On Thu, 12 Feb 2004 23:03:57 +0000, Peter Parry
wrote:

The space has a suspended ceiling (belonging to the flat below) about
1m underneath it.

So, my question is: will 9.5mm of plasterboard and 18mm of chipboard,
plus the suspended ceiling below, give me the 30 mins fire resistance
I require?

If you are going over someone elses property then no matter what the
BR say think of your own security. Make sure the compartment is
smoke proof for a start - fires rarely kill - their combustion
product beat them to it. It used to be that a double layer of
plasterboard was adequate to give 30 min resistance - I'm not sure if
this is still so but it isn't far out.

Thanks Peter, I hadn't thought of that. I'll fill the gaps between the
joists, that ought to do it smoke-wise...

Googling, I think that the floors in the rest of the flat have been
filled with something called `foamed perlite', which apparently has 60
minutes fire resistance, so I'd better meet that in the new
compartment too...

Ben.