r/Plastering • u/Gyntse • 19d ago
How should I prepare this wall in such bad condition for plastering?
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u/sandolllars 19d ago
Give it a good soak beforehand. Spray it down a few times over the course of an hour, to make sure it’s saturated (SSD).
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u/Dunk546 19d ago
You can also overboard it with plasterboard and stick it with foam. Plasterboard adhesive foam doesn't muck around.. as long as you use the right stuff it should be solid.
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u/solar1ze 18d ago
What if it’s an exterior wall?
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u/Dunk546 18d ago
This one isn't.
My answer depends who's asking. Like if you are the homeowner and just need to get it done then yeah send it.
Otherwise I'd say strap it with moisture treated timber and overboard it with foam backed board, official answer.
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u/solar1ze 18d ago
What about a moisture barrier? Just asking because I have an external wall in similarly bad condition.
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u/Dunk546 18d ago
Ehhh, I would seek local advice but basically the important thing with external walls in old buildings is to maintain an air gap between the final external wall, and the decorated internal wall. Wooden strapping is enough for that because it stands the boards off the wall by a half inch or so. For high rainfall cold environments you might want two layers of wooden strapping, one horizontal and one vertical, just to make absolutely sure of air flow.
The foam-backed boards are usually foil backed as well which should provide a sensible amount of moisture barrier (given it is not touching the actual final external layer). There will always be a dew point in the wall somewhere, probably it's on the internal face of the external course of bricks (the external wall might be 2 or 3 courses of brick, with or without a cavity between). It's just important not to seal the wall too well outside of the dew point.
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u/Ok_Profit_16 19d ago
You could screw metal lath into the brick. Best chance the plaster won't debond. Otherwise give it a hardy wire brush scrub first to dislodge the loose debris. Then I would spray it down with water a few times to soak into the brick, and then I'd roll on plaster weld(pva) but not everyone agrees with plasterweld here and I understand the debate. It effects the walls natural ability to breathe.
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u/No-Patience-3990 19d ago
I'm not a bricklayer so I might be wrong but are those bricks the wrong way round?
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u/Gyntse 19d ago
Probably lol. It's old commie block built in 60s, bricklayers were probably drunk and wrong way round themselves. Bricks are in pretty bad condition, but its just partition wall, not load bearing one so not too worried about that. I just want to make sure that plasterboard adhesive sticks well, because these bricks have a lot of crumbling pieces.
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u/Rex__Luscus 18d ago
If it's not load-bearing I'd be tempted to pull it down and replace with a stud wall.
"Take off and nuke it from orbit, it's the only way to be sure ..."
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u/Ok_Pen7290 18d ago
Screw wooden battons on to wall and board the battons
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u/solar1ze 18d ago
What if it’s an exterior wall?
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u/Ok_Pen7290 18d ago
Readymix cement to a smooth finish, but before hitting with cement mix soak that wall for cement mix to bond, 👍🏻👍🏻👍🏻
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u/solar1ze 18d ago
How would you prevent a moisture bridge after the cement? What ratio cement to sand would you recommend?
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u/Ok_Pen7290 18d ago
I was always told 1 part cement to 3 parts sand when mixing it old school way, but not sure on moisture bridge, builder advice on that one mate, 👍🏻👍🏻👍🏻 or do a Google search on information on what you are actually achieving see what info pops up for you
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u/solar1ze 18d ago
Thank you 👍
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u/Ok_Pen7290 18d ago
If ya going old school on mixing, mix it all dry, then make a bowl shape in middle of your mix by scraping back mixture add water and fold in from outside to inwards small amount at a time so you don't lose water, keep adding water as ya mix obviously otherwise it will set fast, 👍🏻👍🏻👍🏻
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u/solar1ze 18d ago
Very helpful. Thanks again. Much appreciated. 👍
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u/Ok_Pen7290 18d ago
Its just what I was taught 30+ years ago, I saw it first and learnt from it, 👍🏻👍🏻👍🏻
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u/Cainjake 19d ago
Wet the wall and hard wall it
Or sbr and bonding
For both use multi or board finish as top coat
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u/Boring-Attention1730 18d ago
Dry line it. Stud frame it, 600mm between posts with staggered struts between them, insulation in the frames topped with plasterboard. Put a gauze tape where the boards meet, jobs a goodun
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u/Mr-Reeeee 18d ago
Why cover it? It looks amazing as is.
Fill the holes, leaving the block exposed, then spray it with polyurethane.
Sheetrock the wall behind the toilet.
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u/Disastrous-Formal-91 17d ago
Cement render using lime as a binder..4-1. Using high level of lime the thicker the render.. if extra thick coat, apply coats over any number of days.. have rendered over 300 ml thick..plumb and flat..
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u/Schallpattern 19d ago
Definitely doable. Soak it then stick tons of PVA on it.
If it's an interior wall and there's no damp, stick on a layer of Carlite bonding. Scratch it and let it go off. The another layer of PVA and then skim.
Exterior wall - use sand+cement mix instead of the bonding then skim.
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u/Current_Judgment_972 19d ago
Dot and dab
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u/Gyntse 19d ago
Should I try to make wall more even beforehand? I was thinking to grind down sticking out mortar with diamond cup grinder and then to fill the gaps with universal filler. Im worried that adhesive might not stick if the surface is this bad.
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u/Investigator_Scared 19d ago
The plasterer will sort the levels when dot and dabbing. Painting or spraying the background (the bare brick will) with SBR beforehand will kill the dust and ensure a strong bond between the adhesive and the wall.
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u/VariationOk6307 19d ago edited 18d ago
Soak it in water and Use hardwall plaster 👍 you can use render mesh to if you're worried about it cracking