Plastering is a huge subject but one part that is essential is the art of rendering a wall. Learning to render is one skill that is totally different to internal plastering and it plays by different rules. However, it can be extremely rewarding if you stick to this guide
In this article we’re going to walk you through the whole process and show you how to render. This is a beast of an article because there is s lot discuss by the here’s the main sections:
- The process behind rendering a wall
- The mix and materials you’ll need for the job
- A list of tools and equipment you will need to use
So here’s what you’ll learn in this article but first let’s discuss the tools you’ll need to start rendering.
Tools You’ll Need For Rendering
Before you start anything we need to make sure you have the right tools. You don’t see artists playing with Crayons and it’s the exact same with Plasterers. We need the right tools!
So here’s a list of tools you’ll need for the job:
- Straight Edge (I prefer the Featheredges)
- Urethene Float
These are the tools you will need! You could use more but this is the essential list of tools and you can’t miss any of these. You’ll need them all. Next up is making sure you have the correct mix!
Mixing Your Render
The most crucial part of rendering is making sure you get the mix right. This is essential! It’s never hard to achieve but ratios are critical and If you get the mix’s wrong then you risk ruining your wall.
For example if your finish coat is stronger than your top (more cement than the scratch), then the finish coat will actually crack. We’ll go into this in detail but what you need to understand is that your mix affects everything.
But before we start we have 2 main stages to rendering. We have:
- Scratch Coat
- Finish Coat
You always have 2 coats of render.
The scratch coat is the foundation of the render and the base to the whole product. This provides strength to the wall but also has the most amount of waterproofing. This is what keeps your building water tight and stops any moisture from getting through into your house.
The finish coat adds thickness to the render but is purely aesthetic. This is where you need to focus on getting your wall flat, straight and looking good. This is where skill comes in.
The scratch coat is easy.
The tough part is making sure that your house looks lovely and desirable from the outside. People are very materialistic so our job is to make the render look like a million dollars. But before that we need to get the mix right!
So here goes. The materials we’ll need are below and then I’ll list the exact measurements we need for each coat.
Materials For Rendering A Wall
We’ll need the following:
- Plastering Sand (make sure it’s plastering sand and nothing else)
- Water Proofers
- Feb Render Mix
- Hydrogenated Lime
This is what you’ll need for the job. It’s quite a cheap process compared to these other products like K-Rend and Stow’s Acrylic render but you need to get the mix’s right.
When Im working, I gauge everything from a standard 12L bucket. I pour everything into the bucket and use this to measure the exact mix I need. And as we mentioned we need to make sure that the scratch coat is stronger than the finish coat and not the other way round.
However, you don’t need to worry about that as long as you follow the measurements then everything will be fine! Here it is:
Materials For Scratch Coat
- 4 buckets of plastering sand
- 1 bucket of cement
- Waterproofers (instructions on the back. They all vary for different companies but just make sure you put enough in)
- Roughly 3 quarters a bucket of water
That’s literally all you need for the scratch coat. The only thing that isn’t a constant is the water. If your sand is wet than it will need less yet if your sand is dry then it may need more.
This is why rendering can be tough because it’s never constant. What I suggest is that you add your water to the mix slowly. Here’s the process I follow when I’m mixing.
- Alway start with some water in your mixer
- Add one bucket of sand
- If it’s dry add more water
- Add your second bucket of sand
- Check for water (you want it quite runny at this stage)
- Add Cement and leave it to mix for a while.
- Check for water. Add more if you need
- Add your third bucket of sand and let it mix
- Check for water (don’t have to too wet now)
- Add final bucket of sand and slowly add water until the mix is just right
This is the process you want to follow. The video below shows what you mix wants to look like. You don’t want it too thick yet you don’t want it too runny either. With time you’ll find your preference but it just takes practice.
The video below shows the perfect mix consistency:
Now here’s the mix for your Finish coat
Materials For Top Coat
- 5 buckets of sand
- 1 bucket of cement
- Half a bucket of Lime
- Feb Rendermix
As you can see there’s more sand which makes the mix weaker. We’ve also added Lime which makes the mix creamier and gives the render flexibility which helps it deal with movement in the building. It also helps with the sea air if you live near the coast.
Finally we have the Feb Render mix. This is a great product. It has water proofers engrained in the product but it also has plasticiser which makes the mix creamy and nice to flatten later down the line.
It’s a gem.
So that’s the mix; that’s one thing you need to follow with strict accuracy. However, if you follow these instructions you can’t go wrong. So we have our tools and we know how to mix the render. Now it’s time for the process
The Process Behind Rendering A Wall
There is a process you need to follow when you’re rendering a wall. It has a specific order and you need to make sure that you follow each step. It’s not complicated but its essential all the same.
