Advice needed on a quick question

Hi there again guys, my construction has been on hold for a week now due to a problem with the bricks that were delivered, i was originally going to use cement bricks but the bricks that were delivered are of a bad qaulity and crumble to pieces easily so i decided to rather go with clay baked bricks. I have now changed my wall structure again due to the fact that i am using a different (smaller but stronger) brick, and the picture you see is of how i plan to construct my studio walls now...... is this still a two leaf wall as in rods book and would this work ok???? i will continue to update this thread with progress of my studio build.

That's a 3-leaf wall ye building. Either lose the airgap and build a more solid (claybrick) wall or lose the wool. With a double builded brickwall there's gonna be good isolation if it's build correct and without leaks. The extra drywall might not be needed, but for esthetics it could. Tho it'll also, again if build correct, stop any leaks from your brickwall. But I wouldn't add'm. Only if necessary (leaks in wall) You could also consider a room-in-room construction (keep the inner (brick) wall for a false ceiling to rest on while it don't touches the exterious wall and concrete roof.

ok thanks for the help, r u sure its not a two leaf though, as far as i know, the pink stuff or rockwool and drywall touching the 2nd brick layer count as one leaf eg: brick, pink stuff, dry wall = 1 leaf the air gap seperates the two leafs? if i build like this, what would be the conseqeunces?

Ro's right - it's a 3 leaf wall. Insulation (pink stuff or rock wool) is considered the same as an air space (per Rod's book) so you have a mass-air-mass-air-mass (brick-air-brick-insulation-drywall) wall.

this whole subject confuses me to death... masonry-insulated cavity-masonry is a standard (and ubiquitous) external wall construction, so what are you supposed to build inside it to provide isolation whilst avoiding triple leaf construction? :?

john h-m wrote:

masonry-insulated cavity-masonry is a standard (and ubiquitous) external wall construction, so what are you supposed to build inside it to provide isolation whilst avoiding triple leaf construction? :?

1. Plaster rendering with lathe right against the inside brick. 2. Find test data to determine if the wall provides sufficient isolation. 3. Accept that it is not the maximum isolation possible with the mass. Andre

if i still decide to build the wall as shown in the picture, what consequences will i have?

You will not have as much isolation at certain bass frequencies as if you would built a two leaf system. Bas frequencies are the most difficult to isolate. How much isolation do you need? Andre

AVare wrote:

john h-m wrote:

masonry-insulated cavity-masonry is a standard (and ubiquitous) external wall construction, so what are you supposed to build inside it to provide isolation whilst avoiding triple leaf construction? :?

1. Plaster rendering with lathe right against the inside brick. 2. Find test data to determine if the wall provides sufficient isolation. 3. Accept that it is not the maximum isolation possible with the mass. Andre

indeed. what i meant was, are all these swanky arrangements of studs, insulation, and green-glued plasterboard all rendered null and void by "traditional domestic construction"? or is the apparent tabu of The Triple Leaf outweighed in the long-run by the benefit gained - albeit not conforming to an ideal - anyway?

hi again Andre, as much isolation as possible, i will be recording mostly rock bands with drums and guitars, i had a look on another website and had an idea, would it benefit me if i filled the air gap between the brick walls with crusher sand?

Preludetojune wrote:

hi again Andre, as much isolation as possible, i will be recording mostly rock bands with drums and guitars, i had a look on another website and had an idea, would it benefit me if i filled the air gap between the brick walls with crusher sand?

We are getting into wall construction designs that I have less knowledge about. My gut guess is yes. Give me some data and I'll do some calculations. What is the mass of bricks per square meter? How thick is the gyproc? How far would the gyproc be from the inner brick wall? Andre

john h-m wrote:

what i meant was, are all these swanky arrangements of studs, insulation, and green-glued plasterboard all rendered null and void by "traditional domestic construction"? or is the apparent tabu of The Triple Leaf outweighed in the long-run by the benefit gained - albeit not conforming to an ideal - anyway?

I do not understand your question. The double brick wall in this thread will beat any but the most dense and thick plasterboard walls. In this part of the world "traditional domestic construction" is plasterboard for inside walls, many facades have vinyl or SIF. I think SIF is right. Styrofoam insulation covered with an acrylic. In this thread I just asked point blank how isolation is required and the answer was "as much as possible." There is no tabu about triple leaf, it just costs considerably more to get the same isolation as with a double leaf. How much do want to spend? You make it sound like a fashion or belief. It is not. It is engineering. Andre

what i have in the drawing is what i will be using for my walls, i just want to get the best isolation i can with what i already have, so filling the air gap between the two brick walls will then make the brick walls a single leaf and the drywalling and pink stuff the 2nd leaf if im not mistaken and thus by adding the sand (mass) i get me better isolation?

what i have in the drawing is what i will be using for my walls, i just want to get the best isolation i can with what i already have, so filling the air gap between the two brick walls will then make the brick walls a single leaf and the drywalling and pink stuff the 2nd leaf if im not mistaken and thus by adding the sand (mass) i get me better isolation and a two leaf wall? Is this a better option as in the pic?

Okay, I understand better now. Can you pour concrete instead? I don't know hat the price of construction materials is in your part of the world. Sand will be a definite improvement. It will also give a constant ouward pressure on the bricks, increasing as the wall gets lower. That is why I am asking about concrete. It solidify and then no longer continously push outward. Andre

YES, pouring Concrete is definately an option, i understand, the pressure from the sand could cause a problem and weaken the walls where as concrete will become solid and no longer put pressure on the walls rather strengthening it, will this however improve isolation substantially and make my wall a two leaf wall?

hahaha, im sure it will also then work well as a bomb shelter for when the pawpaw hits the fan in zimbabwe!!!

