Each council develops its own code for the construction and alteration of premises that sell and supply food and food products. Covering suitable materials for walls, floors, ceilings, windows, doors, openings, servery hatches, service pipes, vermin proofing, and servery bars. Guidelines for the installation of fixtures, fittings, and equipment including refrigerators, freezers, heating appliances, counters, bars, cupboards, cabinets and shelving. Guidelines for washing and other facilities including food conveyors, oyster-opening bays, window displays, butcher shops, staff dressing areas, staff toilets and ventilation.