soundproofing a stud wall partition????

I'm building a stud partition across a room 8' wide using 4" timber and plasterboarded with 12.5mm then skimmed with plaster.

I need to make this "wall" as sound proof as possible.

Whats the best materials to acheive this? ie wool, celotex, insulation slabs, etc etc. Also, would I be better off lining the studwork with something other than plasterboard??

Thanks in advance.................

You could use Isowool 1200 Sound Deadening Quilt between the timbers ( which is just like Rockwool ) and if you can fix a double layer of plasterboard to both sides of the wall with the joints of the boards staggered it will help as well.

I used the compacted rockwool stuff. Wickes sell it at 3-4 times the price of Travis Perkins.
From Travis it cost £20 for quite a bit. Can't remember. 3" thick, by 60 cm wide by 90 cm long? 6 or 8 sheets?
Something like that.
Shop around, it is simple stuff.

If you've not started on this yet, and you want really high performance, then you could try this.

use 4 inch studs with 6 inch plates top and bottom. double the number of studs, but stagger them, so every other one is on face A of the plates, and the alternates on face B. that way, you can weave a continuous strip of sound insulation in and out of the studs, and you have in effect isolated the two plasterboard faces of the studwork from each other, so noise in one room may make that face of plasterboard and stud vibrate, but it can't transmit the vibration to the other face, because you have separated them.
By all means double skin with plasterboard, staggered taped joints etc. - the additional dead weight on the wall makes it harder for noise in the room to get the wall vibrating.

However...
remember that sound can be transmitted by any of maybe half a dozen means. If you eliminate one route, it can still travel by the others. You've got to address them all. So, its no good doing the staggered studs, or the double skins, if you've got a gaping great gap of a couple of mm top or bottom of the wall.
Likewise, however good you make the wall, if the floor and ceiling joists span from one room to the other, they will merrily transmit sound along that route. Even if they span the other way, you may get a little transmission through the floorboards! The weight of the wall should help deaden this though.

Any of you has a audiogram in the hearing test room and noticed the wall tiles are full of holes. Does this break down the sound barrier ?

I think this is to do with absorbing sound within the room rather than to do with sound transmission between rooms - it helps stop particularly higher frequences, reverberating, bouncing around between flat, hard surfaced walls, So the sensitive ear testing isn't interfered with. Smaller irregularities work for higher frequencies, larger ones for lower frequences.

pieman said:

I think this is to do with absorbing sound within the room rather than to do with sound transmission between rooms

Click to expand...

Yes, I think you're right and I was thinking if something similar behind the plasterboards to break the sound down rather than tranferring through the wall.

The sound absorption is good if you are in the same room as the problem noise source - like in the ear test, or maybe in a concert hall, where the thing you are listening too can bounce around or echo between the walls, and these reverberations cover the clear original sound. The sound absorbing material - those chunky panels in a concert hall, for low frequency, or maybe fabics for high frequency
(even having a concert hall full of people helps a lot) actually change the angle the sound is reflected back at, so instead of bouncing back across the room, it rattles around between the chunky panels, or the fibres of the fabrics etc. until its energy is lost.

Problem is, the energy of the sound travelling in the air is lost into the panel, fabric etc. as vibration.
So, if you are in a different room from the problem noise source, having the wall in between absorb the sound doesn't help, as it will still tend to make the wall vibrate, and transmit the sound to the other room where you are.

So the two layers of plaster board works because it is heavy, and hard to start vibrating.
The sound insulation does absorb any sound that has got into the cavity in the thickness of the stud wall.
The staggering studs method separates the two sides of the wall, so that if one side starts vibrating, the studs don't transmit that vibration to the other side, and the sound insulation weaving inbetween stops the vibration passing through the air cavity in the stud wall.

Solid plastered block wall is good at stopping air borne sound, but very bad at structure borne sound - if some one hammers a nail into it the sound comes through really bad. Same thing with high heels clicking on a concrete floor above.

i some time ago (much to most peoples amusement) mentioned that i have been in several recording studios and they have "egg boxes" on the walls / ceilings, now you know why

Many thanks everyone. No I've not yet got to the finishing stage on this so will bear in mind all that has been said. Extra special thanks to Pieman for all that techy stuff!!