Preludetojune wrote:

will this however improve isolation substantially and make my wall a two leaf wall?

Finally, an easy question to answer. YES! Andre

Sorry to keep coming back with this... :oops:

AVare wrote:

I do not understand your question. The double brick wall in this thread will beat any but the most dense and thick plasterboard walls.

Yes, I would have thought so too.

AVare wrote:

In this part of the world "traditional domestic construction" is plasterboard for inside walls, many facades have vinyl or SIF. I think SIF is right. Styrofoam insulation covered with an acrylic.

I am aware that construction methods vary from place to place. I didn't think it was necessary to list them all. :wink:

AVare wrote:

There is no tabu about triple leaf

AVare wrote:

You make it sound like a fashion or belief. It is not. It is engineering.

Do I? "Three- and four-leaf wall systems are evil devious fiends that suck up the money in your wallets and give you less than nothing in return".

AVare wrote:

it just costs considerably more to get the same isolation as with a double leaf.

Well that makes sense. In other words, it works, but less efficiently? I can understand someone being advised not to construct a 3-leaf wall system from scratch, because it's going to cost a lot more in materials/labour to achieve the same reduction as with a 2-leaf system. But what if you already have a 2-leaf system which doesn't perform adequately and needs improvement? Is a 3-leaf system still an evil devious fiend, or, the best you can do under the circumstances? The reason for my questions is that there seems to be a dreadful amount of confusion about what, effectively, constitutes "a leaf". The average UK building is of a cavity wall construction. Technically, that's mass-air-mass. But if the mass elements are dense masonry, is it reasonable to equate their behaviour to sheets of plasterboard on timber studs? I would think not, but it's not a rhetorical question, I would just like to know. Also, many studios are conversions, built within existing buildings. Many of these buildings will be of cavity wall (mass-air-mass) construction. This implies either that constructing a room-within-a-room in such a building is either: (a)"a massive waste of time and money which won't work. why not just plaster the walls? That's mass-air-mass." (b)"more effective than just plastering the walls, but costlier and less effective than it would be in a building of solid masonry construction. But hey, it's the real world, not an ideal, and you're stuck with your cavity walls, so what can you do?" I apologise it that sounds stupid, but, from reading many of the threads here, i suspect i'm not the only person here who might benefit from more clearly emphasised theory.

It is difficult to quote from post because some things are rambling and several times. In no order and an attempt at quotes, which may not be accurate:

Do I? "Three- and four-leaf wall systems are evil devious fiends that suck up the money in your wallets and give you less than nothing in return".

I do not know where the quote is from or the context.

In other words, it works, but less efficiently?

Correct.

But what if you already have a 2-leaf system which doesn't perform adequately and needs improvement?

If it is not done properly, the sound isolation at low frequencies, which are biggest problem in music isolation WILL BE MADE WORSE.

The reason for my questions is that there seems to be a dreadful amount of confusion about what, effectively, constitutes "a leaf."

A nonporous layer that is independent of of other non-porous layers.

But if the mass elements are dense masonry, is it reasonable to equate their behaviour to sheets of plasterboard on timber studs?

The physics remains the same. The amount is obviously different, but the relationships are still governed by the same physical factors and described by the same equations. I hope this helps. Rhetorical and extreme questions are difficult if not impossible to answer. Please keep to clear questions. Andre

OK, so then this would be the most effective solution, and make my walls a 2 leaf wall. will filling the air gap with concrete really improve my isolation drastically than with just leaving the air gap empty? i just want to make 100% sure before i waist money filling the gap with concrete. Thanks for your help.

AVare wrote:

It is difficult to quote from post because some things are rambling and several times.

thanks for the lit crit...

Avare wrote:

The amount is obviously different.

That's my point, really. How different?

AVare wrote:

Rhetorical and extreme questions are difficult if not impossible to answer.

"it's not a rhetorical question" :roll:

AVare wrote:

I do not know where the quote is from or the context.

Home Recording Studio Construction: Build It Like the Pros - Gervais, R.

AVare wrote:

Please keep to clear questions.

Please avoid condescension. Thankyou. :)

Preludetojune wrote:

will filling the air gap with concrete really improve my isolation drastically than with just leaving the air gap empty? i just want to make 100% sure before i waist money filling the gap with concrete.

Yes it will improve your isolation at low frequencies which are most difficult to control. I can say nothing about "drastically" or "waste money" I asked you a clear question a couple of posts ago that was "How much isolation do you need? " and your answer was "i just want to get the best isolation i can." I am working with what you are writing. I asked earlier for data on the materials so I could calculate what the current triple leaf would do. You declined to do that. I in an earlier post you could live with what you building and accept that the isolation will not be as good as it could with the materials you used. It is your choice which way you go with the construction. It is too easy to make mistakes acoustically. Make conscious decisions based on knowledge, not guessing. Andre

I just did some research in NRC IR 586 and with what little information have about details on your construction, I see a potential STC in 80s with the worst TL being around 40 dB @80 Hz. This is nothing to be ashamed about. The limiting factor is flanking transmission through the foundation. If you want the best possible, fill it. If I were you, I would not. Andre

AVare wrote:

I just did some research in NRC IR 586

great link! thanks. 8)