Repointing crumbling brick mortar joints is one of the more satisfying DIY repairs a homeowner can tackle. With the right tools, the correct mortar mix, and a bit of patience, you can restore weathered joints, stop water ingress, and extend the life of your brickwork significantly. Here's how to do it properly in a New Zealand context.
What Is Repointing and Why Does It Matter?
Repointing (sometimes called tuckpointing) means raking out deteriorated mortar from the joints between bricks and replacing it with fresh mortar. In New Zealand's variable climate — from Auckland's humidity to Canterbury's freeze-thaw cycles — mortar joints are constantly exposed to moisture and temperature swings. Over time, the mortar softens, cracks, and crumbles, allowing water to penetrate the wall. Left untreated, this can lead to damp interiors, efflorescence (white salt staining), and structural weakening. Catching it early keeps the repair simple and affordable.
Tools and Materials You'll Need
- Cold chisel (plugging chisel) and club hammer, or an angle grinder with a mortar-raking disc
- Wire brush
- Pointing trowel and a hawk (small mortar board)
- Bucket and mixing paddle (or a drill with a mixing attachment)
- Safety glasses, dust mask (P2 rated), and gloves
- Pre-mixed mortar or separate bags of cement, lime, and sand
- Spray bottle with water
- Stiff brush for finishing
You'll find most of these at Bunnings or Mitre 10, and PlaceMakers stocks a good range of bagged mortars and masonry products.
Choosing the Right Mortar Mix
This is the most critical step. Using a mortar that is too hard (too much cement) can cause more damage than the crumbling mortar itself, because it forces movement stress into the bricks rather than the joint, potentially cracking the bricks.
As a general guide for typical NZ residential brickwork:
| Application | Mix Ratio (Cement : Lime : Sand) |
|---|---|
| Soft or older bricks (pre-1970s) | 1 : 2 : 9 |
| Standard modern brickwork | 1 : 1 : 6 |
| Exposed or high-moisture areas | 1 : 0.5 : 4.5 |
If you're unsure of your brick type or age, lean toward a softer, lime-rich mix. Pre-mixed bagged mortars labelled for repointing are a convenient option — just check the packaging confirms suitability for your brick type. When in doubt, ask at your local builders' merchant or consult BRANZ guidance on masonry.
Step-by-Step Repointing Process
1. Rake Out the Old Mortar
Using a cold chisel and club hammer (or an angle grinder with a raking disc), remove the old mortar to a depth of at least 15–20 mm. Work carefully to avoid chipping the brick faces. Wear your safety glasses and P2 dust mask — old mortar dust can contain silica, which is hazardous to breathe. Check WorkSafe NZ guidance on silica dust if you're doing a large area.
2. Clean the Joints
Brush out all loose debris with a wire brush, then blow or vacuum out the dust. Dampen the joints with a spray bottle — this stops the dry brick from sucking moisture out of the fresh mortar too quickly, which weakens the bond.
3. Mix Your Mortar
Mix to a firm but workable consistency — it should hold its shape when squeezed but not be crumbly or sloppy. Mix small batches so it doesn't dry out before you use it. Avoid mixing in direct hot sun or strong wind.
4. Apply the Mortar
Load a small amount onto your hawk. Use the pointing trowel to press mortar firmly into the joint, working in layers if the joint is deep. Fill horizontal (bed) joints first, then vertical (perpend) joints. Pack it in firmly to avoid air pockets.
5. Finish the Joint Profile
Once the mortar is firm but not fully set (usually 20–40 minutes depending on conditions), finish the joint to match the existing profile. Common profiles include:
- Flush — trowelled flat with the brick face
- Weatherstruck — angled to shed water (good for exposed NZ walls)
- Recessed — slightly set back (avoid in very wet climates)
Use a jointing tool, the edge of your trowel, or a piece of dowel to shape the profile neatly.
6. Clean Up and Cure
Brush off any mortar smears with a stiff brush once the mortar has firmed. Keep the repaired area damp for 2–3 days by misting lightly — this slow curing produces stronger mortar. Avoid repointing in temperatures below 5°C or in heavy rain.
Does This Work Require a Building Consent?
Routine repointing of existing brickwork is generally considered maintenance and falls under Schedule 1 exemptions of the Building Act — meaning no building consent is typically required. However, if the brickwork is part of a retaining wall, chimney, or structural element, or if the damage is extensive, you should confirm with your local council before starting. See MBIE Building Performance for guidance on what work requires consent.
When to Call a Professional
Repointing a small section of a garden wall or a few joints on a house is well within DIY capability. However, call a qualified builder or mason if:
- The damage is widespread across a large wall area
- Bricks themselves are cracked, spalling, or moving
- The wall is structural, load-bearing, or part of a chimney
- You're working at height above a single storey (scaffolding and fall risks apply — see WorkSafe NZ)
- You suspect the issue is caused by subsidence or foundation movement
- The property is a heritage or character building with special requirements
A Licensed Building Practitioner (LBP) can assess the full extent of the damage and carry out restricted building work where required. You can find qualified local builders and stonemasons on tradedirectory.co.nz.