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Cross-market term

Screed

In British and Australian usage, the levelling layer laid over a structural floor to receive the finish. In American usage the word more often means the tool or the act of striking a surface off level, or a fixed edge used to do it.
  • 4Markets
  • NoSame thing everywhere
  • 3Calculators

What it is called, by market

One concept, four markets. Where a name means something else locally, the card says so rather than leaving you to find out on site.

  • United Kingdom

    Same word, different thing

    screed

    also floor screed, sand-cement screed

    The LAYER: a levelling course over the slab, of a stated thickness, receiving the floor finish.

  • Australia

    Same word, different thing

    screed

    also floor screed

    As the UK, the LAYER: a levelling course over the slab. The American sense — the tool or the act of striking off — is not what an Australian specification means.

  • United Statesyours

    Same word, different thing

    screed

    also screed rail, screed board

    The TOOL or the ACT: striking concrete off to level, or the rail that guides it. The layer is an underlayment or a topping.

  • Canada

    Same word, different thing

    screed

    also underlayment, topping

    As the United States for the tool sense; the layer is normally an underlayment or a topping.

The governing standard, by market

  • United Kingdom

    BS 8204-1

    Concrete bases and cement sand levelling screeds — materials and workmanship.

  • United States

    ACI 302.1R

    Concrete floor and slab construction, including toppings and finishing.

Calculators for this

Each works in either measurement system, and the terminology on the page follows whichever market you have selected.

Heated Screed Volume Calculator →Self-Leveling Underlayment (SLU) Volume Calculator →Floor Screed Cubic Yards to Tons Calculator →

Frequently asked questions

Does screed mean a layer or a tool?
Both, in different markets, and it is one of the cleanest false friends in construction English. In Britain and Australia a screed is the levelling LAYER over a structural floor — a sand-cement or proprietary material laid to a stated thickness to bring the floor to level and to receive the finish — and it is priced by area and thickness. In the United States the word more often refers to the ACT of striking a surface off to level, or to the TOOL or rail that guides it; the layer a British reader means is an underlayment or a topping. So an American specification saying "screed the slab" is describing an operation, and a British one saying "75 mm screed" is describing material to be delivered.
What is a weep screed, then?
The American sense: a formed metal edge trim, not a layer. A weep screed is fitted at the base of a stuccoed or rendered wall, providing a stopped edge for the coating and openings through which water that gets behind it can escape. It is a strip of profiled metal a few inches deep, and it has nothing whatever to do with a floor screed. The same applies to a casing bead or a plaster screed rail used to gauge thickness. This site's own catalog holds both senses — a screed volume calculator and a weep screed calculator — which is why the glossary lists each concept's calculators explicitly rather than matching on the word.
Why does screed thickness matter so much?
Because it governs both strength and drying time, and the two pull in opposite directions. Too thin and a bonded or unbonded screed cracks and breaks up under load, particularly at doorways and along its edges; too thick and it takes considerably longer to dry to the moisture content a floor finish will tolerate, which is often the item that delays handover. Whether the screed is bonded to the slab, laid unbonded on a membrane, or floating on insulation changes the minimum thickness substantially, as does whether it carries underfloor heating pipes. So a thickness copied from another job without knowing which of those it was is a guess with two failure modes.