New dream house with studio and workshop.

#1

Hi everyone,

My wife and I are building our new dream home and one of the main criteria is that I get a studio and workshop. We originally intended to build just a studio at our existing home. We got as far as architects designing the building and commissioned Stuart to design the studio itself. Stuart came up with a fantastic design but the building itself was always going to be a compromise due to space limitations of the plot. To cut a long story short we were ready to start building when my wife took seriously ill, so the project got parked. Once she fully recovered we re-evaluated our whole life and decided to find a plot in the country and build a new dream home for a new life.

Two and a half years ago we found the plot and spent nearly w years getting through planning and building control. We finally got everything ready to start building and then the COVID-19 lockdown shut down the entire building industry and put us back around 12 weeks. We finally got to work at the beginning of July this year and are now making good progress.

Unfortunately, as with most things in life, there is a finite budget which is never as big as it really needs to be. Therefore, our current strategy is to build the block-work only for the studio along with the full house and move in. Once we are living in the new house I hope to commission Stuart again to design a dream studio which I will build myself to reduce costs as far as possible.

The studio/workshop block will include 3 main rooms plus toilet and storage. Live Room, Control Room and a woodworking workshop for guitar building. I intend to use the studio mainly for personal projects but would like to be able to carry out some commercial work. A new neighbour was previously a sound engineer and tour manager before moving to the corporate world which, like me, he has now “retired” from. He has a couple of Air b’n’b properties nearby so we have been talking about doing some sort of “residential” project in this idilic location.

I am currently studio a 3 year course at college on stringed instrument making and hope to use the workshop side as a viable building and repair business.

So far we have all groundworks and drainage for both buildings done. The studio is built to the stage of all walls in place. We are having a precast concrete roof installed in the next few weeks. Windows and doors arrive at the beginning of September for the workshop but I will be making the studio windows myself later.

Question No 1

The walls are dense concrete block 215mm thick (140x215 on flat). My understanding is that the windows should have the same mass as the walls for isolation purposes. However, there is no benefit in making the windows more massive than the walls as the system is only as good as its weakest link.

Therefore, how thick does my glass need to be to have the same isolation properties as 215mm dense concrete?

I will upload some photos of progress shortly.

Alan

#2

Hi Alan!

Answering your question, and roughly based on mass law, your glass might have 181mm thickness to have same isolation properties as 215mm dense concrete.

Here's how I got that number:

Concrete block density: 2100 kg/m3
Concrete block thickness: 0,215 m
Concrete block 0,215m thick surface density: 2100 [kg/m3] * 0,215 [m] = 451,5 [kg/m2]

Glass density: 2500 kg/m3

How thick glass needs to be in order to achieve same isolation as concrete? 451,5 [kg/m2] / 2500 [kg/m3] = 0,181 [m]

Since it's almost imposible in real life, due to costs and manufacturing, it's a good question to be answered by someone with more real life experience than me, to tell how thick it could be to not be a bad compromise.

Anyway, I hope my sort of useless answer might be useful for you to understand that into mass equation, the difference between materials is in its surface density, which means how heavy is a square meter of a material which a given thick.

Best regards,

Eric

#3

Thanks Eric.

That is really helpful if slightly scary

I understand the concept at a superficial level but wasn't’ sure about the conversion from m2 to m3 as all the info I could find for concrete was m3 but for glass was m2. I was hoping for around 25mm per pane. The internal glass will be part of a standard stud wall with 2 layers of gyproc so hopefully the full system can can come in with a reasonable compromise for glass thickness.

#4

Hello Alan,

That's great to hear your wife has recovered and you are building a new place and life.

Without knowing more about your build it is difficult to say, but I wonder if you are asking the wrong question, in terms of the glass having to match the mass per area of the outer wall. 181mm thick glass, while no doubt possible, seems unlikely and very expensive.

Would a better question be: what amount of sound isolation is required? And would this be possible with two separated panes of much thinner glass? Perhaps matching the mass of the concrete outer wall is overkill.

For example, there are threads where people have built rooms sufficient to isolate drums from the outside world, and two layers of glass thinner than 181mm was used.

Cheers!
Jennifer

#5

Also, as you have mentioned, your weak link is probably not concrete walls, rather your ceiling and roof structure. From a practical standpoint, you can match the outer wall density, or as Jennifer said, find what your room will require. I will also note that you can lower your target isolation range (resonant frequency) by going with a laminate glass plate, instead of annealed glass) the overall thickness will be less for about the same isolation, but it is isolating in a different frequency range. Rod Gervais book goes through some glass selection quite well. Cheers, Kevin

#6

Thanks Jennifer and Kevin.

