Residential Studio Build in Ireland

Hey there, Myself and a friend are planning on building a studio in my back garden in the next couple of months. We've been talking to people and doing some research here and are feeling a bit overwhelmed by the amount of conflicting information knocking around the web with regards to studio construction and sound isolation techniques. Our plan is to lay 2 seperate foundations (1 for live room, one for control room), build a timber frame structure around the entire size, then build sub rooms inside this on the seperate foundations. The floors in the 2 rooms will be seperate from each other in order to stop sound transmission. We're planning on running piping between the two rooms for cabling and electrical lines etc.. Ive been giving a good contact for some high density 50mm rockwool that we were going to use to soundproof the rooms. I've been told by a friend who has built studio and used this stuff that the 50mm high density rockwool amount to apprx 100-150mm standard rockwool, so we are probably going to double up on this. One layer on the inside of the outer structure and one on the inner sub room. Also in the live room we're considering cladding the inner wall in stone, both for the added layer of density and for the aesthetic and sound qualities that we think this would give the space. The full size of the whole studio will be max 36 square meters, but it'll probably be under that. Sound isolation is key to our project. We have neighbors on each side of us, but luckily none directly behind where we plan to build. Im wondering if anyone could recommend some basic things we should be doing as regards the thickness of the timber framing, the gap between the outer and inner sub walls and also any other information regarding soundproofing that would relate to our project. Also if you guys think that cladding the room where the volume will be in stone will be of any help with regards sound proofing? We also considered building in concrete but are leaning more towards a timber frame design. If anyone has any thoughts on this that would be great! The studio will be used for both recording and rehearsals. We expect it to be pretty loud in there when a full band is cranking the rock on big amps and kits so its vital that the soundproofing is done correctly. I can upload some pictures of designs if that would help in getting some good feedback about our project. We'd really appreciate a bit of discussion about our studio plans and would welcome any criticisms any of you fine people who have experience in a project like this may have. Thanks for taking time to read this!

Hi "warbuttons". Please read the forum rules for posting (click here). You seem to be missing a couple of things! :)

feeling a bit overwhelmed by the amount of conflicting information knocking around the web with regards to studio construction and sound isolation techniques.

Then you are finally in the right place! :) What you will find here on the forum is plain, solid, simple, scientific information about how to do it right. No hype, no "guesses", no "I have a friend who said...". No "I once saw on TV that...". No "I-have-a-cool-video-camera-and-look-at-my-fatastical-studio" YouTube videos. No egg crates on the wall. No carpets on the ceiling. Nobody trying to sell you anything. Just the plain basic facts, based on the science of acoustics, and the laws of physics. That's what this place is about. You can easily tell when you should turn and run from an "acoustics" web site: if they are trying to sell you something, if they make claims that sound too good to be true, if they will not (or cannot) provide independent laboratory tests to back up the claims, or if they claim anything that runs counter to the laws of physics. Those are all clear signs to get out, fast.

Our plan is to lay 2 seperate foundations (1 for live room, one for control room), build a timber frame structure around the entire size, then build sub rooms inside this on the seperate foundations

That is one way to do it, if you need extreme levels of isolation. But you will need three sets of foundations, not two. You need one foundation for each room, plus one for the outer-leaf that encloses them. The foundations need to be dimensioned correctly to support the amount of mass that will be needed for each room, and also laid correctly to ensure maximum damping and maximum isolation. But you might or might not need such extremes: How much isolation do you actually need, in terms of decibels of Transmission Loss? That is the basis for your entire build.

We're planning on running piping between the two rooms for cabling and electrical lines etc..

Fine, but your conduit (the correct name for electrical "pipe") also has to be isolated between the rooms. If not, it becomes a flanking path, and reduces isolation.

Ive been giving a good contact for some high density 50mm rockwool that we were going to use to soundproof the rooms. I've been told by a friend who has built studio and used this stuff that the 50mm high density rockwool amount to apprx 100-150mm standard rockwool, so we are probably going to double up on this.

