basic design to build studio in garden

I would like a 5 x 5.5m sound proof brick built building constructed in my rear garden. It will be single-story, and will be used as a basic recording space all year round. I don't need a control room to begin with, to keep initial costs down. The front of the building will have a thick soundproof door. The building will be double skinned with dense concrete block for the inner course and dense bricks for the outer course, with 4" gap in between. I will put up plasterboard sheets on the inside. 2 sheets of plasterboard will be mounted on a wooden frame, with mineral wool in the middle, so this makes a total of 3 layers: outer layer: brick walls 4 inch air gap middle layer: concrete slabs inside layer: 2 sheets of plasterboard mounted on wood frame with mineral wool inbetween roof will be pointed, with slate. Ceiling will be the same as the inside layer of the walls: 2 sheets of plasterboard mounted on wood frame with mineral wool inbetween. Does anyone know what STC rating I might get with the above? This building is to be used all year round, so it needs a damp proof course, heating and electric installed etc. I'm funding this myself, so the cheaper the better - but not at the loss of decent soundproofing. I'd like to be able to have drums playing in the room, and not hear them 10 metres away. What STC rating do I need to achieve this? I have heard many people have soundproofed up their garage and managed this, so I'm hoping I should easily manage it with a dual skin dedicated building. Will it need foundations or just a flat concrete slab on the floor? Is it necessary to have a floating floor or will it be okay just to have standard foundations? Is there anything else I should consider? I'd really like to keep costs down as low as possible. Will do work myself if necessary. What minimum budget should I be looking at? I'm concerned about hiring el cheapo builders to do the job. Would rather spend a bit more on builders who have experience in making a soundproof space than end up wasting money on a useless building with not very good soundproofing. Are there any dedicated sound-proof builders in the UK / London area? Thanks in advance for your kind and patient advice

... so this makes a total of 3 layers:

It also makes a three-leaf wall, which is generally not a good idea! Search the forum to find out why. That said, in your case you already have a pretty darn good two-leaf with your brick and block walls, so why do you think you need the third leaf? What are you expecting it to do for you?

Ceiling will be the same as the inside layer of the walls: 2 sheets of plasterboard mounted on wood frame with mineral wool inbetween.

So your ceiling will be your weak point, by far. Why bother with all the trouble of "bricks and blocks" for the walls, if you are just going to build a much lower isolation ceiling?

Does anyone know what STC rating I might get with the above?

You will get whatever the ceiling gives you, since it will be the weakest link in the chain, bar far. Not sure here, just guessing, but maybe around the mid 40's, or perhaps the very low 50's, if you get really lucky. Look up one of the IRC papers to get a better idea. There is probably something in there similar to what you are planning.

so it needs a damp proof course, heating and electric installed etc.

It also needs ventilation! It will be doubly-airtight, hermetically sealed. You will need to get air in and out, and do it without losing too much isolation.

I'd like to be able to have drums playing in the room, and not hear them 10 metres away. What STC rating do I need to achieve this?

STC isn't a good system for deciding on drum isolation, since it does not take low frequency sound into consideration, and a lot of energy from a drum kit is of course in the low end. So one wall rated at STC-70 might not do what you want, while another one rated at STC-65 might do the job just fine. It all depends on how well those walls isolate at the bottom end of the spectrum, which STC does not consider. You also need to define what you mean by "can't hear drums 10 m away". How quite is that, in real decibel terms? What is the average ambient level at that 10 m location, at the quietest time of day? You need to be quite a bit lower than that in order to be inaudible.

I have heard many people have soundproofed up their garage and managed this, so I'm hoping I should easily manage it with a dual skin dedicated building.

Yes, but you are proposing a three-leaf building, not a two-leaf building, so the low frequency isolation in your case could end up being WORSE than for those two-leaf buildings.

Is it necessary to have a floating floor or will it be okay just to have standard foundations?

Here is your answer: viewtopic.php?f=2&t=8173

Is there anything else I should consider?

The entire forum! I'm not trying to be funny. There are numerous other things that you need to consider. I'd suggest that you start by reading through a few of the build threads here, from start to finish, to give you an idea of all those things you need to think about. Also, by Rod's book, and read over that a few times. And get the Master Handbook of Acoustics as well. - Stuart -

This is going to take far too much of my time. Aren't there any soundproof room builders in the UK who can do it for me? Checked on google, turned up nothing. I read the link you gave, it looks like I don't need a floating floor, that's good news. I'm in the UK so building work and materials are significantly higher than the US. This is for recording, so the most important thing is to prevent sound coming in. That is why I mentioned a drum practise room where you can't hear from 10 metres away. Most important thing is to prevent noise coming in. I will buy a place away from airports and noises as best I can, to try to keep cost down, but it will still have to contend against wildlife noises, neighbours lawn mowers, children playing, and possibly road noise (although I'll try to minimise this by having it in the garden behind a house. Would be great if you could let me know why a 3 leaf is no good? Since you don't think the ceiling is good, what should I put on the ceiling? Only reason I suggested 2xdrywall and inches of rockwall in between is because it's a bit tricky to build a brick ceiling horizontally. Specific suggestions or links welcome. I'm not worried about treating inside at this stage, just need to get a budget and design planned for a room that won't let sound in. It's for recording very quiet sounds so noise is a big no-no. What sort of approx budget should I be looking at? I need to factor this into the house purchase price. Not got much cash so will ugly material if I have to. I have been reading thru these forums for many many years. If you have and specific suggestions to read, let me know. Thanks

