Will my plan work?

[skinslapper]

Hi there,

I'm going to build a soundproofed room within my existing tin games room in my backyard.
The room is 6m long x 4m wide x 2.6m with a concrete pad and currently offers nothing by means of transmission loss.

I intend to build a wall of solid bricks against the inside of the existing walls with a solid timber doorway. Then a 50mm air gap, then another brick wall lined with 13mm high density plasterboard (soundboard) and repeat doorway. The existing ceiling is sheetmetal and styrofoam over 100mm deep beams that span the width. I plan to put 50mm rockwool on top of 13mm plasterboard hard up against the styro in-between the beams. Then raise another ceiling of the same again just below the existing beams. No coupling.

[skinslapper]

A butt-load of caulk and a split-system air conditioner later and I hope this room will contain my hard rock band at (for safeties sake) 120db. Yes I wear hearing protection.

It should be noted that my neighbors are about 20m away from the room with 2 fibrocement fences between us.

So, do you think this will work and/or do you have any other suggestions re; the construction.

[skinslapper]

Do solid or perforated bricks sound like the better idea here. I'm feeling solid, more mass.

Also would it help to decouple the pad between the two walls?

I guess the ceiling is probably the weakest link here.

[skinslapper]

Hello?

[Randy S]

Your plan will work, use solid block not perforated.  yes cutting the slab between walls will help tremendously.
You might consider using #2 MLV for the ceiling to equalize the value of the room.
http://shop3.mailordercentral.com/supersoundproofing/prodinfo.asp?number=09-00005-48R-2LB 

[skinslapper]

Thanks a heap. I've been trying to track down mvl but im not having any luck finding a distributor in Perth. I'll keep trying though.

[Randy S]

if you cant find MLV or similar, than you want to use your same format for the ceiling and you will need multiple layers of cement board(hardi backer).
MASS and lots of it.

[skinslapper]

When you say, #2 mlv, is that 2 kg's/m squared? I found a distributor here but we call it wavebar. It comes in 2, 4 and 8 kg's/m. I'm guessing the heaviest one would be the best.

Instead of the mlv, would it be more effective to use 2 sheets of 10mm plasterboard with caulk?

One problem I can foresee is my first ceiling. I intend to raise panels of plasterboard in between the existing pine beems, which of course means they will be able to transfrer sound past whatever board and insulation I use. In your opinion, how much insulation is worth putting in this before the transferance renders it obsolete? Bearing in mind the other ceiling, decoupled from this, underneath.

[Randy S]

#2 MLV is 1kg /m2,but yes you are on the right track!
OK, a few things to concern your self with.... Never leave a cavity empty always use absorption in the cavity lose not compressed.
I have reviewed wavebar and yes this product is similar to our MLV, so yes this is ideal to use. a few points that concern me which you should address to increase the performance.

You must seal that product air tight, caulk perimeter of walls and ceiling like a fish tank. lead tape the field seams or caulk and vinyl tape seams if you can not find lead tape.
This should go on the decoupled wall then a padding tape should be applied to wavebar in line with joist/studs to separate the drywall from making contact to wavebar so it remains limpid in the wall.

[skinslapper]

The internal wall will be brick as well.

Ok, I can do that but I'm guessing I'll need to use 2 layers of plasterboard on the lower ceiling. Screw one up to the beems with mlv glued to it, tape it to the mlv on the walls, then screw up another layer of plasterboard to finish it.

The more I think about this option, the more I think I can add this level of deadening afterwards if my original plan doesn't work as mlv is quite expensive.

I think I'll go with the 2, decoupled brick walls with 50mm air gap and 13mm plasterboard face. 2 ceilings of 1 layer of 13mm plasterboard and 50mm insulation. I'll add a layer of mlv to the lower one and caulk it good against the internal walls. This way if plan doesn't work I can easily add more plasterboard and/or mlv afterwards.

[Randy S]

you are referring to a sandwich with MLV in between which will still work... if that product is truly a limpid barrier than you get more bang for buck keeping it limpid like a diaphragm in the ceiling.
Either way you will have decent results from the mass in your system.

[skinslapper]

What is the better insulation, glasswool or mineral fibre (rockwool)?

[Randy S]

mineral fiber (rockwool)