Well, there you are getting into hype and hearsay. The truth is that "high density" rockwool is wrong for good bass absorption. The optimal density for rockwooll (and other mineral wool products) is 48 kg/m3, which is about 3 PSF. However, if you choose to use fiberglass insulation, instead of mineral wool, then the optimum density is about 30 kg/m3, which is about 2 PSF. For details on why this is the optimum density, take a look at the Wyle 73 paper, or also take a look at IR-761. The evidence is conclusive. Those documents also show that higher density is worse for bass absorption and better for high frequency absorption, while lower density is the reverse: better for bass absorption and worse for high frequency absorption. The best balance is at the densities I mentioned. Your friend is also not correct about thickness.Density and thickness are not interchangeable, and 50mm of one density is not the same as 100 mm of another density. In fact, it is not even the density itself that matters: It is a property known as "gas flow resistivity". That is the property of the insulation that describes how it impedes the flow of sound waves, and that is the principle property that matters. But since most manufacturers never bother measuring this parameter, it is hard to find for commonly available products. Fortunately, it turns out that, for each type of insulation, there is a rough relationship between density and gas flow resistivity. Thickness of the insulation is important, but only in relation to the total size of the air gap inside the wall. 50mm of insulation inside a 50mm air gap is fantastic. 50mm insulation inside a 500mm air gap is practically worthless. The purpose of insulation is to damp the resonance inside the cavity, and coverage is an important part of that. Thin cavities only have high frequency resonance, which can be handled by 50mm of insulation. Larger cavities have much lower frequency resonance (which is good!) but also need thicker insulation. But in both cases, the density of the insulation is what matters. Putting higher density insulation in a cavity just to save space or money will NOT improve the overall isolation. In fact, it could make it worse in low frequency isolation, and low frequencies is exactly where you need the most isolation anyway.

Also in the live room we're considering cladding the inner wall in stone,

That does work, yes, and you'll find several examples on the forum of people who have done that. Stone has good diffusion properties, and also looks good. But once again, it has to be done correctly, as part of the overall acoustic design of the room. There is a range of optimum frequency response and time-domain response for recording studios, and having either too much reflection or too much absorption is not good. They have to be balanced. So stone is fine, provided that you balance that with the treatment in the rest of the room.

Sound isolation is key to our project. We have neighbors on each side of us, but luckily none directly behind where we plan to build.

That explains why you are thinking of isolating the foundations. But the big question is: How much, exactly? In terms of decibels. That's the key to everything. If you don't know that, then you can't know what type of materials and techniques to use. Isolating to 50 or 60 dB TL is one thing, while isolation to 90 or 100 dB is major, big-time different other thing. Your first order of business is to define that number.

Im wondering if anyone could recommend some basic things we should be doing as regards the thickness of the timber framing, the gap between the outer and inner sub walls and also any other information regarding soundproofing that would relate to our project.

The basic concept is that the wall is a tuned system. It has two "leaves" to it, the "outer-leaf" which faces the outside world, then the "inner-leaf" of each room, which faces the room itself. (A "leaf" in the context of acoustic isolation is just any large, massive rigid surface with an air-gap next to it, followed by another leaf.) So the wall is a tuned two-leaf system. Technically, it is a "fully decoupled 2-leaf MSM system". "MSM" stands for "Mass-Spring-Mass", since that is the principle of physics that makes it work. The two leaves are the two "masses", and the air between them is the "spring". So it is a resonant system, and that's why it isolates: it will ONLY resonate at its natural resonant frequency (and the harmonics to a lesser extent). So the trick is to tune that resonance to a low enough frequency such that the wall isolates all higher frequencies at the necessary level. You "tune" the wall by changing the mass and the air gap. That's why you need to set your goals in terms of how many decibels of isolation you need, and what is the lowest frequency you need to isolate. Know those two factors allows you to play around with the equations that predict the resonant characteristics of the wall, and the isolation that can be expected.

We also considered building in concrete but are leaning more towards a timber frame design. If anyone has any thoughts on this that would be great!

Concrete will provide much higher isolation, but also costs much more. The key to isolation is mass, and concrete has LOTS of mass. The more mass you have in a wall, the better it will isolate. Concrete is roughly 3 to 4 times more dense that drywall, and is usually much thicker than drywall, so the surface density is many, many times that of drywall, and the isolation is a lot higher. But so is the cost.

