Ok, so it’s pretty widely accepted that plastering is just about the one job that is best left to the professionals – let’s get that out of the way from the off. Even my mum, who has absolutely no DIY experience whatsoever, told me that plastering probably isn’t something I should attempt (I actually think she learnt that from DIY SOS!).
Why is it best left to the pros?
There’re a few different reasons why plastering a wall is a big challenge for the DIYer. There are some important concepts to understand about the speed at which the plaster goes off (dries, to you and me). Plastering for the DIYer is essentially a race against time, and how much time you have is determined by how quickly the plaster will dry on you. Various factors can effect the speed at which the plaster will dry, some are controllable (to a certain extent) such as the suction of the wall, whereas other factors you will have to work with, such as the weather/humidity.
Why does it matter how fast it dries?
The stages at which the plaster dries will determine when you need to proceed to the next stage of the plastering process. A DIYer will almost definitely be a lot slower than a pro plasterer which means by the time you’ve actually finished putting your first coat on, it could have firmed up too much to flatten it in, meaning you’ll be left with ridges and trowel marks that you’ll have to work harder to remove. Also, if the plaster dries too much before you’re getting the second coat on, it won’t bond with the first coat as it’s meant to.
There are other reasons why plastering is a tough DIY job:
- Mixing the plaster to the right consistency is not as easy at it looks.
- There is a high level of skill involved in successfully getting the plaster from the hawk to the right part of the trowel.
- Theres is a high level of skill in getting the plaster from the trowel to the wall.
- There’s an even higher level of skill in making sure the plaster is applied to the wall flat.
- It’s hard work! Plastering is one of the toughest trades of the lot.
Most people would read all of the above and be sufficiently convinced that plastering is best left to the time served experts. But there’s also a select group of people (myself included) who would read the above and it just makes them want to try it even more.
For me, it’s not about saving money. There’s something about plastering that is very appealing. Firstly, with it being so widely recognised as such a tough skill, there’s immense satisfaction on offer if you can actually pull off a flat smooth finish (as difficult as that might be!).
Secondly, it’s therapeutic, especially once the plasters on and you’re into the flattening in stages. Winston Churchill used to find bricklaying therapeutic and satisfying and this is a similar sort of thing.
Thirdly, I like the praise and how much it impresses people when I tell them I plastered the room!
My DIY plastering journey
My first foray into DIY plastering was filling in some chasing out I did whilst raising some plug sockets. I first applied some bonding to fill in the chases leaving 2mm from the existing skim and then went over the bonding with PVA and then with multi finish. I remember spending ages smoothing this small area to try and get as good a finish as possible. Applying water from a spray gun to work it a little more. I was so chuffed with the result and I was fired up to do more.
Knowing that plastering a wall is a different kettle of fish, I decided to learn as much as possible about the process and how to approach it. I’ve probably watched every plastering video that’s ever been uploaded to YouTube and I also pressed a local plasterer for knowledge as well.
Most of the videos and advice is from the professionals, which is obviously very useful but I would also have liked to read more accounts from DIY plasterers who decided to give it a go. That’s why I’ve decided to write up my experience from plastering 6 walls and a ceiling.
Here we go.
DIY Plastering Tools
Having good quality tools will make a difference to the finish you achieve. To plaster a wall you’ll need:
Hawk: do not be tempted by a plastic hawk. Bits of it will come off and end up in your plaster and it’s hugely frustrating.
Trowel: you need a good quality trowel, preferably one that’s been worn in. I regularly looked on eBay for a used, worn in Marshall Town trowel because the edges would have been nice and sharp. I eventually bought a pre-worn Marshall Town rowel from ScrewFix and sharpened it myself.
Bucket trowel: used to get the plaster from the bucket onto your hawk.
Buckets: you need a sturdy bucket to mix the plaster in. Plasterers buckets are tall and narrow and are definitely the easiest to work with.
In addition to the bucket you mix in, you’ll also need two additional buckets full of water.
Paddle mixer: you need something motorised to mix the plaster with. If you’re patching you might get away with manually mixing the multi finish but if you’re plastering a wall, you’ll need help. I picked up a cheap paddle mixer from ScrewFix and it’s been a dream.
If you have an SDS drill, you could add a mixer to that. I have tried mixing with an electric drill but it started smoking after a few mins!
