Cicero wrote:
On Sun, 03 Dec 2006 12:48:16 +0000, Ian Stirling wrote:

Cicero wrote:
On Sat, 02 Dec 2006 20:01:41 +0000, Anna Kettle wrote:

I have allocated a space for a shower-loo-sink room but what I'd
_really_ like is to squeeze a separate loo-sink into the space as well.
After lots of entertainment as I drew the layout on a large sheet of
white paper and walked around to make sure that there is enough space
to fit it all in, the answer is yes it will fit ...

... if I make the wall between the shower-loo-sink and the loo-sink out
of something much thinner than a normal stud wall. I'm thinking of
using 22mm blockboard faced with 9mm plasterboard on one side and faced
with a wall of the shower on the other side.
snip

Your target thickness of 31mm can be achieved as follows. A sandwich
made up from 6mm ply + 30mm PAR timber + 6mm ply. The 6mm ply layers to
be routered into the 30mm timber leaving a cavity of 18mm. The cavity to
be filled with 25mm thick polystyrene (Wickes etc) which will compress
into the 18mm cavity. This will make a very rigid panel with adequate
sound proofing.

I really don't think it will compress. At the least, you're going to get
severe bowing, and unless the PAR timbber is every 6", it's just going to
pop off the fixings.

The trivial way to thickness polystyrene is to put down a couple of
battens, and run a hot wire between them, but a bow-saw, with the blade at
a right angle works just fine, though messily. (glue the polystyrene down
first, or be careful about it pulling up.

As you imply, compressing by 7mm might be difficult - a case of trial and
error really. Given that polystyrene is always messy to cut to size a
simple way to reduce thickness (if necessary) by a few millimetres is to
draw a large sharp saw across it as if using a spoke shave. Very messy but
effective.

True, but in this case it's really wanted to be semi-structural, so
would need to contact either side, this is going to be moderately
difficult freehand, though I don't see why it wouldn't work with a
couple of battens to set the depth. probably better than the 'saw it'
solution, for a few reasons.