I can upload some pictures of designs if that would help in getting some good feedback about our project.

That would be excellent! Photos are always very helpful, so we can see what you are dealing with. - Stuart -

Hey there, Thanks for your reply, its very helpful indeed! What you're saying about the foundations makes sense. I dunno why we didn't think of that. What would you recommend for the gap in the foundations and walls? We were going to dig the foundations, frame off the areas in plywood seperating each section by an inch or two then get concrete poured into each area. As far as the for the amount of isolation we need im not exactly sure, but I do know that the live room will potentially be really loud. We'll be recording everything from folk music to pretty extreme heavy rock (big marshall stacks and ampegs fridges cranked to the max... with drums pounding) so I imagine we'll need it to be in the 90-100 db level for isolation if possible. As regards the density of the insulation used. We were planning on using 50mm of the high density rockwool on the inside of the outer mass wall then plywood sheets with rubber carpet underlay, then the air gap of a few inches, then another partition wall with another layer of rubber carpet underlay, 50mm rockwool, plywood, then cladding that with stone. The thickness of the insulation would fit inside the partition cavities entirely not leaving any gaps. We'll have to do a bit of research on the insulation material I think. The only reason we were going with the 50mm high density stuff was that Ive heard it in a friends studio and it done a really good job and took up less space in the wall cavities. As much as I'd like to do a concrete build I dont think we can afford that, and also for planning permission it makes things more difficult. If it at least looks like a big garden shed I think it will save us alot of hassle from neighbours. Thanks so much for your reply and help, its much appreciated. I should be getting some plans back this week so I'll post them along with some pictures asap. :)

You still need to check those forum rules for posting (click here). You are still missing something important! :)

What would you recommend for the gap in the foundations and walls?

That's probably regulated by your building code, but make it at least few mm wide, make sure nothing falls in that could bridge it, then fill it with suitable acoustic or vibration isolation material, as permitted by code. Probably some type of non-hardening, soft, pliable expansion joint compound to seal off the top.

so I imagine we'll need it to be in the 90-100 db level for isolation if possible.

A loud rock band can be a hundred times louder than that! Up around 115 dBC or even 120 dBC.

We were planning on using 50mm of the high density rockwool on the inside of the outer mass

As I explained before, "high density" might be the WRONG density. You should find out exactly what the density is. High density mineral wool is WORSE at isolating low frequency sounds. So if it is much more dense than 48 kg/m3, then your isolation of drums and cranked bass guitar amps will be poor.

then plywood sheets with rubber carpet underlay,

Whoooaaaa!!! Carpet underlay on the WALLS??? Between the studs and the plywood? :shock: What for???? That makes no sense at all, acoustically. It will not decouple, and will not act as limp mass either. There's no point to that at all.

As regards the density of the insulation used. We were planning on using 50mm of the high density rockwool on the inside of the outer mass wall then plywood sheets with rubber carpet underlay, then the air gap of a few inches, then another partition wall with another layer of rubber carpet underlay, 50mm rockwool, plywood, then cladding that with stone.

That's a THREE LEAF wall! First you have your "outer mass wall", then you have your "plywood on carpet underlay", then you have another "plywood on carpet underlay". That is a 3-leaf wall, and will isolate WORSE than a 2-leaf wall. Even though that is not intuitive, and does not sound logical, it is true. All other factors being equal, a 3-leaf wall will isolate WORSE than a two leaf wall. You need to change your plans here. The plans you have will not get you where you want to go...

The thickness of the insulation would fit inside the partition cavities entirely not leaving any gaps. We'll have to do a bit of research on the insulation material I think.

Yes. You need to find out what its density is. And if it is a lot higher or a lot lower than 48 kg/m3, then it will not be useful.

The only reason we were going with the 50mm high density stuff was that Ive heard it in a friends studio and it done a really good job and took up less space in the wall cavities.

With all due respect to your friend, that's subjective, and not valid, acoustically. A "really good job" might not be that good at all, compared to what it COULD have been if it was done right.... :) You might find this graph informative: Laboratory tests do not lie...

I should be getting some plans back this week so I'll post them along with some pictures asap.

Great! Looking forward to seeing them! - Stuart -