It is essential - for the integrity of the whole ceiling - that you remove each individual wood chip separately. They also need bagging up individually before disposal. You will find teeny-weeny titsy-witsy bags for chust this thing on ebay.
As I take the paper off and get a better idea for the extent of the damaged area, it seems it's only a small area. Providing the laths are in good condition, could I just use ready mix plaster rather than plaster boards?
I suspect you'd need to apply a thicker 'bonding' coat first so's it stays in place and doesn't slump down - on to your face. But I'm sure peeps will come on to advise. The original stuff had all sorts of fibres added to give it bulk and hold it together, so which modern alternative to use I dunno. I thought from your first pics that the area was bulging outwards? If so, why - has the plaster detached? Are there still laths there? If you remove all the damaged bit first, then I think we'll be in a better position to advise. Eg a lot will depend on how deep the layer is you need to fill. Photo?
(Bear in mind that if the existing original plaster is nearing the end of its life - if it's easy to crack and comes loose in places with little effort, then to only patch the most damaged area is chust delaying the inevitable.)
I'll chip off this damaged plaster (I've just managed to finally get all of the woodchip off) and then post a picture. Yes, I presumed some sort of thicker coat would need to be applied there. you're right, though; the suggestions will all depend on what is underneath, so I'll get all of that off first and take a look. As far as the state of the existing original plaster, it looks good for the most part. There are a few cracks here and there, but definetly not something worth ripping the entire ceiling down for. Cheers
So, I've chipped away a fair bit at this damaged plaster and now have a much better idea of what's going on. It turns out there was actually plasterboard under there. As you can see, the laths had been cut and plaster board fixed all the way along the damaged area (no where else, though; the rest of the ceiling is lime and horse hair onto laths) Then it was skimmed which is the pink coat. It was the plaster board that had started to bow after the sulphur leaching problem. So I guess I'll be going the plaster board route and just fixing a piece all the way along like they had done, and then skimming it.
Indeed. Thank you for your help! EDIT: By the way, what is the name of that silver paper preventing the insulation coming down? Obviously that needs removing, but Will I need to replace that with some new when before I fix the plaster board?
No idea. Are you sure it isn't chust the backing paper of foil-backed p'board that may have been used for the repair - it's chust peeled off? In any case, nothing special is required to hold up that insulation - it almost always chust sits on the ceiling p'board. I assume - since it's now bone dry up there - there will be no further issues with what caused both the original problem and the subsequent bulging/sagging of the p'board repair?
It must be the backing to the old plaster board, then. That would make sense. As far as what caused the original problem for them to replaster, I have no idea. All I know is that a small shower room ocupied that space, and the same newish pink plaster that was bowing on the ceiling also covers the walls in that particular area (but is not damaged). Perhaps the ceiling area and the walls were damaged when that shower room was demolished, and they had to replaster that part of the ceiling and the surrounding walls. Either that or it was just a leak in that area of the ceiling and they patched it up. We haven't had any water leaking problems in the area since we've been here (ten years), and the bowing only occurred due to this sulphur leaching problem. So as far as any water leakage, there shouldn't be. We had the sulphur problem sorted at the source, but they did say that we should put some metallic paper on the walls. The reason for this was because although they had stopped the problem, the sulphur was inevitably in the brickwork already, and so it would need to be maintained. The paper would apparently keep it at bay. The mentioned nothing about the ceiling, so it might be worth contacting them before we go further. Basically, it caused efflorescence on the walls, which in turn caused all the wallpaper to start falling off, along with the bowing of the ceiling plaster. The idea with the silver paper would be that you put that in first and then wallpapered. Where you actually buy the stuff I don't know.
You definitely won't need foil in that ceiling hole 'cos you are fitting new p'board covered with new skim. So it's, like, all new. No sulphur. Enjoy.
Although it's new, I am slightly worried that the sulphur in the brickwork may infect the new plasterboard, so to speak. Causing the problem to happen gain.
Multi finish, maybe bonding coat to fill any large gaps around the plasterboard first. Probably worth sealing the edges of the old plaster with pva.
Make the first PVA nicely watery - perhaps 20% water? Brush that well in to all the exposed old plaster edges and lath and stuff. Keep brushing to on if it soaks in. Once dry, you can add a neat coat too. Some peeps say to wait until this coat is tacky before skimming, but you might be safer chust letting it fully dry as well - it'll reactivate enough for the skim to adhere to it even if it's fully dry before. Better fully dry than too wet, 'cos wet = slippery. One thing, tho' - wipe away with a damp cloth any PVA that goes on the ceiling surface, 'cos that can be a pain if you need to sand it or even when it comes to painting it over.
Got it, I shall give it a go, thank you. As far as the plaster goes, can I get away with just using multifinish without adding a bonding coat underneath? Is there a certain thickness that is too much for multi? Cheers
For such a small area, I would stick with multifinish. Yes it's designed as a skim coat, but you can play around with plaster in all sorts of ways... Make up a small amount to use as a 'filler'. Make it perhaps slightly more 'stiff' than usual - less water - and then trowel/filling knife it right in to the gaps. Squeeze it right in. After a half-hour or so it'll start to plasticise and stiffen at which point you can flatten it off a bit more if needed before then applying another layer on top - carry on like this until you've filled all the gaps and have a rough level where the p'board is ready to skim. Chust make sure that each layer has begun to set nicely before adding the next.
Right okay, that makes sense. Would you theoretically be able to use this plaster to fill a couple of other nearby holes and hairline cracks in the ceiling? Or would that not be a good idea (I know British gypsum do a product called easy fill for this purpose) Cheers.
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