the jetty breastsummer (or bressummer), the sill on which the projecting wall above rests; the bressummer stretches across the whole width of the jetty wall the dragon-beam which runs diagonally from one corner to another, and supports the corner posts above and is supported in turn by the corner posts below the jetty beams or joists which conform to the greater dimensions of the floor above but rest at right angles on the jetty-plates that conform to the shorter dimensions of the floor below. The jetty beams are morticed at 45° into the sides of the dragon beams. They are the main constituents of the cantilever system and they determine how far the jetty projects the jetty-plates, designed to carry the jetty-beams or joints. The jetty-plate itself is supported by the corner posts of the recessed floor below. Cantilever Jettying was used for timber-framed buildings, but was succeeded by cantilever which are used for the same reason as jettying, to maximise space in buildings. This is often utilised on buildings which are on a narrow plot and space is at a premium. Forebay The Pennsylvania barn in the U.S. has a distinctive cantilever called a forebay, not a jetty. Mediterranean area The traditional Turkish house is a half-timbered house with a cantilevered or supported overhang called a cumba. In the North African Maghreb, houses in medieval city kasbahs often featured jetties. Contemporary examples still survive in the Casbah of Algiers. The House of Opus Craticum, built before AD 79 in Roman Herculaneum, has a supported cantilever. See also Cantilever – modern buildings still use cantilevered floors, but the term jettying is rarely used. See for example 945 Madison Avenue in New York. Machicolation Overhang (architecture) Corbels, brackets that may be under a jetty References Timber framing Architectural elements Medieval architecture fr:Encorbellement