Steel Structure 50 x50 x 2.5rhs (a suitable load bearing floor is required     Riser board 12mm ply                                                                          Decking 25mm ply                                                                             Curved or straight  rows                                                                          Side cladding                                                                                      Access hatches                                                                                     Steps                                                                                                 Handrails                                                                                               Barriers