Concrete screed: definition and loose usage

What is meant by concrete screed?

Concrete screed is an expression of common usage, not a technical term. It almost always describes a cement-based screed, that is a traditional sand-cement screed or a flow screed with a cement binder.

The confusion is widespread and harmless in conversation. It stops being harmless on a quotation or a drawing, where screed and slab describe two different works, with two functions and two unrelated prices.

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Why does a screed contain no gravel?

Concrete, strictly speaking, is a mix of cement, sand, gravel and water. It is the gravel that gives it its structural strength and its ability to carry load.

A screed contains none. It is made of sand and cement only, which makes it a mortar rather than a concrete. That absence is deliberate: it allows reduced thicknesses, a fine and regular surface able to receive a floor covering, and installation with a screed rail.

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Screed or slab: two works, two roles

The slab is structural. It carries the building or the floor level, it contains calculated reinforcement, and it is sized by an engineer.

The screed carries nothing. It rests on the slab or on a floor, and its role is to form the surface that will receive the tiles, the wood flooring or the vinyl. Removing a screed does not threaten the structure; removing a slab does.

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When the term hides a real problem

A quotation stating concrete screed with no further detail leaves several questions open: is it a traditional or a flow screed, bonded or floating, reinforced or not, and at what thickness.

These parameters determine the price, the programme and the performance. The precise wording to expect states the type, the method of installation, the thickness and the strength class under standard NBN EN 13813. See our screed laying services.