Single-wall pricing is where homeowners most often feel they are being overcharged, and where the arithmetic most needs explaining.
The figure
MyJobQuote puts one wall at £250 to £400, and a patch repair at £100 to £300.
Set that against the square-metre rate and it looks wrong. A typical wall in a 4m by 3m room with a 2.4m ceiling is about 7 to 9 square metres. At the £15 to £25 skim rate, the work itself is £105 to £225. The quote is often double that.
Where the difference goes
The plaster is a small part of what you are buying. A single wall consumes:
Travel to and from the property, often across South London traffic. Unloading tools, boards, a mixer and bags of finish. Sheeting the floor and masking skirting, sockets and door frames. Mixing. The work itself. Then cleaning tools before the plaster sets on them, bagging waste, and reloading the van.
Only one of those scales with wall area. The rest is a fixed cost per visit, and it consumes most of a working day whether the surface is one wall or four.
This is why a whole room at £600 to £850 is better value per square metre than one wall at £300. The overhead is spread across four times the work.
When one wall is the right call
Sometimes it genuinely is: a chimney breast opened up, a wall damaged by a leak, a partition removed. In those cases the job is what it is.
But be aware of the finish problem. A newly skimmed wall will not match the three around it, even under the same paint. Old plaster has a slightly different texture and absorbency, and the join at the corner will catch the light differently. If the room is being redecorated anyway, skimming all four walls often costs less than twice the single-wall price and removes the problem entirely.
Ask the plasterer directly what four walls would cost against one. The gap is frequently smaller than people expect.
Bundling is the real saving
If you have several small plastering jobs around the house, book them as one visit. Three patch repairs on three separate visits will cost close to three minimum charges. The same three in one morning cost barely more than one.
The same logic applies across trades. If a plasterer is coming anyway, that is the moment to have the hole from the old extractor filled, the crack over the door dealt with, and the patch where the radiator was moved made good.
What to check before agreeing
Establish whether the wall needs hacking off or just a skim, because that is the difference between the £15 to £25 band and the £35 to £55 band. Tap the wall: a hollow, drummy sound means the old plaster has lost its key to the brick and will have to come off.
Also agree who is making good the floor and disposing of waste. On a hack-off job the debris from one wall of Victorian lime plaster is heavier and more voluminous than most people anticipate.