A weight reduction element (1) for the construction industry, constituted by at least one disposable formwork (2), substantially shaped like a truncated pyramid, which is hollow and has a closed upper surface (4) and a lower opening (6a).
Such element has, at least proximate to the corners (7) that are adjacent to the lower opening (6a) or proximate to the corners (107) of the upper surface (4), engagement means (10, 110) for temporarily stable, and substantially rotatable, interconnection with grip means (11) associated with the free upper end (12) of a foot (8), of a chosen height.
The weight reduction element (1) comprises the foot (8) which has a lower end (23) that is offset with respect to the grip means (11) and to the temporary engagement means (10, 110).