Soundproofing Party Wall - Weight Worries??

[stu3540]

Looking for some advice please on soundproofing a party wall in our semi detached house. Wall is cavity type, one brick thick. The floor joists 5x2" at 400 centres are resting on sole plate on top of double bricks laid half width on their side into our leaf of party wall. The room is 4.5x2.4m and the combined components of the wall (stud, insulation, sound tec & 2x plasterboard) will weigh I reckon @ 400kg plus

. I appreciate this shall be spread evenly over 4.5m and the wall will be 25mm off party wall - directly over supported joist ends i.e over the bricks. Should this be OK structurally ? My main concern is the bricks although doubled up, are in shear used this way? Photos attached of joist detail. Any tips / suggestions would be appreciated. Thanks,

 

[stu3540]

 

[John D v2.0]

It's got to be heavy to work, but why is the person doing it not isolating it from the wall? Having it rest on the party wall provides a path for the sound to bypass the soundproof part of the wall.

 

[stu3540]

Hi thanks for your reply, the stud wall will be 25mm off the party wall and shall not be attached to it in any way... it shall only be tied into floor, ceiling and two walls either side.

Plan is to have 25mm rockwool between wall and studwork, 50mm rockwool between studs, two layers of plasterboard with soun tec sy70 sandwiched between the pb.

 

[John D v2.0]

Shall not be attached to the wall in any way, but it's attached to the floor and ceiling which are in turn attached to the party wall.
I would have thought taking it down to the over site concrete/hardcore would be better if you can.
I've not done it myself though, just a thought. Impact noise on floors can travel really well around soundproofing if it's attached.