4271 Natural stone veneer walling (25) Natural stone masonry walling, uncoursed or coursed, with dry or mortar joints, to form veneers of cavity construction, or facework tied to a backing 4272 Natural stone facade walling (40) Thin natural stone of all types, worked to required sizes and finishes and fixed to a backing board 4273 Simulated stone facade walling (0) Thin simulated stone of all types, worked to required sizes and finishes and fixed to a backing board 4274 Simulated stone veneer walling (13) Precast concrete cast simulated stone and reconstructed stone walling with mortar joints to form veneers of cavity construction, or facework tied to a backing