Do you have uneven brick or concrete walls? Or are your walls and ceilings at a place where traditional plastering won’t work out like exteriors?
Whatever the case is, if you’re looking to use cement products, like polymer and fiber modified, this article is for you. I use these a lot when I’m working outside so I’ve decided to “put it on paper”.
You can also cement plaster interior walls like you would be rendering outside. It’s not often preferred as it’s hard to sand and most want to work with easier to handle products inside. Imagine sandpapering concrete slab. Still, it’s possible.
If you’re thinking of alternatives to plastering a wall, there are also drywalls for interiors and other boards to exteriors like cement boards. If you’re looking for how to smooth a wall without plastering or an alternative to plastering a ceiling, these can work out too.
Now, to move on to cement plastering, or rendering in other word.
How to prepare a wall for plastering
Plastering old walls is a form of art. If it’s indoors, the walls will be only as hard as the surface they adhere to. If you have an old brick wall or concrete wall with plaster on it if it’s lose it needs to go.
Here is a guide for removing plaster from those surfaces.
Cement plaster mix is made out of sand, cement, and water to simplify it. That’s why it’s usable both inside and outside and it’s durable against weather and once it cures, it makes a really hard surface.
The cement plaster mix ratio can be different from one surface to another. If you do it yourself, 1:4-5 cement to sand will do it for bricks as it’s close to mortar mix and 1:4 would be for outdoors work. The less cement you have, the softer it will be.
To be honest, for me it has been really rare to mix it myself. Only building facades that are done traditionally have been done like that. Most of the time the render mix has been delivered on ready mixed bags. That’s also the easiest to get for households.
Cement plaster is a surface I’d not be sanding so that is out of the picture in this guide. So let us move on to how to plaster a wall with sand and cement then.
Cement plastering work
Cement plastering work is different from plastering in a way that the wall will have to be good when you do the final layer. I mean, you have to get the surface level and smooth. So it involves spreading the cement plaster and also floating it smooth.
Cement plaster finish
The floated cement plaster wall finish can be done in multiple ways. If you want texture, go wild and do it with different methods like spraying with a hopper gun or making marks with a notched trowel. The world is yours.
If you want it smooth, you need to float it. You can’t float the cement plaster straight when you spread it, it needs to start to cure a bit.
When you can touch it without leaving deep finger marks or it starts to turn grey a bit, it’s time to take sponge float, water it, and start doing circles with it on the wall.
If the cement plaster starts to roll with the float, it’s too soon. You should be able to press it gently while you float without it rolling with the sponge.
Other kinds of floats work the same, but you might need to water the wall or ceiling with something like a pump sprayer/garden sprayer to get the surface moist for floating.
How to plaster a damaged wall
How to plaster a hole in the wall? If the hole is big, you don’t. You get a rough patching compound or make it whole like it was built. For small holes, everything goes.
You can’t do fine plastering before you fix the damage on your wall. Small holes and big holes will need to be fixed with cement compounds made for that purpose, like polymer fiber cement mixes if it’s concrete.
If it’s brick wall, get some bricks and mortar for big holes. Try to fix it so that it’s level with the rest of the bricks so you don’t need to grind it level.
When you’re done with the fixes, it’s just like plastering any of the following walls. Here is also guide on fixing holes on plaster walls.
How to plaster a brick wall with cement
With the basics out of the way, it’s time to get to how to plaster a wall with cement plaster in different situations.
How to prepare a brick wall for plastering
Check if the surface of the bricks is smooth or rough. If it’s smooth, it should be roughened a bit so the cement plaster adheres better.
Make sure it’s clean of dust and that it’s level without anything sticking out of it like screws or mortar. If there is, use proper tools to remove them.
After that, you want to make it level. You can do the first layer of cement plaster horizontally spreading it with the trowel. Leave it to dry and when it has cured a bit, go through the high parts with the float.
Next, you need to do the second layer vertically. This way the little low parts you get from spreading the render and also little uneven spots on the brick wall will be filled.
Before you apply any cement plaster, wet the walls with water so they won’t suck all the moisture out of cement plaster. It will help you have more working time and the cement plaster will cure harder
This is the surface you will float so do it carefully. Depending on how big the wall is, you might have to leave the spreading of cement plaster to float if you don’t have a partner. If you have an able guy helping you, you’re good to go fast.
After you’re done, water the walls for 3 days or what the manufacturer label says.
How to plaster a block wall with cement plaster
How to plaster a block wall is the same kind of process as a brick wall. The walls need to be straight so you probably will have to do it twice like the brick wall. Some wizards get these straight on install, but there are many who don’t.
The thing with both of these is that there can be a lot of uneven spots and some can be quite big. These kinds of things should be patched first so you won’t have to do inches of filling with the cement render, even ½ inch is a lot with most products and the best would be ¼ layer.
Again, it’s good to check manufacturer label on what can be done. If you do the cement sand mix yourself, you can make a mix that can handle a lot of filling.
How to skim a wall
If you don’t enjoy the look of floated walls indoors for some reason, you can always skim the wall on top of the cement plaster. It’s a thin coat of drywall finish and you can use it here as well.
Basically you take your trowels and do it on top of the old wall or your cement plaster and make it look new again.
For more decorative ways, check this guide on doing Venetian plaster walls.
I hope these cleared how to plaster a wall with cement plaster. The ceilings work in the same way, you just have to work upwards.
Personally, I like working with the polymer fiber cement renders as they can fill a bit, don’t crack that easily because of the fiber and they make a fine-looking floated surface.
Other kind of mixes work as well, good worker won’t blame the product, but updates their skills to match them.