... pillars are made of square tube or double C section steel, purlin is made of section steelRoof, exterior wall and partition wall:Roof ... fittings included.Staircase:Steel stairMain frame is made of “C” section steel 160x70x20x2.5Hand rail is made of square tube 40x40x2 ... 5mmStep board is made of 3mm steel boardPillar is “L” section steel 36x3Assembly material:Nails, glue, bolts, polyurethane, edge cover ...