Screed: What is it Used For?May 7, 2013
What is Screed?
Effective mixing and application of screed is an important part of the concrete laying process, and understanding exactly how and why it’s used is the only way to create a long-lasting and stable surface.
Fundamentally, screed is a levelling material, usually sand and cement, poured onto a structural concrete foundation layer and flattened to allow for a smooth surface for finishing materials. Wearing screeds are also available, where the screed serves as flooring itself with a visually desirable texture that has been used widely as an architectural feature.
The laying of screed was once a manual job, but has since been automated with the use of specialised screed pump trucks, eradicating the need for a separate pump to administer the materials. The new technology allows for delivery, mixing and pumping from a single vehicle, drastically reducing costs and permitting access to difficult areas, as screed is generally used for internal flooring purposes.
Confusingly, the definition of screed in the US refers to the flat tool used to smooth concrete or plaster, and a number of developments in the manufacture of these products have again led to an industrialisation of the flattening process, with machinery such as power concrete screeds and free floating screeds available.
Standards and Regulations
If not correctly mixed or applied, screed can cause a number of problems, from ‘curling’ (a curling up of the edges of laid screed) to an inefficient ‘crushing resistance’ – the tensile strength of levelling screed when exposed to traffic and heavy loads.
The government has recently introduced changes to building regulations that stipulate that sound privacy between residential dwellings be improved, leading to the development of advanced acoustic screed; a treated material that forms an acoustically resilient layer – particularly necessary between floors in blocks of flats or between new terraced housing.
[The relevant standard that governs the performance suitability of all screed materials, but not the specification of constituent materials, is BS EN 13813, entitled Screed Material and Floor Screeds. Screed material. Properties and Requirements. There are other specifications that cover some areas of screed use, such as BS EN 13318, Screed Material and Floor Screeds – Definitions, as well as specific sections of BS 8204.]
For more information about correct screed usage, or to discuss your screed delivery and mixing needs with a qualified professional, get in touch with the team at Roadmaster Concrete Mixers today.