Brick walls

Hi, I am trying to find some posts regarding the use of brick walls instead of drywall. Can someone point me to some thread(s) regarding this topic? Things I would like to know: - Construction of inner vs. outer walls - Wall thickness - Still framing needed for in-room acoustics (absorption)? The reason I ask is this. It looks like I will be building a completely new (little) building in my backyard to house my home studio. Local regulations demand that I build in a classical Flemish way, which means that the construction at least looks like this (from the outside inwards): - Outer brick wall (red clay bricks): 0.10m thick - Insulation gap (air + insulation): 0.10m thick - Inner brick wall (concrete or cement bricks): 0.15 to 0.20m thick Normally, all inner walls are then built using cement or concrete bricks. However, I would like to know what method will give me the best insulation... Anyway, it would be great to know what to consider when starting the drawing of my plan... Many thanks. Bert

Hai Bert, As you might know, by reading the stickies in this forumthread, the magic word is M-A-M. Don't trust the Bundies in this case ;) MAM stands for Mass, Air, Mass. Same principle as the construction type you just described. You claystone walls will be the MASS. And what a whopping mass it is too, it beats drywall. The density of a red clay brick is about twice the density of drywall (1400 kg/m3 vs 800 kg/m3). For example. A GB wall of 30mm (2 sheets of 15mm) has a total density of about 24kg/m2. A redbrick wall of 100mm has a total density of....drumroll please.... 140kg/m2. That's a ratio of about 1:6 (!) Now, make sure you plaster the brickwall (inside and outside), have insulation between (?) , make it airtight and all you have to do is adjust acoustics. Isolation will be great (providing your doors and windows will be equally threatened) now.. how 'bout the floor and roof?

Hi Ro, Thanks for the reply. Yes I do know about the M-A-M principle, and I do realize that a brickwall is way better. However, it is also taking a lot more space, so I am trying to figure out the best possible construction that will give me the most internal space. At the moment, the only real figures I have are the outer dimensions of the building (10mx6m). (Maybe I should try to post some graphics to show my problems, I'll work on that...) Now, about the internal acoustics. I was wondering if I still will need some framing to cater for the absorption and stuff. Or will hanging the slot absorbers etc. directly to the wall suffice? Thanks for your help again. Bert

Don't need no framing. You can hang panels/clouds etc directly on the wall/ceiling. Basstraps flush against the corners and all that. Further more, 100mm wall x 2 + 100mm air (4 inch) will do fine and only takes 300mm (30cm) of space. A frame with GB will take the same amount of space (imagen 8cm frame + 2x12mm sheets of GB... total 105mm. .) A frame, however, makes a bigger "air" gap between walls. But can't compete with the brick wall. so, yeah there's options. A brick/air/GB construction still isolates very good tho!

Ro wrote:

Hai Bert, As you might know, by reading the stickies in this forumthread, the magic word is M-A-M. Don't trust the Bundies in this case ;) MAM stands for Mass, Air, Mass. Same principle as the construction type you just described. You claystone walls will be the MASS. And what a whopping mass it is too, it beats drywall. The density of a red clay brick is about twice the density of drywall (1400 kg/m3 vs 800 kg/m3). For example. A GB wall of 30mm (2 sheets of 15mm) has a total density of about 24kg/m2. A redbrick wall of 100mm has a total density of....drumroll please.... 140kg/m2. That's a ratio of about 1:6 (!) Now, make sure you plaster the brickwall (inside and outside), have insulation between (?) , make it airtight and all you have to do is adjust acoustics. Isolation will be great (providing your doors and windows will be equally threatened) now.. how 'bout the floor and roof?

Ro, Actually I don't believe that to be the case. I will wait for the poster to comfirm just to be sure - but typically when you construct a double wythe brick building - in order for it to be structurally sound - the 2 brick walls must have a bonding course that joins them - as well as bonding bricks that tie wall faces together within the body of the wall. If that is the case - then I believe this is going to be a single leaf regardless of the air space within the cavity. Bert, could you confirm the construction methods? Rod

Hi Rod, Yes, your description of the construction method is more or less correct. There is indeed a connection between the inner and outer walls, made with some kind of anchors. I'm not sure about the bricks, though. However, I am also inclined to see this construction as a single leaf to the 'outside world'. So both the control room and recording area will need their own wall for best isolation. This will probably be done using 10cm bricks, too. Anyway, thanks for all the information. I have already a much better idea on how to continue (IF I may continue, because it looks like local authorities, called 'stedenbouw', won't grant me the much needed permission to go on...). I'll definitely come back here when I know more... Grtz, Bert

Berre wrote:

. . . it looks like local authorities, called 'stedenbouw', won't grant me the much needed permission to go on...

