Improved sound insulation w/ timber party wall

[fulguros]

I have made an inspection hole in our party wall and it seems to be about 10" studwork with a double layer of 1" Plasterboard on boths sides (assuming the neighbours is the same).

I can easily build a seperate stud wall that is independant of the party wall out of something like 2"x2" so I could leave a void if reccomended but I do not know what would give the best results as far as sound insulation across the whole spectrum and also sound travelling both ways.

Anybody got any ideas as to what I could put?

 

[Deluks]

You can fit new studs in between the existing, which aren't as deep as the current ones, go with 3x2 CLS, have them protrude into your side by about 15mm. Space them between the existing studs to match plasterboard spacing.
It doesn't really matter too much if they are fixed to the existing top and bottom plates (unless you play the drums!) Completely fill the void with rock or glass wool, 10" is a decent enough airspace that you don't need to worry about using any insulation branded as 'acoustic.
Beware of any cable runs which should be kept clear of insulation or run in conduit (get some 40mm waste pipe and cut a slit along it's length).

Double layer of 12.5mm plasterboard on top and you'll be sorted.

ps. did you mean a double layer of plasterboard making a total of 1"?

 

[fulguros]

I meant 1" thick plasterboard and two layers of it giving 2" thick plasterboard.

I would rather not remove that plasterboard and would prefer to build a new stud in the room seperate to the party wall.
I could easily attach it at the ceiling joist level and floor joist level and the end walls which are studs so it would be completely independent.
There woul only be a electric socket which would be extended out from the existing party wall into the new stud.

So I am thinking 1" to .5" gap then a 2"x2" stud filled with Acoustic insulation and then double plasterboarded with sound checked plasterboard with the joints staggered.

Is there any better way to do it?

I am also thinking about thermal insulation, possibly, so I am not heating next door. But that could be 2 layers of Superquilt or something incorporated into the new stud.

 

[Deluks]

I would rather not remove that plasterboard and would prefer to build a new stud in the room seperate to the party wall.

Now it gets complicated, this is a waste of time and money IMO. Unless you really DO play the drums

First of all, is sound transmission a genuine problem at the moment?

2" of plasterboard either side gives an awful lot of reduction against airborne sound. Adding a third wall of plasterboard may actually exacerbate the problem, the middle wall then becomes a 'stepping stone' for low frequency sounds and you may actually amplify them. Crazy as it sounds. (no pun intended!)

If you have a problem with noise then do as in my first reply, and add as many layers of plasterboard as you like, although less is probably better, the current 2" is probably so heavy that the wall has no 'flex' to absorb certain frequencies, I'd suggest a thin layer of mdf or ply in a PB sandwich to break things up a little, theory being that opposing walls should ideally have different materials and thicknesses in their construction to block sound.


Your concern with heating next door reminds me of an episode of "In Sickness..." where Alf Garnett tries to claim some relief on his heating bills because as he is in the downstairs property, all his heat is giving 'free' heating to Mrs Hollingberry upstairs.

This is a double edged sword, as well as denying heat to your neighbours you are also denying yourself any heat from their side. If both properties are heated to a reasonable amount then there will be little transfer of heat either way.