You notice the crack first. A hairline that wasn't there last summer, now creeping above the light switch like it's looking for the ceiling. Then there's the hole your elbow made when you tripped on the vacuum cable in February. It has been looking at you for two months, slowly making the entire hallway feel like a building site.
Plasterboard damage is the sort of job most homeowners assume needs a professional. It usually doesn't. With a handful of tools, one weekend, and the right approach for the type of damage you're dealing with, walls come back to life without the £350 call-out charge. The trick is matching the repair technique to the size of the hole — a nail pop needs something very different to a doorknob-shaped crater.
Types of Plasterboard Damage and What Each One Actually Means
Before reaching for filler, look at what you're fixing. A small surface blemish and a structural hole behind it are completely different jobs, and trying to fix them the same way is why so many DIY repairs look terrible six months later.
Nail Pops and Screw Heads
These show up as small circular bumps or dimples, usually on older properties where the plasterboard has settled or where the original fixings weren't quite right. You'll see them more in ceilings and along the top half of walls. The issue is rarely the plasterboard itself — it's the fixing behind it reacting to temperature, humidity, or simple house movement.
Hairline Cracks
Cracks under 2mm wide, typically running along joints between plasterboard sheets or radiating from corners above doorframes. In most Victorian and Edwardian British homes these appear within the first two winters after any heating upgrade — the house dries out faster than it used to, and the joints open up. They're cosmetic almost every time. If you're seeing new cracks after years of none, and they're widening, that's when you want a surveyor involved.
Small Holes (up to 30mm)
Door handle dents, picture hook failures, or the spot where your toddler drove a toy car into the wall. These are straightforward. No patch needed, just filler and patience.
Medium Holes (30–100mm)
This is where most DIY attempts go wrong. The hole is too big to fill straight but small enough that people try anyway. You'll see the results in any rental property — a lumpy, visible scar because the filler had nothing to grip onto at the centre. Medium holes need a backing patch.
Large Holes (over 100mm)
Doorknob-through-the-wall damage, plumbing access that was never properly reinstated, or failed fixings for a large wall-mounted TV. These need a proper plasterboard patch, screwed into framing or supports, then jointed and skimmed. Still weekend work, but more involved.
The Tool Kit You Actually Need
Pick this up at B&Q, Wickes, or Screwfix for around £40–£70 depending on what you already own. You don't need anything fancy.
- Filling knife set (50mm and 100mm blades — the wider one is essential for anything beyond a nail pop)
- Ready-mixed lightweight filler for small repairs (Polyfilla Deep Gap or Toupret 2-in-1 both work well)
- Setting-type joint compound (Gyproc EasiFill 60 for larger repairs that need strength)
- Fine-grade sanding block or 120-grit sandpaper wrapped around a wooden offcut
- Utility knife with sharp blades
- Stanley tape measure and a pencil
- Self-adhesive fibreglass mesh tape for cracks and small holes
- Offcut of 12.5mm plasterboard if you're dealing with anything over 100mm across
- Dust sheet — you will underestimate how much dust sanding creates
If you're patching anything over 100mm you'll also want a small wood offcut for the backing support, two or three 35mm drywall screws, and a cordless driver.
Repairing Nail Pops and Small Holes
This is the fastest category and the one that transforms a room the most per hour of effort. For a nail pop, drive a new drywall screw about 50mm above and below the original fixing, then tap the popped nail back in and add a second screw next to it. Scrape off any raised paint or filler around the area with the edge of your filling knife. Apply a thin layer of lightweight filler, wider than you think — about 100mm across, feathering at the edges. Let it dry completely (check the tub; most take 60–90 minutes at 18°C but cold rooms take longer). Sand flat. Apply a second thinner coat if needed.
For small dents and holes up to 30mm, the technique is almost identical but you want to fill in two passes. First pass goes in deep and proud — slightly higher than the surrounding wall. Let it dry fully, not just touch-dry. Second pass levels it and extends the feathered edge another 40–50mm out. Sand with the grain of the wall, not across it, or you'll see faint scratches under fresh paint.
Fixing Hairline Cracks Properly
The mistake everyone makes is smearing filler into a crack and calling it done. Six months later the crack is back in exactly the same place. The fix is mesh tape over the crack, then filler over the mesh.
