On Wed, 12 Jun 2013 00:14:04 +0100 DaveyWavey wrote :
I initially assumed it would be a plasterboard stud wall, the same as
the rest. But I got nowhere fast when trying to drive a plasterboard
screw into it -- it went about 1/2in, then hit something hard, and would
go in no further (and made a bit of a mess of the wall).

I investigated the wall's construction by taking the cover off a power
outlet in that wall and having a look. From what I can tell, the wall is
constructed of:

a) a thin layer of what I assume must be plaster
b) behind that, a 1/2in layer of something that resembles plasterboard
(and is soft enough to screw into easily enough)
c) behind that, a 1/2in layer of something that *looks* the same as the
plasterboard, but is much harder (and cannot easily be screwed into)
d) behind that, there appears to be a gap/cavity

So, what I can't work out is: what the hell is layer (c)? And, more
importantly, what sort of fixings can/should I use to fix shelves to
this wall?


Gyproc Fireline board? Never seen the actual product though.

http://www.british-gypsum.com/products/Gyproc-FireLine

--
Tony Bryer, Greentram: 'Software to build on',
Melbourne, Australia www.greentram.com