The plastering vs skimming question comes up on almost every renovation quote. The short version: plastering builds a new wall surface at 10mm to 30mm thick, while skimming refines an existing one at 2mm to 5mm. One is structural. The other is cosmetic.
Get the choice wrong and you either overspend by thousands, or you skim over a problem that comes straight back through the paint.
Plastering vs skimming: the real difference
Both trades use a trowel and both end with a flat wall. That is where the similarity stops.
- Plastering applies sand and cement to bare brick or block. It usually goes on in two coats: a rough scratch coat around 10mm, then a finer finish coat of 5mm to 8mm. Total build-up is typically 15mm to 18mm.
- Skimming applies a thin finishing plaster over a surface that is already sound. It is 2mm to 5mm, sometimes less, and it hides texture and hairline defects rather than filling holes.
Think of plastering as making the wall. Skimming is making the wall look good. A wall can be plastered and never skimmed, and a wall can be skimmed decades after it was plastered.
Thickness is the fastest way to tell them apart
- 2mm to 5mm: skimming or a skim coat
- 5mm to 10mm: a levelling coat, somewhere between the two
- 10mm to 30mm: plastering proper, usually over brickwork
If a contractor says they will “skim” a wall and then talks about 15mm of material, they are plastering. The words get used loosely on site, so ask about thickness rather than the label.
What each job costs in 2026
Pricing follows the material volume and the labour time, which is why the gap is smaller than people expect.
- Internal two-coat sand-cement plaster: roughly R90 to R160 per m2, supplied and applied
- External two-coat waterproofed plaster: roughly R130 to R200 per m2
- Skimming walls and ceilings: roughly R140 to R180 per m2 supplied and applied
- Skim over existing plaster: roughly R150 to R190 per m2 all-in
- Labour only: skimming R40 to R88 per m2; plastering R35 to R132 per m2
Notice that skimming is not automatically cheaper per square metre. It is cheaper on a project because you are not stripping walls, not waiting 28 days for cement to cure, and not repainting a whole house. The saving is in scope and time, not the rate.
For a full breakdown of rates by room and condition, our guide to skimming plaster price per square metre goes through the variables in detail.
When you need plastering
Plastering is the right call whenever the surface itself has failed or does not exist yet.
- New brickwork with no plaster on it at all
- Hollow or drummy plaster that sounds empty when you tap it
- Large sections missing after damp, a burst pipe or removed fittings
- Walls badly out of plumb that need real thickness to straighten
- Structural cracks that need cutting out and rebuilding, not covering
The tap test is the honest one. Knock along the wall with your knuckle. A solid dull sound means the plaster is bonded. A hollow echo means it has let go of the brick, and skimming over it just adds weight to something already falling off.
When skimming is enough
Skimming works when the base is sound but ugly.
- Textured or stippled finishes you want gone
- Old wallpaper scars and glue residue after stripping
- Hairline crazing and shallow surface marks
- Patchy repairs that show through paint as different sheens
- Rough sand-cement plaster that was never finished smooth
This is the majority of older Cape Town homes. The brickwork and plaster are fine after forty years. The surface just looks tired. A skim resets it in days rather than weeks, and our skimming team handles exactly this kind of work.
Ceilings follow different rules
Ceilings are almost always a skimming job rather than a plastering one, because most are board rather than brick. Board joints, nail pops and old jointing compound are surface problems. Our page on ceiling skimming covers the extra prep that overhead work needs.
The mistakes that cost money
- Skimming over failing plaster. The new coat cracks along the same lines within months.
- Plastering when a skim would do. Weeks of mess and curing time for a cosmetic problem.
- Ignoring damp. Neither trade fixes rising or penetrating damp. It comes back through both.
- Painting too early. New sand-cement plaster needs a minimum of 28 days to cure, and an alkali-resistant primer after that.
- Comparing quotes on price alone. One contractor pricing a skim and another pricing a replaster are not quoting the same job.
How to decide on your own walls
Do three checks before you call anyone. Tap the wall for hollow spots. Hold a straight edge or a long spirit level against it and look at the gaps. Then look for damp staining, especially low down and around windows. Plaster and skim products are covered by standards published by the South African Bureau of Standards.
Sound, reasonably flat and dry means skimming. Hollow, badly bowed or damp means plastering, and possibly repairs first. If you want the background on the material itself, our explainer on skimming plaster covers what it is made of and how it behaves.
Honestly, the tap test settles most cases in two minutes. Where it does not, get someone to look. We offer a free assessment with no call-out fee, so send us the details and we will tell you which job you actually need rather than which one is bigger.
Plastering vs skimming: the short version
If you take one thing from this guide on plastering vs skimming, make it this: get the scope written down before anyone starts. Most disputes about plastering vs skimming come from an unclear brief, not bad work.
We quote plastering vs skimming properly, in writing, after seeing the job. Assessment is free and there is no call-out fee on quoted work.
Frequently asked questions
What is the difference between plastering and skimming?
Plastering applies sand and cement at 10mm to 30mm to create or rebuild a wall surface, usually over bare brick. Skimming applies a thin finishing plaster at 2mm to 5mm over a surface that is already sound, purely to make it smooth and paint-ready. Plastering builds the wall, skimming refines it.
Is skimming cheaper than plastering?
Per square metre the rates are closer than people expect. Skimming supplied and applied runs roughly R140 to R190 per m2 in 2026, while internal two-coat plaster runs roughly R90 to R160 per m2. The real saving with skimming is in scope and time: no stripping, no 28-day cure and far less mess and disruption.
How thick is a skim coat compared with plaster?
A skim coat is typically 2mm to 3mm per coat, with two coats giving a total of about 3mm to 5mm. Anything thicker than about 5mm is really a levelling coat and behaves differently, taking longer to dry and being more prone to cracking if it is applied in one pass.
Can you skim over old plaster?
Yes, provided the old plaster is properly bonded to the brickwork. Tap it with your knuckle first: a dull solid sound is fine, a hollow echo means it has separated and needs to be cut out and replastered. Skimming over hollow plaster adds weight to a surface that is already failing.
Do I need to replaster or just skim my walls?
Skim if the walls are sound, dry and reasonably flat but look textured, patchy or tired. Replaster if there are hollow sections, large missing areas, walls badly out of plumb or active damp. A tap test plus a straight edge held against the wall answers it in most homes without any specialist equipment.