Ouch. :( What's the problem? --Keith :mrgreen:

Berre wrote:

However, I am also inclined to see this construction as a single leaf to the 'outside world'. So both the control room and recording area will need their own wall for best isolation. This will probably be done using 10cm bricks, too.

Bert, As I mentioned - you cannot build a structurally sound wall that high using a single course of 10cm bricks........ although the bricks will not fail based on compressive strengh - they will fail under bending strength - if it's 10 cm brick - then it will require 2 courses - otherwise use a 20.32 cm block to make it work with one thickness of materials. Sincerely, Rod

Hi Rod. Yes a friend of mine, who's an architect, also already mentioned something like that... Thanks for the suggestion. Hi Keith, Well, reading through the local regulations documents (and there are a lot of them, I don't have to tell you about that, eh) made me think that the outer dimensions will be too big... way too big. I want 60m² (10mx6m) while the max. allowed surface would be more something in the line of 11m². So that would be quite insufficient. :( But I am still waiting for the answer on my request through 'unofficial channels', meaning that I just drew some rough sketches and gave them to a friend of a colleague who knows someone at... you get the picture. Let's hope I get any answer at all, but who doesn't take the chance... Grtz, Bert

Well, good luck, Berre. I sincerely hope you can come up with a design that your needs that you'll be premitted to build. --Keith :mrgreen:

Just a comment. Do NOT compare M.A.M. of even a good decoupled brick wall with the M.A.M calculations for gypsum board walls or a brick wall with a resilient skin gypsum board wall in front. The comparison of the mass of an additional brick wall inside versus an gypsumboard solution does not apply. The M.A.M of a double brick wall can be significant higher (to > factor 3) than based on the traditional known M.A.M. calculations. And you will find this phenomenon hardly anywhere described. Eric

Eric, As always, thank you my friend for keeping us informed. Sincerely, Rod

Eric_Desart wrote:

Just a comment. Do NOT compare M.A.M. of even a good decoupled brick wall with the M.A.M calculations for gypsum board walls or a brick wall with a resilient skin gypsum board wall in front. The comparison of the mass of an additional brick wall inside versus an gypsumboard solution does not apply. The M.A.M of a double brick wall can be significant higher (to > factor 3) than based on the traditional known M.A.M. calculations. And you will find this phenomenon hardly anywhere described. Eric

Yes, you can't compare peers and apples of course. But Eric, you mean there are hardly any specs/test etc on brick walls for sound applications? In general, mass is master. So brick vs GB will be superior indeed.

Ro wrote:

As you might know, by reading the stickies in this forumthread, the magic word is M-A-M. Don't trust the Bundies in this case ;) MAM stands for Mass, Air, Mass. Same principle as the construction type you just described. You claystone walls will be the MASS. And what a whopping mass it is too, it beats drywall. The density of a red clay brick is about twice the density of drywall (1400 kg/m3 vs 800 kg/m3). For example. A GB wall of 30mm (2 sheets of 15mm) has a total density of about 24kg/m2. A redbrick wall of 100mm has a total density of....drumroll please.... 140kg/m2. That's a ratio of about 1:6 (!)

Ro wrote:

Yes, you can't compare peers and apples of course.

???????????? Thanks Rod for your gentle reply.

:roll: ?????? Eric, you talk about "M-A-M" calculations, what exactly do you mean with that? STR [edit: I mean STC] test etc? (that's what I was referring to with the fruit comment) If MASS is the general key factor, then saying BRICK beats GB might sound valid, not? (I say GENERAL key, not accounting other factors)

Ro wrote:

:roll: ?????? Eric, you talk about "M-A-M" calculations, what exactly do you mean with that? STR test etc? (that's what I was referring to with the fruit comment) If MASS is the general key factor, then saying BRICK beats GB might sound valid, not? (I say GENERAL key, not accounting other factors)

