Most walls that look tired can be rescued with a 2 to 3mm skim coat, but skimming over plaster that has failed underneath is money wasted. The good news is you can work out which camp your walls fall into with a few simple checks before you pick up the phone.
Go around the room and tap the wall firmly with your knuckles, paying attention to corners, around windows, above skirting boards and near the ceiling. Sound plaster gives a dull, solid thud. Failed plaster sounds hollow, a bit like knocking on a door, because it has come away from the brick or the lathes behind it. Plasterers call this blown plaster, and skimming over it just adds weight to something that is already letting go.
A hollow patch the size of a dinner plate is not a disaster; that section can be cut out, patched and then the whole wall skimmed. But if a third or more of the wall sounds hollow, replastering that wall properly is usually cheaper in the long run than patching it piecemeal.
Skimming, sometimes called reskimming, means applying a thin finishing coat over the existing surface to leave it smooth and ready for paint. It is the right choice when the plaster underneath is solid but the surface is scruffy.
On a typical bedroom you would expect a skim to take a day, with walls ready for mist-coat painting after about a week of drying. It is far less disruptive than replastering, with less mess and lower cost.
Replastering means stripping the old plaster back to brick or block and starting again with a backing coat and finish coat. Nobody wants to hear it, but there are situations where anything less fails within a couple of years.
Damp is the big one. If plaster is stained, salty to the touch or crumbling near the bottom of a wall, the source of the moisture has to be found and fixed first, and the contaminated plaster removed, because damp salts will bleed straight through a new skim. A lot of the housing stock across Cheshire, Merseyside and North Wales is Victorian or Edwardian, and homes near the coast take extra weathering, so this comes up often on ground-floor walls and chimney breasts.
Prices vary with room size, ceiling height and how much preparation is needed, so treat these as a guide rather than a quote. Skimming a single average wall often falls somewhere in the range of 150 to 250 pounds, while skimming a full medium-sized room typically lands between 400 and 700 pounds and takes one to two days.
Replastering the same room, including hacking off, waste removal and a two-coat system, is usually somewhere between 1,000 and 2,000 pounds and takes three to five days, plus longer drying times before decorating. Backing coats need a good few weeks to dry fully, so build that into any decorating plans. A decent plasterer will tell you plainly which walls need which treatment; it is common for a room to need one wall replastered and the rest skimmed, and quoting it that way keeps the cost sensible.
If the tap test leaves you uncertain, or you suspect damp, it is worth having someone look before you decorate. A ten-minute inspection can save you paying twice: once for a skim that fails and again for the replaster you needed all along. We look at walls across Cheshire, Merseyside and North Wales every week and will always say if the cheaper option is the right one.
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Photos of the room or elevation help a lot. Phone if it’s urgent.
