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SL72 mesh

SL72 is a welded square reinforcement mesh used in the top of residential slabs. The standard for waffle pod toppings and stiffened rafts on most domestic builds.

By Chalkline. Last updated 29 May 2026. Verified 29 May 2026.

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SL72 is a welded square reinforcement mesh (a “SL series” fabric) used in residential concrete slabs. It is the standard top-mesh grade for the topping over a waffle pod slab and the panel mesh in most stiffened-raft designs, with the heavier SL82 stepping in on higher-load or larger-span panels.

Where it fits

The SL series (SL62, SL72, SL82, SL92, SL102) covers the range of residential and light commercial mesh. SL72 sits in the middle, lighter than SL82 (used on bigger spans and reactive sites) and heavier than SL62 (smaller jobs, garage paths). Designation rule of thumb: higher SL number = heavier wire = more reinforcement per square metre, set by the engineer against load and crack-control requirements.

On a typical residential waffle pod or stiffened raft (verified 2026-05-29, see waffle pod slab):

  • SL72 or SL82 in the topping panel.
  • 30 mm minimum cover to the slab top, achieved with chairs at the specified spacing.
  • Trench mesh (a separate product, bar-reinforced strip) in the edge beams and internal beams, not square mesh.

The engineer’s drawings specify the grade for the job; SL72 is the common default but a Class M or Class H site may step up to SL82 in the same role.

Why it matters

SL72 (and the SL series generally) is governed by AS/NZS 4671 Steel reinforcing materials, the standard a steel-mesh delivery is supplied against. The grade stamp on the bundle is the proof of grade; an unstamped bundle is a non-conformance the certifier will flag at pre-pour. The two recurring site issues:

  • Wrong mesh grade: a SL62 delivered for an SL72 spec is half a grade light; the slab is non-compliant against the engineer’s design.
  • Mesh in the wrong position: the cover and lap have to match the spec. Mesh sitting on the vapour barrier with no chairs is a recurring pre-pour-inspection fail.

Also known as: SL72 reinforcement mesh, SL72 reo.

Category: Materials / reinforcement

See also

Last updated: 2026-05-29. Verified: 2026-05-29. Quarterly review for currency.

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