Filling in hollow concrete walls

[conoral11]

Hi there,

I'm having my house rewired, ready for a new kitchen to go in.

During the process we have had some backboxes removed where sockets are being removed.

During the original installation of these boxes, it appears that the installer has gone right through into the hollow of the blocks. What is the best material to fill these up with before plastering?

Should I use cement + sand mix to fill in the void before plastering, or is there a more suitable material? Its been mentioned that I could try expanding foam, which I've used before, but i'm not certain the plaster will appreciate it.

Best Wishes

Conoral11

 

[John D v2.0]

You don't need to fill it all the way to the back as long as it's strong enough. Are you going to tile the wall? Might be easier to just cut some plasterboard to size and stick it round the edge.

 

[conoral11]

John D,

Thanks for the reply.

We won't be tilling unfortunately, so would you think a bit of plasterboard, possibly glued via grab adhesive, or with wooden battens behind it be strong enough?

Best wishes

Conoral11

 

[John D v2.0]

Probably best not to put wood in an unventilated space, but you can even pack it out with plastic bags, just anything as a backer to support the adhesive until it dries. And don't try to attach any heavy shelves to it!