Screed reinforcement mesh: definition and purpose

What is screed reinforcement mesh?

Screed reinforcement mesh is a welded steel mesh, rolled out over the substrate and then embedded within the thickness of the screed during pouring. It is also simply called screed reinforcement.

It does not make the screed load-bearing and does not change its nature. It changes the way the screed absorbs stresses.

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What does it actually do?

It does not prevent cracking, which is the most common misunderstanding about it. A reinforced screed cracks just as an unreinforced one does, since the shrinkage of cement is unavoidable.

What the mesh changes is the opening and the propagation of those cracks. It holds the two faces of a crack together and prevents it from widening or the pieces from separating. A reinforced screed that has cracked remains serviceable; an unreinforced screed that has cracked can become a set of independent slabs.

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Where should it sit within the thickness?

This is the decisive technical point, and the one most often missed. Mesh laid flat on the substrate and then simply covered with mortar serves no purpose: it sits in the zone that works least.

It must sit in the part of the screed stressed in tension, meaning lifted within the thickness rather than laid at the bottom. On site that means either pouring in two passes, or lifting the mesh with a hook as the pour proceeds.

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Mesh or fibres: which to choose?

Fibres, synthetic or steel, are mixed into the mortar and distribute through the whole mass. They act from an early age, at the moment when plastic shrinkage creates micro-cracking, and they raise no positioning problem at all.

Mesh handles stresses better over long spans and under concentrated loads. Fibres are more reliable in execution. The choice depends on the expected loads and the configuration of the site. See our screed laying services.