Can anyone recommend Soundproof between semi's that works?

[compact]

Have read quite a bit on here about soundproof, different solutions etc.

Looking to hear from those that have carried it out, how successful it was?

I understand you don't completely cut out the noise, so being realistic with what can be achieved.

My situation is 1930's semi, joining wall is sitting rooms and bedrooms.
Carrying out complete renovation, so there is a chance to do something on the walls, but only if it is worth it.
At the moment I can hear conversations, tv etc.
So thinking about trying it out on the rear sitting room, which has chimney (which will have wood burning stove), 2 alcoves etc. Have taken wall back to brick as bad plaster. Have access to crawl space below and thinking of insulating below floor (which will have stone tiles).

So very interested from those who have actually done it, to hear what made a difference and how much.

Cheers

 

[misterhelpful]

I'm no expert in soundproofing but, whatever you do, don't be tempted by Wallrock Sound Insulation. (Basically a paste-the-wall, foam backed, lining paper.)
It not only doesn't make the slightest bit of difference, but it is a pain in the arris to put up, needs to be cross lined and then decorated over. A lot of expense for very poor results.

 

[Symptoms]

com - I did this 20 years ago for friends of mine and they were very pleased with the result ... a massive improvement they said! They also had a pre-war semi.

There's no point in attempting to treat the chimney breast as it has sufficient mass (thickness) not to transmit the sound from next door ... it doesn't vibrate. The back of the fire recess might as this is likely to be double brick to the back of next door's fire but because it has such a small area can be discounted. It's the alcoves that need to be attacked and that includes the below floor sections. Your aim is to 'detach' your new inner wall skin from the party walls in the alcoves and contain an acoustic layer within this void.

Take the floorboards up in the alcoves and examine how the joists terminate at the party wall ... do the ends actually touch the wall? If you can trim off say 5mm off the joist ends so they don't actually touch the party wall as this'll prevent the floor from picking-up vibration (if you can get to the ceiling joists from the bedroom above do the same).

Using tanalised timber (say 75mm x 50mm) erect framing (with noggins to stiffen) within the alcoves fixed to your exterior wall at one side and the chimney breast at the other, fix to ceiling joists above and floor joist at base - this frame MUST NOT touch the party wall although it doesn't really matter how far off it stands. Attempt to fashion a similar frame below floor in void although down there take care to install a DPC for framing to rest on where appropriate (buy a roll of 100mm wide plakka DPC).

Fit your acoustic slabs, something like Rockwool Flexi within the framework then overboard with 12mm plasterboard. Do not be tempted to fix lekky sockets in these new alcove walls as you'll get sound leakage through them'

Re-lay the floorboards.