On 13/05/2013 19:25, imanc wrote:
I'm trying to fit 4 25mm back boxes into walls. I've pepper potted the
area with the drill then used a cold chisel to clear out the plaster and
brick. However, the result is not smooth. There's a lumpy mess and some
cracked brick that is stil somewhat firm, and the back box doesn't seat
right. With one recess the back box is about 5mm too deep.

I'm wondering if I can build up the chase with some polyfilla or
something to make it straight and the right depth before fitting the
back box?

I know that an SDS drill with correct chiselling attachment would do a
much neater job, but I don't have one to hand.

I've got 3 more holes to chisel out so any advice would be appreciated!

Cheers,
imanc




Polyfilla or even plaster will be fine. Ideally you should still have
two fixing screws into wallplugs, but with suitable filler you can get
away with one or even none. Finish plaster is slightly less good because
of shrinkage.

The other trick if you have two good screw fixings is to pack behind the
box with suitable slivers of wood so that the box is square when screwed
down.