Commercially available topsoil (manufactured or naturally occurring) in the United Kingdom should be classified to British Standard BS 3882 with the current version dated 2015. The standard has several classifications of topsoil with the final classification requiring material to meet certain threshold criteria such as Nutrient Content, Extractable Phytotoxic Elements, Particle Size Distribution, Organic Matter Content, Carbon:Nitrogen ratio, Electrical Conductivity, Loss on Ignition, pH, Chemical and Physical Contamination. The topsoil should be sampled in accordance with the British Standard and European Norm BS EN 12579:2013 Soil improvers and growing media - Sampling. During construction of garden areas for housing plots the topsoil should be underlain by a layer of suitably certified subsoil that conforms to the British Standard BS 8601:2013 Specification for subsoil and requirements for use.