Right about now I became tired of constantly waiting for the mason to plaster our small toilet, which is barely 3 square meters.
I've tried to find out how to do it and have a decent understanding. I'm quite handy but have never plastered before.
My first question is how thick should the plaster be? I'm thinking mainly about the thickness of the slats you "saw" against. And which plaster should I use? There is some plaster remaining on one wall and the house was built in the late 60s. Is it C-bruk that should be used?
And my last question, can one figure it out?
I've tried to find out how to do it and have a decent understanding. I'm quite handy but have never plastered before.
My first question is how thick should the plaster be? I'm thinking mainly about the thickness of the slats you "saw" against. And which plaster should I use? There is some plaster remaining on one wall and the house was built in the late 60s. Is it C-bruk that should be used?
And my last question, can one figure it out?
If you haven't plastered before, use gypsum plaster, incredibly easy to work with and to get a good finish, even for a beginner. However, this shouldn't be used in areas with high moisture levels, but since it's a toilet, there should be no issues with moisture. If you have a shower there, it is not recommended. I used Weber's grey variant.
http://www.finja.se/App_Resource/Page/file/betong/gipsputs.pdf
http://www.finja.se/App_Resource/Page/file/betong/gipsputs.pdf
If it needs to be waterproofed, check that your variant of gypsum plaster is okay, otherwise agree that it's incredibly easy to work with. Unfortunately, it's a bit of a detective work to find a gypsum plaster that is recommended directly from the bag on lightweight concrete, the standard formulation seems to be to "contact the manufacturer when using on lightweight concrete". Lightweight concrete has a tendency to absorb water from the plaster, so keep in mind to follow instructions that sometimes involve pre-wetting the lightweight concrete thoroughly or using something primer-like to prevent the moisture from being absorbed.
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As mentioned, read the product description; if you're using finja, primer is required beforehand on absorbent surfaces; for combimix, primer is required on non-absorbent surfaces in certain cases, knauf gypsum plaster primer again, etc. The only general rule is probably to stick to the product description for the surface you're working on.
Finjas gypsum plaster should be primed when plastering on NON-absorbent surfaces - absorbent surfaces should be pre-watered:
Quote page 2:
"If Gypsum Plaster is to be used on non-absorbent materials such as concrete and painted surfaces, the surface should be pre-treated with FinjaGipsprimer. When plastering on absorbent material the surface should be pre-watered."
Quote page 2:
"If Gypsum Plaster is to be used on non-absorbent materials such as concrete and painted surfaces, the surface should be pre-treated with FinjaGipsprimer. When plastering on absorbent material the surface should be pre-watered."
I have done the same exercise multiple times... Have used both Finja and Hornbach plaster.
I bought a sprayer that you pump pressure into (plant watering thing) and spray on the wall first. Make sure it gets damp but not so that it runs. Mix the plaster while the water absorbs for a while (preferably outdoors since it creates quite a bit of dust).
Do not mix too much at once because it starts to set quite quickly, especially before you get used to it!
The consistency should be such that you can place it on a plastering board or putty knife and hold it upside down without the plaster falling off or moving. However, it's better to have it a little too loose than too stiff!
Have a drop cloth on the floor or some board to protect the floor.
I have used both a plastering board and a large putty knife but find it easier to get it even with a putty knife. You don't have to do the whole wall at once, but if you stop in the middle, make sure to "comb" any underlying plaster if you're going to apply another layer.
When the plaster has dried for a while, about 20-30 minutes, and it feels damp and slightly hard, take a "rubber float" (I think that's what it's called, a plastering board with rubber underneath) and moisten the plaster again with a little water from the sprayer and gently stroke the surface with the rubber float to make it smooth. Be careful not to press too hard and water more if it dries out too quickly.
If it's not completely even, you can apply a little wet room filler afterward... no need to be embarrassed the first time you plaster...
Best regards,
Anders
I bought a sprayer that you pump pressure into (plant watering thing) and spray on the wall first. Make sure it gets damp but not so that it runs. Mix the plaster while the water absorbs for a while (preferably outdoors since it creates quite a bit of dust).
Do not mix too much at once because it starts to set quite quickly, especially before you get used to it!
The consistency should be such that you can place it on a plastering board or putty knife and hold it upside down without the plaster falling off or moving. However, it's better to have it a little too loose than too stiff!
Have a drop cloth on the floor or some board to protect the floor.
I have used both a plastering board and a large putty knife but find it easier to get it even with a putty knife. You don't have to do the whole wall at once, but if you stop in the middle, make sure to "comb" any underlying plaster if you're going to apply another layer.
When the plaster has dried for a while, about 20-30 minutes, and it feels damp and slightly hard, take a "rubber float" (I think that's what it's called, a plastering board with rubber underneath) and moisten the plaster again with a little water from the sprayer and gently stroke the surface with the rubber float to make it smooth. Be careful not to press too hard and water more if it dries out too quickly.
If it's not completely even, you can apply a little wet room filler afterward... no need to be embarrassed the first time you plaster...
Best regards,
Anders
I have plastered with plaster mortar (indoors). The first round of plastering was done with masonry and plaster mortar. It was harder to get good. So then it was pure plaster mortar. It was easier to apply.
The important thing is to moisten the lightweight concrete before plastering. As soon as it becomes difficult to get the mortar to stick, spray lightly with water using a pressure sprayer/hand sprayer/plant sprayer on the wall where it is to be plastered.
The important thing is to moisten the lightweight concrete before plastering. As soon as it becomes difficult to get the mortar to stick, spray lightly with water using a pressure sprayer/hand sprayer/plant sprayer on the wall where it is to be plastered.
The last round I did on lightweight concrete, I used thin joint mortar. Not as easy to work with as gypsum plaster, but due to the risk of moisture, gypsum plaster was ruled out. It feels like thin joint mortar is a bit more tolerant of the absorbent lightweight concrete, even though you still have to pre-water properly according to the instructions.
I am going to lay a wall of Ytong with an A-mortar and then reinforce and plaster with a B-mortar.
Does the wall need to be pre-watered before the A-mortar?
Is primer perhaps preferable? Does anyone know?
Does the wall need to be pre-watered before the A-mortar?
Is primer perhaps preferable? Does anyone know?