Quick Answer

Fixing holes and cracks in plasterboard walls is a straightforward DIY job for most Melbourne homeowners. Small nail holes take 5 minutes with filler and a putty knife; fist-sized holes need a patch kit or backing board and take 1–2 hours including drying time. Materials cost $15–$60; hiring a plasterer runs $80–$180 per hour. Most homeowners can achieve a paint-ready finish with patching compound, a few tools and patience.

What You’ll Need

Item Use Cost Where to Buy
Plasterboard patching compound (e.g. Gyprock Lite Fill or USG Sheetrock) Filling and finishing all repair sizes $12–$20 per 4L tub Bunnings, Mitre 10
Fibreglass mesh patch (self-adhesive) Medium holes 50–150mm $8–$15 Bunnings, hardware stores
Plasterboard offcut (same thickness — usually 10mm) Backing board for large holes $5–$15 offcut Bunnings, Gyprock suppliers
Plasterer’s knife / wide putty knife (150–200mm) Applying and feathering compound $12–$25 Bunnings, Total Tools
Sandpaper 120-grit and 180-grit Sanding between coats $5–$10 Bunnings, Mitre 10
Primer (water-based) Sealing before painting $12–$20 per litre Bunnings, paint stores
Dust mask P2 and safety glasses Sanding plasterboard dust protection $8–$15 Bunnings, Total Tools

Repair Method by Hole Size

Hairline Cracks and Nail Holes (Under 5mm)

These are the easiest repairs. Clean out any loose material, press flexible patching compound into the crack or hole with a finger or small putty knife, smooth flush, let dry 2–4 hours, sand lightly with 180-grit, prime and paint. One coat is usually sufficient for small holes.

Medium Holes (5–50mm)

Clean jagged edges with a sharp Stanley knife to create a square or circular opening. Apply a self-adhesive fibreglass mesh patch over the hole. Apply patching compound over the mesh with a 150mm putty knife, feathering edges 50–75mm beyond the patch. Let dry fully (4–6 hours or overnight), sand with 120-grit then 180-grit, apply a second thin skim coat, dry, sand again, prime and paint.

Pro tip: Three thin coats always beat one thick coat. Thick compound shrinks as it dries and cracks. Each coat should be thinner than the last — the final skim coat is almost translucent.

Large Holes (50–200mm)

Large holes need a rigid backing. Cut the hole to a clean rectangle with a plasterboard saw or oscillating tool. Cut a piece of plasterboard offcut 50mm wider and taller than the hole. Score and snap the offcut so it fits snugly as a backer board. Secure with plasterboard screws through the existing wall into the backer. Apply joint tape over seams, then three coats of compound as above.

Very Large Holes (Over 200mm) — Cut to Stud

For holes over 200mm, cutting back to the nearest wall studs (600mm centres in most Melbourne homes) and replacing the full section with new plasterboard gives a stronger repair. This requires locating studs with a stud finder or by tapping, and fixing new plasterboard to the exposed stud edges. Tape and compound the joins as normal.

Safety warning: Before cutting any plasterboard wall in an Australian home, check for electrical wires and pipes using a non-contact voltage tester and pipe detector. Electrical cables run through wall cavities and are not always where you expect them. Never use a reciprocating saw in a wall without first checking.

Finishing for a Paint-Ready Surface

After sanding the final coat to smooth, wipe away all dust with a damp cloth and let dry. Apply a coat of water-based primer over the repair — this is non-negotiable. Unprimed compound absorbs paint differently from the surrounding wall, creating a visible sheen patch even under multiple coats of paint. Sand the primed patch lightly with 220-grit, wipe clean, then paint to match.

Matching Existing Wall Texture

Flat walls are easy to match. Textured walls — common in older Berwick and Narre Warren homes built in the 1990s — require texture matching. Orange peel texture can be replicated with a light spray of diluted PVA then stippled with a sponge before the final coat dries. Skip trowel or knockdown texture requires some practice — use an offcut to test your technique before applying to the wall.

