Rehearsal Studios - New Build

[callummccormick]

This question relates to soundproofing. See attached plan.

I have just committed to an old barn at a working farm. Nearest domestic neighbour about 100 yards away and during the day, the unit each side of me has people working / cutting wood etc. I can hear their radios straight through the walls.

I think I know the answer to many of my own questions but I need some encouragement that I'm going down the right path.

Budget is £10,000 to take this barn and make an attractive and "quite" soundproof series of rooms.

I intent to build double-skin concrete block walls, put an inexpensive floor in and a ceiling and additional floor upstairs.

Before I start ordering anything, I need to confirm that I'm not over-cooking the design. For instance, could I get away with a single skin concrete block wall? I would have thought the mechanical strength (not just the soundproofing) might be lacking. Frankly, I am considering putting absolutely no plasterboard or acoustic wool anywhere near the walls in this design - but you're probably going to think I'm mad! Feel free to tell me. Bear in mind that as a rehearsal space, I'm not going to be as fussy over the shape of the space. I will though take your advise and then work on basic sound-conditioning afterwards.

So, I'm kicking off this thread only for the basic wall structure first. I'll deal with the floor, doors, air-pumps, ceiling (and first floor) and sound rudimentary sound-conditioning afterwards please.

Thanks in advance for your time,

Callum (Birmingham, England).

[Soundman2020]

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

I intent to build double-skin concrete block walls,

You already have one wall around the barn. Adding two more would make a three-leaf wall, so you'd have pretty lousy isolation in low frequencies, and you'd be wasting a lot of space, time and money.

Search the forum for "fully decoupled two-leaf MSM isolation" to find out how to do it right.

put an inexpensive floor in and a ceiling and additional floor upstairs.

So you plan to have extremely massive walls (three of them!) around the sides, but just a single flimsy ceiling above? Why? Conflicting signals. Do you want high isolation, or not?

Before I start ordering anything, I need to confirm that I'm not over-cooking the design.

The first thing you should order are these two books: "Master Handbook of Acoustics" by F. Alton Everest , and "Home Recording Studio: Build it Like the Pros", by Rod Gervais. They will teach you the basics of what you need to know in order to design and build a home studio, and especially how to avoid the mistakes you are making at present.

For instance, could I get away with a single skin concrete block wall?

Probably, depending on how you design it. You could probably also get away with a stud-framed wall with sheetrock on one side ("drywall"), depending on how you build it.

I would have thought the mechanical strength (not just the soundproofing) might be lacking.

You should probably also get a book on basic structural engineering, to learn about how structures work in buildings. A properly designed and built concrete wall is way, way, WAY stronger than a timber-framed wall, and even that can be built more than strong enough for a simple home studio.

Frankly, I am considering putting absolutely no plasterboard or acoustic wool anywhere near the walls in this design

It sounds like you are trying to design a room that has extremely terrible isolation, and extremely terrible acoustics, such that nobody would every want to rehearse there. Is that the plan?

but you're probably going to think I'm mad!

Right! Unless you really do want a room with lousy isolation and terrible acoustics...

Bear in mind that as a rehearsal space, I'm not going to be as fussy over the shape of the space.

Shape doesn't matter much for that, but size does, construction does, and acoustic treatment does.

So, I'm kicking off this thread only for the basic wall structure first.

Your entire studio should be built using the principles of fully-decoupled 2-leaf MSM isolation!. It really is that simple.






- Stuart -

[callummccormick]

Thanks so much for your tips. I did read the rules (typical internet junky) however I'm just paranoid about overall sound "leakage" right now. By the way, the frame of the building leaks sound completely, The only thing it's useful for it to keep the wind and rain out.

I'm going down the route of a single 6 inch dense block work wall up to about 3m high then studwork, acoustic wool and plasterboard. The ceiling and floor above will be isolated (!) but the initial issue is this basic shape / wall density.

I will genuinely deal with the sound quality when I have the shape right that fits the building.

I shall order the books you mentioned and keep you posted.

Watch this space. I need this built for the spring.

Callum.

[Soundman2020]

I did read the rules (typical internet junky)

... but you missed the most important one of all! Better take another look...

however I'm just paranoid about overall sound "leakage" right now.

Fair enough, but you need to start by answering one single question: How much isolation do you need, in decibels? That's the single most basic question you need to ask, and answer. That will lead you to the correct construction technique and construction materials that you need in order to get that level of isolation. You won't get there by guessing, which is what you seem to be doing right now.

Acoustics is a science: there are simple equations for figuring these things out. You can't guess, since many, many things in acoustics are not intuitive, nor obvious. For example, who would guess that a wall consisting of three separate leaves would have WORSE isolation than one consisting of only two leaves, with the same total mass and thickness? That makes no sense, intuitively, yet it is absolutely true. A 3-leaf wall will ALWAYS have worse isolation than the equivalent 2-leaf wall, all other factors being equal. Not guessable. Not intuitive. But predicted by the equations, and demonstrated to be true in numerous laboratory tests and real-world studios.

By the way, the frame of the building leaks sound completely, The only thing it's useful for it to keep the wind and rain out.

Then you already have a problem that will prevent you from building a properly isolated studio at low cost, without taking up excessive space. The very first order of business is to either seal that existing leaf such that it it is air-tight and has consistent mass (surface density) all around, or to "bite the bullet" so to speak and build a new leaf just inside that one, that is sealed properly and has consistent mass on it. Then build the three final inner-leaf rooms independently (not jointly, as you show in your diagram) within that shell. Yes, that would be a 3-leaf system, so you would have to take the necessary precautions to compensate for the 3-leaf effect: Yo would need to tune your new walls to a low enough frequency that the 3-leaf issue would not be a problem any more.

