Reinforcement Mesh Calculator — Sheets, Overlap & Chairs

A142 (6mm wires) for paths and light-use slabs. A193 (7mm) for driveways and domestic floors — this is the most common choice. A252 (8mm) for heavy-duty floors and raft foundation edges. A393 (10mm) for industrial floors and raft foundations. The letter A means square mesh (same spacing both directions, 200mm). For bar reinforcement in structural elements, see our Rebar Calculator.

Mesh sheets must overlap by at least 2 squares — for standard 200mm spacing, that's 450mm (rounding up from 400mm to include a tie point). At every overlap, tie the sheets together with wire at 600mm centres. The overlap ensures continuity of reinforcement across sheet joints. Never butt sheets together without overlap.

Spacer chairs (bar chairs or stools) hold the mesh at the correct height within the concrete slab — typically at mid-depth for single-layer mesh, or at specific cover depths. Space chairs at 600mm centres in both directions. Without chairs, the mesh sinks to the bottom during pouring and provides no structural benefit.

Standard sheet sizes are 4.8m x 2.4m (11.52 m²). Nominal weights per sheet (BS 4483): A142 = 25.6 kg, A193 = 34.8 kg, A252 = 45.5 kg, A393 = 71.0 kg. A193 sheets are manageable for two people. A393 sheets are heavy and may need mechanical lifting. Mesh can also be ordered in custom cut lengths.

Steel or polypropylene fibres can replace mesh in some applications (mainly crack control in non-structural slabs). However, for structural slabs, foundations and any application requiring a specific reinforcement area, mesh or rebar is essential. Fibres don't provide the same structural capacity as mesh. Always follow the structural engineer's specification.