Reo (reinforcement)
Reo is builder shorthand for steel reinforcement (mesh or bar) embedded in concrete to resist tensile forces. Placement, cover and grade are engineer-specified.
Ask Chalkline about this →Reo is builder shorthand for steel reinforcement: the steel mesh (welded wire fabric) or deformed bars embedded in concrete to resist tensile and bending forces that plain concrete cannot handle alone. On residential slabs, reo is specified by the structural engineer: mesh grade (e.g. SL72, SL82, RL818), bar sizes, spacing, lap lengths, and the concrete cover (the distance from the steel to the nearest concrete face).
Correct concrete cover is critical. Under NCC 2022 Housing Provisions, the minimum cover is 30 mm where a vapour barrier is installed beneath the slab and 40 mm where concrete is directly in contact with the ground. Cover is maintained using bar chairs (plastic stools placed under the mesh before the pour). Sagged mesh with insufficient cover is the most common defect found at pre-pour inspections.
Reo must comply with AS/NZS 4671:2019 (steel reinforcing materials) and be placed to the engineer’s drawings before the certifier’s pre-pour inspection is called.
Also known as: Reinforcement, reinforcing steel, rebar (US term, less common in AU).
Category: Structural.
Related
See also
Last updated: 2026-05-07. Verified: 2026-05-07. Quarterly review for currency.