I'm going down the route of a single 6 inch dense block work wall up to about 3m high then studwork, acoustic wool and plasterboard.

Why have you made that decision already when you do not even know how much isolation you need, or what frequencies you need it at? Once again, you are guessing at answer without yet having the question clear. Your question should be "What is the least expensive type of construction that will give me ZZ decibels of isolation between my rooms, and YY decibels of isolation to the outside world, down to XX frequency?" What you are proposing won't do a very good job for any of that...

The ceiling and floor above will be isolated (!)

How do you plan to isolate the floors? You don't need to do that to start with, and you don't have enough budget to do it correctly either.

You might want to read this thread:

http://www.johnlsayers.com/phpBB2/viewt ... f=2&t=8173

but the initial issue is this basic shape / wall density.

Basic shape is simple. These are the requirements

A) 1.1 W / H ≤ L / H ≤ 4.5 W / H – 4
B) L / H < 3
C) W / H < 3
D) No dimension with 10% of any other dimension.

If your rooms do not meet all four criteria, then they will not be acoustically usable.

I will genuinely deal with the sound quality when I have the shape right that fits the building

That will not work: Sound quality DEPENDS on the shape ans size of the rooms!!! If you don't start out with good shapes and sizes, then you will NEVER be able to get good acoustics inside the rooms, no matter how you treat it. Acoustics is governed by the laws of physics, and there are limitations imposed by those laws. You cannot get around them by hoping or guessing.

For example, the amount of isolation you can get from a single-leaf wall is limited by an equation know as "Mass Law". It is impossible to get more isolation than that from a single leaf, no matter what materials you use to make the wall, or how you build them, or how thick you make it. But that's the absolute limit: you wont actually achieve that in real rooms, because there are always other factors that reduce isolation in one way or another.

Another example is room volume: the smaller a room is, the worse the acoustics will be, due to modal support, travel distance, Schroeder frequency, critical distance, etc.

There are many factors that can make or break a room, most of them are not obvious, intuitive, or even visible at first glance.

In other words, you CANNOT first decide on the size/shape of your rooms without considering the acoustic consequences, and in turn the shape and size will depend on the amount of isolation you need, which also affects the acoustics.

Watch this space. I need this built for the spring.

I'm looking forward to it!


- Stuart -

[callummccormick]

Thank goodness you're sticking with me Stuart

OK, I've changed my plan completely, two large rooms almost identical. I also used this: http://www.bobgolds.com/Mode/RoomModes.htm

I can't change or do anything to the outside walls. They are 80mm foam based agricultural sheets. You can hear someone talking on the other side of the wall and the room is not "sealed" as you would describe at all. For instance, there's air gaps where steel goes through the roof etc, however it's dry and wind proof. I really consider that the three-leaf issue won't be an issue.

Stuart, I now finally realise that building a recording studio is a science but in light of the fact that this is for rehearsal only and that I'm in a pretty remote place, all I need do is dampen the noise down, trading effectiveness -vs- cost and I'm coming to the conclusion that a block concrete cavity walls with a ceiling connected to the inner wall and the floor above connected to the outer walls will give me an airtight seal between the leafs. I will add some material between the two walls / ceiling / 1st floor etc. No idea what on earth I'll do with the floor. Probably pretty basic.

I think the real issue is that since I read your first post on Sunday morning, I have been reading much data on design but because I have such a busy life, I might have to make some mistakes to get this thing off the ground. You'll just have to watch and laugh at me! The good news is that I've tracked down a 35 years experience recording engineer with good engineering and construction skills who seems to know this topic pretty well. Hopefully you won't need to laugh that much

Just scanning your post now (which I genuinely value BTW!) :

.. you are guessing at answer without yet having the question clear

I know fella. Obviously you have a very clear idea based on experience about how to do these things. I wish that common sense worked. Clearly it doesn't. I have a teeny rehearsal studio at home (3.6 x 4.5 x 2.4). Playing live with a 2k rig, my wife can still watch TV on the other side of the wall and the sound isn't too bad inside the room either. Apparently it should sound awful All I need to do is reduce this by another x db (and I don't know what x should even be bearing in mind the neighbour about 120 yards away).

The floor is a heavy concrete pad.

I believe my dimensions aren't perfect but it's what I have: The two rooms will now be 6.7 x 4.3 x 2.44 (I could go higher with the ceiling, perhaps to 3m height).

So.. Bottom line is that rightly or wrongly, I'm going to start a materials bill to include for starters a cavity layer of 4 inch dense concrete block filled with something (to be determined) and dab some heavy plasterboard on the insides. Both you and my "man" will assuredly tell me I'm crackers - however I might want to build up sooner rather than later and this will give me a good base to work up from (and my "bricky" is cheap) if I get him to do this part over Christmas.

Oh, I will need to tie one cavity wall to the other. I've read up on cavity wall acoustic ties. Do you know of these?

PS. Read the forum rules on Sunday again. I'm non the wiser. Must be my "condition"!

PPS. I all my tools in next weekend!

Callum.

[Soundman2020]

You really should take another look at the forum rules. The one written in big blue letters, especially. About half way down the page, or a bit before. It's hard to miss...

- Stuart -