How to plaster a wall

Plastering can seem like a daunting task for even the most proficient of DIYers, but with the right preparation and guidance, it’s possible to achieve a smooth finish.

To help you get started, we’ve asked plastering expert Ross Stagg, a Which? Trusted Trader, for his expert advice on how to plaster a wall, or just fix holes and cracks in plaster.

Bear in mind that plastering is a physically demanding job and can take practice to get right. If you have any concerns about any part of the job, from choosing the right plaster to plastering round tricky areas, speak to a professional.

You can use Which? Trusted Traders to find a reliable, vetted professional near you.

How to plaster a wall: step by step

In most cases, you'll be plastering over old plaster or new plasterboard. For this, follow the steps below.

If you’re plastering onto bare brick, the steps you’ll need to take are slightly different. For this, jump to How to plaster a brick wall. 

1. Get the room ready

Empty the room as much as possible of furnishings. You may also need to remove radiators, curtain rails and the like. If you’re plastering around electrical sockets or switches, tape over them to avoid plaster getting in, and turn off the electrics to the room. 

Lay down dust sheets to protect floors and any items you can’t move out, and to collect debris. You can also open windows to improve ventilation, but avoid strong draughts, as they can cause plaster to dry too quickly and crack.

2. Prepare the walls

If you’re plastering over new plasterboards, use joint tape over the seams between boards to give you as smooth a base as possible. If you’re plastering over already plastered walls, remove any old wallpaper and scrub and clean them down to remove any loose plaster, dust and grime. Small holes and cracks can be covered with joint tape. 

We suggest checking for any hollow-sounding or loose plaster by tapping the wall – this should be removed before you start, as new plaster won’t bond properly to it.

3. Prime the walls

Apply a PVA adhesive over the entire wall to help the plaster stick. Dilute as per the manufacturer’s instructions, and roll or brush the glue onto the wall. Wait for it to partially, but not completely, dry (it should still be a bit sticky when you apply the plaster). Be careful not to get PVA on any areas that you will be painting, as the paint will not adhere well.

As an alternative to PVA, you could use a bonding agent such as SBR, or a grit-based primer like Febond Blue Grit, which helps plaster adhere to smooth surfaces.

4. Mix the plaster

Pop on a dust mask as protection from the dry plaster. Fill a clean bucket with tap water and gradually add the plaster (don’t add water to the plaster). The manufacturer’s instructions will indicate the correct proportions of water to plaster; 50/50 is common.

Stir until the plaster mixture is smooth and free of lumps, making sure you incorporate any excess dry plaster from around the edges of the bucket. Ideally, use a power mixer on a slow speed to stir, as this will make your life much easier, though it is possible to do by hand. Clean the stirring tools as soon as possible to avoid the plaster drying and becoming harder to remove.

5. Apply the first coat of plaster

Use the plastering trowel to place some plaster onto a plasterer’s hawk board. Don’t overload the hawk board, as this will make it too heavy to hold very easily. 

Pick up a small amount of plaster from the hawk board with the trowel. If you’re right-handed, work from the top left-hand corner of the wall, with even pressure, to spread the plaster firmly onto the wall. If you’re left-handed, you may find it easier to start from the top right. Hold the trowel at a slight angle away from the wall to start with, flattening it to the wall at the end of each stroke. 

Continue working along the wall, filling from top to bottom before moving onto the next section. Overlap each new section slightly with the previous one to avoid gaps. Work as quickly as possible – you can even out trowel marks later. 

6. Smooth bumps and gaps

Let the plaster dry for around 20 minutes, then go over it again with a trowel to smooth out marks and bumps. If the plaster has dried out too much, using a spray bottle to dampen it can help. Use a wet paintbrush to smooth out corners and edges.

This stage is about flattening rather than perfecting, so focus on removing major ridges rather than achieving a polished finish.

7. Apply the second coat of plaster

Mix up a second batch of plaster. This will usually be a bit thinner than the first coat, to ensure a smooth finish – check the manufacturer’s instructions. Before the first coat has fully dried out, apply the second coat in the same way that you applied the first one. 

Some people like to scrape the surface of the first coat of plaster using a devilling float or old kitchen fork before applying a second coat. This creates a rough texture that helps the next layer of plaster stick better.

You might read some advice that talks about ‘skimming’ a wall, which only requires one thin coat of plaster. While it does depend on circumstances, Ross Stagg, of Plastering Stagg in Stockport, a Which? Trusted Trader, recommends two coats of plaster, as this will usually give you a better finish.

8. Smooth and polish

‘The flattening-off stage is the most important part of plastering,’ says Ross. ‘If you don’t get the plaster flat at this stage, then you’ll need to mix up and start the process again.’ He recommends the following multi-step process to smooth out the final coat of plaster:

• Wait till the plaster firms up a little bit, so it’s still wet but doesn’t stick to your fingers. 
• Flatten out the plaster to take out any bumps or hollows. A tool known as a speedskim or xskim can help with this. 
• Use a wet trowel to take out any tiny, final imperfections. 
• Go over with a wet trowel once more, to get the wall feeling smooth. 
• ‘Polish’ the plaster with a dry trowel, to take out any last watermarks and make the plaster feel super-smooth, ready for painting. 

Ross recommends that DIYers consider mixing a product called Extratime Plaster Retarder into the plaster before applying it to the wall. It slows down the plaster setting time by up to 60 minutes, which buys you more time to get a good finish.

Wondering where to buy everything you need to plaster a wall? Check out our guide to the best DIY and decorating shops, according to our research

What tools do you need to plaster a wall?

