Rehearsal+Recording space

I don't understand what you are trying to accomplish like that. The pads for the individual rooms are not decoupled from the main slab, so why go to all that trouble? I can't see the extra mass making a worthwhile amount of difference. Can you explain the theory behind that design? What is each layer in there supposed to accomplish? - Stuart -

Sorry guys, I think I couldn't make myself clear. Apparently it looked like that "I wanted to build four separate rooms in that space". Actually, all of that space belongs to only one big live room. Since the mat foundation will be coupled to existing walls and ceiling thru steel pillars and joists I need to decouple main slab and put the new walls on it. So I came up with the "compacted earth" idea to break direct contact of main slab and foundation. Does it work that way? Thank you.

I don't think compacted earth is going to act like a spring very well! It might damp things a fraction (debatable!), perhaps, but I don't see it being able to float your floor. If you are going to all that expense and trouble of "almost" floating it, then why not do it right? Get yourself some proper isolation springs of the right characteristics, do the math, and float it properly. Like this: viewtopic.php?f=2&t=8173 http://www.nrc-cnrc.gc.ca/obj/irc/doc/p ... /ir802.pdf But do you really need to do that? I don't recall your numbers, but what is your isolation goal here? How many db TL are you aiming for? - Stuart -

Soundman2020 wrote:

But do you really need to do that? I don't recall your numbers, but what is your isolation goal here? How many db TL are you aiming for?

My loudness estimate is around 115-120 dB average and aiming for 30 dB outside, which requires 85-90 dB TL. We want to be flexible about the working hours. The less perceptible noise outside=later working hours. This document states that my current walls have around 52 dB STC rating. I'm planning to use 18.5cm (700kg/m³) hollow clay bricks with 3cm plaster for inner walls. (A Knauf document states 41 dB Rw rating for 17.5cm (800kg/m³) hollow clay brick with 2cm plaster). I can also have the bricks sand filled if it helps. Below is a revised section. Thank you.

My loudness estimate is around 115-120 dB average and aiming for 30 dB outside, which requires 85-90 dB TL

:shock: WOW! That's a pretty serious goal! Not too many studios need that kind of isolation, but if you really do need it, then floating your floor probably is the only way to go. I can't see you getting 90 dB of isolation without it. We are talking SERIOUS isolation! And SERIOUS budget! Maybe you should look into those two links that I posted for you, on how to do it right. You are going to need jack-up spring isolators and some very careful calculations to get that right. This is what we are talking about here: http://pdf.directindustry.com/pdf/farra ... 01-_5.html http://www.mason-uk.co.uk/pages/fs.pdf http://www.kineticsnoise.com/arch/lsm.aspx Take a close look at this: It is not easy, and not cheap to do. You might want to consider getting professional advise on this. Another big issue is going to be doors and windows that can get you 90 dB of isolation. That's a pretty hard thing to do! Have you looked into that yet? You are talking about a pair of hugely massive doors, with multiple seals, to get that kind of level. Isolating your HVAC system is also going to be a major issue. But anyway, if you are serious about needing 90 db ( :shock: :shock:) , then floating your floor is undoubtedly the way to go. - Stuart -

As a matter of physics, not only is your multiple vapor barrier in the wrong spot, it is too many as well. One barrier does one thing. If you have 2 barriers, they still do the same one thing, but now they are doing it together in a reverse fashion. Basically, the top barrier is attempting to slow the path of "warm to the cold side"(which is the direction that vapor moves) and the bottom one is attempting the same thing. But air/vapor does not exist that does not have some level of moisture. So your double barrier is working like this. The top barrier is going to trap moisture on the top side. Then the bottom barrier is going to trap moisture on the bottom side. And both will trap moisture as a unit, from the bottom side of the top barrier to the top side of the bottom barrier, respectively. Just for the record, it does not matter who told you do it like this or how much you are paying them to tell you this or where in the world you live, it does not change the form or function of a potential multiple vapor barrier as part of a monolithic slab.

Soundman2020 wrote:

:shock: WOW! That's a pretty serious goal! Not too many studios need that kind of isolation, but if you really do need it, then floating your floor probably is the only way to go. I can't see you getting 90 dB of isolation without it. We are talking SERIOUS isolation! And SERIOUS budget! ...It is not easy, and not cheap to do. You might want to consider getting professional advise on this. ...But anyway, if you are serious about needing 90 db ( :shock: :shock:) , then floating your floor is undoubtedly the way to go.

Time to reconsider the goals. The wise thing to do is to measure loudness (after final cellulose spray layer application) and be realistic about the levels. We're short of time and budget actually, though I'll try to see if I can find a proper applicator for slab springs. Btw, I still need to think about a less ideal alternative, so please check out my "almost floating" section below.

xSpace wrote:

Just for the record, it does not matter who told you do it like this or how much you are paying them to tell you this or where in the world you live, it does not change the form or function of a potential multiple vapor barrier as part of a monolithic slab.

Thank you for the warning. I trashed the second barrier. ---- Stuart and Brien, thank you for your valuable inputs. It's helping a lot!

Btw, I still need to think about a less ideal alternative, so please check out my "almost floating" section below.

You can probably replace the compacted earth with some for of insulation, but how to do that is a bit out of my depth. You might find some info on that in the links I gave you, or maybe someone else has more info. I do recall reading about people who do that, but I'm not sure what the procedure is, or what type of material you need. Brien might know... ? - Stuart -

Looking forward to hear about it. (Btw. crushed rock layer should continue along main slab on above pic. I missed it.)

Hi, It looks like I won't be able to easily get away with my walls being coupled to mat foundation. Here are three alternatives for slab pouring. Which one is better? (Or some other better workaround?) (1st pic shows the mat foundation poured. 2nd one is 5cm crushed rock fill inside) Thank you.

Here are the latest steps of mat foundation and the slab pouring. Part 2 and the explanations are on the next reply.

Here are revised sections of wall and slab applications according to "If you can't float it properly, don't bother and pour it properly" motto. A few questions: - I would prefer laying my inner walls on top of the slab but because the mat foundation must to be poured anyway, nudging walls will cost space. What do you think? Is doing it the way I pictured below going to kill my isolation? - Is 13.5cm air gap sufficient? - There will be three booths with folding doors. Is it better to separate and create 3 slabs for booths or leave it as it is? * I'm borrowing the "plastic sheet over rock wool" idea from this thread. It will prevent rw particles falling off and filling the space eventually. * Support board between mat foundation and slab is going to be removed. Thank you.

Mat foundation rebars.

New photos after base foundation pour and support woods.

We want to hang the (400~500 watt) PA speakers from (inner leaf) ceiling . Does it help with low-frequencies if I put up another layer of brick right behind the speaker? That wall is the only one which is adjacent to a residential building.

Maybe build some stands instead? You can fill them with insulation and wrap with cloth to add some absorption and they won't be couple to your isolation structure or swinging.

Here are the updates and the PA cabin sketch. PA cabin Mat foundation supports Foundation pouring Waiting for water to fill... Time to work Pouring finished Supports removed Stucco 2cm foam arrives. For decoupling the slab. Slab pour steps