Cracked brick veneer is a common sight on New Zealand homes, especially after ground movement, seasonal temperature swings, or normal settling. Many hairline and mortar cracks are straightforward DIY repairs, but some cracks signal serious structural or weathertightness problems that need a licensed professional. Read on to understand the difference and how to tackle the job safely.
Assess the Crack First — This Step Is Critical
Before picking up a trowel, take time to understand what you're dealing with. Not all cracks are equal.
- Hairline cracks (under 1 mm wide) in mortar joints are usually cosmetic and caused by normal thermal movement or minor settling. These are generally safe to repair yourself.
- Wider cracks (1–3 mm) may indicate more significant movement. Monitor them over several weeks by marking the ends with a pencil and date before repairing.
- Cracks wider than 3 mm, stair-step cracks following mortar joints, or cracks with displacement (one side higher than the other) can indicate foundation movement, lintel failure, or structural issues. Stop and get a professional assessment.
- Horizontal cracks are particularly serious and may indicate wall tie failure or soil pressure problems.
If your home was built before the 1990s, check whether it has adequate wall ties connecting the brick veneer to the timber framing behind. Corroded or missing ties are a known issue in older NZ homes and require professional remediation.
Also consider whether the crack is allowing water ingress. Brick veneer is a drained cavity system under the NZ Building Code (Clause E2 — External Moisture). Cracks that breach the weathertightness of the wall need prompt attention to prevent moisture damage to the framing behind.
Tools and Materials You'll Need
- Cold chisel and club hammer (for raking out loose mortar)
- Wire brush and vacuum
- Safety glasses and dust mask (P2 rated)
- Pre-mixed mortar or bagged mortar mix matched to your existing mortar colour
- Pointing trowel or mortar gun
- Sponge and bucket of water
- Masonry crack filler or flexible sealant for very fine cracks
- Masonry paint or sealer if repainting (optional)
For mortar colour matching, take a photo or a small sample to your local Mitre 10 or Bunnings store. Getting the colour right makes a big difference to the finished look.
Step-by-Step: Repointing a Cracked Mortar Joint
1. Rake Out the Damaged Mortar
Using a cold chisel and club hammer, carefully remove loose or crumbling mortar to a depth of at least 15–20 mm. Work gently to avoid damaging the brick faces. Always wear safety glasses — flying mortar chips are a real hazard.
2. Clean the Joint
Brush out all dust and debris with a wire brush, then vacuum. Dampen the joint with clean water — this stops the existing masonry from drawing moisture out of the fresh mortar too quickly, which weakens the bond.
3. Mix and Apply the Mortar
Mix mortar to a firm but workable consistency (similar to peanut butter). Press it firmly into the joint in layers if the gap is deep, allowing each layer to firm up slightly before adding the next. Finish the joint to match the profile of surrounding joints — a weathered or raked profile is common on NZ homes.
4. Cure and Clean Up
Keep the repair damp for 24–48 hours by misting with water, especially in hot or windy weather. This helps the mortar cure properly. Clean any smears off brick faces with a damp sponge before the mortar fully sets.
Repairing Cracks Through the Brick Face
If the crack runs through the brick itself (not just the mortar), the options are more limited for a DIYer:
- Small surface cracks can be filled with a flexible masonry crack filler, then painted with a masonry sealer or paint from Resene or Dulux to blend in.
- Cracked or spalled bricks ideally should be replaced. Removing and replacing individual bricks is possible for a confident DIYer, but sourcing matching bricks can be tricky — try salvage yards or specialist brick suppliers.
- If you can't find a match, a builder may be able to rotate a brick from a hidden area (inside a garage wall, for example) and use it in the visible repair.
Safety Notes
- Always wear safety glasses, gloves, and a P2 dust mask when cutting or grinding masonry.
- Working at height? Use a properly secured ladder or scaffold. Falls are the leading cause of serious injury on NZ building sites — see WorkSafe NZ for safe working at height guidance.
- Older homes may have mortar containing lime — this is generally fine to work with but avoid skin and eye contact.
- If your home was built before the 1980s, be aware of the small possibility of asbestos-containing materials in associated renders or sealants. If in doubt, contact a licensed asbestos assessor before disturbing any materials.
When to Call a Professional
Call a Licensed Building Practitioner (LBP) if you notice any of the following:
- Cracks wider than 3 mm, or cracks that keep returning after repair
- Stair-step cracking, horizontal cracking, or displaced brickwork
- Signs of water getting into the wall cavity (damp patches inside, mould, or rotting timber)
- Suspected wall tie failure (the wall sounds hollow when tapped, or bricks are bowing outward)
- Cracks near lintels above windows or doors
- Any structural concerns at all
Significant repairs to brick veneer may require a building consent — always check with your local council before starting work. Some minor repairs fall under Schedule 1 exemptions, but confirm this with your council first. You can find qualified local builders on tradedirectory.co.nz.
For guidance on what work requires consent, visit MBIE Building Performance.
Registered Master Builder
Licensed Building Practitioner (LBP)
