Kumar IronUpdated
In this guide
Where weldmesh is used
- Ground floors, driveways and warehouse floors, to control shrinkage and temperature cracking.
- Thin slabs, sunshades, chajjas of small span and precast items, where an engineer has specified it.
- Plaster, at junctions between different materials.
- Fencing and cages, which is a separate use, see the fencing guide.
Mesh vs loose bars
Mesh comes as flat sheets or rolls with wires welded in a grid, so it arrives pre-spaced. Laying it is faster than cutting and tying individual bars, and spacing is consistent. Loose bars give you freedom of bar diameter, spacing and bending to suit the structure, which is why main roof slabs, beams and columns of a house are normally done with TMT bars.
Mesh for concrete reinforcement is covered by IS 1566 for hard drawn steel wire fabric. Look for the wire diameter, grid spacing and sheet size on the label, and ask your engineer which one is right.
Anti-crack mesh in plaster
Cracks often start where brick or block meets a concrete beam or column, because the two materials expand and move differently. Fixing a strip of mesh across the junction before plastering helps hold the plaster together.
- Use a strip that extends about 150 mm on each side of the joint, or as advised for your job.
- Fix it firmly with nails or fasteners, and keep it flat against the wall.
- Mesh should sit inside the plaster, not on its surface, so apply a base coat, and plaster over it.
- Also use it over service chases, behind electrical conduits and around openings.
- Galvanised mesh avoids rust stains in damp areas.
Lap and cover in slabs
Sheets must overlap so the load and stress carry across. A common practice is to overlap at least one full grid square, and often more, as the engineer's detail shows. Tie laps with binding wire at regular spacing.
Keep the mesh away from the formwork with cover blocks or chairs, so concrete wraps around it. Mesh lying on the shuttering will rust and give no strength. Follow the same cover rules as for bars, see the cover blocks guide.
Limits you should know
- Light mesh is not a substitute for structural steel in roof slabs, beams and columns unless a structural engineer has designed it.
- Mesh controls cracking, it does not carry design loads in ordinary house slabs.
- Never reduce the TMT steel on the drawing to replace it with mesh without engineer approval.
- Poor cover, poor curing and wrong concrete mix will still crack the slab, whatever mesh is used.
Cure the slab as advised in the curing guide. Tell the store where you plan to use the mesh and we will help you pick the right wire size and sheet.
Frequently asked questions
- Can weldmesh replace bars in a house slab?
- Not unless a structural engineer has designed it that way. Normal house slabs use TMT bars.
- How much should weldmesh sheets overlap?
- Commonly at least one full grid square, but follow the engineer's detail.
- Does mesh stop plaster cracks completely?
- It reduces cracking at joints. Good curing and mortar mix matter too.
- Where do I fix anti-crack mesh?
- Across brick to concrete junctions, over chases and around openings, before plastering.