Rule 32.9.403 - INTERIOR STRUCTURAL SURFACES(1) The walls, ceilings, partitions, and posts of rooms in which milk or dairy products are processed, manufactured, handled, packaged or stored (except dry storage of packaged finished products and supplies) or in which utensils are washed and stored, must be smoothly finished with a suitable material of light color, which is substantially impervious to moisture. The surfaces must be kept clean. They must be refinished as often as necessary to maintain a neat, clean surface. A wainscoting of a suitable material of a darker color may be used to a height not exceeding 60 inches. For easier cleaning, new construction should have rounded cove at the juncture of the wall and floor in all receiving, pasteurizing, manufacturing, packaging and storage rooms.(2) The floors of all rooms in which milk or dairy products are processed, manufactured, packaged or stored or in which utensils are washed must be constructed of tile properly laid with impervious joint material, concrete, or other equally impervious material. The floors must be smooth, kept in good repair, graded so that there will be no pools of standing water or milk products after flushing. All openings to the drains must be equipped with traps properly constructed and kept in good repair. On new construction bell-type traps may not be used. The plumbing must be so installed as to prevent the backup of sewage into the drain lines and to the floor of the plant. Sound, smooth wood floors which can be kept clean may be used in rooms where new containers and supplies and certain packaged finished products are stored.Secs. 81-2-102, 81-22-102 MCA; IMP, Secs. 81-2-102, 81-22-102 MCA;