At all manufacturing establishments or rebuilding, storage or repair places permitted
in an IU-1 District, all materials and products shall be stored and all manufacturing,
rebuilding, storing or renovating operations shall be carried on entirely within an
enclosed building or confined and completely enclosed within masonry walls not less
than six (6) feet in height; provided the water frontage of shipyards, dry docks,
boat slips, and like uses may be open.