In article ,
benpost writes:
i have a long (metre or so) gap in the wall about 1.5 inch deep and 1
inch high where i think cables used to be. how would i fill this ? it
seems to big a gap to use standard filler.

Providing the wall is dry, I would just fill it with plaster.
A large bag of plaster can be cheaper than small bag of filler.

You need to do it in two layers. The first layer fills the
hole to within about 2mm of the surface, and then you do a
finish coat for the final 2mm. You need finish coat plaster
for the finish coat, and bonding coat for the bulk. You can
make your own bonding coat from finish coat just by adding
some PVA into the mix, so you can get away with buying only
a bag of finish coat plaster. This bonding coat will shrink
and crack as it sets, but that doesn't matter. Old/out-of-
date plaster is good for this as it will set quickly.

If the wall has any chance of rising or penetrating damp,
use a cement based mortar with a waterproofer additive for
the bulk, and then plaster or a filler for the final 2mm.

--
Andrew Gabriel
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