12 CONSTRUCTION MATERIALS, TO WIT: PREFABRICATED METAL BUILDINGS-NAMELY, DWELLING HOUSES, AIRCRAFT HANGARS, GARAGES, SMALL INDUSTRIAL BUILDINGS, WAREHOUSES, TRUCK STORAGE BUILDINGS, TRUCK TERMINAL BUILDINGS, FARM IMPLEMENT STORAGE BUILDINGS AND UNDERGROUND STORAGE BUILDINGS; METAL RETAINING WALLS, SHEET PILING AND TREMIE SHEETING; METAL DOCKS; METAL HIGHWAY GUARD RAILS AND POSTS; PORTABLE METAL TREADWAYS FOR PAVEMENTS AND TEMPORARY ROADWAYS; METAL DOORS; METAL OVERHEAD DOORS; FABRICATED HEAVY DUTY METAL PLATES; METAL TRUSSES; METAL FLOORING, DECKING AND ROOFING; METAL FORMS FOR CONCRETE; SHEET METAL AND PLATE PRODUCTS FABRICATED TO CUSTOMER ORDER FOR USE IN BUILDING AND GENERAL CONSTRUCTION; FORMED STRUCTURAL STEEL SECTIONS-NAMELY, LINTELS, JOISTS, CHANNELS AND SPECIAL ANGLES; WELDED METAL PLATE CONSTRUCTIONS; WELDED METAL STRUCTURAL SECTIONS-NAMELY, CHANNELS, ANGLES, BEAMS, TRUSSES, AND JOISTS FORMED OF METAL PARTS ASSEMBLED TOGETHER AND CONNECTED BY WELDING; METAL WINDOW WELLS AND METALRIDGE ROLLS