mineral wool floating floor construction and MSM calculation

Nikodemos · Post by **Nikodemos** » Sat Sep 01, 2007 3:56 am

well when i said "rests on the floor" i meant the construction you described.

about the floor, i maybe don'y know how to describe it....i mean a wooden parqeut finish...i know that there are some that are aplied directly on the slab with adhesive or panels attached to each other and some nailed on wood joists (at least that's what happens here...)....i didn't mean building a floating wooden deck on top of a floating concrete floor.....or at least i didn't want to say so

anyway, thanks once again for your advises and guidelines....you're really helpfull.

Nikodemos

rod gervais · Post by **rod gervais** » Sat Sep 01, 2007 5:06 am

Nikodemos,

OK - that makes more sense - I have no problem with the installation of a wood (parquet or not) floor over the concrete -

I don't even suppose i would with wod slats as long as the vavity was completely filled with rockwool to the point that it completly damped the wood

I would not want (and this has nothing to do with 3 leaf BTW) the wood to be able to vibrate freely......

Rod

Nikodemos · Post by **Nikodemos** » Sat Sep 01, 2007 8:11 am

in order to make this thread more spicey and colourfull i uploaded some pics of my space

as i said this is a concrete basement 2/3 underground with 3,50m height and with an area of about 220m2. I have "drawn" some shape lines on the floor

Nikodemos

Eric_Desart · Post by **Eric_Desart** » Sat Sep 01, 2007 9:54 am

Nikodemos wrote:in order to make this thread more spicey and colourfull i uploaded some pics of my space
as i said this is a concrete basement 2/3 underground with 3,50m height and with an area of about 220m2. I have "drawn" some shape lines on the floor

Nikodemos

That's not making the thread spicey, that's making people jealous. (or are that synonyms?)

Nikodemos · Post by **Nikodemos** » Sun Sep 02, 2007 7:56 am

well, actually i must admit i used photoshop to remove the flloded water, rats,snakes and the other usual habitants of this "hole"

.....but i think the space has potentials

still researching on the floor options.....
i hope it's ok to keep this thread as my "construction" thread

and a couple of my usual questions

How "wrong" it would be to lift the walls all the way to the existing ceiling, as in Everest's books, using some kind of anti vibration mounts-pads ot reduce the transmission of vibrations to the concrete ceiling? I ask because this would allow me to use as much height as possible.

I would like to have pipes under the floating floors for audio wiring between rooms.....if i build the walls on the existing slab and not on the floating floor then i'll have to open holes in these walls in order to pass the pipes through.....how bad that would be?

thanks
Nikodemos

rod gervais · Post by **rod gervais** » Sun Sep 02, 2007 8:38 am

Nikodemos wrote:How "wrong" it would be to lift the walls all the way to the existing ceiling, as in Everest's books, using some kind of anti vibration mounts-pads ot reduce the transmission of vibrations to the concrete ceiling? I ask because this would allow me to use as much height as possible.

It would be exactly the same height available with the ceiling joist resting on the walls or supported completely by the ceiling - one is not driving the other - if your walls are framed perpendicular to the existingf beams/jiosts - then there would be no problem adjusting your wall heights to follow the contour of the existing ceiling.

I will provide you with a details for a sidewall brace that you can use instead of the baces at the ceiling - and you still maintain maximum isolation from the existing structure.....

I would like to have pipes under the floating floors for audio wiring between rooms.....if i build the walls on the existing slab and not on the floating floor then i'll have to open holes in these walls in order to pass the pipes through.....how bad that would be?

It wouldn't be a big deal - just be as neat as you can - after all - you're going to also penetrate the deck itself - and that's the point of your greatest isolation.............

what you have to do is "just do and don't worry about it" - but when you have a choice always opt for maximum isolation.

In the case of the floating slab - I can tell you that you will not succeed with fiberglass (or mineral wool) and the walls sitting on the slab - so forget that approach completely because it doesn't work at all.......... see how simple that is?

Rod

Nikodemos[/quote]

Nikodemos · Post by **Nikodemos** » Mon Sep 03, 2007 12:53 am

understood Rod

to Rod, Eric (and everyone else interested of course)
new question

as i plan things the control room and tha practice room will be positioned next to each other "physicaly" separated by these huge concrete supporting beams walls shown in the first pic above. I'm planning to fill the space between the 2 beams with sand filled concrete blocks to create a contineous 25cm thick wall....now the question; building the inner cells of the rooms will create a 3 leaf system right?
How would this 3 leaf perform(TL) compared to the normall 2 leaf system of my design? I mean compared to the "all drywall" 2 leafs between the rooms and not the outter concrete drywall 2 leaf.....would it be the same, worst or better due to the huge difference in mass and stifness of the concrete wall....i mean if it's worst well it is just something that i have to live with...but if it would be better then maybe i should concider building the same way around the whole practice room since this is going to be the loudest room and my main sound isolation concern...
i've attached horizontal plans of the 2 and 3 leaf systems i'm talking about

thanks

Nikodemos

Nikodemos · Post by **Nikodemos** » Wed Sep 05, 2007 6:23 am

i guess this was out of topic

Post by **John Sayers** » Wed Sep 05, 2007 7:57 am

I'm planning to fill the space between the 2 beams with sand filled concrete blocks to create a contineous 25cm thick wall....

why??

cheers
john

rod gervais · Post by **rod gervais** » Wed Sep 05, 2007 9:03 am

John Sayers wrote:
I'm planning to fill the space between the 2 beams with sand filled concrete blocks to create a contineous 25cm thick wall....
why??

cheers
john

I have the same response.........

why??

