several extruded aluminum parts hollow extruded aluminum planks 60 are fitted in grooves of front extrusion 62 and rear extrusion 61 larger views of the profiles of 61 and 62 are shown in fig8 planks 60 are stitch welded together 66 and to extrusions 61 and 62 as shown to create a simple rigid lightweight one piece assembly the opposite side not shown of planks 66 are grooved as part of the extrusion process to form a skid resistant surface for outdoor use since there are no weld points on the upper surface it is totally planar a clear anodized finish affords abrasion and corrosion resistance for a quieter surface for indoor use a mat of rubber or industrial carpet material is adhesively bonded to the top surface of the deck module fig1 shows several three seat modules 45 attached to respective floor deck attachment flanges 61 of decks 60 as well as a plurality of upright handrail picket members 74 the unique indoor outdoor seating system of the present invention is one of the most innovative and easily demountable seating systems with vandal resistant hardware this seating system includes a modular structure with easy set up that requires minimal hardware tools and manpower to.