Start by widening the crack very slightly with the tip of your utility knife — just enough to remove loose edges. Brush out the dust. Press a strip of self-adhesive fibreglass mesh tape directly over the crack, extending at least 50mm past each end. Apply setting-type joint compound over the tape, pushing it into the mesh with a 100mm filling knife held at a 15-degree angle. Once it's dry, add a second feathering coat at least 200mm wide. Sand lightly with 120-grit, prime, and paint.
That said — if a crack reappears exactly where you filled it, widens, or runs diagonally across multiple rooms, stop and get a structural survey. Fillers don't fix subsidence, and painting over structural movement just delays the problem.
Patching Medium Holes
Holes between 30mm and 100mm are where the California patch technique earns its keep. Cut a piece of scrap plasterboard about 50mm larger than the hole in every direction. On the back of that piece, score and snap the outer 25mm of plasterboard so only the paper facing remains — leaving a plasterboard plug in the middle with a paper flange around it.
Hold it up to the wall, draw around the plug, and cut that shape out of the damaged area with a utility knife or drywall saw. The plug should drop snugly into the wall cavity. Butter the paper flange with joint compound, press the patch into the hole so the plug fills it and the flange sits flat against the surrounding wall, and smooth out. Feather the compound out another 75–100mm, let it dry overnight, then skim again and sand. Done properly, you won't find the repair once it's painted.
Patching Large Holes Above 100mm
For anything doorknob-sized or larger, you need a proper backing. Cut away the damaged area with a utility knife, squaring it off into a neat rectangle. Measure a piece of scrap timber (a 50×25mm batten works perfectly) longer than the hole's width. Slide it inside the wall cavity, hold it against the back of the plasterboard, and screw through the existing wall into the timber at both ends. You've now got a solid support behind the hole.
Cut a piece of plasterboard to fit the opening — ideally the same thickness as your existing board (12.5mm in most British homes, 9.5mm in some ceilings). Screw it into the timber support. Tape the joints with paper joint tape or mesh, skim with setting compound in three coats (each thinner than the last, each feathered wider than the last), sand between the second and third coats, and paint.
This is a half-day job for someone who has never done it, a two-hour job for someone who has. The temptation is to rush the drying between coats — don't. Each coat needs to be fully dry before the next, or you'll trap moisture and end up with bubbling months later.
Priming and Painting Without Seeing the Repair
Even a perfect patch shows through fresh paint if you skip priming. Fresh filler and plasterboard facing absorb paint at a different rate than the surrounding wall, so without priming you get a slightly duller patch that catches the light. A quick coat of acrylic primer, or a watered-down first coat of your topcoat, sorts it. Use a roller, not a brush, so the finish matches the surrounding texture.
If you're painting a whole wall after the repair, do the patch with primer first and let it dry, then paint the whole wall in one go. Spot-painting almost always shows, especially in satinwood or silk finishes under daylight. Matt emulsion hides repairs better than anything else — which is why most British rentals use it.
When to Call a Professional
There are situations where DIY is the wrong call:
- Holes over 300mm in ceilings, where working overhead with compound and falling patches becomes genuinely dangerous
- Walls showing damp staining, salt deposits, or peeling paint around the damage — this is a moisture problem, not a plasterboard problem
- Cracks wider than 5mm, running diagonally, or appearing around window and door frames in recent months
- Load-bearing wall damage, especially anywhere that now shows daylight
- Artex or textured-plaster ceilings installed before about 1985, which may contain asbestos and should never be disturbed without a specialist survey
A plasterer working on a medium repair will typically charge £120–£200 in London, £80–£150 elsewhere in the UK. That's cheap insurance if the damage looks beyond one weekend's work.
The Finishing Details Most People Skip
Three things separate a repair you can see from one you can't. First: feather your edges further than feels necessary. If the filler is 100mm wide, make the feathered edge extend to 200mm. Second: sand with the wall, not the repair — move your sanding block in long strokes across the whole patched area into the untouched wall, so the transition disappears under your touch before you ever paint. Third: check the repair in raking light before painting. Hold a torch parallel to the wall and look along the surface. Any lumps, dips, or ridges will cast shadows you'd never spot under normal lighting — and they'll still be there after the paint dries.
That last trick is what professional decorators use, and it's the difference between a repair that survives close inspection and one that everyone spots the moment they walk in.