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PostPosted: Mon Dec 17, 2018 3:09 pm 
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Location: West Wales, United Kingdom
Hi guys I'm looking for advice on the construction of a soundproof room which will be used as a control room but also to record vocals, a home studio/single room type construction.

My family have an account with a company which can supply concrete blocks and cement mix for a reduced price, on top of that they can claim VAT back because we own a farm, this means that price-wise it looks to be cheaper for me to erect a two leaf masonry structure rather than one concrete wall- air gap-stud wall with gypsum.

I have been through tens of threads here and on other forums and have learnt the importance of creating a low resonant frequency and decoupling structures, I have learnt that a two leaf structure is the best.

Depending on the cost the dimensions of my single room will be 3M Height, 5M width and 7M length, but if this ends up being too expensive I shall have to reduce that to 3M height 4.2M width and 5.7M length.

Budget £20,000 Maximum

I shall share with you my plan and the questions I have and I hope that you can help me out.

The Plan

Erect the outer wall giving it an independant foundation that is only twice as wide as the wall, then for a Mass-Spring-Mass system, I would need to leave say a 150/200mm gap? is that enough? and build the second inner wall on a slab foundation which spans the entire surface area of the floor area. Block thickness will be 140mm, The only gap in the walls will be for double door system.


Questions:
1. What type of insulation is best to use between the walls?
2. If the structure is to be decoupled, what do I place on the ground between the walls to stop the insulation from getting wet? anything rigid like a plank of wood would ruin the decoupled system?
3. Will this insulation keep the structure at all warm?
4. When I install a roof, how can I maintain the decoupling I have achieved by seperating the walls foundations? Surely the roof will be attached to both walls and thus serve as a flanking path?
5. What material should I be using for the roof, it has to be equal surface density right?
6. To avoid a 3 leaf system, does that mean I can't plaster the internal side of the inner wall? If not, what do I put on the walls? do i leave them as a bare concrete and paint them? Either way I will be using bass trapping and treating primary reflection points.
7. I think a double door system seems like the most soundproof, would I be able to get away with installing one expensive super soundproof door and a second behind it, that is still soundproof but not so expensive for about 70% of the cost of the initial door, or would that compromise the first door's TL capabilities?


TL I am looking for

Noises coming out- Only my voice is relevant here, need to block myself at loud singing level, not thrash metal level though. I will be mixing with subwoofer but couldn't care less if people can hear it outside it won't bother anyone in the farmhouse.

Noises coming in
Now this is the main problem, I live on a farm so there are always Tractors, Bobcats, Landrovers Quadbikes etc about
and machinery can be very loud, I'm pretty sure the tractor can hit 90db SPL when you're right next to it, and less a few metres away, reducing the dominant frequencies of a tractor engine shouldn't be too hard right? at about 1500 HZ, most high STC constructions can silence that, but what about the low end rumble they also produce? I'm assuming I will need at least a 40-45DB TL in the LF considering the whole DB/A chart and how we perceive LF of the same intensity as quieter due to structure of the human ear?

Ceiling: as well as a roof, what would I use for a ceiling? a floating ceiling? what else would you recommend?


Most Important Question: Can a two leaf masonry single room studio construction of the specified size with a TL capability prevalent enough to kill a tractor's engine from a couple metres away, including a door, Ventilation (No fancy temp gauges needed just air in so I don't die from oxygen deficiency), A roof, (No windows) and adequate heating capabilities be finished for Less than £20,000 Pounds Sterling

Thanks in advance to anyone contributing the valuable information I seek

-Jacob

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PostPosted: Thu Jan 10, 2019 5:48 pm 
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…………...well thanks

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PostPosted: Fri Jan 11, 2019 6:12 am 
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Hi Jacob!

Sorry about the late reply. Your thread must have slipped by me (and maybe everyone else as well!).

Quote:
Erect the outer wall giving it an independant foundation that is only twice as wide as the wall, then for a Mass-Spring-Mass system, I would need to leave say a 150/200mm gap? is that enough? and build the second inner wall on a slab foundation which spans the entire surface area of the floor area. Block thickness will be 140mm, The only gap in the walls will be for double door system.

