Skimming over ply

[thezappa]

We are decorating our lounge and the previous (or possibly previous before that) blocked up a door but left the architrave on.
I took it off and am left with just the sheet of ply that covers the opening and some messy plaster round the edge.
To get a flat finnish, one option I have is taking the ply off and replacing it with plasterboard. I would prefer not to do that if I can as there are shelves on the other side which I think are stuck to the ply.
The other option I’ve read about is attaching mesh to the ply or scrim tape all over it, and skimming over that.

Anyone done this sort of thing or have any better ideas?

 

[Sin_Chase]

Skimming directly to timber is a bad idea. It will have seasonal movement and undoubtedly your skim will just crack.

Get some plasterboard and directly affix it your ply and skim that if the space allows.

 

[Participant]

Post pics

 

[robj20]

I've never had long term success when it comes to plaster over timber.
Get some 9mm plasterboard and cover the lot, then skim it.

 

[thezappa]

Ordinarily I would have boarded over it but you can see the depth of its recess is small so I would have to get a very thin piece of board (which as far as I know doesn’t exist). It’s difficult to see the gap between the level and the board but I would estimate it was about 3-5mm.
I’ve core drilled a small hole in it and measured the thickness of the board that’s there - it is 15mm, so I’m going to take this board out and put some 12.5mm plasterboard in instead and skim over it, but suspect it will need quite a bit of building up to get it flush.

Pics:

 

[MassiveJim]

definitely remove it and do it properly, you are now fixing someone elses bodge, there is no point boding the bodge.
replacing the ply with plasterboard is very little extra effort on top of the plastering you are already planning to do you might as well do it properly.

 

[JRJ]

Ply out as planned, but I'd be looking at removing the lining and re framing so that the plaster board sits against the old plaster, or trim the lining back 10mm.

 

[200sols]

Board out with plasterboard, tape the joints and use easy fill 60. Don't skim the whole lot, feathering it in is a nightmare.

 

[JBuk]

Shim behind the new plasterboard to bring it level or close to level with the existing wall, tape the seams and easifill 60 , sand it smooth and flush when finished if required , paint over any filler with zinnser 123 to prime it (or paint the whole board) - I’ve found when using easifill normal emulsion will flash if not primed first. , also best to use a small roller as you don’t want brush marks in the middle of a wall

 

[~Divine~Wind~]

Aye weve used strips of like 3 mm ply to pack bits like that out before a slab or plasterboard. Or just get a sheet of thicker plasterboard. Think the fattest we used was the fireproof stuff under the stairs.

 

[thezappa]

Thanks all.
Got some 12.5mm p/board. The existing is actually mdf. In any case it’s a good shout to pack it out behind and board over it. Will save using more plaster and I’ve got some 3mm mdf somewhere. Will check if if I’ve got some easy fill 60. I did buy a bag of EF but think it’s a different one.
Anyway will see how I get on.
Cheers.