"Lobster" wrote
| I want to apply sound insulation to an internal soil pipe, which runs
| vertically from ceiling to floor. I've built a timber frame around it,
| which I'm going to cover with two layers of 12.5mm plasterboard and
| have skimmed. I know the ideal way would be to fill the boxing with
| sand to deaden the sound, but that would cause too much grief (can't
| quite imagine filling up all my boxing - which has to be quite
| large - with sand; plus there's a rodding eye at the base for which
| access is needed). So I propose to fill the void with Rockwool.

Sounds good. Esp if the pipe is plastic, I'd suggest stiffening it by
glueing some of those deadening felt panels used in loudspeaker cabinets
around it. Probably won't need to be completely covered, but should deaden
the noise of upstair's turds flowing down inside the wall as you're trying
to enjoy a radox moment.

Alternatively/as well, box round the rodding eye and then fill the cavity
with e-x-p-a-n-d-i-n-g foam.

Owain