Kevin, it was actually that chapter in Rod’s book that caused me to ask the question

The roof is a also concrete so the windows are clearly the weak link in the system. I have rather more window than would be considered Ideal as I have stunning views which would be a shame to waste.

Although our nearest neighbours will be over 100m away the nature of a glen next to a loch means that sound does tend to travel particularly on still days. As there are only a handful of people living in the glen the general noise level is very low. There is one fly in the ointment for isolation FROM the outside world though. The road past the studio is the access road to a working forest. We have up to 8 loads of timber passing each day. However, the speed limit on the road is only 10mph so the noise is relatively low. The sheep, cows and birds make more noise

#7

This is the location for the studio

You can probably see why I have made the windows a little larger than normal in relation to isolation requirements.

#8

That looks amazing! I'm trying to figure out roughly in Scotland where it is but can't quite manage it :-)

If you've not already done so, it would be useful to put a decibel figure on the amount of isolation you require. Stuart has written a post about this here https://www.digistar.cl/Forum/viewtopic.php?f=17&t=745

Cheers,
Jennifer

#9

endorka wrote:Source of the postI'm trying to figure out roughly in Scotland where it is but can't quite manage it :-)

Me too! My thoughts are The Trossachs or a tad further west or north. It looks a nice way to start a new dream.

PS. You wouldn't happen to be Alan, by any chance, Wheresthedug?

#10

Starlight is bang on

It is Balquhidder. Between Callander and Lochearnhead. The water is Loch Voil. It is oart of the Loch Lomon and Trossachs National Park.

Jennifer - the answer is “lots”

I want to be able to play full rock band or soul band with horn section without annoying my wife (who can hear a bar fart in China from our current living room in Glasgow) or the neighbours. Fortunately, the nearest neighbours other than our house will be over 100m away. The closest point of the house to the live room will be 20m. However, the forestry trucks run past about 10m from the live room (on the window side). They are restricted to 10mph so there isn’t masses of noise but there is enough to want to keep it out. My target is as close to 82db reduction as I can manage (hence 215mm think concrete walls and concrete roof) but in reality if I can manage over 70db I should be OK. That is a rough guestimate rather than a fact.

#11

That is an excellent area of the country indeed. Many fond childhood memories of holidaying around there :-)

Alan, have you seen Purelythemusic's build thread? He's going for a similar level of isolation; viewtopic.php?f=6&t=32

Stuart has posted about a site built door and windows for high isolation. To 55dB for these ones, but it might give you some idea of how to take it further to your requirements;
viewtopic.php?f=12&t=23
viewtopic.php?f=12&t=86

Cheers,
Jennifer

#12

If your 215mm concrete-walled building will also have its concrete roof 215mm thick and windows and door to match then your building - perhaps we should say bunker - will provide 52dB sound isolation as a single wall is subject to the mass law.

To get over 70dB you will need to be thinking of a proper room-in-a-room studio to get the additional benefit of MAM (mass air mass).

It's now after midnight here and I am just off to bed so I will do the maths for you tomorrow to show what can be achieved.

#13

Greeting Alan,

I used to live near logging country in the western US. Those trucks are indeed loud, even with the speed restriction (they drive like maniacs in the US, regardless of the posted speed). However, I think your biggest concern from them would be the low-frequency rumble entering the studio.

As Eric pointed out:

Answering your question, and roughly based on mass law, your glass might have 181mm thickness to have same isolation properties as 215mm dense concrete.

I wonder how thick the glass (or whatever the "windows" are) is on deep-sea submersible vehicles (given the pressure it has to withstand)...

perhaps we should say bunker

A bunker with portholes. In a STUNNING setting. Wow!

All the best,

Paul

#14

I did actually investigate the idea of making it a bunker but costs multiply when you go underground.

#15

Alan,

Sorry but this gets messy in a mathematics way.

The single basic figure for sound isolation - I said 52dB - is what is called the STC or Sound Transmission Class. It is a simple figure that is useful for places where speech will occur, such as offices and meeting rooms. The two problems with it for musicians is that no room provides a set level of isolation across all frequencies, and as musicians we tend to use a wide range of frequencies, as I am sure you are aware.

