Decorating - need help bodging patches of unbonded lath and plaster

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I need to redecorate one of the bedrooms whilst we're in lockdown. It's a Victorian house, original plaster, thick heavy patterned wallpaper. Three walls have brick and plaster which seems sound, the fourth wall is lath and plaster but there are a few areas where the plaster has come loose from the lath and bounces when you press on it behind the wallpaper.

Ideally I'd prefer to just emulsion over the wallpaper but putting wet paint on may end up bringing it off as some of the seams are starting to part. If I have to dispose of the paper and go back to plaster walls, bits of loose plaster may come off and I know from experience that once small areas fall off the rest follows suit if it's not well bonded to the lath. Obviously I can't get anyone in to replaster the wall for me and my only previous experience of DIY plastering ended in disaster so I need a bodge fix if the wallpaper comes off.

I've seen a technique on Youtube for repairing lath and plaster:
  • drill holes over the loose plaster where there is a strip of lath using a masonry bit
  • vacuum out the dust
  • inject some sort of dilute PVA water "conditioner" into the holes (wait to dry or go onto next step?)
  • inject adhesive into the holes
  • screw into some of the holes and hold plaster to lath with "plaster washers"
  • remove screws and plaster washers
It sounds appealing. Is there a catch or is this a reasonable bodge strategy to rebond plaster? I can cope with troweling in a bit of Polyfilla if there are small blemishes in the plaster but can't face the prospect of anything bigger.

If it's worth doing what type of adhesive would I need, and do I need to wait for the dilute PVA to dry first? I read somewhere you can use PU glue and that needs moisture to set?

In case it makes a difference I'm in the UK - most of the Youtube repair advice is in the US and I'm not sure if 100 year old American plaster is different to Victorian British plaster? Also I haven't seen anywhere in the UK that sells plaster washers - what do folks use in this country if anyone repairs walls in this way?
 
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dontbelieveawordofit

when you drill the holes the loose mortar will crumble and fall off the wall.
when you hoover the dust it will suck the loose mortar off the wall.
the adhesive you inject will just run relentlessly behind the mortar .
the pu option is the least outrageous option , but even that is a no go as it expands when it cures and will blow your already loose mortar off.
 
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Thanks, that's what I was looking for. Videos of folks in the USA doing it makes it look like a real alternative to removing plaster completely and starting afresh, but also is there something about them using horsehair in their plaster so it holds together better too? Sounds like best option for now is paint over old wallpaper and hope it holds for a few more years!
 
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when you drill the holes the loose mortar will crumble and fall off the wall.
when you hoover the dust it will suck the loose mortar off the wall.
the adhesive you inject will just run relentlessly behind the mortar .
the pu option is the least outrageous option , but even that is a no go as it expands when it cures and will blow your already loose mortar off.

I take it you haven't watched the video.
 
D

dontbelieveawordofit

there was no link ,didn’t really fancy trawling thousands of videos .
besides tipping pva into a lath and plaster void didn’t appeal to me for some reason.(y)
 
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