Injectable filler behind dry-lining?

[Albumen]

One of my rooms was dry-lined and plastered. I wish I'd insisted on browning/skim, but too late now. The dry lining was fixed with board adhesive, and behind that is brickwork.

I need to fix lots of things. Some of them fairly heavy - shelves, loudspeakers etc.

When I've fixed a couple of other things in this room, if the fixing ends up being on a void (between board and brickwork), the board will crack as I tighten. Is there someway to get something behind the board? I'm imagining something like this:

1. Drill fixing holes where I want them.

2. If there's a void behind any of them, inject something through the hole, which will set.

Obviously it needs to be runny enough to get through the hole, but thick enough to stay in place and set.

Any ideas?

Thanks

PS. The picture that seems to be my avatar isn't one of the walls I'm talking about! That was a different plastering disaster.

 

[dontbelieveawordofit]

depends how deep the void is?
I carry large diameter 12” rawl strips in my van that i can cut to the correct length and leave them flush to the board .They’re quite stiff and usually allow a good fix because they don’t compress.
otherwise you could backfill the void the day before with a low expanding foam/ foam adhesive.
https://www.toolstation.com/soudal-...MIyrengIja7QIVjevtCh0NiQH1EAQYASABEgKLMvD_BwE

https://diy4u.co.uk/Item/cut-to-len...MI_euMloja7QIVu2DmCh2-iQa_EAQYAyABEgJJMvD_BwE

 

[Albumen]

depends how deep the void is?
I carry large diameter 12” rawl strips in my van that i can cut to the correct length and leave them flush to the board .They’re quite stiff and usually allow a good fix because they don’t compress.
otherwise you could backfill the void the day before with a low expanding foam/ foam adhesive.
https://www.toolstation.com/soudal-...MIyrengIja7QIVjevtCh0NiQH1EAQYASABEgKLMvD_BwE

https://diy4u.co.uk/Item/cut-to-len...MI_euMloja7QIVu2DmCh2-iQa_EAQYAyABEgJJMvD_BwE

Thanks for the reply.

I think the void isn't that deep. The wall behind is decent brickwork, so fairly flat (not uneven masonry). And whenever I've drilled through before I've not felt a big gap as the drill went from board to brickwork.

I'm a bit of a belt and braces chap, so I'll probably do both of those things, thanks very much for the advice.