Repairing large hole in plaster (paramount partition)?

edinburgher

The lovely people we bought our house from declined to mention the huge crack in the wall that they had hidden behind a wardrobe (round, roughly 30cm 'square', maybe 10cm deep).

The hole goes through the plaster revealing a void behind where there are quite large plaster 'struts' arranged in a hexagonal pattern (reminds me of the panels of a football). Someone has suggested that this is paramount partition, although it's not the variety with cardboard in it that I've seen on a few forums.

Behind the void is wooden board. Initial inspection suggests that it's relatively thin, so I won't be able to screw into it (newly tiled bathroom wall on the other side!).

Considering the size of the hole, what choices do I have for repair? My initial thought had been a plasterboard patch or similar but a) it's plaster, not plasterboard per se, b) it's larger than any patch that I've seen online and c) I worried that there would be too much flex due to the size of the hole.

Another idea had been using a patch of some sort, but supporting it with some light weight wooden batten glued directly to the board backing to give it a bit of strength so that I could at least plaster over the top of it?

Slightly flummoxed, perhaps best left to a professional plasterer to repair?

Grenage

Your last suggestion is what I'd do, and what I have done.

Use some plasterboard adhesive or whatever to secure some plasterboard from the other side; just make sure it's wide enough in the width to give some adhesion room on two sides, but narrow enough to get through the hole.

Once it's set, you can fill away.

edinburgher

It's not so much a hole as a chasm.

As the hole is circular, would it make sense to carefully cut away at the sides so that it's closer to square? Also, how would I determine what thickness of plasterboard to use? Match the depth of the top layer of plaster over the 'honeycomb'?

Grenage

I'd cut it square and use normal 12mm plasterboard, you can probably get an off-cut in B&Q for a quid or less.

Most recycling centres have plasterboard bins. If it's a dry day you might even be able to get a piece there.

edinburgher

Good idea, colleague with a messy garage has also offered to see if they have a spare chunk.

phil24_7

Buy some metal ribbed lath and fix in the hole. This can be plastered straight over.