Plaster: there’re various types of plaster available depending on what you’re plastering. Thistle Multi Finish is probably the most common and suitable for nearly all skimming jobs. I would recommend using multi finish but you could look into plaster that’s easier to sand down if you’d prefer to have that option as a safety net.
It’s crucial (as a DIYer especially) that you make sure the plaster you buy is well in date and hasn’t been opened. Similarly, it’s also important that you close any half used bags properly and store them as instructed. Out of date plaster or plaster that’s been opened will go off much faster, leaving you less time to get it onto the wall and flatten it out.
Scrim tape: a self adhesive fibre mesh tape that you’ll apply over weak areas that are prone to cracking, such as corners and the joins where plasterboard buts together.
Paint brush: a good sized paint brush is needed for corners and for flicking water on the wall to liven the plaster up when trowelling.
Kettle: if you’re lucky, you’ll get a couple of nice breaks in between trowelling so have a brew. Unfortunately, I can’t do that because for some reason I can’t bring myself to leave the plaster.
Angle beads: angle beads will give you nice crisp, sharp corners.
PVA: PVA glue helps you control the suction of the wall you’re plastering onto.
Preparation is absolutely mission critical. I’d heard this time and time again whilst doing my research and never really gave it the attention it deserved. After all, preparation is boring, I just want to get on a plaster the wall.
Preparing to skim a wall is mainly about three things – ensuring the wall is flat, ensuring there’re no raised parts to the wall and controlling the suction.
Ensuring the wall your about to skim is flat
Get a straight edge such as a long spirit level or long straight piece of wood and hold it up to various parts of the wall to see how flat it is. If you notice big hollows (more than 2-3mm) or you notice the wall isn’t flat, it’s worth spending some time bonding those areas with Thistle Bonding. You apply the bonding and the use you’re straight edge to run over the bonding, ensuring it’s flat.
Small undulations are ok.
I was always of the impression that you could skim over anything and it’d be fine but if the wall you’re skimming isn’t flat, it will be nearly impossible for the DIY plasterer to get a flat finish. You need to make your life as easy as possible because it’s a tough enough project as it is!
Checking for raised parts and other debris
Have a look for anything on the wall that might get stuck in the plaster or is raised. If it’s an old wall and you’ve taken the wall paper off, you might find some old bits you’ve missed. If you’ve got plasterboard screws, make sure they’re not protruding. Screws should be sunk into the plaster board without breaking the paper.
If you’ve removed the skirting, check the nails or screws used to fix it are removed. Our skirting was fitted to wooden blocks sank into the masonry and I removed these prior to skimming in case they moved and cracked the plaster. I filled the hole they left with sand and cement.
Give the walls a brush down if they’re particularly dusty.
If you’re plastering over old walls make sure the existing bonding is sound. If you give it a tap and it sounds hollow, it usually means that part of the bonding is no longer adhered to the wall. Ideally, this should be carefully chipped out and filled with fresh bonding. If the majority of the wall sounds hollow, it’s time to consider taking the whole thing back to brick and re-bonding. A messy job that I did 3 times, but it’s the right thing to do. Skimming over blown plaster is risky and not worth it. Take it back to brick and either dot and dab some plasterboard onto the wall or bond it out (which is the more traditional way of doing it, but takes longer and is more skilful).
Controlling the suction
If you’re skimming over an old wall or even a new wall that’s been bonded out, you need to get a grip of the suction. What this means is that you need to control/reduce the rate at which the surface draws the moisture out of the plaster. If you don’t do this, the wall your skimming will draw all of the moisture out of the skim which will leave it prone to cracking and it’ll also go off on you like a rocket. This gives you much less working time and you run the risk of the plaster setting before you get chance to flatten it in and trowel it.
You can significantly reduce the rate at which the wall draws moisture from the plaster by adding a coat of diluted PVA to the wall before you plaster it. Mix 1 part PVA to 3 parts water and apply a coat the wall the night before you plan on plastering it. Do the same again before you mix up your plaster which will mean the PVA solution will be tacky on the wall when you begin to skim, this is exactly how you want it.
The PVA and water mix will create a barrier and leave the water in the plaster.
If you’re skimming onto plasterboard, there’s no need to apply PVA.