"]It also makes a three-leaf wall, which is generally not a good idea! Search the forum to find out why. " Already done that. Can you let me know why or give me a specific link to read? "That said, in your case you already have a pretty darn good two-leaf with your brick and block walls, so why do you think you need the third leaf? " Because I need top-notch isolation for recording quiet sounds. "Why bother with all the trouble of "bricks and blocks" for the walls, if you are just going to build a much lower isolation ceiling?" What would you specifically suggest for the ceiling? Thanks "so it needs a damp proof course, heating and electric installed etc. It also needs ventilation! It will be doubly-airtight, hermetically sealed. You will need to get air in and out, and do it without losing too much isolation." As soon as I can find any designed for ventilation that will be the next step. Right now most important thing is to have the soundproof room design sorted. "STC isn't a good system for deciding on drum isolation, since it does not take low frequency sound into consideration, and a lot of energy from a drum kit is of course in the low end. So one wall rated at STC-70 might not do what you want, while another one rated at STC-65 might do the job just fine. It all depends on how well those walls isolate at the bottom end of the spectrum, which STC does not consider." Thanks. What would you suggest? "Yes, but you are proposing a three-leaf building, not a two-leaf building, so the low frequency isolation in your case could end up being WORSE than for those two-leaf buildings." What would you specifically suggest? Please don't tell me to "read forums" because I have already done this, if you have any specific suggestions, or if you don't have the time to make suggestions, then a link that I can read would be great. "Here is your answer: viewtopic.php?f=2&t=8173" Thanks, brilliant. So now I just need to find answers to all the rest. "The entire forum! I'm not trying to be funny. There are numerous other things that you need to consider. I'd suggest that you start by reading through a few of the build threads here, from start to finish, to give you an idea of all those things you need to think about. Also, by Rod's book, and read over that a few times. And get the Master Handbook of Acoustics as well." I have read a LOT of the newbuild threads. I was hoping to get some advice by posting my question. If you have any suggestions or specific links, please do let me know. Thanks so much for your help.

"It also makes a three-leaf wall, which is generally not a good idea! Search the forum to find out why. "

Already done that. Can you let me know why or give me a specific link to read?

Well, on this forum, there are literally dozens of explanations for three-leaf walls and why they are so bad for isolating sound. I know they are there, since I wrote many of them myself, and I've read many that others have written too. You really should be able to find them with the "search" feature at the top of this page. Look for things like "MSM" and "three-leaf".

"That said, in your case you already have a pretty darn good two-leaf with your brick and block walls, so why do you think you need the third leaf? "

Because I need top-notch isolation for recording quiet sounds.

In that case, a three-leaf wall would be a BAD idea, since it provide LESS isolation that a two-leaf wall, all other factors being equal. Simple physics. But not intuitive at all. (Practically nothing about acoustics is intuitive).

What would you specifically suggest for the ceiling? Thanks

Build it the same as the walls. Two-leaf, fully decoupled, no mechanical connections at all between leaves, both leaves totally airtight, lots of mass on both leaves, large air gap between, filled with mineral wool or fiberglass. You have to have the same construction all around your room, on all sides. Anything less wont work. Just like you cannot build an aquarium by using glass for the back wall, paper for the front, sponge on each side, and cardboard underneath. It has to be glass all around to work. Same for your studio: it has to have the same level of construction all around. Otherwise it will "leak" sound through the weaker sides, just like the aquarium would leak water.

As soon as I can find any designed for ventilation that will be the next step. Right now most important thing is to have the soundproof room design sorted.

The design of the ventilation system IS part of the soundproofing! Yo cannot do one without the other. It all goes together. To isolate, your room has to be airtight. Hermetic. Sealed. But the ventilation system is obviously a hole through that airtight seal. It has to be designed right, acoustically, or the entire isolation breaks down. A studio isn't a set of individual things that you can add up one by one: it is an entire system, where everything you do affects everything else. HVAC is a big part of it.

Thanks. What would you suggest?

TL (Transmission Loss) gives you a much better picture of how well a give structure isolates, for purposes of studios.

Please don't tell me to "read forums" because I have already done this,

I don't think you have, since I do know that the information you are looking for is all over this forum, in numerous places. And it can be found using the "search" feature. Sorry if that sounds harsh, but this forum is mostly a "self-service" forum, where you help yourself to the vast mountain of material here, and only if you get stuck or don't understand, then by all means ask. The thing is, many of us here have posted the same answers to the same questions dozens of times already, and it gets to be a bit annoying when someone asks the exact same thing yet again, without having looked. But I'm in a good mood right now, so I'll do some of your homework for you! :)

Does anyone know what STC rating I might get with the above?

IR-586 will answer that: http://irc.nrc-cnrc.gc.ca/pubs/ir/ir586/ir586.pdf (Also check out BRN-217, from the same web site. IR-766 and IR-811 might also be helpful.)

What STC rating do I need to achieve this?

The Wyle 1973 report will help you understand that: I cant' find a link right now, but I'll look for it and get back to you.

Will it need foundations or just a flat concrete slab on the floor?

Your contractor or structural engineer will be able to tell you that.

Is there anything else I should consider?

I'd suggest that you buy Rod Gervais's book on building studios. It addresses all of the issues you have mentioned so far, and is easy to understand.

This is going to take far too much of my time. Aren't there any soundproof room builders in the UK who can do it for me?

In reality, the BUILDING part of your project isn't the problem: It is the DESIGN part of it where 90% of the problems are, and no builder can help you with that. If you don't have the time to learn all this yourself, then you need to hire an experienced studio designer to design it for you, not a "soundproof room builder". I'd suggest that you send John Sayers a private message directly, and ask him for a quote on designing your studio. Once you have that in hand, THEN you can look for building contractors, who can actually turn it into realty. The builder has to work from a plan, and John is the guy who can make the plans. - Stuart -