Different Types of Reinforcing Steel Mesh in NZ

Different Types of Reinforcing Steel Mesh in New Zealand

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Which Type of Reinforcing Mesh Do I Need?

Choosing the right reinforcing steel mesh for your concrete project is essential for strength, durability and compliance with New Zealand building standards. Whether you're working on a residential slab, driveway or engineered structure, understanding the differences between seismic and yard mesh - and the specific types available (like 668, 665, 663, 661, SE62, SE72, SE82, SE92) - will help you select the best concrete mesh for your needs.

Seismic vs Yard Mesh

Yard (Hard Drawn) Mesh - For General Use

Yard mesh can be used where an engineer's approval is not required. This non-ductile reinforcing steel mesh is used for non-structural concrete work such as driveways, footpaths, patios and garden slabs. While it helps control cracking and distributes loads more evenly in slab pours, it's not suitable for engineered structural applications. The different types of yard mesh available in NZ is 668, 665, 663 and 661 yard mesh.

Hard drawn yard mesh (often referred to as general-purpose, driveway, or non-structural mesh) is primarily manufactured from deformed (or ribbed) hard-drawn wire. While the manufacturing process involves cold-drawing to achieve high strength, a "deformed" or "ribbed" pattern is added to the wire to improve its bonding with concrete. 

Seismic Mesh - Specified by Engineers

Seismic mesh, often referred to as Grade 500E reinforcing mesh, is usually specified by engineers and is designed to meet stringent ductility and tensile strength standards (AS/NZS 4671:2001 & NZS 3604) to perform under seismic loads. This type of reinforcing steel mesh is typically specified for structural concrete in buildings where safety under earthquake conditions is critical. This type of concrete mesh has larger wire diameters and wider grid centres (200 mm) for enhanced structural performance. The different types of seismic mesh available in NZ is SE62, SE72, SE82 and SE92 seismic mesh.

Seismic mesh in New Zealand is predominantly made from smooth (plain) bars rather than deformed (ribbed) bars because of the manufacturing process required to produce high-ductility (Grade 500E) steel, which is necessary for withstanding severe earthquakes. The high ductility (allowing the steel to stretch without breaking) is achieved by micro-alloying the steel with elements like vanadium and then producing it in a smooth,, hot-rolled, or cold-drawn form. The process of creating deformation ribs on small-diameter mesh wires can sometimes negatively affect the steel's ductility, whereas smooth, high-grade steel ensures the required flexibility.

Different Manufacturers - Different Dimensions

It is interesting that different steel mesh manufacturers in New Zealand produce their reinforcing mesh with slightly different dimensions (usually within 10mm-15mm from each other) for no other reason than "being different than the rest". This is also a way for them to identify whether the steel mesh that has been delivered to a specific project site came from their factory or from a competitor. All in all, it comes down to the overall area covered by each mesh sheet and generally the mesh from all different manufacturers are pretty much the same in terms of their area of coverage.

Types of Yard Mesh + Their Specifications

The most common yard mesh types available in New Zealand have been listed below. As explained earlier there are subtle differences in the overall steel mesh sheet dimensions between different manufacturers. The below dimensions and masses are therefore only indicative, but can still be used with a high degree of confidence.

668 Yard Mesh

• Wire diameter: 4.0mm
• Wire centres: 150mm
• Sheet dimensions: 4.56m × 1.97m
• Gross sheet cover area: 8.98m²
• Nett sheet cover area: 7.52m² (after overlapping)
• Mass: Approx. 12.4kg per sheet

Uses: This is the most commonly used and most economical type of concrete mesh in New Zealand. This is often referred to as "driveway mesh" and is commonly used in concrete driveways, paths and small slabs where no engineered design is required.

665 Yard Mesh

• Wire diameter: 5.3mm
• Wire centres: 150mm
• Sheet dimensions: 4.56m × 1.97m
• Gross sheet cover area: 8.98m²
• Nett sheet cover area: 7.52m² (after overlapping)
  
• Mass: Approx. 22kg per sheet

Uses: Stronger than 668 mesh; excellent for heavier foot traffic areas like garage slabs and heavier duty driveways.

