be making sure I have a lot more ceiling height to work with! It is great to finally get started though the end will be at least a few months off. Stuart, I still have a bit of time to adjust the baffle box design and hope to get a slightly modified drawing through to you. Thanks, Ben

Hi again, I thought I'd post a few more progress pics. We are aiming to lift the first ceiling baffle box panel this Thursday with a genie lift that is rated at around 300kg. The HVAC installers are also calling through to look at the job now that the core drilling and some framing is in place. They are due in 3 weeks to do the HVAC install. With the first ceiling panel/baffle box up at least one baffle box connection can be completed at HVAC install time and any issues sorted out. We are hoping that we will be able to do the connections as we complete the other boxes, but, if need be then the HVAC installers will be asked back each time we complete a box. The electrician also came today and ran power, cat6 and lights and left all the runs coiled at their locations so that we can pull them through the walls and ceiling panels as we go and then seal them off. Power runs were placed in conduit to ensure that the rock wool filled air gap meets the required fire code, i.e., to ensure that there is no risk of heat build up. Below are a few pics of the first box being built and some close ups of the cut in point for the HVAC. The baffle box has been lined with 2 sheets of 16mm Fyrchek separated by Green Glue and then finished with an internal lining of Bradford Ultratel with a smooth black Ultraphon coating. In the pics below the top of the box is still to be fitted. All joins inside and out of the box have been sealed with Green Glue Company caulk. In fact everything is getting caulked as we go and at the end for redundancy I will be sealing the inside of the finished room too. I hope that will work well and pay off.

Hi again, A bit more progress to show below. In the photos there is some temporary wood in place to support framing and you can also see that while some panels have already been double sheeted with green glue in between others are still just empty 90 x 45 LVL. This is because some framing will need to be moved as part of installing the last few baffle boxes and other ceiling panels. So the sheeting is being left until they go back in for the last time. I now understand how heavy a double sheeted 16mm Fyrcheck is and given the weight the frame sections that have to be moved they are best left un-sheeted until they are ready to be raised into their final location. While I understand that I will have some vertical seems where the wall panels join I am simply resided to this and will accept whatever isolation loss flows from this. All wall seams and sheeting are tight and are essentially air tight, i.e, there is no visible gap. Of course there is still some amount of gap. The point where the sheeting seems do line up vertically are covered by 90mm x 45mm LVL that has a density of approx 600kg/m3 (roughly half that of the Fyrcheck). Still the Fyrchek seam is still there behind the LVL and yes I know this equals loss of mass and is a weak spot from that point of view, I will just have to live with that. Each seam is being carefully sealed with caulk at build time and all inside frame/panel joins will also be caulked at the end to ensure the CR and LR are air tight. On the upside the framing for the LR and CR is complete (aside from 2 x LR/CR door lintels and double studs) and close to 50% of the entire sheeting job and a large part of the air gap rock wool is also done. This Thursday the HVAC installers will be here and after they have done their thing we will get back to the last bit of framing and sheeting that can be done before moving on to: * Building 1 x LR ceiling panel and LR air return baffle box and lifting them into place * Sheet the final LR wall and rock wool line the air gap * Sheet the opposite CR room wall and stand it up * Build the CR air in baffle box and lift it into place. * Build the CR air out baffle box and lift it into place. * Sheet and finish a final CR wall panel and stand it up * Finish the framing and sheeting by lifting and propping a few last ceiling panels and raising the final lintel panel above the CR entry door So, still lots to do. Tomorrow I'm off to the glass supplier to pick up the knocked down frames for the doors and having a final last chat to the glass estimator to make sure that our final frames are exactly on tolerance for the day that the glaziers come to drop the panels in. As the laminated glass is so heavy the glaziers are delivering and installing. We will handle the installation of the inner leaf fixed 1200mm x 1200mm window. I have been told that it should not be more than about 50-55kg. Still that will be enough for me, I'm already looking forward to the heavy stuff being done and dusted.

Howdy, I thought I'd post a few more quick pics for progress. We are moving along, although it may appear as if we are de-constructing at the moment more than constructing at the moment! That is because we are working in a fairly tight space and built all of the framing to make sure everything would be 100% tight, straight and true before adding heavy double sheeted fyrchek. So, we have taken away a few frames to make room to get the LR air return baffle box built and then lift it. As you can see it is all but built and just needs its top. We'll finish it today and lift it over the weekend. Then we can stand up and sheet the final wall of the LR and it will be complete except for the door. You can also see the first HVAC duct is connected. This is the air in to the LR. The HVAC suppliers are being fantastic and have agreed to call through each time we have a box to connect. This allows us to keep the area above where we are working as clear as possible to stand up and lift panels.