It is one of the most common questions we are asked before quoting a job, and the honest answer is: it depends on what is underneath. Getting this wrong is expensive, so here is how to tell the difference between a wall that needs a light skim and one that needs stripping back and starting again.
Skimming means applying a thin finish coat, usually around 2mm to 3mm, over an existing sound surface to give you a smooth, paint-ready finish. Replastering means removing old, failed plaster back to the brick or block, then building the wall back up with a base coat and a finish coat.
Skimming is quicker and cheaper because the hard structural work is already there. Replastering is a bigger job because you are effectively rebuilding the surface from scratch, so it costs more in both labour and materials.
If your existing plaster is firmly attached and the problem is purely cosmetic, a skim is usually all you need. This is common on walls that have been badly patched over the years, covered in old textured coatings like Artex, or left rough after removing wallpaper.
Some walls are past skimming. If the plaster itself has failed, adding a fresh skim on top will simply crack and blow again within a year, so it is money wasted. In older Cheshire and North Wales properties, especially solid brick and stone cottages, we often find the original lime or gypsum plaster has come away from the wall behind.
Across our patch, from Victorian terraces in Merseyside to older stone-built homes in North Wales, damp is the single biggest reason plaster fails. There is no point skimming or replastering over a wall that is still wet, because the moisture and any salts will push straight back through the new finish.
The right order is to fix the source first, whether that is a leaking gutter, failed pointing, or rising damp, let the wall dry out, and only then replaster using a suitable sand and cement backing coat or a breathable lime system where the building calls for it. We would always rather tell you this up front than take the job and watch it fail.
As a guide, skimming a single average room might take a day and typically runs from a few hundred pounds, while a full replaster of the same room can take two to three days and cost noticeably more once the old material is stripped and skipped. Prices vary with wall condition, access, ceiling height, and whether damp work is needed, so treat these as ballparks rather than fixed figures.
The best way to know for certain is to have someone tap the walls and look properly. We are happy to take a look and give you a straight answer, even if that answer is that you only need a tidy-up rather than the bigger job.
Free, fixed-price quotes. Most jobs visited within the week.
Photos of the room or elevation help a lot. Phone if it’s urgent.
