Basic Plastering for Beginners
Learn the basics of skimming and patching plaster - and know when to call in a professional.
Difficulty
Hard
Time
1-2 days
Cost
£40 - £120
Before You Start
Plaster is alkaline and irritates skin and eyes. Wear gloves and safety goggles when mixing and applying. Keep the room ventilated. Plaster dust is very fine - wear a dust mask when sanding dried plaster. Protect floors thoroughly as plaster is extremely difficult to remove from carpets.
Plastering has a reputation as the hardest DIY skill to learn, and honestly that reputation is partly deserved. Full room replastering is genuinely difficult and best left to a professional. However, patching small areas and skim-coating a single wall is absolutely achievable with practice. The key is working fast because plaster starts setting within 20-30 minutes - so mix small batches and only work on areas you can finish quickly.
What You Will Need
Tools
- - Plastering trowel (stainless steel, 11 or 13 inch)
- - Hawk (to hold plaster)
- - Bucket trowel (for scooping plaster)
- - Mixing bucket (large, flexible)
- - Mixing drill with paddle attachment
- - Spray bottle (water)
- - PVA glue and brush
- - Sandpaper (fine, for finishing)
Materials
- - Multi-finish plaster (Thistle is the standard UK brand)
- - PVA adhesive
- - Clean cold water
- - Scrim tape (for joins and cracks)
Step-by-Step Instructions
Assess What You Need
Small holes and cracks: use filler, not plaster. Damaged areas up to 1 square metre: you can patch with plaster. Entire walls or ceilings: this is a skim coat and requires more skill. If the old plaster is blown (sounds hollow when tapped), it needs hacking off and replastering from scratch - call a plasterer.
Prepare the Surface
Remove any loose or flaking plaster. Apply PVA solution (1 part PVA to 4 parts water) to the area with a brush. This seals the surface and helps the new plaster bond. Let the PVA go tacky but not fully dry before applying plaster. Apply scrim tape over any cracks or joins.
Mix the Plaster
Add plaster to water (never water to plaster). Fill a bucket half with clean cold water and gradually sprinkle in plaster while mixing with a drill and paddle. Aim for a thick, creamy consistency - like yoghurt. Mix until completely smooth with no lumps. You have about 30-40 minutes of working time.
Apply the First Coat
Load plaster onto your hawk. Scoop a sausage of plaster from the hawk with the bottom edge of your trowel. Starting from the bottom, press the trowel against the wall at a slight angle and sweep upward in a smooth arc. Apply an even coat about 2mm thick. Do not worry about making it perfect - this is the base coat.
Flatten the First Coat
Once you have covered the area, wait about 10 minutes until the plaster starts to firm up (it feels slightly stiff when you touch it). Then use clean trowel to smooth over the surface, pressing firmly. Work in long, sweeping strokes. Scrape off any ridges.
Apply the Second (Skim) Coat
Apply a very thin second coat - about 1mm. This fills any imperfections from the first coat. Spread it as evenly as possible. The thinner this coat, the easier it is to get a smooth finish.
Polish the Surface
As the plaster firms up further (about 20 minutes after the second coat), splash a small amount of water onto the surface with a brush and then trowel over it firmly. This polishes the surface smooth. Repeat 2-3 times as it continues to set. The final surface should be glass-smooth.
Let It Dry
Fresh plaster takes 2-7 days to dry fully depending on thickness, temperature and ventilation. It changes from dark pink to pale pink/white as it dries. Do not paint until it is completely dry and a uniform light colour. Apply a mist coat of diluted emulsion as your first paint coat.
Pro Tip: Small Batches
Never mix more plaster than you can use in 20 minutes. Once plaster starts setting in the bucket, it is ruined - do not add water to try to revive it. Clean your bucket and tools between mixes.
Pro Tip: Keep Your Trowel Clean
Wipe your trowel blade with a wet cloth between passes. Any dried plaster on the trowel creates grooves and lines in the fresh surface.
Common Mistakes to Avoid
- - Mixing too much plaster at once - it sets in the bucket and you waste money
- - Applying plaster too thickly in one coat - it sags, cracks and takes weeks to dry
- - Working the surface too long after it starts setting - you tear the finish instead of smoothing it
- - Not applying PVA first - plaster does not bond to dusty or sealed surfaces properly
- - Painting before the plaster is fully dry - the paint peels off and traps moisture
When to Call a Professional
Plastering full rooms, ceilings, or dealing with blown plaster that needs removing is genuinely best left to a professional plasterer. Also if you need to replaster after damp treatment, a plasterer will use specialist renovating plaster that resists future damp. A full room skim typically costs around 300-500 pounds.