The most common question when booking a plasterer is whether a room needs a light skim or a full replaster. The right answer depends on the condition of your existing walls.
What is Skimming?
Skimming applies a thin 2–3mm coat of finish plaster over existing walls or plasterboard. It creates a smooth finish without needing to remove the existing surface. Skimming is appropriate when the existing plaster is sound, just rough, slightly uneven or previously textured (e.g. Artex that has been removed).
What is a Full Replaster?
A full replaster involves hacking off all the existing plaster down to the bare masonry, then applying new base coats and a finish skim. This is more disruptive, more expensive and takes longer — but it is the only correct solution when existing plaster has failed.
When is Each Approach Appropriate?
| Situation | Recommended approach |
|---|---|
| Plaster is sound but rough/textured | Skim coat |
| Plasterboard walls with no plaster | Skim coat |
| Artex removed, surface is stable | Skim coat |
| Plaster is blown (hollow when tapped) | Full replaster |
| Damp-damaged plaster | Full replaster (after damp fixed) |
| Old lime plaster crumbling | Full replaster |
| Property undergoing renovation | Usually full replaster |
The Tap Test
Run your knuckles firmly across the wall. Solid plaster makes a dense sound; blown plaster sounds hollow and may flex slightly under pressure. If large areas sound hollow, skimming over the top is not advisable — the blown plaster will eventually fall away and take the new skim with it.
Cost Comparison
Skimming a room typically costs £250–£500; a full replaster of the same room costs £500–£900 or more. However, skimming over problem plaster just defers the issue — so a full replaster is often better value long-term.
Get Quotes for Either Job
Describe your walls to local plasterers and get up to 3 free quotes for the right approach.