A corner bead that has been knocked off is one of the more satisfying DIY plaster repairs you can tackle at home — no specialist licence required, and with a bit of patience you can get a result that's virtually invisible. The key is preparing the surface properly, choosing the right bead and compound, and allowing adequate drying time between coats.
What Is a Corner Bead and Why Does It Matter?
Corner bead is the metal or plastic strip fixed to external (outside) corners of plasterboard walls to protect the edge and give a crisp, straight line. In NZ homes, you'll most commonly find galvanised steel beads or PVC (plastic) beads. Steel beads are traditional and very durable; PVC beads are rust-proof and a good choice in higher-humidity areas like bathrooms or near exterior walls. The bead is embedded in stopping compound (also called joint compound or plaster) and then finished flush with the wall surface.
When a corner takes a knock — from furniture, a doorknob, or a moving mishap — the bead can crack away from the wall, buckle, or pull completely free. Left unrepaired, the corner is vulnerable to further damage and looks unsightly.
Tools and Materials You'll Need
- Replacement corner bead (metal or PVC, matching the existing profile — typically 25 mm or 32 mm wing width)
- Stopping compound (pre-mixed or powder — brands like GIB Tradeset or a pre-mixed all-purpose compound work well)
- Screws or staples suitable for your bead type (or construction adhesive for adhesive-fix beads)
- Drill/driver or staple gun
- 150 mm and 250 mm broad knives (plasterer's trowels)
- Fine sandpaper (120–180 grit) and a sanding block
- Damp cloth or sponge
- Primer and touch-up paint
Step 1 — Remove the Old Bead Completely
Don't try to patch over a partially attached bead — it will fail again. Use a broad knife or old chisel to carefully prise away any remaining sections. Remove all loose or crumbling stopping compound back to a firm edge. If the underlying plasterboard (GIB board) is damaged or the paper face is torn, stabilise it with a thin skim of compound and let it dry fully before proceeding.
Step 2 — Measure and Cut the New Bead
Measure the corner height accurately and cut your new bead to length with tin snips (for metal) or a utility knife and straight edge (for PVC). Cut cleanly and deburr any sharp metal edges with a file.
Step 3 — Fix the New Bead in Place
There are two common fixing methods:
Screw or Staple Fix
Position the bead so it sits snugly on the corner with both wings flat against the wall. Fix through the bead's perforations into the plasterboard at roughly 200 mm centres. Use fine-thread drywall screws or a staple gun — don't overdrive and buckle the bead.
Adhesive Fix (Clinch Bead / Stick Bead)
Some modern PVC beads are designed to be bedded directly into a generous coat of stopping compound applied to both wings. Press the bead firmly into position, check it's plumb with a spirit level, and allow to firm up before coating.
Always check the bead is plumb and straight before the compound sets — a twisted bead is very hard to fix later.
Step 4 — Apply Stopping Compound
This is the most important stage for a quality finish. Apply compound in thin coats, feathering out at least 200–250 mm either side of the bead nose:
- First coat: Fill the bead wings and bring the compound flush with the nose. Don't try to finish in one thick coat.
- Second coat (after full drying — typically 24 hours): Sand lightly, wipe dust away with a damp cloth, then apply a wider, thinner coat.
- Third coat (if needed): A final skim coat feathered well out from the corner gives the smoothest result.
Pre-mixed compounds shrink slightly as they dry, so what looks flush when wet will often need another pass. BRANZ recommends following the plasterboard manufacturer's finishing system for best results.
Step 5 — Sand and Prime
Once the final coat is fully dry, sand smooth with 120–180 grit paper. Work carefully — you want to blend the repair into the surrounding wall without sanding through the paper face of the plasterboard. Wipe away all dust.
Apply a plasterboard primer or sealer before painting. Skipping this step causes the repaired area to flash (appear different in sheen) through the topcoat. Resene and Dulux both offer suitable interior primers. Once primed, apply your topcoat paint to match the existing wall.
Tips for a Better Result
- Work in a well-ventilated area — compound dust is irritating to lungs; wear a dust mask when sanding.
- In humid NZ climates (especially Auckland or coastal areas), allow extra drying time between coats.
- If the corner is in a high-traffic area, consider a bullnose or heavy-duty bead for added impact resistance.
- Replacement beads and compound are readily available at Bunnings, Mitre 10, and PlaceMakers.
When to Call a Professional
This repair is generally within DIY reach, but consider calling a qualified plasterer if:
- The underlying plasterboard is significantly damaged or water-affected (which may indicate a moisture issue requiring investigation under the NZ Building Code clause E3)
- You need a large section of bead replaced across multiple walls or a whole room
- The finish needs to match a textured or specialist wall coating
- You simply want a guaranteed seamless result first time
A skilled plasterer will have the tools and experience to finish the repair invisibly. You can find qualified local plasterers on tradedirectory.co.nz.
Safety note: Corner bead work involves sharp metal edges and fine dust. Wear gloves when handling cut metal beads and a P1 or P2 dust mask when sanding.
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