Ceiling is the under covering of a roof, floor, etc., concealing the timbers from the room below; now usually formed of plaster, but formerly most commonly of boarding; also the under surface of the vaulting in vaulted rooms and buildings. During the Middle Ages, the ceilings were generally enriched with gilding and, coloring of the most brilliant kind, traces of which may often still be found in churches, though in a faded and dilapidated condition. Plaster and wood ceilings under roofs are often made flat, as at Peterborough Cathedral and St. Alban's Abbey, both of which are Norman with old-style painting, but they frequently follow the line of the timbers of the roof, which are sometimes arranged so as to give the shape of a barrel- vault, especially in Early English and Decorated work.
In the Perpendicular style they are more common than in any other, and are usually either flat or canted, and divided by ribs into square panels, See RIB.
The ceiling in churches, immediately over the altar, and occasionally also that over the rood loft, is sometimes richly ornamented, while the remainder is plain, as at Ilfracombe, Devon. This custom continued as late as to the time of Charles II.