• Cutting knife
• Devilling float or old fork (optional) – to score the surface of the first coat of plaster before adding a second
• Emulsion roller and tray
• Paddle mixer
• Plasterer’s hawk board – a flat board that holds your plaster as you work with it (plastic is lighter, but a wood board will last longer)
• Plastering brush (or a decent paintbrush will do the job too)
• Plastering trowel – stainless steel is best
• Sandpaper
• Speedskim or xskim tool – this is a wide tool with a long, flat edge, used to level and smooth plaster across large areas

You'll also need:

• Cloth/rags – to clean tools and any stray plaster
• Dust sheets and dust masks
• Joint tape – to cover gaps between plasterboards or any small holes or cracks in old plaster
• Large bucket (for mixing)
• Plaster (hardwall for bare brick and deep holes; board finish for plasterboard or multi-finish for most surfaces)
• PVA adhesive
• Spray bottle

Toolbox essentials: Find out what every homeowner needs in their toolbox, plus which tools can be easily borrowed for specific jobs

How to fix a hole in a plastered wall

There’s no hard and fast way to do this. The circumstances – such as the depth of the hole – will dictate what to use.

‘If it's deeper than 5mm, like when an electrician has chased through to the brick, then you’ll need a bonding coat, or back coat, followed by two finishing coats of plaster,' says Ross. 

If it's a smaller hole – say you've removed some wallpaper and a bit of plaster has come away – then you can just seal it first with some diluted PVA or a water-based sealer like Zinsser Gardz, then patch it with a multi-finish plaster.

Ross offers the following advice: 'To get the patch seamless with the rest of the wall, brush along the patch line a few times with a damp paint brush to feather the edge, and run the trowel along the patch line.' 

How to fix cracks in plaster

As with fixing a hole, there’s no single way to do this. You can use filler, or you can opt for scrim tape (a self-adhesive, fibreglass mesh tape) and plaster. 

'I would scrim tape the crack, then patch it with multi-purpose plaster, as above, but a decorator would just use filler,' says Ross. 'Both are good ways to do it – my way is "proper" and the decorators way would be quick and easy.'

Either way, it's good practice to use a raking tool or sharp knife and chase the crack out to no more than 1-3 mm deep. Then clean the dust out of the crack, and with a precision brush, carefully apply diluted PVA or a water-based sealer called Zinsser Gardz into the crack to seal and prime the area. 

If you're using filler, apply two coats of filler in the crack, then sand once it’s dry. Try the following fillers:

• Toupret – SQUIRREL_TEXT_50027349
• Gyproc Easifill – SQUIRREL_TEXT_50027350 

Alternatively, apply scrim tape over the crack and apply two coats of multi-finish plaster. Use the same feathering technique as outlined above to ensure a seamless finish.

How to plaster a brick wall

‘There are two ways to plaster a brick wall,’ says Ross. ‘The traditional method is to use a back-coat plaster – hardwall, or sand and cement. 

'Or the new, faster method is to dry-line the wall in plasterboard, using an adhesive to stick the plasterboard to the wall.’ 

Whichever method you use, you then apply regular multi-finish plaster over the top. 

How long does it take to plaster a wall?

Assuming there’s not too much preparation required, plastering a wall would take a professional about four hours on average, depending on the size of the wall. A whole room would take a couple of days. For a first-time DIYer, though, it’s likely to take longer, so allow yourself at least three days for a full room.

The time taken for a plastered wall to dry varies depending on several factors, including:

• The thickness of the plaster – a thicker coat will take longer to dry. 
• The humidity of the room – greater humidity will mean a longer drying time. 
• The temperature – plaster will dry faster on a hot summer's day than it will in the depths of winter. 

Generally, you can expect a plastered wall to take a minimum of five days to fully dry in the summer, in good drying conditions, but it could take two weeks or more in some cases.

How can I speed up plaster drying?

You can speed up drying in poor conditions by improving ventilation – use a dehumidifier if the air is damp, and a heater if it’s very cold. Don’t whack the heat up too high, though – around 15℃ is best. If the plaster dries out too fast, it could crack and ruin your hard work. 

You can usually tell when plaster is dry and ready to paint when the whole area turns from brown to a pale pink colour. If in doubt, leave it a bit longer, because painting onto plaster before it’s ready is likely to cause the paint to flake off.

For our expert product recommendations, consult our guides to the best dehumidifiers and best electric heaters.

How to paint a freshly plastered wall

After waiting days or weeks for plaster to dry, you might be keen to slap the first coat of paint on as soon as you can, but applying paint directly on to bare plaster risks the plaster absorbing moisture from the paint, which can cause cracking. 

It’s a good idea to apply a ‘mist coat’ to the freshly dried plaster, which acts as a primer. This is simply a watered-down emulsion paint – roughly a 50:50 ratio of water to paint (it needs to be quite thin). Many white emulsions include details of the best ratio for a mist paint, so it’s worth checking. 

Mix up the mist paint in a clean bucket, then use either a roller or paintbrush to apply it evenly to the plastered area. Leave to dry for 24 hours before applying your top coats.

Getting mist coat ratios wrong can risk them failing. Ross recommends an actual primer for new plaster walls – it’s slightly more expensive, but offers reassurance.

Try the following primers:

• Zinsser Gardz – SQUIRREL_TEXT_50027351 
• Tikkurila Optiva Primer – SQUIRREL_TEXT_50027352 

What is dry lining a wall?

Dry lining a wall is a faster and cleaner alternative to traditional wet plastering. You attach plasterboard to a wall, finish it with joining compound and joining tape, then paint or wallpaper straight onto it. 

It probably won’t give as good a finish as a professionally plastered wall, but it can be easier for beginners to achieve a decent result. If you’re not happy to paint straight onto the plasterboard, you can add a skim-coat of plaster over the top. 

Dry lining is more expensive than plaster alone though, and it will lose you a few centimetres from the size of the room.

If you need a professional, use Which? Trusted Traders to search for a reliable tradesperson in your area: