"Philip Roberts" pjr@ k e a n e r o b e r t s . d o t c o ....GreatBritain
wrote in message ...

"Lobster" wrote in message
...
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.

Question is - should I insert Rockwool in it's 'natural' state, ie,
unpack
the stuff and let it expand to its maximum, and not allow any
compression
when I put it round the pipe (which I know would be best if I was
dealing
with thermal insulation here), or should I cram as much Rockwool into
the
void as I possible can? Would that be better/worse/similar to option
1?
The stuff is pretty dear, so I don't want to overstuff the boxing if
it's
not going to be beneficial.


I've never used it, but there is plasterboard that it designed to work as
a
sound check (a bit like the fire check plasterboard) there might be some
info on the lafarge website.

That's a good thought; however the BCO has already decreed the use of two
layers of plasterboard (as being equivalent to fire-check board which my
application needs, for reasons I won't go into here.)

Thanks to Owain for the suggestion about using speaker wadding; a good idea
too although I wonder if it would it be much better than Rockwool (given
that I already have the Rockwool and would have to source and buy the
acoustic wadding!). I think I'll pass on the expanding foam - bit too
'permanent' for my liking; if it turns out not to work as well as hoped I'd
be stuffed.

Can anyone comment on my original Q above - how much Rockwool to use?

Cheers
David