Ro, I don't feel like answering any single question of you anymore. I'm one single person. Hence the only reason I intervened here is because it's in the interest of others. You spoke about MAM and called it mass-air-mass. Hence I logically assumed you knew what you were talking about. MAM can be calculated, that's how prediction models in function of TL are build up. The formulas to calculate MAM are in the NRC/IRC documents and possibly/likely on Green Glues site (and elsewhere). Hence if I speak about MAM I speak about exactly the same thing as you did. You compare the insulation of a double leaf system comparing GB and brick mainly on their mass. And I told that the traditional MAM calculations do NOT apply here, hence several factors in a double leaf system will limit/influence this comparison. The MAM calculated based on mass and cavity width as traditionally found for double leaf GB systems does not apply, which means indeed that this increased mass of brick will not show as possibly could be expected versus GB. That Paul Woodlock's studio was build with 6 to 7 layers of GB was a wittingly choice to limit mass (function of floating floor needing to carry that mass) while still maintaining high TL. I just wanted to put this in context without giving an in-depth explanation. A few points: With GB you insulate BELOW the critical frequency or coincidence area. This means that one has a radiation degree lower than 1. This means that not all vibration of the GB is transformed again in airborne sound at the receiving side. That makes such flexible walls so efficient. The Dutch language has a specific acoustic notion for this which I never could find an English alternative for: "Buigslappe wand" With heavy brick walls you insulate ABOVE this coincidence area where a radiation degree applies from 1, meaning that every single bit of vibration is transformed again into airborne sound at the other side. The Dutch language also here has a specific acoustic notion for this not found in English: "Buigstijve wand" That's quite a different behavior. I can measure the TL values of a heavy brick wall via vibration measurements on that wall, since I can recalculate this vibration in intensity and sound radiation. With GB I can not use this technique. This difference has also effect on the MAM. If you use the standard MAM formulas for GB and apply them on double leaf brick walls the calculated MAM will be a factor 3 to 4 too low, meaning that's a significant drawback related to the brick wall. If this coincidence frequency of less heavy brick walls (thinner or lower density material as cellular concrete and so on) comes in the 100 to 500 Hz range such combinations can show relative poor insulation. It's neither one nor the other anymore. This area is limited by what is called the isolation plateau, which is in fact a flattened version from the coincidence dip shifted downwards into an important audio TL range. Hence mass is one factor. I've been involved in investigating a huge pop-concert hall (after the facts): - Walls coupled with as little as possible special resilient ankers. Wall (can't remember exactly without checking) 10 to 12 m high. One side building (appartments) 30 cm brick. New decoupled wall 200 mm concrete at a cavity of 100 mm. Perfect decoupled roof in concert hall with very high mass (very thick steel-plates were additionally mounted) Level in concert hall: +/- 105 to 110 dB(A) (but high low frequent content) Level at some neighbors around 57 dB(A). (At some over 60, some lower). There is more to acoustics than just comparing mass. But you can safely repeat that again. Nobody will dispute that a heavy brick wall is better than 2 GB layers. With my original post I just wanted to put something in context, which Rod did notice and understood.

Okay, thanx for clearing that up Eric. In my original post I should write only MASS instead of MAM. Cuz that's exactly what I was talking about, so my mistake. I know about the stiffness of materials. Hence I wrote "not accounting other factors". But your post just made it more clear that MASS isn't "holy" on it's own. Right? Excuse me for choosing the wrong words and incomplete knowledge, I'm learning everyday a bit more ;) I'm sure others do appreciate your time and effort as well.

Hi everybody, I am SOOO excited! :D I just came back from the local building authorities' office. We had a very nice talk about the possibilities of building my own studio in my backyard and it seems that the sky has cleared up big time. It looks that my plans for my (smallish) studio (60m2 in total) will probably be accepted! A big WOOHOO is appropriate here, I think :D Even better, I can change a lot to the 'outer shell' so that it can be built a lot cheaper (no need for traditional double leaf brick wall), and resulting in some more space inside (including height up to 3m)! So it looks I will be nagging you all with a lot of questions the coming months! (I'll probably drop by regularly at the studiotips forum as well.) Now, first I'll start with finishing the tremendously interesting diary of Paul W's bomb shelter building project at Studiotips' (I am about half way)... And then I'll have a nice talk to the money supplier (bank)... And then... (lot's of work coming up, hehe)! Cya...

congrats man! Keep us posted on progress, and ofcourse any questions you have. There's always some keen guy eager to answer whatever Q.