MASS-AIR-MASS Question

Julián Fernández · Post by **Julián Fernández** » Mon Apr 18, 2005 6:50 pm

Hi guys! I have a question about the AIR between my 2 layers...

HOLLOW BRICK WALL (Rendered on both sides)

AIR (10 cm)

WOOD FRAME (filled with fiberglass)+2 layer of gypsum...

Can i achieve better insolation if I fill the air space between my two layers with 13 kg/m3 wool? Or should I leave the air space empty?
I can buy that stuff for a low price, but i don´t know if it can help me...

AVare · Post by **AVare** » Tue Apr 19, 2005 12:29 am

Fill it. The insulation will increase the TL and reduce the mam resonace frequency.

Andre

{edit} put a "c" in "reduce."

knightfly · Post by **knightfly** » Tue Apr 19, 2005 1:11 am

Julian, I'm not sure we're communicating just yet; WHICH two layers are you talking about? Maybe a sketch to show what you mean? The way I read your question, you might be talking about putting insulation between the two ADDED layers of wallboard, or between the wallboard and the bricks, or even INSIDE the bricks - which is it? Steve

AVare · Post by **AVare** » Tue Apr 19, 2005 8:53 am

Thanks Steve. Re-reading the original post, it is ambiguous.

Unambiguously;
Andre

Julián Fernández · Post by **Julián Fernández** » Tue Apr 19, 2005 10:27 am

Sorry guys, you´re right... the right question is:
Can i achieve better insolation if I fill the air space between my two WALLS with 13 kg/m3 wool? Or should I leave the air space empty?
The outer wall is the brick wall, then i have the air gap, and then the wood frame (filled with 50 kg/m3)... I think that Andre understood that way in his first reply...

F air gap B
R air gap R
A air gap I
M air gap C
E air gap Ks

(that´s a simple idea of my two "masses" and the air gap)
The air gap is where i´m wondering to put some extra wool.

rod gervais · Post by **rod gervais** » Tue Apr 19, 2005 12:23 pm

Julian,

What you're describing is a 5 leaf system, the hollow brick creates (effectively) 2 leafs - the 2 existing outer layers create 3 and 4 - the innner frame and drywall will be leaf 5.

One of the issues is that systems other than 2 leafs are not good isolation systems. Another issue is that I have no way of determining exactly what your final system will end up giving you.

Is there any way that you can fill the hollow brick? Grout or sand would work fine to turn it into a single leafm also - is it possible for you to lose the outer leaves?

It would help if you could explain the construction of those outleafs as well.

Rod

knightfly · Post by **knightfly** » Tue Apr 19, 2005 1:09 pm

Descriptions still aren't "cutting it" here;

for example, the phrase "WOOD FRAME (filled with fiberglass)+2 layer of gypsum..."

can mean either a single stud frame with a single layer of gypsum each side, filled with insulation in between the two layers, OR

it can mean "single stud frame, two layers of gypsum on the SAME side of the frame, with insulation between the studs -

can you put up a SKETCH showing the location of EACH part of your ENTIRE wall SYSTEM, roughly to scale? Thanks... Steve

AVare · Post by **AVare** » Wed Apr 20, 2005 3:31 am

Post a drawing. That will clear up the ambiguity on your design(s).

Graphivally;
Adnre

Julián Fernández · Post by **Julián Fernández** » Wed Apr 20, 2005 4:17 am

Okey... This is the idea... like you can see, i was meaning single stud frame, two layers of gypsum on the SAME side of the frame, with insulation between the studs...
I can´t use regular bricks (no hollow), because i´m building in the terrace of my new house, and the architech said that i should use hollow bricks, because i don´t wanna overload my terrace... so filling them is not a choice neither...
Do you see something wrong with this plan?

AVare · Post by **AVare** » Wed Apr 20, 2005 8:57 am

Great drawings. Thanks.

Yes filling the gap with inulation will help, as per my first post in this thread.

Good Luck!
Andre

Julián Fernández · Post by **Julián Fernández** » Wed Apr 20, 2005 9:23 am

How about the hollow bricks? Am i creating a 3 leafs system by using the rendered hollowbricks? I´m a little concerned now...

knightfly · Post by **knightfly** » Wed Apr 20, 2005 6:16 pm

Yes, you are; a standard, hollow brick/block wall works the same as a stud frame with panels on both sides; so your construction in the drawing would be a triple leaf wall, unless the blocks get filled with sand or concrete.

Also, your drawing appears to have included some sort of floated floor; is this what you intend, and can you give more details on that? Steve

AVare · Post by **AVare** » Wed Apr 20, 2005 11:26 pm

We try and help as much as possible. Your original question was if filling the space will help sound isolation. We answered that.

Yes you have a triple leaf system. It would be better to fill the hollows in the blocks.

As Steve wrote, what is the story witht eh floatingfloor system? If not done (designed and built) properly, a floating floor will BE WORSE than the original floor for music isoaltion.

Andre

Julián Fernández · Post by **Julián Fernández** » Thu Apr 21, 2005 12:07 am

Thanks Guys! The floating floor is based on John´s design on SAE site...
I don´t know how many neoprene pads i will use, i´m working on that right now... (check out the picture)
I was afraid at first thinking that the hollow bricks could create a triple leaf system... the thing is, i can´t fill them (i can´t put much weight on my terrace)... so, what can i do to improve the insolation of the system? How about NOT rendering the inner side of the wall..?

knightfly · Post by **knightfly** » Thu Apr 21, 2005 3:31 am

Walls - you may have hit on something; if you render the OUTSIDE of the blocks but not the INSIDE, this will lessen (but not FIX) the bad effects of multi-leaf; if you then maximize the air gap between blocks and your inside gypsum, that will also help; if you can add another layer to the gypsum it will help even more.

Floor - can you describe the existing floor - thickness, material, layer by layer, support, etc? You're making me VERY NERVOUS mentioning weight limits and floated floors in the same breath... Steve