In uk.d-i-y, Neil Catley wrote:
All,
I am currently decorating my new flat and would like to mount things
(shelves etc) on the plasterboard. I have bought some plasterboard plugs
from screwfix (quote 58219) but these dont appear to have a long enough
'neck' to reach through to the other side before they split out into the
arrow head. The walls appear to be about and inch thick.

I've never got on well with that type of fixing. For relatively
light duty things - small shelves, CD racks, & the like - I've
found the metal screw-in drivers (s-fix 11923) to be easy to position
exactly and quick to use. I tend to drill a small (5mm dia) pilot first,
more to see if there's a stud behind (if so, happy happy joy for strength,
use a woodscrew direct into the wood instead) than to make the ReadiDriva
go in more easily, though that's a handy side-effect. They also come out
again easily leaving a reasonable hole for Polyfilling; though they'll
often crack the skim coat just around the fixing as you apply that
final tighten...

For heavier loads - yes, shelves full of paperbacks - I've been happy
with the "hollow wall anchor" they sell - 18266, 12229, and 11143,
depending on thickness of plasterboard and thickness of fitting. Just
sometimes the should-be-captive nut at the back on these decides not
to be captive, leaving you spinning the mounting screw uselessly instead
of bending the legs of the fitting up against the back of the board; I've
taken to doing a half-turn or so with the fitting not yet inserted to
check for this. On a few occaisions it's still gone wrong, and I've had
to partially unscrew then snap off the head of the fitting (it comes off
easily, presumably deliberately) and pushed the half-bent body of the
fitting back into the unknown depths of the cavity ;-) These fittings
are quite nice at redecoration time, as the bolts screw out allowing
you to take the shelf/cupboard/whatever off the wall, and then replace
it with the same bolts into the same anchor - unlike gravity toggles,
which fall into the cavity if you ever take the screw out.

For *really* heavy stuff - TV wall mounting bracket, say, or the long
run of Spur uprights holding 4 room-length and 2 most-of-room-length
shelves in the study-at-home where I'm sitting right now, which are
full of papers & hardback books, I took the trouble to find the studs
at their 60cm intervals and screwed straight in with bigass woodscrews
almost-but-not-quite into the plasterboard forming the wall of the room
next door ;-) I'm also lucky with the construction of this house, which
though 'modern' timber-frame and PB-n-stud walls is a good Swedish-kit
instance of same, where the builders seem to have used PB which is 12.5
or 15mm thick rather than the 9.5mm which is more common; so what
works well in this thickness of PB may be a little dodgier in thinner
- "standard" - stuff.

Stefek