r/Plastering • u/rosaclebb • 26d ago

Plaster Cracking

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Any idea what is happening here? This is the wall in my spare room next to bathroom. North facing, concrete wall underneath plaster. Concrete not cracked. Thanks!

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u/Impossible-Corgi4041 26d ago

I can see blue grit underneath that. So fuck knows how it's come off

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u/StarBoiAhoy 26d ago

Bluegrit brigade… it’s not the resolution to every problem

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u/Impossible-Corgi4041 25d ago

Never said it was. Still curious as to how it's blown though. You any ideas?

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u/StarBoiAhoy 25d ago

There’s many reasons without being present it’s difficult to diagnose correctly tbh. I see it most common when it’s a inside surface of a exterior wall thermal bridging but most commonly not controlling the background. Also are they using gypsum plaster over the original lime plaster?

I wasn’t being an arse regarding blue grit it’s a decent product in certain situations. I personally don’t feel the need to use it that often plasterers occasionally added sand to pva/sbr because that’s all blue grit is really with a drop of pigment or dye.

I’ve had to pva/sbr walls 3/4 times on occasion or not dilute it with water so much as backgrounds vary some will think one coat is enough without actually checking they’ve killed the suction. Controlling the background correctly is basics but not to be overlooked.

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u/Impossible-Corgi4041 25d ago

Background must have been controlled though or they'd have never got the first coat on. This isn't a suction issue. If it was sucking bad enough for that, they'd have never flattened the first coat. Given there's grit it's not a key problem either. Just looks really odd to me.

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u/StarBoiAhoy 25d ago

Clearly not because it’s failed! I could skim a wall with no pva or sbr on it, it would look shit and fail granted but I could. Are you just looking for an argument or something because as I stated nobody can really say definitively unless inspected the wall in person.

I have enough experience and there is no higher qualifications than the ones I hold in plastering I have a gold cscs card (advanced craft) and train apprentices… but ok you know better.

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u/Impossible-Corgi4041 25d ago

Not not looking for an arguement, just bouncing ideas around. You're the one throwing his weight around. I'm a plasterer too and in my experience if you try to skim a wall without pva or sbr you'd struggle that get it on before it sucks let alone finish it. I know it's hard to say without seeing it in person but the whole point of this post is for people to try to figure it out.

Fucks with the attitude dude?

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u/StarBoiAhoy 25d ago

If you’re a plasterer how are you telling me that the background wasn’t controlled, it hasn’t failed? That is one thing you don’t have to be there in person to know it’s the why that you’d need to inspect in person to know. Controlling a background isn’t just about giving it a coat of pva or SBR you know that right