Hard to say if that is enough. You should calculate (or use my calculator which is a sticky at the top of the design forum) how you should construct your walls in order to achieve the amount of isolation you need.
If you're recording drums or full bands, you might experience 110+ db C weighted inside the room. Use that figure to calculate how much isolation you need at your property line or other tenants on your property.

Quote:
1. What type of insulation is best to use between the walls?

One that is the right density or has the correct gas flow resistivity for the resonant frequency of your MSM system. Typically, you want to use insulation that has great absorption coefficients at lower frequencies.

Fiberglass in kg/m³ would then be Low Freq = 20-25

Mineral Wool in kg/m³ would then be Low Freq = around 30 (others say 40-45)

Quote:
2. If the structure is to be decoupled, what do I place on the ground between the walls to stop the insulation from getting wet? anything rigid like a plank of wood would ruin the decoupled system?

Sorry, I don't fully understand your question. Are you referring to the gap between de-coupled slabs or just de-coupled room framing?

Quote:
3. Will this insulation keep the structure at all warm?

The insulation between your leaves would probably be similar to a normal house insulation-wise. But, you will have more insulation inside your inner leaf which will increase your R value. Furthermore, your outer and inner leaves will be air-tight due to extreme amounts of sealant. THIS will be the difference between a leaky normal home and your studio. This is why you really need to nail your HVAC design.

Quote:
4. When I install a roof, how can I maintain the decoupling I have achieved by seperating the walls foundations? Surely the roof will be attached to both walls and thus serve as a flanking path?

Your inner leaf ceiling will sit on your inner leaf walls. No flanking.

Quote:
5. What material should I be using for the roof, it has to be equal surface density right?

Anything that meets your local building code and maintains the density you've calculated that you need.

Quote:
6. To avoid a 3 leaf system, does that mean I can't plaster the internal side of the inner wall? If not, what do I put on the walls? do i leave them as a bare concrete and paint them? Either way I will be using bass trapping and treating primary reflection points.

Without seeing a SketchUp of your idea, I don't know what your walls will be made of or anything. You can totally plaster the inner leaf if you'd like. Plaster doesn't count as a leaf.

You could build your walls using John's inside out technique which opens up tons of possibilities for acoustic treatment. It also saves on framing materials.

Quote:
7. I think a double door system seems like the most soundproof, would I be able to get away with installing one expensive super soundproof door and a second behind it, that is still soundproof but not so expensive for about 70% of the cost of the initial door, or would that compromise the first door's TL capabilities?

The idea of having two doors is that on each leaf, there is a door. This door matches the mass and therefore the transmission loss of that leaf. In order to match the transmission loss of a decoupled MSM system, you'd need EXTREME mass for a single door. Like and impossible amount in the given space. So, that's why two doors are recommended. It would be silly to have one massive door and one light door. The MSM equation is based around each leaf being similar in mass.

As an example, say you had a really massive (heavy) wall. If you put a piece of cardboard up as your second leaf, do you think there would be any real improvement in isolation? Nope. But, if you split the massive wall in half and decoupled the two halves, you would achieve amazing isolation. I hope that analogy helps connect the dots.

Quote:
Noises coming out- Only my voice is relevant here, need to block myself at loud singing level, not thrash metal level though. I will be mixing with subwoofer but couldn't care less if people can hear it outside it won't bother anyone in the farmhouse.

Okay, but, unless you want your vocal recording trashed by sounds like lawn mowers, vehicles, rain, thunder, etc, you need to build your room to block those sounds from getting INTO your room.

Quote:
Now this is the main problem, I live on a farm so there are always Tractors, Bobcats, Landrovers Quadbikes etc about
and machinery can be very loud, I'm pretty sure the tractor can hit 90db SPL when you're right next to it, and less a few metres away, reducing the dominant frequencies of a tractor engine shouldn't be too hard right? at about 1500 HZ, most high STC constructions can silence that, but what about the low end rumble they also produce? I'm assuming I will need at least a 40-45DB TL in the LF considering the whole DB/A chart and how we perceive LF of the same intensity as quieter due to structure of the human ear?

