CEILING

the overhead surface or surfaces covering a room, and the underside of a floor or a roof. Ceilings are often used to hide floor and roof construction. They have been favourite places for decoration from the earliest times: either by painting the flat surface, by emphasizing the structural members of roof or floor, or by treating it as a field for an overall pattern of relief. Little is known of ancient Greek ceilings, but Roman ceilings were rich with relief and painting, as is evidenced by the vault soffits of Pompeian baths. During the Gothic period, the general tendency to use structural elements decoratively led to the development of the beamed ceiling, in which large cross-girders support smaller floor beams at right angles to them, beams and girders being richly chamfered and molded and often painted in bright colours. In the Renaissance, ceiling design was developed to its highest pitch of originality and variety. Three types were elaborated. The first was the coffered ceiling, in the complex design of which the Italian Renaissance architects far outdid their Roman prototypes. Circular, square, octagonal, and L-shaped coffers abounded, with their edges richly carved and the field of each coffer decorated with a rosette. The second type consisted of ceilings wholly or partially vaulted, often with arched intersections, with painted bands emphasizing the architectural design and with pictures filling the remainder of the space. The loggia of the Farnesina villa in Rome, decorated by Raphael and Giulio Romano, is a good example of this. In the Baroque period, fantastic figures in heavy relief, scrolls, cartouches, and garlands were also used to decorate ceilings of this type. The Pitti Palace in Florence and many French ceilings in the Louis XIV style illustrate this. In the third type, which was particularly characteristic of Venice, the ceiling became one large framed picture, as in the Doges' Palace. In modern architecture ceilings may be divided into two major classesthe suspended (or hung) ceiling and the exposed ceiling. With ceilings hung at some distance below the structural members, some architects have sought to conceal great amounts of mechanical and electrical equipment, such as electrical conduits, air-conditioning ducts, water pipes, sewage lines, and lighting fixtures. Most suspended ceilings use a lightweight metal grid suspended from the structure by wires or rods to support plasterboard sheets or acoustical tiles. Other architects, emphasizing the aesthetic of the exposed structural system, delight in revealing the mechanical and electrical equipment. In response to this desire, many structural systems have been developed that have an expressive power in themselves and make admirable ceilingse.g., Frank Lloyd Wright's Johnson Wax offices in Racine, Wis., and Pier Luigi Nervi's Exposition Hall in Turin, Italy.