Rod

Nikodemos · Post by **Nikodemos** » Wed Sep 05, 2007 4:34 pm

ooooops!!! seems like my plan is a major stupidity

....or i described it completely wrong(i hope so

)
So let me try again...and please remember that i am a tottal crap in these things......show mercy

if you see at my floor plan you'll notice that the control room and the practice(rehearsal) room are placed side to side separated in the original structure by a concrete wall. This concrete wall doesn't go all the way between the rooms....i mean its lenght is 3,50m and the lenght of the rooms is 6,20m. I thought it would be better to have the same wall structure all the way between these 2 rooms....I mean the concrete wall is there and it can't be moved, so a triple leaf wall is going to exist even at the half of the wall lenght...or this wouldn't be a 3 leaf

? So that's why i thought it would be better if the concrete wall was as long as the rooms.....i've attached a pic showing the part i was planning to build with concrete blocks......i hope that this is not stupid and nonsense because it seems quite logical to me

I hope that i just made a terible explanation on my previous post

Anyway i still wonder if the 3 leaf system i described on my previous post would "beat" the the 2 leaf one.....i mean in all the "3 leaf vs 2 leaf" topics and info i've found on the net there was a comparison between the same amounts of mass in the 2 walls....i mean i underestand that if, ypothetically speaking, i could split the mass of the concrete wall and distribute it on the outter leafs, this new 2 leaf system would easily overcome the 3 leaf, right?......

Thanks for all your help and comprehencion......
Nikodemos

Eric_Desart · Post by **Eric_Desart** » Sat Sep 08, 2007 12:47 am

Nikodemus,

This is a difficult question.

John and Rod indeed correctly responded without seeing your additional explanation where you ask: do I need to respect some acoustic symmetry in my construction to close that door opening and the surrounding walls.

My calculation models aren't adjusted to compare this exactly.
Still I try based on calculations and some additional guessing.

Your drywall:
37.5 mm GB = 28.5 kg/m2
300 mm cavity with wool
40.5 mm GB + lead = 71.7 kg/m2

Your MSM here is around 25.8 Hz

Your one heavy wall is with the GB 27.6 Hz
Your one heavy wall is with the GB + lead 18 Hz
This results as a tripple leaf around 29 Hz (rough guestimated, don't have my model here).

But your mass of the wall is greater which compensates.

I estimate the heavy wall combination around 11 - 14 dB better than the drywall.
However you should lower your drywall MSM to ca 18 Hz if you should add the thickness of the wall to the cavity of the drywall (meaning your drywall runs flat over the opening of that door, keeping it completely in line with the surrounding area with a cavity then of ca 200 + 220 + 200 mm = ca 620 mm).
I roughly estimate this will gain you 7 to 8 dB back.

This is all plain theory, not taking whatever side effects into account.
And I didn't made an in-depth study. (should need to make a model to do this).

This is also based on the normal spectral energy content I use for studios (a lot of lows).
At 25 to 35 Hz (less energy) you heavy wall will not be better, certainly not if you increase cavity of the plain drywall combination.

You do not really need to add more wool in that cavity when you should increase that (no complete filling needed).

Nikodemos · Post by **Nikodemos** » Sat Sep 08, 2007 1:30 am

thank you very much.....i really apreciate it

Nikodemos

Nikodemos · Post by **Nikodemos** » Mon Sep 10, 2007 8:54 pm

well we just finished repairing the outter concrete cell (waterproofing, closing some windows etc) and the place looks quite better

I decided to build the separating wall between the 2 rooms....i was thinking that since the TL on the very low frequencies would be pretty much the same getting the highest TL possible above 200 - 300Hz should be the goal. On the other hand i'll use the "double-drywall-with-huge-gavity" on the walls separating the practice room from the main recording room......and then when the studio is finished i'll test them both and let you know the "in place" test results

.....

On the floating floor:
I'm still trying to figure the cost/m2 for the Vibro pads to see if it would fit my budget.....I'm thinking to use the pads for the most critical(regarding TL) rooms and go for the mineral wool in the others

Nikodemos

rod gervais · Post by **rod gervais** » Mon Sep 10, 2007 11:01 pm

Nikodemos wrote: On the floating floor:
I'm still trying to figure the cost/m2 for the Vibro pads to see if it would fit my budget.....I'm thinking to use the pads for the most critical(regarding TL) rooms and go for the mineral wool in the others

Nikodemos,

So then you think that just some of them you do with concrete?

Rod