663 Yard Mesh

• Wire diameter: 6.3mm
• Wire centres: 150mm
• Sheet dimensions: 4.56m × 1.97m
• Gross sheet cover area: 8.98m²
• Nett sheet cover area: 7.52m² (after overlapping)
• Mass: Approx. 31kg per sheet
  

Uses: Heavier duty yard mesh used where thicker slabs or higher load resistance are desired (e.g. industrial slabs or larger concrete pours).

661 Yard Mesh

• Wire diameter: 7.5mm
• Wire centres: 150mm
• Sheet dimensions: 6.06m x 2.42m
• Gross sheet cover area: 14.67m²
• Nett sheet cover area: 12.76m² (after overlapping)
• Mass: Approx. 70kg per sheet
  

Uses: Heaviest duty yard mesh used where very thick slabs or extremely high load resistance is desired (e.g. heavy duty industrial slabs or larger concrete pours).

Types of Seismic Mesh + Their Specifications

Seismic reinforcing steel mesh types are named with the pattern "SEXX", where "S" stands for "Square" (shape of the grids) and "E" stands for "Earthquake" (seismic grade). The two "XX" symbols are numbers - the first number reflects wire diameter (mm) and the second indicates wire centre spacing (usually 200 mm).

As explained earlier there are subtle differences in the overall reinforcing steel mesh sheet dimensions between different manufacturers. The below dimensions and masses are therefore only indicative, but can still be used with a high degree of confidence.

SE62 Seismic Mesh

• Wire diameter: 6.1mm (smooth / plain bar)
• Wire centres: 200 mm
• Sheet dimensions: 6.05m x 2.42m
• Gross sheet cover area: 14.64m²
• Nett sheet cover area: 12.36m² (with 200mm* overlapping)
  
• Mass: Approx. 36kg per sheet

* 200mm is generally considered to be the recommended lapping for SE62 mesh, however please consult your engineer if a specific overlap splice is required.

Uses: Residential slab reinforcement for engineered foundations and suspended slabs.

SE72 Seismic Mesh

• Wire diameter: 7.0mm (smooth / plain bar)
• Wire centres: 200 mm
• Sheet dimensions: 6.06m x 2.43m
• Gross sheet cover area: 14.73m²
• Nett sheet cover area: 12.36m² (with 250mm** overlapping)
  
• Mass: Approx. 47kg per sheet
  

Uses: Stronger seismic mesh for heavier residential and light commercial slab applications.

SE82 Seismic Mesh

• Wire diameter: 8.0mm (smooth / plain bar)
• Wire centres: 200mm
• Sheet dimensions: 6.06m x 2.43m
• Gross sheet cover area: 14.73m²
• Nett sheet cover area: 12.36m² (with 250mm** overlapping)
  
• Mass: Approx. 61kg per sheet
  

Uses: Used where increased reinforcement is needed for engineered slabs and ground beams.

SE92 Seismic Mesh

• Wire diameter: 9.0mm (smooth / plain bar)
• Wire centres: 200mm
• Sheet dimensions: 6.06m x 2.43m
• Gross sheet cover area: 14.73m²
• Nett sheet cover area: 12.36m² (with 250mm** overlapping)
  
• Mass: Approx. 77kg per sheet
  

** Please consult your engineer if a specific overlap splice is required

Uses: One of the strongest standard seismic meshes; ideal for heavily loaded slabs or structural ground floors.

Summary: Choosing the Right Reinforcing Mesh

• For engineered structural work (homes, commercial slabs): Choose seismic grade 500E mesh like SE62, SE72, SE82, SE92 - these meet NZ seismic and ductility requirements.
• For non-engineered slabs (driveways, garden slabs): Select yard mesh such as 668, 665, 663, 661 as this offers excellent crack control at lower cost.

Always consult your engineer or a building professional to ensure the reinforcing steel mesh you select matches your site conditions, design loads and NZ building code requirements.