So here’s the full breakdown on how to render.
- Apply the first coat of render
- Scratch the first coat
- Wait a day to allow the scratch coat to dry
- Apply the top coat of render
- Float it when it’s gone touch dry
- Sponge finish shortly after floating
This is what you need to do when your rendering a wall. Now here’ s a brief summery but if it makes no sense then that’s absolutely fine because I’m going to break down each section and explain it all in detail.
And it all starts with applying your render but to help you visualise the whole process here’s a video where I walk you through the whole thing. Watch it below:
Applying 1st Coat Of Render
The aim of this stage is to get the 1st coat of render onto your wall. It isn’t rocket science but there are a few things to consider. For example, the first thing I do before I apply the render is to give the wall a light spray with water.
This creates a bit of a key for the render to stick to. If you render directly onto a dry masonry background then the render may not stick and eventually weaken due to a soft grip. So always give your wall a light spray of water.
The other thing you need to consider is how you apply the render. Obviously, you want to take the plaster from your Hawk onto your trowel and from there you can proceed to apply the render to the wall.
However, you need to make sure that you’re applying enough pressure to the render as you spread it. You can’t just trowel it onto the wall. you need to really push the render into the surface with a firm amount of pressure. This provides a strong bond making your render tough and solid.
The final thing to consider when you applying your render is to avoid playing with it. You simply want to apply your render, flatten it a little bit and then leave it. If you overtrowel the render then something sinister can happen.
You can actually weaken the strength of your wall. When you trowel sand cement/ render you bring the moisture from the back of the render to the front which makes the surface shiny. This doesn’t seem like a massive problem but unfortunately it is.
This takes all the moisture from the back which makes the render pull from your wall. It weakens the grip and makes the render “Drummy”. This basically means that your wall will sound hollow when it’s finished.
This isn’t good. This compromises the strength of your render which will eventually crack. So apply your render, flatten it a little bit and then leave it. Don’t play with it!
Just let it dry and do it’s thing! I usually render a a small section at a time ready for the next step which is…
Scratching Your Base Coat Of Render
This is a very simple process but critical all the same. When you’ve applied your first coat of render you need to scratch it with a tool called a Plastering Scratcher. This is very simple and extremely easy.
We are basically providing a mechanical key for your 2nd coat of render. If we didn’t do this then the top coat of render wouldn’t stick and would slide down your wall. This key allows your render to stick and gives the render something to grip to.
It’s very easy but I would recommend to render a section at a time and scratch it as you go. If you wait too long then the render will dry and it will be tougher to get a decent key into your scratch coat.
That’s why we always called the first coat of render a scratch coat because we scratch it (pretty obvious ay!). I’ve created a quick video showing you how to do it:
Now we let the scratch coat dry and usually leave it for at least one day. Then it’s time to move onto the next step which is applying your top coat of render.
Applying Your Top Coat Of Render
This isn’t to much dissimilar to applying your scratch coat. Actually it’s the exact same process. Give your wall a light mist of water, apply your render with lots of pressure and make sure you don’t play with it.
This is the general rule of thumb and there’s not much difference from stage 1. The one thing I will say is that if your working to corner beads then I often apply the render slightly thicker than the beads.
This is because when it comes to the next stage of rendering (ruling the render), then you won’t have to constantly be reapplying render to the low spots. If you add a slightly thicker coat then it’s going to be a lot easier for the next stages.
Trust me, its saves a lottt of time and effort.
And that’s what its all about. So keeping to the same rules as stage 1 but just make sure you add a bit more render than you would usually. The other thing to reinforce is that your not expected to apply the render flat.
You won’t do it! Thats where the next stage comes in which is ruling your work.
Ruling Off When Rendering A Wall
This is the part where we start getting the render flat. This part is crucial and this is where we start using the trusty Featheredge. This is basically a lot, straight piece of metal designed to flatten plaster and render.
The way it works is that you scrape the excess render off the wall using your straight edge. This takes the render that isn’t needed and makes the remaining render nice and flat. It’s quite a skill but with time you can get your walls perfectly flat using this process.
So here’s how it works
- Apply your top coat in sections
- Whilst it’s still wet, deploy your Featheredge
- holding the Featheredge flat to the render scrape any high spots.
- Starting from the bottom, pull the straight edge up your rendered wall
- You will notice sections that haven’t been effected
- Apply more render to the low spots and fill any missed areas.
- Deploy the Featheredge again and continue to flatten the wall
- Repeat until the whole area has been flattened
If you follow this process then you will have a flat rendered wall. However, you will notice that the render will look extremely grainy and it may even have a few lines where the render has dragged due to the process of ruling.