Adding corner beads
Corner beads allow you create sharp angles easily. You can use them on any external corners and around window reveals. They’ll need to be cut to length with some tin snips and stuck on with blobs of skim. Apply blobs of skim around 300mm apart on the corner you want the bead on. Push the bead into the corner and use a spirit level to ensure the bead is straight. Hold the bead for a few minutes until the skim hardens a little and then scrape away any plaster that’s pushed through the holes.
The plaster will go off quickly and the bead will be stuck in place ready for you to plaster up to it.
Adding scrim tape
Self adhesive scrim tape should be applied over any joints, cracks or weak points on the wall. It’s also worth adding some tape to any areas that you missed with the PVA.
Scrim tape will ensure that weak areas are less likely to crack so it’s worth making sure you get this part right.
If you need to bond any areas out or fill any gaps, it’s best to apply the scrim tape before doing this work. If you do the bonding and apply the scrim tape on top, it’ll be less effective.
Mixing the plaster
You’ve prepped the wall, you’ve got all your tools sorted and you know what you’re doing.
We’re about to start mixing the plaster so things are about to get serious.
For British Gypsum multi finish, the recommended amount of water is 10.5 litres to a 25kg bag. For a DIY plasterer, I think 11.5l to a 25k bag is better but it’s important to get used to eye balling the consistency for yourself and deciding when it’s a good consistency.
There are many different guides which try and give you an idea of the thickness for your first coat of plaster. Here are the ones I’ve commonly heard whilst researching:
- Thick cream
- Thick yoghurt
- Melted ice cream
- Loose mashed potato
- Angel delight
- Raw meringue
For me, melted ice cream was the one that resonated most. Of course, you could melt ice cream down to almost a liquid state, which isn’t what we want. But when I think about melted ice cream it’s still quite thick and you can form peaks with it. This is the consistency that you’re after.
Other tips I’ve heard include mixing it until you can form around a 1inch peak when you lift the mixer out.
Some people recommend mixing until you can turn the bucket trowel upside down without the plaster falling off but of course, you could over mix it thinking like this. Some people also suggest mixing until you get to a point where if you put your bucket trowel sideways, only half of the plaster falls off.
What you really don’t want to do is mix the plaster too thickly, which is a common thing a DIY plasterer will do because the plaster is easier to work with. Whilst the plaster will be much easier to handle on your hawk and trowel and easier to apply to the wall, spreading it flat will be more difficult.
Ideally, you want the plaster as thin as you can handle because it’s easier to spread thin plaster flat.
Once you’re happy with the mix, it’s time to get it on the wall.
Applying your first coat to the wall
You’ll have no doubt watched some videos on the correct plastering technique so I want to keep this section succinct and to the point. I had a million different things running through my mind the first time I attempted to plaster a wall and it wasn’t helpful.
Remain calm and don’t panic
The first thing I want to make you aware of is that as soon as you start getting the plaster onto the wall, you may start to panic and forget your plan and everything you’ve learned. That’s exactly what happened to me and I went completely off piste. So first of all, don’t panic! You will most likely drop a lot of plaster and it won’t smooth out as you like and there’ll be lumps and holes and the phone might ring. Just take a breath and don’t rush.
Key points for the first coat
1) Your first coat should be around 2mm thick. To be honest, this didn’t really mean a lot to me when I did my first wall. It’s often difficult to see the thickness of the plaster when you’re applying it but still keep this in mind when you’re working.
2) The first coat is really just a base coat and it doesn’t need to be perfect. You want to try and get it on as flat as possible, but don’t worry about smoothness or filling in every last hole and removing every trowel mark, that can happen later.
3) Getting the plaster spread onto the wall flat mainly comes down to consistently running your trowel across the wall at the same angle. You want the leading edge of the trowel around 15mm away from the wall, consistently. Any more than this and you’ll drag the plaster off the wall.
When you first apply the plaster, you’ll have to have your trowel open and as you push the plaster onto the wall, you’ll gradually flatten the trowel to the wall. Once the plaster is on the wall, you flatten it by keeping your trowel angle consistent.
Most videos you’ll have seen will be professional plasterers who can do this very quickly. As a DIY plasterer, you won’t be able to go this fast whilst maintaining a consistent trowel angle, I know because this is a mistake I made. I tried to get the first coat on as quickly as possible and wasn’t consistent with my trowel angle, which led to a bumpy surface. Just slow it down and keep a constant eye on the angle of your trowel.