Plastering | How to Plaster a Wall

Plastering is a task that many people usually leave to the experts. But by preparing your space well and following a practised method, figuring out how to plaster a wall is highly achievable.

Before you start mixing, check out our handy how-to video to see exactly how we approached the project. The finished result will be a smooth, flat wall that's ready to accept fresh paint or wallpaper. Let's get your room prepared.

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You must prepare your wall by scrubbing it clean and applying a diluted PVA glue mixture to ensure the fresh plaster sticks securely.
Plaster is mixed to the consistency of thick custard and applied using a hawk and a stainless steel trowel, working upwards and outwards from the bottom left corner.
You should apply two coats in total, allowing the first coat to set for roughly 20 minutes before smoothing it and adding a slightly thinner second coat.

Preparing the wall

Plastering can be quite a messy process. Having a clear, unobstructed work area is vital, so remove all furniture from the room. Depending on the job, you may also need to remove curtain rails and radiators. Tape up your electrical sockets to prevent dust from getting inside them.

Lay out heavy-duty protective sheets. If you're removing old plaster first, you'll need two sets of sheets. Use one set for the removal stage and a clean set for applying the new plaster as otherwise you risk old dust contaminating your fresh mix.

Clean and scrub the wall thoroughly, removing any wallpaper, loose pieces, grease, and dust. This is incredibly important, as any debris left behind will stop your plaster from sticking.

If you're working on new plasterboard, apply plaster tape over all the joints and trim the edges neatly with your knife.

Next, apply PVA glue. This is essential for holding the plaster to your wall. Dilute the PVA following the manufacturer's instructions. A ratio of one part glue to four parts water is standard. Brush or roll the glue onto the wall and wait until it feels slightly sticky to the touch before you begin plastering.

Mixing the plaster

If you're wondering what plaster is made of, it's a dry mixture of gypsum dust and water. Always follow the manufacturer's instructions when mixing. Take a clean bucket and fill it with clean tap water, then steadily add your dry plaster.

Adding water first helps you avoid a lumpy mixture.

Use a bucket trowel to scrape the edges and incorporate any dry powder.

Then, use your power mixer at a low speed so you don't overwork the mixture. Keep stirring until it's totally smooth. You're aiming for a consistency similar to thick custard.

Remember to clean your stirrer immediately before the mixture sets on the blades.

Applying the plaster

For large areas, pour your mix onto a spot board.

Use your bucket trowel to cut away a section and transfer it to your plastering hawk. Pick up a small amount of plaster from the hawk using your plastering trowel.

Spread the plaster firmly using an upwards stroke, keeping the trowel angled slightly away from the wall. Flatten the trowel at the end of each stroke to smooth it down. Work from the bottom left-hand corner upwards and outwards. Use short sweeps to start with, then longer sweeps as you go.

Allow your first coat to dry slightly for about 20 minutes. Then, go over the surface again with your trowel to smooth out any bumps. You can spray a little water onto the wall to make the plaster respond better.

Apply a second coat of plaster using the exact same steps. The main difference is that this coat needs to be slightly thinner to create a perfectly smooth finish. Once applied, leave it until the surface is slightly damp but firm to the touch.

Finishing the plaster

Once the plaster is firm, you need to polish your work. Go over the surface lightly with a clean trowel blade, dampening the wall with your spray bottle as you go.

Use a small, damp paintbrush to polish off the tight corners and edges.

Taking the time to prep your walls and carefully mix your materials ensures a brilliant, smooth surface. Plastering is a valuable skill that can completely transform a tired room, and once your plaster has dried, you’ll need to know how to paint your newly plastered room.

FAQs

Yes, you can plaster over a painted wall provided the paint is in good condition. You must clean the wall thoroughly, sand the surface slightly to create a texture for the new plaster to grip, and apply a coat of diluted PVA glue first.

No, you should never plaster directly over wallpaper. The moisture in the wet plaster will cause the wallpaper adhesive to fail, meaning your new plaster will simply crack and fall off the wall. Always strip the paper and clean the wall completely.

The exact cost depends entirely on the size of your room and whether you need to plaster the ceiling too. Doing it yourself is a highly cost-effective method, as you only need to pay for your basic plaster tools, PVA glue, and the bags of dry mix.

A freshly plastered wall typically takes anywhere from two to four days to dry completely. This timeline varies depending on the thickness of your coats, the temperature of the room, and the overall humidity in your home.

While it's tempting to speed up the process, you should let plaster dry naturally. Turning up the central heating or using a dehumidifier can cause the moisture to evaporate too quickly, which leads to hairline cracks across your new wall. Simply open a window to allow natural ventilation.

If you have small amounts of unused dry plaster, seal the bag tightly and store it in a dry place. If you need to dispose of plaster that has already set, you must take it to your local household waste recycling centre, as it cannot go in your standard household bin.