This is normal. Don’t panic! The main aim of this stage is to get the wall flat and as I said, it does take practice. But it is a skill that can be perfected.
Once its flat and the whole area has been ruled continue onto the next section of your wall and repeat the whole process until your wall has been covered.
Then make yourself a brew and wait. You’ll need the render to dry slightly ready for the next stage:
Floating The Render
This is one of the most important stages to rendering because this is the time where you fill any holes whiles getting your render FLAT. It’s quite a dark art and it does take some practice. however, if you follow our guidelines there’s no reason you can’t master the art of floating.
The principle is simple. The float flattens the render by removing any high spots whilst filling in any areas that have little to no render. It’s ingenious really and whoever came up with this trick is a living legend.
First off, let’s talk about your weapon of choice which is the float itself. I recommend you buy yourself a Plastic Float at 11IN X 4.5/16IN which you can buy from the link here. This size is perfect, (especially for beginners) because they are so much easier to use compared to the bigger sizes.
I also find they provide better results.
However, before you start I recommend that you rub the new float up and down a concrete block until the texture has worn down. This helps to “break in” the float before use which makes it 10 times easier. Trust me, you’ll thank me because this makes a HUGE difference when you’re using it.
So thats the tools and the prep but how do we do it?
How To Use A Float When Rendering A Wall
This is where the funs starts and where the skill lies when you’re rendering a wall. Before we begin, you need to make sure that the wall has dried. You will never be able to render a wall whilst it’s still wet – it needs to be solid before you can start floating.
So make sure that its tough to the touch. You don’t want it to be completely dry but you do need it to firm. If you push it still holds it shape then your good to go.
The best thing is to test it. So if you feel it’s a good time to start then give it a try. You’ll find 2 things will happen:
If it’s too soon you will notice the render move and you may even pull some render off the wall as you’re floating. This is a big no go. If this happens leave it to dry and try again later.
The second scenario is that the render will move with the float but in a more positive motion. You’ll be able to apply pressure without worrying about pulling the render off and any areas that have little holes will start to fill with your movement. This is what we want!
The low spots will start to fill and the rough texture will become uninformed. This is where the render takes shape and one of the biggest things is getting your timings right. The process is simple.
All you have to do is hold your float flat to the render. Don’t tilt it, just hold it flat to the render and slowly start to move the render in small circular motions. If you time it right you’ll find that you can apply pressure and you can almost srub the render into shape.
This is what we want. You’ll notice you wall start to look consistent and this is where the wall starts to take shape.
If it feels like the render has dried too much, don’t panic. You can give the wall a light spray with water and when it comes to floating you’ll find the sand cement come back to life. It’s amazing because unlike our tradition finish plaster, this can be sprayed and reignited.
It’s magic really! SO if it is too dry to threat because you can always bring it back!
Follow this whole process until the wall in floated. Then we are ready for the final stage of rendering…
Finishing The Render – Sponging!
This is the last and final stage to rendering and this is where we get our finished texture. All you’ll need is a fresh bucket of water and a sponge. I like to use the big sponges that people buy to clean their cars with. I always find they give the best results when you’re rendering a wall.
Take your sponge, dunk it in the clean water and drain all the water out until it’s damp. We don’t want it soaking, we just need it damp. Otherwise, you’ll bring the sand cement back and the water will foam the render.
Then you take your damp sponge and gently rub it in circular motions. Again, hold the sponge flat to the wall and gently rub the render until the sand comes to the surface. If you’re doing it right, you’ll see the aggregate in the sand form a lovely texture.
This is what your typical sand cement render will look like. When you sponge starts to leave little lines clean it off in the clean water and start again. The is probably the easiest part of rendering because all your doing is rubbing the wall to get a lovely soft finish.
The trick here is to always keep your sponge clean!
The softer your touch, the smoother the finish. The trick is to be really soft with your grip. If you’re heavy handed you’ll notice lines in the render. this is where you’re pulling the sand on the surface – if you’re soft handed you’ll only see the aggregate rather than lines following behind.
This is where you truly master sponging. And if you’ve come to this stage you have officially rendered a wall!
This is a lot to take in and I understand that there’s a lot to learn. It’s a huge subject to follow and I know that some of this might not make much sense to you. However, knowing the process is one of the biggest things in rendering a wall.
Most people wouldn’t know where to start! At least you can officially say that you know the process and if it came to testing, you’d know where to begin.
So thats that!
If you want to find out more about plastering visit this link and discover the ultimate guide to plastering a wall.
Otherwise have a look around our site for more information on plastering. Thanks for reading!