Patching a hole in a plasterboard (also called GIB board in New Zealand) wall is one of the most satisfying DIY repairs you can tackle at home. With the right materials and a bit of patience, you can achieve a finish that's virtually invisible once painted — even if you've never done it before.
Assess the Size of the Hole First
The method you use depends on how big the damage is. As a general guide:
| Hole Size | Category | Recommended Method |
|---|---|---|
| Up to 20 mm | Small (nail, screw, small anchor) | Filler compound only |
| 20 mm – 150 mm | Medium | Backing patch or mesh tape |
| 150 mm+ | Large | Timber noggin and new plasterboard |
Always check what's behind the wall before you start cutting — power cables and plumbing pipes can run through wall cavities. If you're unsure, use a stud finder and a cable/pipe detector, available from Bunnings or Mitre 10.
Tools and Materials You'll Need
- Plasterboard filler or jointing compound (e.g. GIB Tradeset or a pre-mixed compound)
- Fibreglass mesh tape or a backing patch for medium holes
- Replacement plasterboard and timber noggins for large holes
- Broad-bladed filling knife (75–150 mm)
- Fine-grit sandpaper (120–180 grit)
- Primer and paint to match your wall
- Safety glasses and a dust mask
Patching a Small Hole (Up to 20 mm)
- Clean the edges of the hole, removing any loose paper or crumbling plaster.
- Apply a small amount of pre-mixed filler with a filling knife, pressing it firmly into the hole.
- Feather the edges out so the filler blends smoothly with the surrounding wall.
- Allow to dry fully — drying time varies by product and humidity, so check the manufacturer's instructions.
- Sand lightly with fine-grit sandpaper until flush.
- Wipe away dust, prime, and repaint.
Tip: Pre-mixed fillers shrink slightly as they dry. For deeper holes, apply two thin coats rather than one thick one.
Patching a Medium Hole (20 mm – 150 mm)
For holes in this range, you need something for the filler to bond to.
Option A: Fibreglass Mesh Patch
- Clean and square off the hole edges if needed.
- Stick a self-adhesive fibreglass mesh patch over the hole (these are sold as repair kits at most hardware stores).
- Apply jointing compound over the mesh with a broad knife, feathering well beyond the patch edges.
- Allow to dry, then apply a second coat to fill any low spots.
- Sand smooth, prime, and paint.
Option B: Backing Strip Method
- Cut a piece of plasterboard slightly larger than the hole.
- Thread a thin timber strip or offcut through the hole and hold it against the back of the wall while you screw through the face into it — this creates a backing.
- Cut a plasterboard patch to fit snugly in the hole and screw it to the backing strip.
- Apply paper jointing tape and compound over the joins, feathering out in layers.
- Sand, prime, and paint once fully cured.
Patching a Large Hole (150 mm+)
Larger repairs need proper structural support.
- Mark and cut a neat rectangle around the damaged area using a plasterboard saw or jigsaw. Cut carefully to avoid hidden services.
- Locate the nearest wall studs on either side (typically at 400 mm or 600 mm centres in NZ framing to NZS 3604).
- Fix timber noggins horizontally between the studs at the top and bottom of your cut-out to give the patch something to screw into.
- Cut a new piece of GIB plasterboard to fit and screw it in place (use appropriate plasterboard screws at roughly 200 mm centres).
- Apply paper tape and jointing compound to all joins, building up in thin coats and feathering wide (300 mm or more) for a flat finish.
- Once fully dry, sand smooth, prime with a suitable primer, and repaint.
For guidance on plasterboard systems and jointing, GIB publishes detailed technical information on their website.
Getting the Paint Finish Right
A patched area will show through paint if you skip priming. Always apply a water-based primer or sealer over the repaired area before topcoating — bare filler is porous and will cause the paint to look flat or patchy. Resene and Dulux both offer suitable interior primers and can help you colour-match your existing wall paint.
For best results, repaint the entire wall rather than just the patch — spot-painting rarely matches perfectly, especially on older or faded walls.
Safety Notes
- Always wear safety glasses and a dust mask when cutting or sanding plasterboard — the dust is a respiratory irritant.
- Never cut into a wall without checking for hidden electrical cables or plumbing. If in doubt, consult a professional. Electrical work is restricted work under NZ law and must be carried out by a registered electrician — see the Electrical Workers Registration Board for more information.
- Similarly, any work affecting plumbing pipes must be done by a licensed plumber registered with the Plumbers, Gasfitters and Drainlayers Board.
When to Call a Professional
Consider calling a qualified plasterer or builder if:
- The hole is large or the surrounding plasterboard is water-damaged or mouldy (which may indicate a leak requiring investigation)
- You're not confident achieving a smooth, flat finish over joins
- The wall is in a high-visibility area like a living room or hallway
- You suspect asbestos in older textured coatings (homes built before the mid-1980s may be at risk — contact WorkSafe NZ for guidance before disturbing any material)
A skilled tradesperson will have the tools and experience to produce a seamless result quickly. You can find qualified local plasterers and builders on tradedirectory.co.nz.