Troubleshooting

Problem Cause Fix
Compound cracking as it dries Applied too thick in one coat Let crack fully, sand, apply fresh thin coat
Repair visible as shiny patch after painting Not primed before painting Apply water-based primer over repair, let dry, repaint
Edges lifting or bubbling Wall surface too dusty or oily before patching Scrape back, clean wall surface, reapply
Patch sinking back into large hole No rigid backing behind patch Install plasterboard backer before compounding
Colour mismatch after painting Different paint sheen or aged wall colour Repaint full wall panel for uniform finish

When to Call a Professional Plasterer

Call a licensed plasterer for: holes larger than 400mm, repairs in high-moisture areas (bathroom walls or ceilings with waterproofing requirements), extensive crack patterns suggesting structural movement, ceiling repairs at height, or texture matching on heritage plaster (pre-1950 homes in Frankston, Mornington and inner suburbs). Expect $80–$180 per hour for a qualified plasterer in SE Melbourne.

Top 8 Tips and Gotchas

  1. Gyprock Lite Fill vs regular compound — Lite Fill (lightweight compound) dries faster and sands easier than regular setting compound. Use it for finishing coats. Use regular compound for base coats on large holes where strength matters.
  2. Don’t rush drying time — compound that is not fully dry will crack when sanded. It should be completely white (not grey) with no cool spots before sanding.
  3. Sand lightly — plasterboard paper face is thin. Aggressive sanding will scuff the paper face and create a fuzzy texture that soaks up paint. Use 180-grit and light pressure.
  4. Buy a 200mm putty knife — most DIYers use a 75mm knife and can’t feather properly. A 200mm wide knife makes invisible repairs dramatically easier.
  5. Match plasterboard thickness — Melbourne homes typically use 10mm plasterboard for walls and 13mm for ceilings. Check the label on the edge of existing sheets before buying a backer piece.
  6. Prime before you paint — this is the step most DIYers skip and the reason most repairs remain visible. Water-based primer seals the absorbency difference between compound and surrounding wall.
  7. Check for asbestos in older homes — homes built before 1987 in SE Melbourne may have fibrous cement (“fibro”) sheeting or asbestos-containing textured paints. If in doubt, don’t sand — get a certified asbestos assessor to test first. WorkSafe Victoria has a guide.
  8. Painting over a repair in the same room — even a perfect repair will be visible if you paint only the patch. Repaint the entire wall panel (corner to corner) for an undetectable result.

Frequently Asked Questions

How long does plasterboard filler take to dry between coats?

Lightweight compound (Gyprock Lite Fill) typically dries in 2–4 hours under normal Melbourne indoor conditions. Regular setting compound takes 4–8 hours. Cold winter conditions slow drying significantly — allow overnight between coats in June–August. The compound must be completely white with no grey wet patches before sanding or applying the next coat.

Can I use Polyfilla on plasterboard?

Yes — Polyfilla and similar pre-mixed fillers work well for nail holes and hairline cracks up to 10mm wide. For larger patches, use dedicated plasterboard joint compound (Gyprock, Knauf or USG brands) which is designed for feathering and sanding to a flat finish. Polyfilla can be difficult to feather smoothly over large areas.

How do I stop cracks coming back in the same place?

Recurring cracks at the same location suggest movement — either seasonal thermal movement (very common in Melbourne’s clay soil suburbs), structural settlement, or a poorly-taped original joint. For recurring cracks, use a fibreglass mesh tape over the crack before compounding, and apply a flexible caulk product (not rigid filler) for joints at corners where different building materials meet.

How do I know if my walls contain asbestos?

Asbestos-containing sheeting (fibrous cement) was commonly used in homes built before 1987 and occasionally to 1990 in Australian construction. If your home was built in this era, don’t sand or cut wall materials without testing first. A licensed asbestos assessor can test a sample — WorkSafe Victoria maintains a directory of assessors.

Melbourne Local Resources

  • Bunnings — Gyprock Lite Fill, mesh patches, putty knives, sandpaper, primer
  • Mitre 10 — plasterboard offcuts, compound, professional finishing tools
  • Total Tools — quality putty knives, oscillating tools, stud finders
  • WorkSafe Victoria — Asbestos — licensed asbestos assessors and safe work guidance