On Sun, 30 May 2004 07:14:21 +0000 (UTC), Philip Roberts wrote:

I've built a timber frame around it, which I'm going to cover with
two layers of 12.5mm plasterboard and have skimmed.

Don't forget access, not just for maintenance you mention a rodding
eye but you also have a hand between floors cable duct for phone,
network, TV etc. It almost certainly runs from roof space to ground
floor as well...

Question is - should I insert Rockwool in it's 'natural' state, ie,
unpack the stuff and let it expand to its maximum,
snip
should I cram as much Rockwool into the void as I possible can?

TBH two layers of 12.5mm plasterboard are going to do far more than a
bit of rockwool no matter how much or little you put in. Make sure
that there are no holes/cracks for the sopund to sneak through as
well. Stagger and board joints buy as much as possible indeed I'd be
tempted to seal the edges of the lower layer of board before putting
the top layer on and seall all those edges as well.

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.

Worth looking at I would have thought or maybe some heavy matting to
sandwich between the PB layers.

--
Cheers
Dave. pam is missing e-mail