If you have had two quotes and one says "skim" while the other says "re-plaster", you would be forgiven for thinking they are the same thing at different prices. They are not. Here is how to tell which your walls actually need, based on what we see day to day in Bow, Bethnal Green and the wider East End.
Skimming is a thin finishing coat, usually 2 to 3mm, applied over a surface that is already sound and flat. It gives you a smooth, paintable finish. Plastering is the broader job: building up a wall from bare brick or block with a backing coat, then skimming on top.
So skimming is a type of plastering, but not all plastering is just skimming. When a builder says "it needs a full re-plaster", they mean the backing coat has failed or was never there, and there is considerably more material and labour involved.
Knock gently across the wall with your knuckles. A solid, dull sound means the plaster is bonded to the wall behind it. A hollow, drummy sound means it has blown, and that section needs hacking off back to brick and re-plastering properly. Skimming over blown plaster is a waste of money because the skim comes away with it, often within a year or two.
Look at the flatness too. Hold a spirit level or a straight edge against the wall. If you can see daylight of more than 3 or 4mm under it, a skim will follow that hollow rather than fill it. That is a dot and dab or a float and set job.
Common cases we come across locally:
A skim is a one day job for an average room in most cases: prepare and seal the surface, tape any joints, apply two thin coats of multi finish, then trowel up as it sets. It stays workable for a few hours, which is why plasterers do not like being interrupted mid room.
A backing coat job adds a day or more. Bare brick gets sand and cement render or browning, left to dry properly before skimming. Overboarding, where plasterboard is fixed over the existing wall, is often quicker and cleaner than hacking off, though you lose about 12 to 25mm off the room and have to move sockets and skirting.
Drying time matters more than people expect. Fresh plaster goes from dark brown to a uniform pale pink as it dries, typically 4 to 7 days for a skim and 2 to 4 weeks where there is a thick backing coat, longer in a cold flat in winter. Paint it too soon with normal emulsion and you trap moisture and get peeling. Use a watered down mist coat first.
In East London, skimming a standard bedroom ceiling or a single wall typically starts in the low hundreds, with a full average sized room skim usually landing somewhere in the several hundreds to around a thousand depending on size, height and condition. Full re-plastering with hacking off and a backing coat is commonly double, sometimes more, because of the labour, muck away and extra drying time.
Treat all of that as a ballpark. The things that genuinely move a quote are access, ceiling height, whether skips or waste removal are needed, how much making good is required around windows and reveals, and whether the property is occupied while the work runs. Anyone giving a firm figure without seeing the wall is guessing.
A straight answer to these will tell you quickly whether a quote is realistic:
No. The paste and paper will lift once wet plaster goes on, taking your new finish with it. Wallpaper needs stripping back to a sound surface first.
For a room or two, no, though it is dusty and the room will be humid while drying. For a whole flat being re-plastered, most people find it easier to stay elsewhere for a week or so or work room by room.
Usually it dried too fast, often from heating being turned up or a dehumidifier run hard in the first few days. Fine hairline cracks can be filled and painted over, but wide or repeated cracking points to movement or a problem with the backing coat.
Call, send a WhatsApp or use the form. Photos of the job help, and the quote and the advice cost nothing either way.