Plastering has fewer formal qualifications and registration schemes than electrical or gas work, so the checks available to you are different. There is no plastering equivalent of Part P or Gas Safe. That makes the questions you ask more important, not less.
Are you quoting a skim or a full replaster?
The single most useful question. A skim runs roughly £15 to £25 per square metre and a two-coat replaster £30 to £40, so this one answer explains most of the gap between two quotes on the same room.
Get it in writing. "Plaster the back bedroom" is not a specification.
Have you tapped the walls?
A plasterer who has quoted without touching the walls has guessed. Sound plaster knocks solid; plaster that has lost its key to the brick sounds hollow and has to come off.
This matters enormously in South London's Victorian and Edwardian stock, where original plaster is often a century old and either sound or badly blown with little in between.
What happens if it turns out to be blown?
Even after tapping, some of the wall's condition is only revealed once work starts. Ask what the price becomes in that case, and agree it before anyone starts hacking.
A plasterer with a clear answer has done this before. One who waves it away will produce a number on the day, when you have a half-stripped room and no leverage.
Who removes the waste?
Old lime plaster off a Victorian wall is heavy and voluminous, and a hack-off job across a room can fill a skip. Establish whether disposal is in the price or a separate cost, and whether you are expected to arrange it.
Is VAT included?
Many plasterers working alone are below the VAT threshold and do not charge it. Larger firms do. That is a 20 per cent difference between two otherwise identical quotes, and it is better discovered now than on the invoice.
What else is worth checking
Ask to see recent work, ideally in person and in daylight. Plastering is judged in raking light, and photographs taken with a flash hide almost every defect that matters. A wall that looks perfect head-on can show ripples from an angle.
Ask about public liability insurance. There is no registration scheme to check, but insurance is a reasonable minimum and any established plasterer will have it.
Ask how they will protect the rest of the house. Plaster dust travels, and the answer tells you something about how they work.
Ask what they will use on a period solid wall. If the property is listed or in a conservation area, or simply has no damp-proof course, lime rather than gypsum may be the correct specification.
What we can and cannot tell you
Our listings are compiled from public Google Maps data and filtered to businesses rated three stars or higher with at least three reviews. Tradespeople who submit their own details are reviewed before publishing.
We do not hold insurance certificates or qualification documents for the businesses listed here, and we do not verify them. Ask to see them yourself, and confirm anything that matters to you directly with the tradesperson before work starts.