Screed has three meanings in building construction: # A flat board (screed board, floating screed) or a purpose-made

aluminium Aluminium (aluminum in AmE, American and CanE, Canadian English) is a chemical element with the Symbol (chemistry), symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately o ...

tool used to smooth and to "

true True most commonly refers to truth, the state of being in congruence with fact or reality. True may also refer to: Places * True, West Virginia, an unincorporated community in the United States * True, Wisconsin, a town in the United States * ...

" materials like

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most ...

stucco Stucco or render is a construction material made of aggregates, a binder, and water. Stucco is applied wet and hardens to a very dense solid. It is used as a decorative coating for walls and ceilings, exterior walls, and as a sculptural and a ...

and plaster after they have been placed on a surface or to assist in flattening; # A strip of plaster or wood applied to a surface to act as a guide for a screed tool (screed rail, screed strip, screed

batten A batten is most commonly a strip of solid material, historically wood but can also be of plastic, metal, or fiberglass. Battens are variously used in construction, sailing, and other fields. In the lighting industry, battens refer to linea ...

); # The material itself which has been flattened with a screed (screed coat). In the UK, ''screed'' has also come to describe a thin, top layer of material (

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a soil texture, textur ...

and

cement A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel (aggregate) together. Cement m ...

magnesite Magnesite is a mineral with the chemical formula ( magnesium carbonate). Iron, manganese, cobalt, and nickel may occur as admixtures, but only in small amounts. Occurrence Magnesite occurs as veins in and an alteration product of ultramafic ...

or calcium sulphate), poured in situ on top of the structural concrete or insulation, on top of which other finishing materials can be applied, or the structural material can be left bare to achieve a raw effect.

Screed board

US Navy 091022-N-2571C-042 Seabees use a long board to screed wet concrete

In the United States, screeding is the process a person called a concrete finisher performs by cutting off excess wet concrete to bring the top surface of a slab to the proper grade and smoothness. A power concrete screed has a gasoline motor attached, which helps smooth and vibrate concrete as it is flattened. After the concrete is flattened it is smoothed with a concrete float or power trowel. A concrete floor is sometimes called a solid ground floor. A

plasterer A plasterer is a tradesman or tradesperson who works with plaster, such as forming a layer of plaster on an interior wall or plaster decorative moldings on ceilings or walls. The process of creating plasterwork, called plastering, has been ...

also may use a screed to level a wall or ceiling surface in

plasterwork Plasterwork is construction or ornamentation done with plaster, such as a layer of plaster on an interior or exterior wall structure, or plaster decorative moldings on ceilings or walls. This is also sometimes called pargeting. The process of ...

. This sense of screed has been extended to asphalt paving where a free floating screed is part of a machine that spreads the paving material.

Screed rails

A ''weep screed'' or ''sill screed'' is a screed rail which has drainage holes to allow moisture which penetrated an exterior plaster or stucco coating to drain through the screed.

Liquid and flow screeds

Flowing screeds are made from inert fillers such as sand, with a binder system based on

or often calcium sulphate. Flow screeds are often preferred to traditional screeds as they are easier and faster to install and provide a similar finish. Flow screed is often used in combination with underfloor heating installation. Liquid flow screed is self-levelling. No vibration is necessary to remove bubbles and densify the liquid mass. Due to the easy consolidation thickness can sometimes be reduced in comparison to conventional screeds. This minimises heat storage leading to a floor that reacts quickly to user requirement hence raising the efficacy of underfloor heating.

Screed coats

A development in the UK is the delivery, mixing, and pumping of screed from a single vehicle. Where previously screed jobs required a separate pump to administer the screed, these new machines can now administer the screed directly from the mixing pan to the floor at a range of up to 60 meters. For example, the material called granolithic.

References

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