For most residential garden paths in New Zealand, SL62 reinforcing mesh is the go-to choice. It's lightweight, widely available, and provides adequate crack control for a slab that only needs to handle foot traffic. That said, the right mesh depends on your path's width, thickness, and ground conditions — so read on before you head to the hardware store.
What Is Reinforcing Mesh and Why Does a Path Need It?
Reinforcing mesh is a grid of steel rods (called bar) welded together at regular intervals. In a concrete slab, it doesn't stop cracks from forming entirely — concrete will always shrink a little as it cures — but it holds any cracks tightly together so the slab stays level and structurally sound. Without mesh, a garden path can crack and shift over time, especially in areas with clay soils, tree roots, or seasonal wet/dry cycles, which are common across much of New Zealand.
Understanding NZ Mesh Designations
In New Zealand, reinforcing mesh is described by a letter-number code. The letter indicates the bar spacing and the number relates to the bar diameter:
| Mesh Grade | Bar Diameter (approx.) | Grid Spacing | Typical Use |
|---|---|---|---|
| SL52 | 5 mm | 200 mm × 200 mm | Very light slabs, thin overlays |
| SL62 | 6 mm | 200 mm × 200 mm | Garden paths, patios (foot traffic) |
| SL72 | 7 mm | 200 mm × 200 mm | Driveways, light vehicle areas |
| SL82 | 8 mm | 200 mm × 200 mm | Heavier driveways, garage floors |
For a standard garden path (typically 75–100 mm thick, foot traffic only), SL62 is the standard recommendation. If your path is wider than about 1.2 m or sits on poor, soft, or fill ground, consider discussing SL72 with a concreter.
How Much Mesh Do You Need?
Measure your path length and width, then add around 10–15% for overlaps and waste. Mesh sheets typically come in 6 m × 2.4 m panels from suppliers like Bunnings or PlaceMakers, though availability can vary by region. Some stores also sell smaller cut lengths. Always check with your local supplier for what's in stock.
As a rough guide only: a 10-metre path that is 1 metre wide needs approximately 10 m² of mesh, so one standard panel with some trimming to spare.
Preparing the Base Before You Lay Mesh
The mesh is only as good as what's underneath it. A well-prepared sub-base is just as important as the steel:
- Excavate to a depth of at least 150–200 mm below finished level (100 mm of compacted base + 75–100 mm of concrete).
- Compact the subgrade thoroughly — a plate compactor hired from a local hire shop works well.
- Lay 75–100 mm of compacted AP20 or AP40 basecourse (crushed aggregate) for drainage and stability.
- On very wet or clay-heavy sites, consider a layer of geotextile fabric beneath the basecourse.
Good drainage under the slab is especially important in wetter NZ regions. BRANZ has useful guidance on slab construction and moisture management.
Placing the Mesh Correctly
Mesh must sit in the middle to lower-middle third of the slab thickness to be effective — not flat on the ground and not poking out the top.
- Use bar chairs (plastic or wire supports) to hold the mesh at the correct height — typically 30–40 mm up from the bottom for a 75–100 mm slab. These are inexpensive and available at concrete suppliers.
- Overlap adjoining sheets by at least one full grid square (200 mm) and tie overlaps with tie wire.
- Keep mesh at least 50 mm back from all edges of the slab to prevent corrosion.
- Cut mesh with angle grinder or bolt cutters — wear gloves and eye protection, as cut ends are sharp.
Concrete Mix for a Garden Path
For a garden path, a 20 MPa mix is generally sufficient for foot traffic. You can use bagged premix concrete for small jobs or order ready-mix for anything over about 0.5 m³. Ask your ready-mix supplier for a mix suitable for a residential path — they'll know what's appropriate for your area.
Do You Need a Building Consent?
In most cases, a simple garden path does not require a building consent under Schedule 1 of the Building Act 2004 — but this depends on factors like proximity to boundaries, drainage implications, and your local council's rules. Always confirm with your local council before starting, as requirements vary. You can find general guidance at MBIE Building Performance.
When to Call a Professional
While laying a garden path is a popular DIY project, there are situations where it's worth bringing in a qualified concreter:
- Poor or unstable ground — fill, clay, or areas with tree roots nearby.
- Paths near retaining walls, drainage channels, or structures — these may have engineering implications.
- Large areas — anything over about 20 m² can be difficult to finish properly without experience.
- Sloped sites — formwork and finishing on a slope requires skill to get right.
A professional concreter will also know the right mesh, mix, and joint spacing for your specific conditions. You can find qualified local concreters on tradedirectory.co.nz.
Safety Note
Concrete is caustic — always wear gloves, eye protection, and waterproof boots when handling wet concrete or cutting mesh. Prolonged skin contact can cause serious burns. Keep children and pets away from the work area.
Sources & Further Reading
- BRANZ – Concrete slabs and construction guidance
- MBIE Building Performance – Building consent information
- Bunnings – Reinforcing mesh and concrete supplies
- PlaceMakers – Concrete and reinforcing products
- WorkSafe NZ – Safe handling of construction materials
- Standards NZ – NZS 3109 Concrete Construction
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