Yes, outside noise pollution needs to be stopped from getting in. The low end rumble is the problem. That's why you can't look at dB charts in A weighting. C weighting is what matters because A weighting filters out low frequencies.
Attachment:
A vs C Weighted SPL.png

The MSM calculator I mentioned above will give you a rough idea of how your room construction will isolate lower frequencies. They're the hard frequencies to stop.

Quote:
Ceiling: as well as a roof, what would I use for a ceiling? a floating ceiling? what else would you recommend?

Your inner leaf ceiling will sit on top of your inner leaf walls. It would be silly if you don't build your inner leaf ceiling inside out.

Quote:
Most Important Question: Can a two leaf masonry single room studio construction of the specified size with a TL capability prevalent enough to kill a tractor's engine from a couple metres away, including a door, Ventilation (No fancy temp gauges needed just air in so I don't die from oxygen deficiency), A roof, (No windows) and adequate heating capabilities be finished for Less than £20,000 Pounds Sterling

You're mentioning several different areas where your isolation can be compromised.

For your walls and ceiling, use the calculator to determine what materials/mass you need to attenuate the problematic frequencies to your desired level.

For doors, you need to have at least the same mass but door handles and jamb perimeters will be the weak links. So, for door handles, don't use through-door handles. Use automatic door closers. For your seals, use 4731 or some similar intense seals including automatic door bottoms. Use at least 2 seals around your doors like a bank vault. There are lots of threads on how to build the doors. In SketchUp, there are some great acoustic doors in the 3D warehouse by Gulfo (I believe that's how you spell his name).

For your HVAC, unless you live in a part of the world (like Hawaii) where the temperature is almost always perfect or an imaginary place where the humidity is perfect year round, you will need more than just ventilation.

To maintain your isolation, you need an equivalent amount of insertion loss by way of silencer boxes. There are many threads on here covering the design of HVAC systems and silencer boxes. Things to figure out are sensible and latent loads, CFM, fresh air CFM (30%), total static pressure, air velocity and probably other things that slipped my mind right now. As you've pointed out, this isn't just about acoustics so much as safety. So don't avoid diving into the subject or asking questions here on your thread!

Quote:
Thanks in advance to anyone contributing the valuable information I seek

Jacob, sorry again for leaving you hanging. Every contributing member on the forum is answering questions free of charge on their spare time. Personally, I have 5 jobs, 2 kids, 2 cars, 1 wife, and 1 large studio I'm designing and building. Things come up in our lives that take away from our time on the forum. For example, among my jobs, family and studio build, I had to do a pretty major repair on my wife's SUV. Furthermore, we all just finished an extensive holiday period.

Having said that, unless you've hired a studio designer, you may have to "bump" your thread or just have patience (maybe a week or so) before someone chimes in to answer your questions. But even if you hire a studio designer, chances are you might have to wait that long to get answers from them as well. I have about 5 studios I'm being paid to help design and consult for and there just isn't enough time in a day to get everything done I'd like to!

Once you get your SketchUp design going, you'll realize that on your list of to-do items, most of the questions you have can wait a week to have an answer because you'll have a million other items on your list to address!

I hope you haven't lost faith in the forum. Please stick with us as we'd love to help you bring your studio to life!

Greg


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PostPosted: Fri Jan 11, 2019 9:05 am 
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Faith Restored! I am glad I got a reply, I knew everyone would be busy over Christmas period was simply disappointed nobody had given me any advice by now, thank you for your time Greg :)

Quote:
Sorry, I don't fully understand your question. Are you referring to the gap between de-coupled slabs or just de-coupled room framing?


I am indeed referring to the gap between decoupled slabs, in fact I assumed decoupled slabs meant separate slabs for each wall?

Quote:
The insulation between your leaves would probably be similar to a normal house insulation-wise. But, you will have more insulation inside your inner leaf which will increase your R value. Furthermore, your outer and inner leaves will be air-tight due to extreme amounts of sealant. THIS will be the difference between a leaky normal home and your studio. This is why you really need to nail your HVAC design.



"Inside" my inner leaf? as in inside a concrete wall? and yes I have learned the importance of a solid HVAC design I wouldn't want to skimp out on it cause it could compromise the whole structure.


