(a) Walls including non-supporting partitions, wall covering and ceilings of the walk-in refrigeration units, food preparation areas, equipment and utensil washing areas, toilet rooms and vestibules should be light in color or meet the requirements and approval of the regulatory authority.(b) Darker-colored coverings for the items listed in subsection (a) of this section may require additional lighting, as specified in Food Code, §6-303.11, or meet the requirements set by the regulatory authority, to allow cleaning of the surface.