Cladding in construction is the application of one material, wood for example, over another, brick for example, to provide a skin or layer. There is a cavity between the materials so that rain can run down. Cladding is supplied in panels. Cladding panels can be made of many materials including brick, metal wood, concrete or aluminium. The cladding process sees the installation of carrier boards, cladding subframes, insulation and the cladding panels. EWI is also a cladding system – it stands for External Wall Insulation and the main difference is that there is no cavity between the materials.