Most plaster problems are a symptom of something else, and the crack or bulge you can see is usually the last part of the story rather than the first. Get the cause right and a repair can last decades; skim over it and you will be looking at the same patch again next winter. Here is how to work out what you are actually dealing with in a typical Grangemouth home, and what a sensible fix looks like.
Tap the affected area gently with your knuckle. A solid, dull sound means the plaster is still bonded to the wall behind it and you are likely looking at a surface crack. A hollow, drummy sound means the plaster has lost its grip, and no amount of filler will bring it back. Anything drummy needs cutting out.
Then look at the pattern. Fine hairline cracks radiating from door and window corners are usually movement and shrinkage, and are cosmetic. Horizontal staining with a tide mark low down points to rising damp or a bridged damp proof course. Damp patches high on a gable wall or below a window more often mean rainwater ingress, blocked gutters or failed pointing, all of which are common on the exposed, wind-driven west and south elevations you get near the Forth estuary.
A lot of the town is interwar and post-war housing, plus the 1950s and 1960s ex-council semis and terraces around Bowhouse, Newlands and Charing Cross. Two things come up repeatedly in properties of that age.
First, lath and plaster ceilings in the older stock. If your ceiling has sagging areas, long cracks and a slight bounce, the plaster keys holding it to the timber laths have snapped. Patching buys you a little time; overboarding or a full take-down and reboard is the honest fix.
Second, artex and textured coatings. If the texture was applied before 2000 it may contain a small amount of asbestos, and it should not be sanded or scraped dry. A sample test is inexpensive and worth doing before any work starts.
Salt contamination is the other one worth knowing about. Where plaster has been wet for a long time, salts migrate into it and keep drawing moisture from the air, so the wall stays damp looking even after the leak is fixed. That plaster has to come off back to the masonry and be replaced with a suitable render and skim, not simply painted over.
A patch repair suits isolated damage such as a knocked corner, a removed radiator or a small blown area. The join can sometimes show under low-angle light, especially on a wall painted in a sheen finish, so a patch on a prominent wall is often better followed by a full skim of that wall.
A skim coat over existing sound plaster gives you one flat, continuous surface and is the usual answer where the wall is basically fine but tired, patched or covered in old wallpaper scars. A full re-plaster, meaning stripping back and starting again, is for walls that are extensively blown or salt damaged.
Timings are worth planning around. A single room skim is typically one to two days on site, and the plaster then needs roughly three to seven days to dry out fully, longer in a cold room or in winter. Fresh plaster wants a watered down mist coat first, never a direct topcoat of vinyl emulsion, which will peel.
Prices depend on access, ceiling height, how much preparation is needed and whether damp work is involved, so treat these as broad ranges rather than quotes. A small patch repair generally sits somewhere around £120 to £250. Skimming an average bedroom ceiling might be £250 to £450, and skimming the walls of an average room £400 to £700. Taking down and reboarding a lath and plaster ceiling is a bigger job, commonly £600 to £1,000 per room.
Be wary of any quote given without someone seeing the wall, and be more wary of one that includes no mention of fixing the cause of the damp. A cheap skim over a live leak is money spent twice.
No, not if the damp is still active, because the new plaster will blow or stain within months. The source has to be dealt with first, and where salts are present the old plaster needs stripping back to the masonry.
Usually three to seven days for a skim, but go by colour rather than the calendar: wait until the whole surface has gone an even pale pink with no darker patches. Start with a mist coat of emulsion thinned with water so the plaster can absorb it properly.
A hairline crack is normally just movement and nothing to worry about. Sagging, a springy feel underfoot from the room above, or bits of debris falling into the loft space are different, and that ceiling should be looked at promptly.
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