I have just had a look at your calculator and I achieved these values from using 140mm thick concrete walls as both leaves with the sheathing as a single layer of 5/8 inch gyproc wallboard on leaf 1, and the same on leaf 2.

These are the values I got, are these a weighted or c weighted or neither? they seem too good to be true!

20 Hertz- 82.71 TL
25 Hertz- 84.65 TL
31.5 Hertz- 86.65 TL
40 Hertz- 88.73 TL
50 Hertz- 90.67 TL
63 Hertz- 92.67 TL
80 Hertz- 94.75 TL
100 Hertz- 96.69 TL
125 Hertz- 98.63 TL
160 Hertz- 100.77 TL
200 Hertz- 102.71 TL

400 Hertz and above- 105.67 TL

One important question about your calculator though, does concrete mean poured concrete or concrete block walls? because surely they would have different values, and I think poured concrete's a lot more expensive but I could be wrong.

-Jacob

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PostPosted: Fri Jan 11, 2019 9:06 am 
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Thank you for your valuable input as well I shall look in to everything you have mentioned.

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PostPosted: Fri Jan 11, 2019 12:44 pm 
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Location: St. Albert, Alberta, Canada
Quote:
I am indeed referring to the gap between decoupled slabs, in fact I assumed decoupled slabs meant separate slabs for each wall?

I'd ask your local inspector what material would pass an inspection that would remain soft to prevent flanking.

Quote:
"Inside" my inner leaf? as in inside a concrete wall? and yes I have learned the importance of a solid HVAC design I wouldn't want to skimp out on it cause it could compromise the whole structure.

Inside your inner leaf as in your acoustic treatment insulation.

Quote:
I have just had a look at your calculator and I achieved these values from using 140mm thick concrete walls as both leaves with the sheathing as a single layer of 5/8 inch gyproc wallboard on leaf 1, and the same on leaf 2.

First off, are any of your concrete walls exposed to the outside world? If so, you will probably need vapour barrier. If that's the case, you shouldn't add gyproc to your outer leaf. I believe you'd need vapour barrier touching your final gyproc layer inside your room.

You didn't indicate how big of gap between the leaves you entered in the calculator.

Quote:
These are the values I got, are these a weighted or c weighted or neither? they seem too good to be true!

This isn't weighted at all. These are values obtained by the formulas at the bottom of the calculator.

The values seem extreme for sure, however, if you look at the mass of 5.5" of concrete and 5/8" of drywall, that is a LOT of mass. Sealed, with a large gap, you're going to get awesome isolation for sure. But, there is a limit to what you can actually obtain before flanking happens through the ground.

Quote:
One important question about your calculator though, does concrete mean poured concrete or concrete block walls? because surely they would have different values, and I think poured concrete's a lot more expensive but I could be wrong.

Poured.

Greg

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PostPosted: Sun Jan 13, 2019 11:35 am 
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Hi Jacob,

Welcome to the forum! I'm also building a studio in West Wales, where about are you based?

Paul


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PostPosted: Sun Jan 13, 2019 3:25 pm 
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Paulus87 wrote:
Hi Jacob,

Welcome to the forum! I'm also building a studio in West Wales, where about are you based?

Paul


On a farm in the border between Pembrokeshire and Carmarthenshire! about 25 minutes from carmarthen :)

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PostPosted: Sun Jan 13, 2019 3:28 pm 
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Gregwor wrote:
Quote:
You didn't indicate how big of gap between the leaves you entered in the calculator.



I used 200mm, and thanks for clarifying :)

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PostPosted: Sun Jan 13, 2019 8:43 pm 
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Jre96 wrote:
Paulus87 wrote:
Hi Jacob,

Welcome to the forum! I'm also building a studio in West Wales, where about are you based?

Paul


On a farm in the border between Pembrokeshire and Carmarthenshire! about 25 minutes from carmarthen :)


That’s cool, Sounds like we’re pretty close! I’m about 10 mins from Newcastle Emlyn. I’d love to see your progress and offer some advice, send me a pm and we can arrange it. You’re also welcome to visit my build if you’re interested.

Paul


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