The isolation according to the Mass Law is calculated using the formula
R = 20 log (fm) -47dB
where f is the frequency and m is the surface density of the mass (kg/m2)
Here are a few sample calculations using Eric's figure for the surface density of 215mm of (hopefully Scottish) concrete:
R = 20 log (16 x 451.5) -47 = 30dB @ 16Hz
R = 20 log (32 x 451.5) -47 = 36dB @ 32Hz
R = 20 log (63 x 451.5) -47 = 42dB @ 63Hz
R = 20 log (125 x 451.5) -47 = 48dB @ 125Hz
R = 20 log (250 x 451.5) -47 = 54dB @ 250Hz
R = 20 log (500 x 451.5) -47 = 60dB @ 500Hz
R = 20 log (1,000 x 451.5) -47 = 66dB @ 1kHz
R = 20 log (2,000 x 451.5) -47 = 72dB @ 2kHz
R = 20 log (4,000 x 451.5) -47 = 78dB @ 4kHz
R = 20 log (8,000 x 451.5) -47 = 84dB @ 8kHz
R = 20 log (16,000 x 451.5) -47 = 90dB @ 16kHz
You can see that as the frequency doubles, so does the sound isolation. That is why outside a night club no one notices the cymbals, mainly the bass. It is possibly the lorries rumbling by just 10 metres away will present a problem. It would be worth getting Stuart or another professional to advise you regarding this.

If you built a detached room inside the concrete outer shell then you will not be subject to the mass law - which requires you to double the thickness of the wall to get an extra 6dB isolation at each frequency.

I have done the calculations for adding a two layers of plasterboard inner room wall and ceiling but don't want to post them as my figures have some kind of mistake in them I cannot see. On seciond thoughts, it may be easier for someone to see my mistake and offer a correction if they see my maths.

The forumlae are based on what is in Marshall Long's book Architectual Acoustics on pages 320-331.

Outer wall (215mm concrete) density = 451.5 kg/m2
Inner wall (2 layers of 18mm fire-rated plasterboard) density = 26 kg/m2
Gap between the walls (d) = 15cm

TL = 14.5 * log (M * 0.205) + 23 dB
M = Surface density in kg/m2
14,5 * log (451.5 * 0.205) + 23 dB = 52 dB = R1 or m1
14,5 * log (26 * 0.205) + 3 dB = 34 dB = R2 or m2

f0 = C [ (m1 + m2) / (m1 x m2 x d)]^0.5
C=constant = 43 (metric) if you fill it with suitable insulation
m1=mass of first leaf (kg/m^2)
m2=mass of second leaf (kg/m^2)
d=depth of cavity (m)
f0 = 43 [ (451.5 + 26) / (451.5 x 26 x 0.15)]^0,5 = 22Hz

R = 20log(f * (m1 + m2) ) - 47 ...[for the region where f < f0]
R = (R1 + R2)/2 + 20log(f * d) - 29 ...[for the region where f0 < f < f1]
R = R1 + R2 + 6 ...[for the region where f > f1]
f1 is 55/d Hz = 55/0.15 = 367Hz

R = 20log(f * (m1 + m2) ) - 47 ...[for the region where f < f0]
R = 20log(16 * (451.5 + 26) ) - 47 = 30dB @ 16Hz

R = (R1 + R2)/2 + 20log(f * d) - 29 ...[for the region where f0 < f < f1]
R = (52 + 34)/2 + 20log(32 * 0.15) - 29 = 43+20log6.45-29 = 28dB @ 32Hz
R = (52 + 34)/2 + 20log(63 * 0.15) - 29 = 43+20log9.45-29 = 34dB @ 63Hz
R = (52 + 34)/2 + 20log(125 * 0.15) - 29 = 43+20log18.75-29 = 39dB @ 125Hz
R = (52 + 34)/2 + 20log(250 * 0.15) - 29 = 43+20log37.5-29 = 45dB @ 250Hz

R = R1 + R2 + 6 ...[for the region where f > f1]
R = 52 + 34 + 6 = 92dB above 367Hz

If you add an inner room, creating a MAM (mass air mass) system, you should get better results but it doesn't look that way. The key figures from those calculations are:
30dB @ 16Hz

28dB @ 32Hz
34dB @ 63Hz
39dB @ 125Hz
45dB @ 250Hz

92dB above 367Hz

You can see that the middle section, for frequencies between 22 and 367Hz, are lower than just the single leaf wall, which surely cannot be correct. I need someone's help!

Soundman2020 - Studio Design Forum