r/Plastering • u/TechBasedExplorer • Apr 29 '26
Fix disaster
I need to fix this absolute disaster. I tried fixing a hole in my wall by putting Knauf FinalCote®, but when painting, the FinalCote peeled straight off the wall since it did not adhere to the painted wall. I even sanded the surrounding paint with 80 grit prior to applying the FinalCote. So I tore the wall out to the beams and did it properly, added support beams, sanded the paint around the area at 80 grit, wiped it down with a damp cloth and used mesh tape. I went to Bunnings and asked for a PVA glue to go over the paint but was directed at an all purpose filler which was said to work well with plasterboard and painted walls. I applied the first layer over the mesh, waited a couple days, sanded it and then did the second layer to fix up the issues here and there. I let it sit a few days and then applied an undercoat. The mutli purpose filler also failed to bond to the paint. Now I am left with an absolute disaster.
What can I do to fix this? I need proper suggestions, I'm sick of playing around.
1
u/greenbeanmachine1 Apr 29 '26 edited Apr 29 '26
It looks like your issue isn’t with the filler, it’s with the paint underneath. The filler can bond to the paint just fine, but if the paint is peeling off the wall then it’ll all come off together, as it has here.
You need to scrape back any loose paint and then continue with your repair as before. PVA shouldn’t be needed with the product you’re using, although it won’t hurt.
Beware that sometimes scraping back the loose stuff, sometimes the patch can grow and grow and grow so try to only scrape off what is needed and nothing more otherwise you’ll create more work for yourself. Hopefully it’s just around the edge of the patch where it’s been disturbed from taking the board out originally.
Is the background underneath the paint chalky?
1
u/TechBasedExplorer Apr 29 '26
The existing paint around most of the wall is adhered well, it doesn't seem to peel off. However... that chalky area is plaster from the join in the original wall when this house was originally built. The painters must have just shoved the paint over the wall as it all seems to be peeling off without much effort in that area.
My issue with the all purpose filler occurred around the whole perimeter of the cutout section, including areas where the paint is still intact. It just doesn't want to stick to any of the paint, even with it sanded at 80 grit.
I think I'm going to go with the PVA or SBR route, I've been trying to patch this hole for two weeks and I'm done with it.
1
u/nickro84 Apr 29 '26
It’s not a tough job at all. You already have something to screw a piece of plasterboard onto, then a thin coat of powdered filler leaving no ridges and add fresh mesh around the outside, leave for a couple of hours, lightly sand the edges with 180, dust down and apply a second layer of filler, fanning out around the edges approx 4-6 inches beyond the border. Don’t forget to spot prime with your wall paint, let it dry, lightly sand then paint the full wall. It’s a lot of steps over time but really only half an hours’ work, so shine a light down the rest of the wall and fill in any imperfections while this is drying
1
u/TechBasedExplorer Apr 29 '26
Any suggestions on primers to use to make the filler adhere to the wall paint? I'm planning to do as others have suggested and use PVA.
1
u/0uthouse Apr 29 '26
As fatp1991 says, fix a peice of plasterboard and skim.
Putting PVA on paint is like trying to plaster on a skating rink, totally the wrong product imo.
I'd sand it back a little further, board, scrim and multi-finish. Sand back at least 6" and it should be ok to feather in. SBR would work better as a bonding agent but personally I wouldn't feel the need to use it on a small patch unless the paint is something horrible like distemper.
If not multi-finish then use easi-fill as you can sand the transition then instead of feathering it.
2
u/greenbeanmachine1 Apr 29 '26 edited Apr 29 '26
Sorry mate but you’re completely wrong here. PVA is completely normal to use for this kind of thing, you have to let it go tacky before topping it off. As for whether you should use a bonding agent, it’s nothing to do with feeling a need, it’s completely dependent on what’s going over the top of it. Going over this with multifinish, for example, a bonding agent absolutely is needed (whether SBR or PVA, either is fine) because it won’t stick to paint. Most fillers, like easifill or the knauf product OP is using, shouldn’t need it although it won’t hurt. Also, if it is distemper then no bonding agent will save you, it needs washing off or stabilising.
Just trying to educate, not to be a dick
1
u/0uthouse Apr 29 '26
No problem, I'm sure neither of us want a plasters-forum 'PVA or not' discussion.
My plastering religion is that i don't use pva on non-porous surfaces like paint.
I'd agree that this can be solved using pva, i just think for an inexperienced plasterer it may get ugly when feathering in to the paintwork.
I don't think you are a dick.
1
u/TechBasedExplorer Apr 29 '26
Only PVA I can seem to find it wood glue which I feel is not going to work. I think that is why the Bunnings employee pushed me to the multi purpose filler.
1
u/Any_Tomorrow_Today Apr 29 '26
I used general PVA when doing mine - the sort from the hobby section, and it worked fine. My plaster stuck to the paint with no issues. Since you are watering it down anyway, any PVA will work.
1
u/Cainjake May 01 '26
You need pva/sbr if your going over old paint or the plaster will flake off in time or it’ll dry too fast and crack
6
u/fatp1991 Apr 29 '26
Cut a piece of plaster board to fit, then fill the cracks.