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the part of a pile foundation (beam or slab) that connects the tops of the piles and acts as a support for the erection of structural elements. Grillage is considered to be high if it is located considerably above the ground or water level (for example, in wharf structures for ports); it is considered low when placed near the ground or deep into it (for example, in the foundations of houses and industrial buildings). The preferred materials for grillage are plain and reinforced concrete (prefabricated or cast-in-place); the use of wood and metal is not common. The word “grillage” derives from previously used supporting structures, which were in the form of a grid of wooden beams on which plank flooring was laid.