In message , The Natural Philosopher
writes
Tim Lamb wrote:
In message
,
sm_jamieson writes
OK, I put loft-style glass fibre insulation compressed to half its
natural thickness in my new stud partitions (they are near doorways
anyway, acoustic wool not required for building regs, but stops the
hollow sound.
However, I want to put in some proper acoustic stuff inside the boxing
around the PVC soil pipe to minimise the flushing sounds. It seems the
decent stuff is at least 45kg/m^3 and best stuff up to 60kg/m^3.
Probably will be delivered due to the weight.
Where is the best place to get this stuff (I am in the Midlands) ?
Is expanding foam not suitable?


No. acoustic deadening needs MASS.

Undoubtedly. However mechanical connection through brackets or direct
contact should also be avoided.

mass and compliance are what you want. Sand is of course excellent.

My very limited experience of doing this concerned an existing boxed
soil pipe which was conducting *pongs* from some discharge point to a
flat conversion. The cure was to inject some fire resistant foam which
also happened to reduce noise.

regards

--
Tim Lamb