Subclass 2/18: Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels (materials or manufacture, see the relevant places, e.g. B27N, B29, D21J; made in situE04B; specially designed for insulation or other protection E04B 1/62; load-carrying floor structures E04B 5/02, E04B 5/16; roofs consisting of self-supporting slabs E04B 7/2; roof- or like covering elements E04D 3/00; for lining or finishing E04F 13/00) characterised by specified materials (translucent E04C 2/54) of wood, fibres, chips, vegetable stems, or the like; of plastics; of foamed products (E04C 2/26 takes precedence) of fibres, chips, vegetable stems, or the like with binding wires, reinforcing bars, or the like