Removing old loose render from a brick wall is a job many NZ homeowners can tackle themselves with the right preparation, tools, and safety measures. Done properly, it sets you up for a quality re-render that will last for years — done poorly, it can damage the underlying brickwork or expose you to health hazards like silica dust or even asbestos.
Safety First — Know What You're Dealing With
Before you swing a hammer, consider two important hazards:
- Asbestos: Render applied before the mid-1980s in New Zealand may contain asbestos fibres. If your home was built or renovated before 1990, treat the render as potentially hazardous until proven otherwise. Do not dry-scrape or grind it. Contact a licensed asbestos assessor or removalist, and check guidance from WorkSafe NZ before proceeding.
- Silica dust: Even asbestos-free render contains crystalline silica. Grinding or chipping creates fine dust that can cause serious lung disease (silicosis). Always wear a properly fitted P2 respirator (not a basic dust mask), safety glasses, and gloves.
Personal protective equipment (PPE) checklist:
- P2 respirator
- Safety glasses or goggles
- Heavy-duty gloves
- Long sleeves and sturdy footwear
- Hearing protection if using power tools
Tools You'll Need
| Tool | Best used for |
|---|---|
| Cold chisel & club hammer | Hand-chipping loose sections |
| Bolster chisel (wide blade) | Larger flat areas |
| SDS rotary hammer with chisel bit | Stubborn or thick render |
| Angle grinder with diamond cup wheel | Flush grinding (use sparingly) |
| Stiff wire brush | Cleaning residue from brick joints |
| Dust sheets & tape | Protecting windows, doors, and garden |
You can hire rotary hammers and angle grinders from most hire centres or pick up tools at Bunnings or Mitre 10.
Step 1 — Identify the Loose Areas
Start by tapping the wall systematically with a rubber mallet or the handle of your hammer. A hollow, drum-like sound indicates render that has delaminated from the brick behind it — this is what needs to come off. Solid-sounding areas may be well-bonded and can sometimes be left in place if you're doing a patch repair rather than a full strip.
Mark loose sections with chalk so you have a clear map before you start.
Step 2 — Set Up Your Work Area
- Lay dust sheets on the ground to catch debris and make clean-up easier.
- Tape plastic sheeting over windows, doors, and any garden beds directly below.
- If working at height, use a properly rated scaffold or platform — never lean a ladder against the wall and chip one-handed. For anything above 3 metres, consider hiring a scaffold tower.
- Wet the render lightly with a garden hose before chipping. This suppresses dust significantly.
Step 3 — Remove the Loose Render
Hand chipping (recommended starting point)
Hold your cold chisel or bolster at a low angle (roughly 30–45°) to the wall surface and strike firmly with the club hammer. Work from the edges of the loose section inward. Avoid driving the chisel straight into the wall at 90° — this risks cracking or spalling the brick face.
Power chipping
For large areas or render that's thicker than about 20 mm, an SDS rotary hammer with a flat chisel bit speeds things up considerably. Use a medium setting — too much force can damage the mortar joints between bricks. Work in short bursts and keep the chisel moving.
Angle grinding
Use an angle grinder with a diamond cup wheel only to remove thin, stubborn render that won't chip cleanly. This generates the most dust, so wet the surface first and keep your P2 respirator on at all times.
Step 4 — Clean Up the Brick Surface
Once the bulk of the render is off, use a stiff wire brush to remove loose particles and render residue from the brick face and mortar joints. Brush out the joints to a depth of at least 5–10 mm — this gives the new render a mechanical key to grip.
Rinse the wall down with clean water and allow it to dry before assessing whether re-rendering can begin. Check for any cracked or crumbling mortar joints; these should be raked out and repointed before new render goes on.
Step 5 — Assess the Brickwork
With the render removed, inspect the wall carefully:
- Cracked bricks may indicate structural movement — get a builder or engineer to assess before re-rendering.
- Efflorescence (white salt deposits) should be brushed off and the source of moisture investigated.
- Damp or wet bricks need to dry fully. Applying render over damp substrate is a common cause of future delamination.
For guidance on weathertightness and external wall performance, BRANZ publishes excellent technical resources relevant to NZ conditions.
Does This Work Require a Building Consent?
In most cases, removing and replacing render on an existing wall is exempt from building consent under Schedule 1 of the Building Act 2004 — but this depends on the scope of work and your specific property. Always confirm with your local council before starting, particularly if the wall is part of a heritage building or if structural repairs are involved. See MBIE Building Performance for general guidance on consent exemptions.
When to Call a Professional
Call a licensed renderer or plasterer if:
- The render contains or may contain asbestos (pre-1990 buildings)
- The wall shows signs of structural cracking or movement
- You're working at significant height and don't have safe access equipment
- The area to be stripped is very large and you want a quality result guaranteed
- You're unsure about the correct render system for re-application
A qualified renderer will also know which products and systems suit NZ's varied climate conditions — from the wet West Coast to the UV-intense Hawke's Bay. You can find experienced local renderers on tradedirectory.co.nz.
Licensed Building Practitioner (LBP)
